Production method of multi-conductor flat cable

Abstract

The invention discloses a production method of a multi-conductor flat cable, which is used for solving the production problem of the flat multi-conductor cable by taking polytetrafluoroethylene powder as an insulating layer raw material. The pasty raw material of the insulating layer and the conductor are extruded together, the raw material of the insulating layer is coated on the wire, and the raw material of the insulating layer comprises polytetrafluoroethylene powder and a boosting agent. After the polytetrafluoroethylene is sintered, the polytetrafluoroethylene is adhered to the surfaces of the conductors to form the insulating layers, so that the multi-conductor flat cable is obtained, the insulating layers are not cracked and not whitened, the adhesive force with the conductors is good, the dielectric loss of the insulating layers is lower, the cable conductors are not subjected to core shift, the outer diameter is stable, and the insertion loss of the conductors can reach the level of FEP (Fluorinated Ethylene Propylene) insulated 25AWG conductors under the specification of 26AWG.

Description

Technical Field

[0001] This invention relates to a method for producing flat cables, and more particularly to a method for producing multi-conductor flat cables with polytetrafluoroethylene (PTFE) as the insulation layer. Background Technology

[0002] Cables generally consist of a conductor (cable core), an insulating layer surrounding the conductor, and sometimes an external protective layer. Early cables used single-conductor round wires, but with technological advancements, single-conductor cables could no longer meet the demands of practical industries, leading to the development of multi-conductor coaxial cables and multi-conductor round wire cables. As the number of conductors increases, the diameter of these cables also increases. Multi-conductor flat cables, also known as ribbon cables, multi-wire planar cables, or multi-core flat cables, use multiple (at least two) parallel conductors arranged in the same plane and wrapped with insulating material. As a signal transmission line, they are mainly used in dense wiring scenarios such as spacecraft, computers, and missile systems, and are widely used for interconnecting electronic and electrical equipment.

[0003] Multi-conductor flat cables allow for precise control and isolation of conductors, arranged in parallel, making them a high-quality transmission line. Multi-conductor flat cables are typically manufactured using the following methods: The first method involves individually preparing each conductor using the same method as for single-conductor cables, covering each conductor with an insulation layer, then arranging the insulated conductors side-by-side, and finally applying an additional insulation or protective layer to secure them. This method has very low production efficiency.

[0004] The second method involves melting the insulating material and continuously extruding it along with multiple conductors, as disclosed in patents such as FR2463488A1 and JP2013143290A. The prerequisite for melt extrusion is that the insulating material can melt well and has good flowability.

[0005] Fluorinated polyolefins are a class of good insulating materials and can be used as insulating layers to wrap conductors. Currently, the main type used in the market is tetrafluoroethylene / hexafluoropropylene copolymer (FEP, perfluoroethylene propylene) as cable insulation. FEP particles are dried, melted and plasticized to form a uniform melt, and then continuously extruded through a pipe pile mold to form the cable insulation layer. However, the dielectric loss tangent tgδ of mainstream FEP-insulated cables on the market is too large, especially the dielectric attenuation at high frequencies, which still needs to be improved.

[0006] Among fluorinated materials, polytetrafluoroethylene (PTFE) is a highly crystalline polymer that is prone to fibrosis under shear stress. Furthermore, PTFE has extremely poor flowability. 327°C is the melting point of PTFE; strictly speaking, above this temperature, the crystalline structure of PTFE disappears, transforming into a transparent amorphous gel state. Even in this gel-like melt, its viscosity remains as high as 10 at 360°C.10 -10 11 Pas., it still cannot flow, and it cannot even be melted and extruded at the decomposition temperature. This characteristic determines that polytetrafluoroethylene (PTFE) cannot be molded using general thermoplastic resin melt extrusion methods. Furthermore, PTFE is insoluble in any solvent and cannot be molded using polymer solutions.

[0007] Polytetrafluoroethylene (PTFE) is primarily processed using a combination of molding and sintering methods similar to powder metallurgy. However, for long and thin cables, it is impossible to create such long and thin molds, or to keep the cable in the mold for a period of time to complete the molding process, which is also impractical for cable production lines. Therefore, there are currently no reports on the use of PTFE extrusion to manufacture cables.

[0008] The cable disclosed in CN110277196A combines perfluoroethylene propylene with polytetrafluoroethylene, resulting in excessive insulation material and making it unsuitable for manufacturing multi-conductor flat cables.

[0009] CN102306515A uses "soluble polytetrafluoroethylene" to extrude and prepare the insulation layer. In fact, "soluble polytetrafluoroethylene" is a copolymer containing perfluoropropyl perfluorovinyl ether monomer units, which is too expensive.

[0010] FR2463488A1 uses ethylene-tetrafluoroethylene copolymers and tetrafluoroethylene-propylene copolymers to improve the processability of polytetrafluoroethylene through copolymerization of ethylene or propylene monomers. However, the addition of ethylene and propylene monomers will degrade the material's insulation, dielectric loss, weather resistance, and corrosion resistance.

[0011] FR2552922B1 discloses an insulation material comprising polytetrafluoroethylene (PTFE), an expanding agent, a pore-forming agent, bentonite, and lubricating oil, obtained through cold extrusion. The patent also discloses a water dispersion method for obtaining the PTFE composition. This patent produces coaxial cables. Unlike flat cables, coaxial cables have a single centerline and generally do not exhibit eccentricity. However, flat cables have multiple parallel conductors, and especially when PTFE is difficult to extrude, uneven stress can easily occur during extrusion, leading to conductor deformation and eccentricity. Furthermore, the high moisture content of the raw materials prepared by the water dispersion method can also cause insulation cracking. In addition, when PTFE contains bentonite, lubricating oil, or other components, improper dosage or volatilization control can lead to residual components that affect the physical and chemical properties of PTFE, such as causing insulation cracking. These residual components can also result in incomplete sintering, causing the insulation to turn white and preventing the conductor from bonding to the insulation. Furthermore, if polytetrafluoroethylene (PTFE) undergoes fiberization under shear stress, it can lead to insufficient transverse strength and longitudinal cracking. Moreover, the patent claims that special tools are required for cold extrusion, but it does not disclose any knowledge regarding these "special tools." Summary of the Invention

[0012] This invention provides a method for producing multi-conductor flat cables, using polytetrafluoroethylene powder as the insulation layer material, thereby solving the production problems existing in multi-conductor flat cables.

[0013] The method for producing a multi-conductor flat cable provided by the present invention includes: An extrusion die is provided, comprising a male die and a female die. The male die includes a male die body and a guide pin connecting the male die body. A flat conductor channel is provided inside the male die, penetrating both the male die body and the guide pin. The outer surface of the male die body is an inclined surface, with one end connected to the first end of the guide pin and the other end inclined away from the conductor channel. The female die includes a female die body, which has a cavity connected to the male die body and a guide pin channel. The first end of the cavity is an open end located on the surface of the female die body, and the second end of the cavity is connected to the guide pin channel. The wall of the cavity is an inclined wall, with the inclined wall having the same inclination direction and angle as the inclined surface. The male mold is placed inside the female mold, and the male mold and the female mold are coaxially arranged. A gap is left between the inclined surface and the inclined wall for the insulating layer material to pass through. The guide pin is placed in the guide pin channel, and the gap is connected to the inside of the guide pin. At least two conductors are arranged side by side and do not touch each other, with the center lines of each conductor lying in the same plane; each conductor passes through the conductor channel at the same speed; a paste-like insulating material enters from the gap and enters the guide needle to contact the conductor; after the conductor leaves the conductor channel, the insulating material covers the conductor; the insulating material includes polytetrafluoroethylene powder and a propellant. Then, polytetrafluoroethylene (PTFE) is sintered to adhere it to the surface of the conductor.

[0014] In a preferred embodiment, the conductor has a diameter of 26 AWG.

[0015] In a preferred embodiment, the propellant in the insulating layer material may be kerosene.

[0016] In a preferred embodiment, the propellant content in the insulating layer raw material is 10-30% by weight, more preferably 13-28%, more preferably 15-26%, more preferably 16-25%, more preferably 18-24%, such as 20% or 22%.

[0017] In a preferred embodiment, the particle size of the polytetrafluoroethylene powder is preferably ≤200μm, more preferably 1-200μm, more preferably 5-180μm, more preferably 10-150μm, more preferably 20-130μm, more preferably 30-100μm, such as 50μm, 60μm, 80μm.

[0018] In a preferred embodiment, the polytetrafluoroethylene powder and the propellant in the insulating layer raw material are mixed and stored at 20-50°C (preferably 25-45°C, more preferably 30-40°C) for at least 30 minutes, more preferably at least 45 minutes, more preferably at least 1 hour, more preferably at least 1.5 hours, and more preferably at least 2 hours.

[0019] In a preferred embodiment, the insulating material is pre-compressed before entering the gap, and the bulk density of the pre-compressed insulating material is 1.5-2.5 g / cm³. 3 The preferred concentration is 1.7-2.2 g / cm³. 3 More preferably, it is 1.9-2.0 g / cm³. 3 .

[0020] In a preferred embodiment, the insulating material is located within the gap and the guide pin, and the insulating material is at a first temperature, wherein the first temperature is 19-29°C, more preferably 20-28°C, and even more preferably 23-25°C.

[0021] In a preferred embodiment, the insulating material is placed in the gap and the guide pin. A pushing force is applied to the insulating material to make the insulating material pass through the gap and the guide pin. The direction of the pushing force is towards the extension direction of the guide pin, and the pushing force is preferably 5-50 MPa, more preferably 10-40 MPa, and even more preferably 10-20 MPa.

[0022] In a preferred embodiment, after the insulating material leaves the guide pin, the insulating material is raised to a second temperature, which is preferably 120-200°C, more preferably 140-180°C, such as 150°C, 160°C, 170°C, etc.

[0023] In a preferred embodiment, the insulating layer material is maintained at the second temperature for at least 30 minutes, more preferably at least 1 hour, more preferably at least 1.5 hours, more preferably at least 2 hours, and more preferably at least 2.5 hours.

[0024] In a preferred embodiment, after the insulating layer material is maintained at a second temperature, the insulating layer material is raised to a third temperature, the third temperature being greater than or equal to the melting point of polytetrafluoroethylene in the insulating layer material, more preferably, the third temperature minus the melting point of polytetrafluoroethylene in the insulating layer material is 0-80°C, more preferably 5-70°C, and even more preferably 10-50°C.

[0025] In a preferred embodiment, the insulating material is maintained at a third temperature for at least 60 minutes, preferably at least 80 minutes, more preferably at least 90 minutes, more preferably at least 100 minutes, such as 75-180 minutes, preferably 90-150 minutes, and more preferably 100-120 minutes.

[0026] In a preferred embodiment, the heating rate of the insulating layer raw material to the third temperature is 1-10℃ / min, more preferably 3-8℃ / min, such as 5-7℃ / min.

[0027] More preferably, during the process of raising the insulating layer material to the third temperature, the temperature is first raised to 50°C below the melting point of polytetrafluoroethylene in the insulating layer material (preferably 40°C, more preferably 30°C), and then raised to the third temperature. More preferably, the heating rate of "then raised to the third temperature" is 1-10°C / min, more preferably 3-8°C / min, such as 5-7°C / min.

[0028] In a preferred embodiment, the insulating layer material is heated to a third temperature in an inert gas atmosphere and maintained at the third temperature.

[0029] In a preferred embodiment, after the insulating layer material is maintained at a third temperature, it is lowered to a fourth temperature. The fourth temperature is preferably at least 30°C below the melting point of polytetrafluoroethylene in the insulating layer material, more preferably at least 40°C, and even more preferably at least 50°C.

[0030] In a preferred embodiment, the cooling rate to the fourth temperature is preferably 1-10℃ / min, more preferably 2-8℃ / min, and even more preferably 3-7℃ / min, such as 4℃ / min, 5℃ / min, and 6℃ / min.

[0031] In a preferred embodiment, the insulating layer is allowed to cool naturally after reaching a fourth temperature.

[0032] In a preferred embodiment, the number of guide pins is the same as the number of wires, with each wire using a separate guide pin, and gaps formed between the guide pins.

[0033] In a preferred embodiment, the distance between the inclined surface and the inclined wall, and the distance between the inner wall of the guide needle channel and the outer wall of the guide needle, are each independently 0.1-6 mm, more preferably 0.2-4.5 mm, more preferably 0.3-2 mm, and more preferably 0.5-1 mm.

[0034] In a preferred embodiment, the total length of the slit and the guide pin is preferably at least 10 cm, more preferably at least 20 cm, even more preferably at least 50 cm, such as 0.2-2 m, preferably 0.5-1.5 m, such as 0.8 m, 1 m, 1.2 m.

[0035] In a preferred embodiment, the length ratio of the slit to the guide pin is 1:(2-5), preferably 1:(2.5-4.5), and more preferably 1:(2.5-4).

[0036] In a preferred embodiment, the angle between the inclined surface and the conductor channel is preferably 10-20°, more preferably 12-18°, such as 14°, 15°, or 16°.

[0037] In a preferred embodiment, the center distance between adjacent conductors is preferably 0.05-0.15 mm, more preferably 0.08-0.13 mm, such as 0.1 mm or 1.2 mm.

[0038] In a preferred embodiment, the multi-conductor flat cable has two or more conductors, such as two, three, four or more.

[0039] In a preferred embodiment, all conductors have the same diameter.

[0040] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1) This invention uses polytetrafluoroethylene (PTFE) as the insulation layer to prepare multi-conductor flat cables. The insulation layer does not crack or turn white, has good adhesion to the conductor, and has lower dielectric loss. Under the 26AWG specification, the conductor insertion loss can reach the level of FEP insulation 25AWG conductor.

[0041] 2) The method of preparing multi-conductor flat cable of the present invention results in a cable conductor that is not eccentric and has a stable outer diameter. Attached Figure Description

[0042] The accompanying drawings, which constitute a part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the cross-sectional structure of the multi-conductor flat cable described in this invention; Figure 2 This is a schematic diagram of the mold structure described in this invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0044] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0045] Example 1: Figure 1 This is a schematic diagram of the interface structure of the dual-conductor flat cable prepared according to the present invention. The cable includes two conductors (cores) arranged side by side, and the conductors 1 are wrapped with a polytetrafluoroethylene insulation layer 2. Depending on the needs, other layers, such as a protective layer, can also be wrapped on the outside. These other layers can be prepared by methods such as braiding.

[0046] The method for preparing the dual-conductor flat cable in this embodiment is as follows: Provide extrusion molds, such as Figure 2As shown, the extrusion die includes a male die 11 and a female die 21. The male die 11 includes a male die body 12 and a guide pin 13 connected to the male die body 12. The male die 11 has a flat conductor channel 14 inside, which passes through the male die body 12 and the guide pin 13. The outer surface of the male die body 12 is an inclined surface 15. One end of the inclined surface 15 is connected to the first end of the guide pin 13, and the other end is inclined away from the conductor channel 14. The female die 21 includes a female die body 20. The female die body 20 has a communicating male die body receiving cavity 22 and a guide pin channel 23. The first end of the male die body receiving cavity 22 is an open end, which is located on the surface of the female die body 20. The second end of the male die body receiving cavity 22 is connected through the guide pin channel 23. The wall of the male die body receiving cavity 22 is an inclined wall 24. The inclined wall 24 has the same inclination direction and inclination angle (the angle with the conductor channel) as the inclined surface 15, and the inclination angle is 18°.

[0047] The male mold 11 is placed inside the female mold 12, and the male mold 11 and the female mold 12 are coaxially arranged. A gap is left between the inclined surface 15 and the inclined wall 24 to allow the insulating layer material to pass through. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0048] In this embodiment, the insulating layer material is composed of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with the propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer material is pre-compressed. The density of the pre-compressed insulating layer material is at least 1.8 g / cm³. 3 .

[0049] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material is pushed into the guide pin through a gap under a 10MPa compressive force. The temperature of the insulation material within the gap and guide pin is controlled at 25°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0050] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0051] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0052] Example 2: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0053] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0054] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material is forced into the guide pin through a gap under a 10MPa compressive pressure. The temperature of the insulation material within the gap and guide pin is controlled at 22°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0055] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0056] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0057] Example 3: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0058] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0059] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material is pushed into the guide pin through a gap under a 10MPa compressive pressure. The temperature of the insulation material within the gap and guide pin is controlled at 20°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0060] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0061] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0062] Example 4: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0063] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0064] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material is forced into the guide pin through a gap under a 10MPa compressive pressure. The temperature of the insulation material within the gap and guide pin is controlled at 28°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0065] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0066] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0067] Comparative Example 1: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0068] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0069] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material is forced into the guide pin through a gap under a 10MPa compressive pressure. The temperature of the insulation material within the gap and guide pin is controlled at 31°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0070] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0071] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0072] Comparative Example 2: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0073] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0074] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material is forced into the guide pin through a gap under a 10MPa compressive pressure. The temperature of the insulation material within the gap and guide pin is controlled at 33°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0075] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0076] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0077] Comparative Example 3: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0078] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0079] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material is pushed into the guide pin through a gap under a 10MPa compressive pressure. The temperature of the insulation material within the gap and guide pin is controlled at 16℃. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0080] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0081] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0082] The applicant discovered that polytetrafluoroethylene (PTFE) is a highly crystalline polymer. At temperatures below 19°C, PTFE powder becomes fibrous, thus becoming anisotropic and prone to longitudinal cracking. However, at temperatures above 29°C, PTFE is easily deformed after being extruded from the mold, resulting in internal cracking.

[0083] Comparative Example 4: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0084] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0085] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 25°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0086] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at that temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is directly heated to 350°C and maintained at that temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0087] The cable blank continues to advance under tension, passing through the first cooling zone for natural cooling, resulting in the final cable.

[0088] The applicant discovered that polytetrafluoroethylene has poor thermal conductivity and undergoes significant volume changes at temperatures near its melting point. Therefore, heating and cooling near the melting point (e.g., ±50°C) requires slow heating and cooling rates; otherwise, uneven internal and external temperatures can easily lead to significant internal stress, resulting in cracking of the insulation layer.

[0089] Example 5: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 16°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0090] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0091] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 25°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0092] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0093] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0094] Comparative Example 5: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 21°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0095] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0096] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 25°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0097] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0098] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0099] Comparative Example 6: Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 25°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0100] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0101] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 25°C. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0102] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0103] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0104] When the tilt angle is ≤20°, the extrusion pressure is reduced, resulting in a more stable outer diameter of the billet and the final product, and a smooth surface. When the tilt angle exceeds 20°, the extrusion pressure is too high, and the outer diameter of the PTFE fluctuates due to its resilience.

[0105] Example 6 Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 0.2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0106] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0107] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 22℃. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0108] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0109] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0110] Example 7 Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 4mm, the gap length is 3cm, and the guide pin length is 8cm.

[0111] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0112] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 22℃. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0113] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0114] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0115] Comparative Example 7 Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 0.07mm, the gap length is 3cm, and the guide pin length is 8cm.

[0116] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0117] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 22℃. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0118] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0119] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0120] Comparative Example 8 Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 7mm, the gap length is 3cm, and the guide pin length is 8cm.

[0121] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0122] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 22℃. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0123] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 150°C and maintained at this temperature for 45 minutes. It then passes through the second heating zone, where the insulation material is heated to 280°C, and then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0124] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0125] The gap spacing should be between 0.1-6mm. If the gap is too small, the insulation material will be subjected to excessive shearing, and the macromolecules will become excessively fibrous. The fibrous polymer will squeeze the conductor, resulting in the slender conductor exhibiting off-center core phenomenon. Conversely, if the gap is too large, the flow rate of the insulation material will slow down. Theoretically, this would increase the wrapping pressure of PTFE on the conductor, resulting in a tighter wrapping. However, the applicant found that in this case, the insulation material's pressure resistance is too low, and it cannot be properly pressed onto the conductor. The adhesion force to the conductor is too weak, which easily causes unevenness on the surface of the conductor. Moreover, PTFE cannot fill the area between the conductors well.

[0126] Comparative Example 9 Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°. The gap spacing is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0127] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0128] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 22℃. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0129] Under tension, the cable blank continues to advance, passing through the first heating zone where the insulation material is heated to 280°C. It then enters the third heating zone, where the temperature is increased to 350°C at a rate of 3°C / min and maintained at this temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene (PTFE) to the conductor surface to form the insulation layer.

[0130] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0131] Comparative Example 10 Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°, the gap distance is 2mm, the gap length is 3cm, and the guide pin length is 8cm.

[0132] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0133] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 22℃. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0134] Under tension, the cable blank continues to advance, passing through the first heating zone, where the insulation material is directly heated to 350°C and maintained at that temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene to the conductor surface to form the insulation layer.

[0135] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0136] The applicant discovered that if the insulation material is heated to an excessively high temperature after leaving the mold, the polytetrafluoroethylene will be sintered, and some kerosene will not be able to evaporate. This will not only cause cracking, but also cause oily substances to adhere between the insulation and the inner conductor, resulting in insufficient adhesion or even no adhesion to the conductor.

[0137] In addition, the applicant also found that during the sintering process, the sintering temperature (third temperature) is preferably 0-80°C higher than the melting point of polytetrafluoroethylene in the insulating material. If the sintering temperature is too low, the insulating material may not be fully sintered. At this time, the temperature difference between the inside and outside will cause uneven shrinkage during cooling, resulting in low adhesion to the conductor. If the sintering temperature is too high, the insulating material will become overcooked, i.e., dead glue, which will also lead to a decrease in adhesion to the conductor.

[0138] In addition, the sintering time (third temperature holding time) should be at least 60 minutes. If the billet moves too fast, resulting in insufficient billet residence time, or if the distance between the sintering zones is too short, resulting in insufficient billet residence time, the billet will enter the cooling state before it is fully heated. This will result in the material not being fully burned, leading to a decrease in adhesion to the conductor.

[0139] Comparative Example 11 Referring to Embodiment 1, in this embodiment, the inclination angle between the inclined wall 24 and the inclined surface 15 is 18°, the gap distance is 2mm, the gap length is 3cm, and the guide pin length is 3cm.

[0140] The insulating layer raw material consists of polytetrafluoroethylene (PTFE) powder and kerosene. The PTFE powder has a particle size of 150 μm, and the kerosene content is 15% by weight. After mixing the PTFE powder with a propellant, the mixture is stored at 30°C for at least 30 minutes, and then the insulating layer raw material is pre-compressed. The density of the pre-compressed insulating layer raw material is at least 1.8 g / cm³. 3 .

[0141] At least two 26AWG cable conductors are arranged side-by-side without contacting each other, with their centerlines in the same plane and a center-to-center distance of 0.08mm. Under tension, each conductor passes through the conductor channel at the same speed, maintaining a straight line as much as possible during this process. Simultaneously, a paste-like insulation material passes through the gap and guide pin sequentially under a 10MPa extrusion pressure. The temperature of the insulation material within the gap and guide pin is controlled at 22℃. After the conductors leave the conductor channel, the insulation material coats the conductors, forming the cable blank.

[0142] Under tension, the cable blank continues to advance, passing through the first heating zone, where the insulation material is directly heated to 350°C and maintained at that temperature for 90 minutes. During this process, kerosene evaporates, sintering and adhering polytetrafluoroethylene to the conductor surface to form the insulation layer.

[0143] The cable blank continues to advance under tension, passes through the first cooling zone, and is cooled to 280°C at a rate of 2°C / min, then naturally cooled to obtain the final cable.

[0144] The applicant discovered that if the insulation material is heated to an excessively high temperature after leaving the mold, the polytetrafluoroethylene will be sintered, and some kerosene will not be able to evaporate. This will not only cause cracking, but also cause oily substances to adhere between the insulation and the inner conductor, resulting in insufficient adhesion or even no adhesion to the conductor.

[0145] In addition, the applicant also found that during the sintering process, the sintering temperature (third temperature) is preferably 0-80°C higher than the melting point of polytetrafluoroethylene in the insulating material. If the sintering temperature is too low, the insulating material may not be fully sintered. At this time, the temperature difference between the inside and outside will cause uneven shrinkage during cooling, resulting in low adhesion to the conductor. If the sintering temperature is too high, the insulating material will become overcooked, i.e., dead glue, which will also lead to a decrease in adhesion to the conductor.

[0146] In addition, the sintering time (third temperature holding time) should be at least 60 minutes. If the billet moves too fast, resulting in insufficient billet residence time, or if the distance between the sintering zones is too short, resulting in insufficient billet residence time, the billet will enter the cooling state before it is fully heated. This will result in the material not being fully burned, leading to a decrease in adhesion to the conductor.

[0147] A gap-to-guide pin length ratio of 1:(2-5) is preferred, as this range ensures stability of the insulation outer diameter and a smooth surface. If the guide pin is too long, the kerosene will not easily evaporate; however, if the guide pin is too short, the polymer will be unstable, leading to significant fluctuations in the outer diameter.

[0148] Comparative Example 11 Referring to Example 1, in this example, FEP (perfluoroethylene propylene) is heated and melted as the raw material for the insulation layer, and co-extruded with a 26AWG conductor using the CN110277196A method.

[0149] Comparative Example 12 Referring to Example 1, in this example, FEP (perfluoroethylene propylene) is heated and melted as the raw material for the insulation layer, and co-extruded with a 25AWG conductor using the CN110277196A method.

[0150] Table 1. Comparison of cable performance between Example 1 and Comparative Examples 11-12 Example 1 Comparative Example 11 Comparative Example 12 length 100 meters 100 meters 100 meters Conductor material copper copper copper frequency 53GHz 53GHz 53GHz Insertion loss 11.7dB 15.1dB 12.2dB Compared with FEP as the insulating layer, the present invention uses 26AWG specification, which can achieve insertion loss of 25AWG specification (in AWG specification, the smaller the number, the larger the diameter), significantly improving dielectric attenuation at high frequencies.

[0151] The specific embodiments of the present invention have been described in detail above, but they are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A method for producing a multi-conductor flat cable, characterized in that, include: An extrusion die is provided, comprising a male die and a female die. The male die includes a male die body and a guide pin connecting the male die body. A flat conductor channel is provided inside the male die, penetrating both the male die body and the guide pin. The outer surface of the male die body is an inclined surface, with one end connected to the first end of the guide pin and the other end inclined away from the conductor channel. The female die includes a female die body, which has a cavity connected to the male die body and a guide pin channel. The first end of the cavity is an open end located on the surface of the female die body, and the second end of the cavity is connected to the guide pin channel. The wall of the cavity is an inclined wall, with the inclined wall having the same inclination direction and angle as the inclined surface. The male mold is placed inside the female mold, and the male mold and the female mold are coaxially arranged. A gap is left between the inclined surface and the inclined wall for the insulating layer material to pass through. The guide pin is placed in the guide pin channel, and the gap is connected to the inside of the guide pin. At least two conductors are arranged side by side and do not touch each other, with the center lines of each conductor lying in the same plane; each conductor passes through the conductor channel at the same speed; a paste-like insulating material enters from the first gap and enters the guide needle to contact the conductor; after the conductor leaves the conductor channel, the insulating material covers the conductor; the insulating material includes polytetrafluoroethylene powder and a propellant. Then, polytetrafluoroethylene (PTFE) is sintered to adhere it to the conductor surface.

2. The method for producing multi-conductor flat cables according to claim 1, characterized in that, The polytetrafluoroethylene powder has a particle size of ≤200μm; the propellant content in the insulating layer raw material is 10-30% by weight.

3. The method for producing multi-conductor flat cables according to claim 1, characterized in that, In the raw materials of the insulating layer, the propellant is kerosene.

4. The method for producing multi-conductor flat cables according to claim 1, characterized in that, In the insulating layer material, polytetrafluoroethylene powder is mixed with a propellant and stored at 20-50°C for at least 30 minutes; and / or the insulating layer material is pre-compressed before entering the gap, and the bulk density of the pre-compressed insulating layer material is 1.5-2.5 g / cm³. 3 .

5. The method for producing a multi-conductor flat cable according to claim 1, characterized in that, The insulating material is located within the gap and the guide pin, and the temperature of the insulating material is 19-29°C; and / or The insulating material is placed in the gap, and a pushing force is applied to the insulating material to make it pass through the gap. The direction of the pushing force is towards the extension direction of the guide needle, and the pushing force is 5-50 MPa.

6. The method for producing a multi-conductor flat cable according to claim 1, characterized in that, After the insulating material leaves the guide needle, the insulating material is raised to a second temperature of 120-200°C and maintained at the second temperature for at least 30 minutes. After the insulating material is maintained at the second temperature, the insulating material is raised to the third temperature, the third temperature is greater than or equal to the melting point of polytetrafluoroethylene in the insulating material, and is maintained at the third temperature for at least 60 minutes. After the insulating material is maintained at a third temperature, it is lowered to a fourth temperature, which is at least 30°C below the melting point of polytetrafluoroethylene in the insulating material.

7. The method for producing a multi-conductor flat cable according to claim 6, characterized in that, During the process of raising the insulating layer material to the third temperature, the temperature first rises to 50°C below the melting point of polytetrafluoroethylene in the insulating layer material, and then rises to the third temperature; the heating rate of "then rises to the third temperature" is 1-10°C / min. The cooling rate to the fourth temperature is 1-10℃ / min.

8. The method for producing a multi-conductor flat cable according to claim 1, characterized in that, The distance between the inclined surface and the inclined wall, and the distance between the inner wall of the guide pin channel and the outer wall of the guide pin, are each 0.1-6mm; the total length of the two gaps and the guide pin is at least 10cm; the length ratio of the gaps to the guide pin is 1:(2-5); and the angle between the inclined surface and the conductor channel is 10-20°.

9. The method for producing a multi-conductor flat cable according to claim 1, characterized in that, In the multi-conductor flat cable, all conductors have the same diameter.

10. The method for producing a multi-conductor flat cable according to claim 1 or 9, characterized in that, The center distance between adjacent conductors is preferably 0.05-0.15 mm.

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