Waterproof conductor airtight wire and preparation method thereof

Abstract

The invention relates to the technical field of cable conductors, in particular to a waterproof conductor air-tightness-resistant conductor and a preparation method thereof.The waterproof conductor air-tightness-resistant conductor comprises a conductor, and the conductor is formed by jointly twisting a plurality of metal wires and at least one high-strength fiber yarn; the waterproof glue layer is formed by TPU (Thermoplastic Polyurethane) hot melt glue and is directly coated on the outer surface of the conductor; the insulating layer is made of irradiation cross-linked polyethylene and is coated on the periphery of the waterproof glue layer; the invention aims to provide a novel wire structure which can fundamentally improve adhesion sealing performance from a conductor interface and is suitable for efficient and continuous production and a preparation method.

Description

Technical Field

[0001] This invention relates to the field of cable conductor technology, specifically to a waterproof conductor with airtightness and its preparation method. Background Technology

[0002] With the rapid development of fields such as electronics, automobiles, medical devices, and outdoor security, higher requirements have been placed on the waterproof, moisture-proof, airtight, and long-term reliability of wires and cables used in key components.

[0003] Currently, common methods in the industry to improve the waterproof performance of wires can be mainly divided into two categories:

[0004] One method is end-sealing, which involves locally sealing the ends of the conductor or connector by injecting sealants such as silicone or epoxy resin. While this method can prevent moisture from entering from the ends to some extent, it has significant limitations: 1. It only protects the ends of the conductor and is ineffective against water seepage caused by micro-cracks or pinholes in the conductor body; 2. The bonding interface between the sealant and the conductor insulation layer is prone to peeling under thermal cycling or mechanical vibration, posing a risk of seal failure; 3. The process is time-consuming, relies on manual operation, is difficult to automate and achieve efficient production, and the curing time of the adhesive significantly affects the production cycle.

[0005] The second method is the overall encapsulation process, which involves extruding a layer of waterproof material (such as polyurethane or rubber) around the conductor or core as an isolation layer. While this method provides overall protection, it still has the following drawbacks: 1. The extruded thermoplastic or thermosetting material has high viscosity in the molten state, making it difficult to completely fill the microscopic gaps created by the conductor stranding. Tiny pores are easily left at the interface, becoming channels for water vapor penetration; 2. Due to the smooth surface of the conductor and the significant difference in physicochemical properties between it and the waterproof material, the bond strength between the two is usually low. Under stress during subsequent processing or use, the interface is prone to separation, leading to a sharp decline in waterproof performance.

[0006] In summary, existing waterproof conductors and their manufacturing methods generally suffer from problems such as low bonding strength between the waterproof layer and the conductor interface, incomplete microscopic sealing, low production efficiency, or poor consistency, making it difficult to meet the demand for highly reliable and long-life waterproof conductors. Therefore, there is an urgent need for a novel conductor structure and preparation method that can fundamentally improve adhesion and sealing at the conductor interface and is suitable for efficient continuous production. Summary of the Invention

[0007] Technical problems to be solved To address the aforementioned shortcomings of existing technologies, this invention provides a waterproof conductor with airtightness, aiming to provide a conductor structure and preparation method that achieves overall waterproofing from the conductor level, is simple in process, and has high reliability.

[0008] Technical solution To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a waterproof and airtight conductor, comprising a conductor, the conductor being formed by twisting together multiple metal wires and at least one high-strength fiber filament; a waterproof adhesive layer, the waterproof adhesive layer being composed of TPU hot melt adhesive and directly covering the outer surface of the conductor; and an insulating layer, the insulating layer being composed of irradiated cross-linked polyethylene and covering the outer periphery of the waterproof adhesive layer.

[0009] Another aspect of the present invention provides a method for preparing a waterproof conductor with airtightness, characterized by comprising the following steps: S1: Conductor stranding, which involves stranding multiple metal wires together with at least one high-strength fiber filament to form a composite conductor; S2: Preheating treatment, preheating the composite conductor to 60-80℃; S3: Coating and molding, the preheated conductor is passed through a coating mold containing molten TPU hot melt adhesive to form a continuous waterproof adhesive layer on the outer surface of the conductor; S4: Cooling and shaping, gradient cooling of the conductor with the molten waterproof adhesive layer; S5: Insulation coating, a polyethylene layer is extruded over the shaped waterproof adhesive layer and then subjected to irradiation cross-linking treatment to form an insulation layer.

[0010] In the early stage of cooling and molding, a force control module is used to apply a uniform radial constraint force to the outer surface of the conductor covered with a waterproof adhesive layer.

[0011] Furthermore, the twisting pitch of the metal wire and the high-strength fiber filament in the conductor is 8-12 times the conductor diameter.

[0012] Furthermore, the high-strength fiber filament is aramid fiber or polyester fiber.

[0013] Furthermore, the thickness of the waterproof adhesive layer is 0.05-0.3 mm; the melt index of the TPU hot melt adhesive at 190°C is 15-45 g / 10 min.

[0014] Furthermore, in step S4, the gradient cooling sequentially includes an air cooling stage, a water mist cooling stage, and a room temperature air drying stage, wherein a uniform radial constraint force is applied to the outer surface of the conductor at the end of the air cooling stage. The air cooling stage reduces the conductor temperature to 80-100℃; the water mist cooling stage uses fine water mist particles to further reduce the conductor temperature to 40-60℃; the room temperature air drying stage removes residual trace moisture from the surface of the conductor and uniformly reduces the overall temperature of the conductor to room temperature, completing the final shaping.

[0015] Furthermore, the radial constraint force applied by the tension control module is used to compensate for the volume shrinkage of the waterproof adhesive layer during the cooling process, so as to prevent it from peeling off from the conductor surface.

[0016] Furthermore, the radial constraint force is controlled to make the radial pressure on the conductor equivalent to an axial tensile force of 2-5 N.

[0017] Furthermore, in step S3, the coating mold is provided with a flow channel that allows the adhesive to spiral forward along the conductor axis, and the spirally moving adhesive wraps around the conductor passing through in a three-dimensional manner from all sides.

[0018] Furthermore, the spiral angle of the flow channel is 15°-30°, and a smooth cylindrical channel is provided at the end of the spiral flow channel. The cylindrical channel is used to finally calibrate the outer diameter of the adhesive layer and make it flow out smoothly.

[0019] Beneficial effects The technical solution provided by this invention has the following advantages compared with known public technologies: This solution utilizes a synergistic process of "fiber-reinforced tightly stranded conductor" and "preheat coating + tension cooling" to manufacture the product's conductor. It abandons the traditional "patchwork" end-sealing approach, creatively constructing a continuous, dense, and highly adhesive TPU hot melt waterproof layer directly on the conductor's outer surface. This layer completely encapsulates the conductor from the structural source, fundamentally blocking any path of moisture or gas penetration along the conductor's axial and radial directions, achieving inherent waterproofing. Even if the product's conductor is arbitrarily cut, the cut end remains tightly protected by the waterproof adhesive layer, and its waterproof performance is unaffected. This overcomes the inherent defects of traditional methods, such as incomplete protection and reliance on specific installation techniques. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the cross-section of the conductor of the present invention; Figure 2 This is a perspective view of each tissue layer of the wire of the present invention; Figure 3 This is a flowchart of the wire fabrication process of the present invention.

[0022] The labels in the diagram represent: 10, conductor; 11, metal wire; 12, fiber filament; 20, waterproof adhesive layer; 30, insulation layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0024] The present invention will be further described below with reference to embodiments.

[0025] Example: This invention provides a waterproof conductor with airtightness, referring to... Figure 1-2 It includes a conductor, which is made of multiple metal wires and at least one high-strength fiber filament twisted together; wherein the twisting pitch of the metal wires and the high-strength fiber filament in the conductor is 8-12 times the diameter of the conductor.

[0026] The waterproof adhesive layer is composed of TPU hot melt adhesive and directly and completely covers the outer surface of conductor 1. TPU material with a melt index of 30 g / 10 min is selected, and through subsequent process control, the resulting waterproof adhesive layer has a uniform thickness of approximately 0.12 mm. It also includes an outer protective insulating layer, which is composed of irradiated cross-linked polyethylene and covers the outer periphery of the waterproof adhesive layer, with a thickness of approximately 0.35 mm, providing excellent electrical insulation, heat resistance, and mechanical protection.

[0027] Specifically, the ratio of the stranding pitch (P) of the metal wire and the high-strength fiber filament to the calculated outer diameter (D) of the stranded conductor, i.e., the pitch ratio (m = P / D), is limited to between 8 and 12. This is a tight, small-pitch stranding design that forms a dense substrate with a tightly flat conductor surface, providing a uniform and solid base for the adhesion of the TPU adhesive layer.

[0028] In this embodiment, the conductor is composed of 24 tin-plated copper wires with a diameter of 0.08 mm and one 1140 Dtex aramid fiber filament twisted together. The twisting employs a small pitch design; the calculated outer diameter of the conductor after twisting is approximately 1.50 mm, and the actual controlled twisting pitch is 15.0 mm. This pitch perfectly complements the addition of the high-strength fiber filament. The fiber filament is uniformly wrapped during twisting, and its high strength properties are effectively utilized in this tight structure, jointly resisting cooling tension and various stresses during use, preventing conductor breakage or deformation.

[0029] Reference Figure 3Another aspect of the present invention provides a method for preparing a waterproof conductor with airtightness, comprising the following steps: S1: Conductor stranding, which involves stranding multiple metal wires together with at least one high-strength fiber filament to form a composite conductor; the above 24 tin-plated copper wires and 1 aramid fiber filament are stranded together using a tubular stranding machine, and the stranding pitch is stabilized at 15.0 mm by precisely controlling the traction speed and the speed of the winch, thus forming a dense composite conductor.

[0030] S2: Preheating treatment, preheating the composite conductor to 60-80℃, passing the stranded composite conductor through an infrared preheating device, preferably with the median value of 70℃ as the preheating value; S3: Coating and Molding. The preheated conductor is passed through a coating mold containing molten TPU hot melt adhesive, forming a continuous waterproof adhesive layer on the conductor's outer surface. Specifically, the preheated conductor is vertically pulled through a dedicated coating mold. The mold contains TPU hot melt adhesive that has been heated and maintained at 175°C. Inside the mold is a spiral flow channel with a spiral angle of 20°. Driven by pressure, the molten adhesive advances along the spiral flow channel, forming a swirling flow that comprehensively and evenly coats the conductor passing through in a straight line, ensuring uniform coating. The adhesive finally flows out through a smooth cylindrical sizing channel at the end of the flow channel, forming a continuous adhesive layer approximately 0.12 mm thick.

[0031] S4: Cooling and shaping, gradient cooling of the conductor with the molten waterproof adhesive layer.

[0032] S5: Insulation coating. A polyethylene layer is extruded over the shaped waterproof adhesive layer and then subjected to radiation cross-linking treatment to form an insulation layer. The cooled and shaped wire is fed into an extruder, and a layer of polyethylene is extruded over the waterproof adhesive layer. Then, it is treated by electron irradiation cross-linking equipment to form a stable radiation cross-linked polyethylene insulation layer, thus obtaining the finished wire.

[0033] In the initial cooling and molding stage, a force control module applies a uniform radial constraint force to the conductor coated with a waterproof adhesive layer. This radial (i.e., from all sides) uniform and gentle constraint force is applied to the waterproof adhesive layer, which is still in a semi-molten state. Its function is to counteract and compensate for the volume shrinkage that occurs when the TPU adhesive layer cools from a molten state to a solid state.

[0034] Detailed process implementation instructions: In step S4, the gradient cooling sequentially includes an air cooling stage, a water mist cooling stage, and a room temperature air drying stage. At the end of the air cooling stage, a uniform radial constraint force is applied to the outer surface of the waterproof adhesive layer, so that the peel strength between the final formed waterproof adhesive layer and the conductor surface is not less than 15 N / cm.

[0035] In the air-cooling stage S41, the adhesive layer, which has just emerged from the mold and is in a high-temperature plastic state, undergoes preliminary cooling and surface shaping. Simultaneously, radial constraint forces are applied to actively counteract the shrinkage stress generated by cooling, preventing initial separation between the adhesive layer and the conductor interface. In the specific process, the coated conductor enters a forced-air-cooling tunnel, designed to be 2-4 meters long, with evenly distributed circumferential air outlets inside. The cooling medium is filtered and dehumidified ambient air at room temperature, with the air velocity at the outlets controlled at 3-5 m / s. The airflow direction is at a certain angle to the conductor axis to create turbulence and enhance heat transfer uniformity. The conductor surface temperature drops from the coating temperature to 80-100℃ within 1-2 minutes, at which point a stable "skin" forms on the TPU adhesive layer surface.

[0036] At the end of this stage, a radial tension control module is installed. This module consists of a set of circumferentially evenly arranged, independently adjustable pressure rollers or flexible bushings. Their inner diameter is slightly smaller than the current conductor's outer diameter, forming an interference fit of approximately 0.1-0.3 mm. This module applies uniform, gentle radial pressure to the conductor, with the force effectively controlled to generate an axial tensile resistance of 2-5 N. This pressure continues throughout the air-cooling stage, ensuring that the adhesive layer remains constrained and tightly adhered to the conductor during the critical transition from the molten state to the glassy state.

[0037] In the water mist cooling stage S42, the wire enters the water mist cooling chamber, which is filled with fine water mist with a particle diameter of ≤40μm generated by an ultrasonic atomizer. Within about 60 seconds, the temperature of the wire is further reduced to about 50°C, completing the rapid and deep curing of the TPU adhesive layer.

[0038] In the S43 stage of ambient temperature drying, residual trace moisture on the surface of the conductor is removed, and the overall temperature of the conductor is uniformly and slowly reduced to room temperature to complete the final shaping and eliminate internal residual stress. Finally, the conductor passes through a 2-meter-long ambient temperature drying tunnel, which is filled with low-speed, constant-temperature circulating air. The tunnel mainly utilizes convection heat transfer to balance the conductor temperature to room temperature and ensure that the surface is completely dry, providing a clean and dry substrate for subsequent insulation extrusion.

[0039] The precise coordination of the above three stages enables full control over the cooling process of the TPU adhesive layer. The design of the entire cooling process is the key guarantee for achieving the outstanding effect of a peel strength of not less than 15 N / cm between the waterproof adhesive layer and the conductor surface.

[0040] In step S3, to achieve uniform, dense, and bubble-free coating of TPU hot melt adhesive on the conductor surface, this invention designs a dedicated coating mold. The core feature of this mold is its internal flow channel that allows the adhesive to spiral forward along the conductor's axial direction. Preferably, the spiral angle of the flow channel is 15°-30°. Molten TPU hot melt adhesive is injected from the inlet under pressure (0.2-0.5 MPa) and immediately enters the spiral groove. Driven by pressure, the adhesive does not move in a straight line but is forced to move along a spiral path. The spirally moving adhesive continuously overflows from all sides through micropores on the flow channel wall or directly from the end of the spiral groove, achieving a three-dimensional, vortex-like coating of the conductor passing in a straight line, effectively avoiding "adhesive accumulation" or "coating blind spots" caused by gravity or uneven flow. Finally, a smooth cylindrical channel is provided at the end of the spiral flow channel. The cylindrical channel is used for final calibration of the adhesive layer's outer diameter and to ensure its smooth flow.

[0041] This solution utilizes a synergistic process of "fiber-reinforced tightly stranded conductor" and "preheat coating + tension cooling" to manufacture the product's conductor. It abandons the traditional "patchwork" end-sealing approach, creatively constructing a continuous, dense, and highly adhesive TPU hot melt waterproof layer directly on the conductor's outer surface. This layer completely encapsulates the conductor from the structural source, fundamentally blocking any path of moisture or gas penetration along the conductor's axial and radial directions, achieving inherent waterproofing. Even if the product's conductor is arbitrarily cut, the cut end remains tightly protected by the waterproof adhesive layer, and its waterproof performance is unaffected. This overcomes the inherent defects of traditional methods, such as incomplete protection and reliance on specific installation techniques.

[0042] The conductors prepared in the examples were subjected to performance tests. The peel strength between the waterproof adhesive layer and the conductor was tested according to relevant standards, and the results were all greater than 17 N / cm, far exceeding that of products made using traditional processes (typically <10 N / cm). The conductors also exhibited good flexibility and resistance to environmental aging, fully verifying the beneficial effects of the technical solution defined in the claims of this invention.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A waterproof conductor gas-tight wire, characterized by, include: A conductor, wherein the conductor is formed by twisting together multiple metal wires and at least one fiber filament; A waterproof adhesive layer, which is composed of TPU hot melt adhesive and is directly coated on the outer surface of the conductor; An insulating layer, which is composed of irradiated cross-linked polyethylene and covers the outer periphery of the waterproof adhesive layer.

2. The waterproof conductor gas-tight wire according to claim 1, wherein The twist pitch of the metal wire and high-strength fiber in the conductor is 8-12 times the conductor diameter.

3. The waterproof conductor gas-tight wire according to claim 1 or 2, characterized by, The high-strength fiber filament is aramid fiber or polyester fiber.

4. The waterproof conductor with airtightness according to claim 1, characterized in that, The thickness of the waterproof adhesive layer is 0.05-0.3 mm; the melt index of the TPU hot melt adhesive at 190℃ is 15-45 g / 10 min.

5. A method for preparing a waterproof conductor with airtightness, characterized in that, Includes the following steps: S1: Conductor stranding, which involves stranding multiple metal wires together with at least one high-strength fiber filament to form a composite conductor; S2: Preheating treatment, preheating the composite conductor to 60-80℃; S3: Coating and molding, the preheated conductor is passed through a coating mold containing molten TPU hot melt adhesive to form a continuous waterproof adhesive layer on the outer surface of the conductor; S4: Cooling and shaping, gradient cooling of the conductor with the molten waterproof adhesive layer; S5: Insulation coating, a polyethylene layer is extruded over the shaped waterproof adhesive layer and then subjected to irradiation cross-linking treatment to form an insulation layer; In the early stage of cooling and molding, a force control module is used to apply a uniform radial constraint force to the outer surface of the waterproof adhesive layer on the conductor covered with the waterproof adhesive layer.

6. The preparation method according to claim 5, characterized in that, In step S4, the gradient cooling sequentially includes an air cooling stage, a water mist cooling stage, and a room temperature air drying stage, wherein a uniform radial constraint force is applied to the outer surface of the conductor at the end of the air cooling stage. The air cooling stage reduces the conductor temperature to 80-100℃; the water mist cooling stage uses fine water mist particles to further reduce the conductor temperature to 40-60℃; the room temperature air drying stage removes residual trace moisture from the surface of the conductor and uniformly reduces the overall temperature of the conductor to room temperature, completing the final shaping.

7. The preparation method according to claim 5, characterized in that, The radial constraint force applied by the tension control module is used to compensate for the volume shrinkage of the waterproof adhesive layer during the cooling process, so as to prevent it from peeling off from the conductor surface.

8. The preparation method according to claim 7, characterized in that, The radial constraint force is controlled such that the radial pressure on the conductor is equivalent to an axial tensile force of 2-5 N.

9. The preparation method according to claim 5, characterized in that, In step S3, the coating mold is provided with a flow channel that allows the adhesive to spiral forward along the conductor axis, and the spirally moving adhesive wraps around the conductor passing through in a three-dimensional manner from all sides.

10. The preparation method according to claim 9, characterized in that, The spiral angle of the flow channel is 15°-30°, and a smooth cylindrical channel is provided at the end of the spiral flow channel. The cylindrical channel is used to finally calibrate the outer diameter of the adhesive layer and make it flow out smoothly.

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