Thermal and freeze protection cable

Abstract

The present application relates to cable manufacturing technical field, disclose a kind of heat preservation anti-freezing cable, cable includes conductor, insulating layer and double-layer co-extrusion functional sheath covered in the outer side of insulating layer, the sheath is composed of cold-resistant stable layer and water gate layer sequentially arranged;Cold-resistant stable layer adds nano silicon nitride dispersion liquid, water gate layer adds polytetrafluoroethylene micro powder, both form the double protection system of physical barrier and structural support, strengthen interlayer adhesion, reduce interlayer gap, block moisture invasion path.Its preparation method includes raw material pretreatment, conductor cleaning and drying, insulating layer extrusion, plasma activation, double-layer co-extrusion and finished product drying step.The present application solves the problem that the existing cable multilayer sheath is easy to cause frost heaving cracking due to moisture penetration, the anti-frost heaving damage capacity is significantly improved, applicable to high-cold high-humidity environment, guarantee power transmission stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable manufacturing, in particular to a heat preservation anti-freezing cable. BACKGROUND

[0002] Cables are the core carriers in power transmission systems, usually composed of conductors, insulation layers, sheaths and other structures, and are widely used in industrial production, urban construction, power supply in remote areas and other fields. The stability of the cable is directly related to the safety and continuity of power transmission. In harsh environments such as high cold and high humidity, low temperature can cause the sheath and insulation layer materials of the cable to become brittle, and moisture in the environment is easy to adhere to the surface of the cable or penetrate into the structure. Under low temperature conditions, the volume of water ice expands, which can cause extrusion stress on the cable sheath, leading to sheath cracking, interlayer peeling and other problems. In severe cases, it can damage the insulation performance and cause power transmission to be interrupted. Therefore, heat preservation and anti-freezing treatment of the cable is the key to ensuring its reliable operation in low temperature and humid environments.

[0003] At present, the industry mainly adds cold-resistant additives to the cable sheath material to improve the low temperature resistance of the material itself, or uses a multi-layer composite sheath structure to enhance the protection effect and reduce the impact of low temperature on the cable. However, in use, the interface adhesion between the layers of the multi-layer sheath structure is insufficient, and small interlayer gaps are easily formed during the forming process. These gaps become a channel for water to penetrate, making it difficult to effectively block the invasion path of water into the cable. When the water in the gap expands, it will further exacerbate the interlayer peeling and sheath cracking, making it difficult for the cable to meet the use requirements in high-cold and high-humidity environments. SUMMARY

[0004] The present application provides a heat preservation anti-freezing cable, which solves the problem of insufficient interface adhesion between the layers of the multi-layer sheath structure, which makes it difficult to effectively block the invasion path of water into the cable, resulting in the difficulty of the cable to meet the use requirements in high-cold and high-humidity environments.

[0005] To achieve the above purpose, the present application is implemented by the following technical scheme: a heat preservation anti-freezing cable, comprising a conductor, an insulation layer and a double-layer co-extrusion functional sheath wrapped outside the insulation layer, the double-layer co-extrusion functional sheath comprising a cold-resistant stabilizing layer and a water-stopping layer arranged in sequence, the cold-resistant stabilizing layer being composed of the following raw materials by weight: linear low density polyethylene 30-70 parts, ethylene-octene copolymer 20-60 parts, maleic anhydride grafted polyethylene 2-8 parts, stearyl methacrylate 4-16 parts, dicumyl peroxide 0.08-0.30 parts, hindered phenol antioxidant AO-1010 0.10-0.40 parts, phosphite antioxidant AO-168 0.10-0.40 parts, and nano silicon nitride dispersion liquid 0.5-2 parts.

[0006] The water stop layer is composed of the following raw materials by weight parts: linear low density polyethylene 35-75 parts, ethylene-octene copolymer 10-45 parts, maleic anhydride grafted polyethylene 1-6 parts, vinyl trimethoxysilane 2-10 parts, polyethylene glycol methyl ether methacrylate 2-10 parts, zinc neodecanoate 0.02-0.20 parts, dicumyl peroxide 0.06-0.25 parts, hindered phenol antioxidant AO-1010 0.10-0.40 parts, phosphite antioxidant AO-168 0.10-0.40 parts, polytetrafluoroethylene micro powder 1-3 parts.

[0007] By adopting the technical scheme, the heat-preservation anti-freezing cable comprises a conductor, an insulation layer and a double-layer co-extrusion functional sheath covering the outer side of the insulation layer, the double-layer co-extrusion functional sheath comprises a cold-resistant stable layer and a water stop layer arranged in sequence, the cold-resistant stable layer is composed of linear low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, stearyl methacrylate, dicumyl peroxide, hindered phenolic antioxidant AO-1010, phosphite antioxidant AO-168 and nano silicon nitride dispersion liquid, the linear low-density polyethylene and the ethylene-octene copolymer constitute a basic matrix of the cold-resistant stable layer, the maleic anhydride grafted polyethylene improves the compatibility of the linear low-density polyethylene and the ethylene-octene copolymer, ensures uniform dispersion of each component of the matrix, the stearyl methacrylate is combined with the matrix to improve the cold resistance of the cold-resistant stable layer, the dicumyl peroxide acts as a crosslinking agent to promote crosslinking reaction of the matrix and improve the structural strength of the cold-resistant stable layer, the hindered phenolic antioxidant AO-1010 and the phosphite antioxidant AO-168 synergistically inhibit oxidative degradation of the cold-resistant stable layer during long-term use, the nano silicon nitride dispersion liquid is distributed in the matrix to hinder heat transfer by low thermal conductivity and to form structural support by filling the internal gaps of the matrix to hinder the migration of ethylene-octene copolymer, stearyl methacrylate and other cold-resistant additives in a low-temperature environment and reduce additive precipitation; the water stop layer is composed of linear low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, vinyl trimethoxysilane, polyethylene glycol methyl ether methacrylate, zinc neodecanoate, dicumyl peroxide, hindered phenolic antioxidant AO-1010, phosphite antioxidant AO-168 and polytetrafluoroethylene powder, the linear low-density polyethylene and the ethylene-octene copolymer constitute a basic matrix of the water stop layer, the maleic anhydride grafted polyethylene improves the compatibility of each component of the matrix, the vinyl trimethoxysilane and the polyethylene glycol methyl ether methacrylate participate in the crosslinking reaction of the matrix to improve the structural density of the water stop layer, the zinc neodecanoate acts as a crosslinking accelerator to speed up the crosslinking reaction process, the dicumyl peroxide promotes crosslinking of the matrix to improve the structural strength of the water stop layer, the hindered phenolic antioxidant AO-1010 and the phosphite antioxidant AO-168 inhibit oxidative degradation of the water stop layer, the polytetrafluoroethylene powder is uniformly dispersed in the matrix to fill the small gaps of the matrix, form a physical barrier and reduce the path of water infiltration through the gaps, and limit the migration channel of cold-resistant additive molecules.The cold-resistant stabilizing layer and the water-stopping layer are closely attached through a double-layer co-extrusion process, the cold-resistant stabilizing layer provides structural support for the water-stopping layer, the water-stopping layer blocks the moisture from contacting the cold-resistant stabilizing layer, and the two layers work together to block the invasion path of moisture to the cold-resistant stabilizing layer, avoid the destruction of the sheath structure caused by the penetration of moisture and low-temperature frost heaving, inhibit the low-temperature migration and precipitation of the cold-resistant additive, ensure the structural stability and cold-resistant performance of the cable in a low-temperature environment, solve the problems of sheath cracking, moisture penetration and performance attenuation of conventional cables in a low-temperature and humid environment, meet the power transmission demand in high-cold and high-humidity areas, and prolong the service life of the cable.

[0008] Preferably, a preparation method of a heat-preservation anti-freezing cable comprises the following steps:

[0009] S1, raw material pretreatment: preparing a cold-resistant stabilizing layer master batch and a water-stopping layer master batch respectively;

[0010] S2, conductor pretreatment: cleaning and drying the conductor;

[0011] S3, insulating layer extrusion: extruding an insulating layer outside the treated conductor and cooling and shaping;

[0012] S4, insulating layer surface plasma activation pretreatment: activating the surface of the extruded insulating layer by plasma;

[0013] S5, double-layer co-extrusion functional sheath forming: using a double-layer co-extrusion machine to extrude a cold-resistant stabilizing layer and a water-stopping layer outside the activated insulating layer in sequence, and then gradient cooling and shaping;

[0014] S6, finished product post-treatment: drying the cable.

[0015] Through the above technical scheme, S1 raw material pretreatment prepares a cold-resistant stabilizing layer master batch and a water-stopping layer master batch respectively, which uniformly disperses the components of the cold-resistant stabilizing layer and the water-stopping layer, ensures the uniform distribution of the nano-silicon nitride dispersion liquid in the cold-resistant stabilizing layer matrix to play the low thermal conductivity and space barrier effect, and ensures the uniform dispersion of the polytetrafluoroethylene micro powder in the water-stopping layer matrix to lay the foundation for subsequent inhibition of low-temperature migration and precipitation of the cold-resistant additive;

[0016] S2, conductor pretreatment: cleaning and drying the conductor to remove oil stains and impurities on the surface of the conductor, avoid the influence of impurities on the interfacial adhesion between the conductor and the insulating layer, and prevent the interface gap from becoming a water penetration channel; S3, insulating layer extrusion: extruding an insulating layer outside the treated conductor and cooling and shaping to form a continuous and dense insulating layer outside the conductor, and cooling and shaping to ensure the dimensional stability of the insulating layer and provide a flat attachment substrate for the subsequent double-layer co-extrusion functional sheath;

[0017] S4 Insulating layer surface plasma activation pretreatment The surface of the insulating layer after extrusion is subjected to plasma activation, the surface energy of the insulating layer is improved, the interfacial bonding force between the insulating layer and the subsequent extrusion of the cold-resistant stabilizing layer is enhanced, the interlayer gap is reduced, and the path of water infiltration through the interlayer gap is blocked.

[0018] S5 Double-layer co-extrusion functional sheath forming A double-layer co-extrusion machine is used to extrude a cold-resistant stabilizing layer and a water stop layer outside the activated insulating layer in sequence, and then gradient cooling is performed for shaping. The double-layer co-extrusion process makes the cold-resistant stabilizing layer and the water stop layer closely adhere to each other, avoids the problem of loose interlayer bonding caused by step-by-step extrusion, optimizes the crystalline structure of the double-layer sheath by gradient cooling, avoids micro-cracks caused by uneven cooling rate, improves the stability of the sheath structure, and at the same time ensures that the nano-silicon nitride dispersion liquid and the polytetrafluoroethylene micro-powder maintain a uniform distribution state in their respective matrices, continuously exerting the physical barrier effect.

[0019] S6 Post-processing of finished products The cable is subjected to drying treatment to remove residual moisture on the surface of the cable, avoiding the destruction of the sheath structure caused by ice formation in a low-temperature environment.

[0020] Preferably, in the S1 step, the preparation steps of the cold-resistant stabilizing layer master batch are as follows: linear low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, stearyl methacrylate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168, and nano-silicon nitride dispersion liquid are prepared and uniformly dispersed in a high-speed mixer. After mixing is completed, the mixture is sent to a twin-screw extruder for melt granulation to obtain a cold-resistant stabilizing layer master batch.

[0021] The preparation process of the water stop layer master batch is as follows: linear low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, vinyl trimethoxysilane, polyethylene glycol methyl ether methacrylate, zinc neodecanoate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168, and polytetrafluoroethylene micro-powder are prepared and uniformly dispersed in a high-speed mixer. After mixing is completed, the mixture is sent to a twin-screw extruder for melt granulation to obtain a water stop layer master batch.

[0022] By adopting the above technical scheme, linear low density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, stearyl methacrylate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168 and nano silicon nitride dispersion liquid are used as raw materials, all of which are put into a high-speed mixer, and each raw material component is contacted and uniformly dispersed by the stirring action of the high-speed mixer, so that the nano silicon nitride dispersion liquid can be uniformly distributed between other raw materials, avoiding local enrichment or uneven dispersion; after mixing is completed, the mixed material is sent into a double screw extruder, the mixed material is melted under the heating action of the double screw extruder, and the mixing uniformity of the material is further improved through the shearing and conveying action of the screw, and at the same time, each component interacts preliminarily, and finally the cold-resistant stable layer master batch is formed through extrusion and granulation, which ensures that each component in the subsequent formed cold-resistant stable layer is uniformly distributed, and lays a structural foundation for the nano silicon nitride dispersion liquid to play a low thermal conductivity and space blocking effect and hinder the migration of cold-resistant additive molecules. The preparation of the water stop layer master batch is to use linear low density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, vinyl trimethoxysilane, polyethylene glycol methyl ether methacrylate, zinc neodecanoate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168 and polytetrafluoroethylene powder as raw materials, which are put into a high-speed mixer, and each raw material component is uniformly mixed through high-speed stirring, so that the polytetrafluoroethylene powder can be uniformly dispersed in the raw material system, avoiding the agglomeration phenomenon; after mixing is completed, the mixed material is sent into a double screw extruder, and each component is deeply fused through heating melting, screw shearing and conveying, and then the water stop layer master batch is formed through extrusion and granulation, which ensures that the polytetrafluoroethylene powder in the subsequent formed water stop layer is uniformly distributed, and provides structural support for filling the small gap inside the sheath, forming physical barrier, reducing the water permeation path and limiting the additive migration channel.

[0023] Preferably, when preparing the cold-resistant stable layer master batch, the mixing temperature of the high-speed mixer is 85-95℃, the mixing speed is 800-1000r / min, and the mixing time is 8-12min;

[0024] The screw temperature of the double screw extruder is 165-185℃, and the screw speed is 200-250r / min;

[0025] The solid content of the nano silicon nitride dispersion liquid is 25-35%.

[0026] By adopting the technical scheme, when the cold-resistant stable layer master batch is prepared, the high-speed mixer is set to a mixing temperature of 85-95°C, which can improve the molecular activity of each raw material component, promote the diffusion and contact between the components, and avoid premature melting and adhesion of the raw materials due to too high temperature or insufficient dispersion power due to too low temperature; the mixing speed of 800-1000 r / min can generate sufficient shear force to break the agglomeration state of the raw material particles, so that the linear low-density polyethylene, ethylene-octene copolymer and other matrix raw materials can fully interweave and contact with the nano-silicon nitride dispersion liquid and other additives; the mixing time of 8-12 min ensures that the dispersion of each component reaches a stable state, avoiding uneven composition inside the master batch due to incomplete dispersion. The screw temperature of the twin-screw extruder is 165-185°C, which can completely melt the material after high-speed mixing, provide temperature conditions for deep fusion and preliminary crosslinking of each component, and avoid degradation of the raw materials or failure of the additives due to too high temperature; the screw speed of 200-250 r / min further refines the dispersed phase of the molten material through the shearing and conveying action of the screw, improves the uniformity of the component mixing, and ensures that the nano-silicon nitride dispersion liquid forms a uniformly distributed barrier structure in the molten matrix. The solid content of the nano-silicon nitride dispersion liquid is controlled at 25-35%, which not only ensures that the dispersion liquid has good fluidity and can uniformly penetrate into the raw material system, but also ensures that the concentration of nano-silicon nitride in the dispersion liquid meets the needs of forming effective physical barrier and structural support, avoiding the problems of insufficient barrier effect due to too low solid content or poor fluidity and difficult uniform dispersion of the dispersion liquid due to too high solid content, and finally ensuring that the cold-resistant stable layer master batch can stably play the role of hindering the low-temperature migration and precipitation of cold-resistant additives.

[0027] Preferably, when the water stop layer master batch is prepared, the mixing temperature of the high-speed mixer is 80-90°C, the mixing speed is 700-900 r / min, and the mixing time is 10-15 min.

[0028] The screw temperature of the twin-screw extruder is 170-190°C, the screw speed is 180-220 r / min, and the particle size of the polytetrafluoroethylene powder is 5-10 μm.

[0029] By adopting the technical scheme, when the water-stopping dam layer master batch is prepared, the high-speed mixer sets the corresponding mixing temperature, which can regulate the molecular activity of each raw material component, avoids excessive temperature from causing the raw materials to melt and stick together in advance or insufficient dispersion power caused by too low temperature, and promotes the diffusion and contact of the base materials such as linear low-density polyethylene and ethylene-octene copolymer with polytetrafluoroethylene powder and other additives; the corresponding mixing speed can generate suitable shear force to break the agglomeration state of the polytetrafluoroethylene powder and other raw material particles, so that each component is fully interwoven and contacted; the corresponding mixing time ensures that the dispersion of each component reaches a stable state, avoiding incomplete dispersion which causes uneven internal composition of the master batch. The double-screw extruder adopts the corresponding screw temperature, which can completely melt the material after high-speed mixing, provides temperature conditions for deep fusion of the components such as linear low-density polyethylene, ethylene-octene copolymer, vinyl trimethoxysilane and polyethylene glycol methyl ether methacrylate, and avoids excessive temperature from causing degradation of the raw materials or invalidation of the additives; the corresponding screw speed further refines the dispersion phase of the molten material through the shearing and conveying action of the screw, improves the uniformity of component mixing, and ensures that the polytetrafluoroethylene powder forms a uniformly distributed structure in the molten matrix. The polytetrafluoroethylene powder sets the corresponding particle size, which enables the powder to effectively fill the small gaps inside the subsequently formed water-stopping dam layer, forming a continuous physical barrier structure, which not only reduces the path of water infiltration through the gaps, but also limits the migration channel of cold-resistant additive molecules, ensuring that the water-stopping dam layer plays a role in blocking water intrusion and inhibiting the low-temperature migration and precipitation of additives, thereby supporting the anti-frost heaving performance and long-term low-temperature service stability of the cable.

[0030] Preferably, the cleaning is ultrasonic cleaning, the cleaning frequency is 28-40 kHz, and the cleaning time is 5-10 min;

[0031] The drying is hot air drying, the drying temperature is 60-80 ℃, and the drying time is 10-15 min.

[0032] By adopting the technical scheme, the conductor cleaning is ultrasonic cleaning, the ultrasonic wave acts on the surface of the conductor through the vibration of a specific frequency, so that the oil stains and impurities attached to the surface of the conductor are separated from the conductor, and the corresponding cleaning time ensures that the surface attachments are completely removed, avoiding the influence of impurity residues on the interfacial bonding state between the conductor and the subsequent extruded insulation layer, preventing the formation of voids at the interface due to the presence of impurities; the drying is hot air drying, the hot air evaporates the residual moisture on the surface of the conductor through heat transfer, and the corresponding drying temperature and drying time ensure that the moisture is completely removed, avoiding the formation of ice in the subsequent process or low-temperature service environment, which causes the insulation layer and the conductor interface to peel off or produce micro-cracks, thereby reducing the formation of water infiltration channels, providing a basis for the close combination of the insulation layer and the cold-resistant stable layer, indirectly supporting the performance of the cable in blocking water intrusion and resisting frost heaving, and ensuring the structural stability of the cable.

[0033] Preferably, the insulation layer is extruded by a single screw extruder, the temperature of each section of the extruder is set as follows: 100-120℃ for the feeding section, 130-150℃ for the compression section, 150-170℃ for the homogenization section, and 160-180℃ for the head section; the screw rotation speed is 50-80r / min, and the traction speed is 10-20m / min.

[0034] After the extrusion is completed, the insulation layer is cooled and shaped in a cooling water tank, the cooling water temperature is 20-30℃, and the cooling time is 5-10min.

[0035] By using the above technical solution, the insulation layer is extruded by a single screw extruder, the temperature gradient of the feeding section, the compression section, the homogenization section and the head section of the extruder is set, so that the insulation layer raw material is gradually heated and melted from solid state, avoiding local temperature too high causing raw material degradation or too low causing insufficient melting, ensuring that the raw material forms a uniform molten state; the cooperation of the screw rotation speed and the traction speed makes the molten raw material uniformly and continuously extruded on the outside of the processed conductor, ensuring that the insulation layer has consistent thickness and is closely attached to the surface of the conductor, avoiding the occurrence of voids or poor adhesion. After the extrusion is completed, the insulation layer is cooled and shaped in a cooling water tank, the cooperation of the cooling water temperature and the cooling time makes the molten insulation layer quickly cool and solidify, stabilizing the size and shape of the insulation layer, avoiding internal stress caused by too fast cooling or size deformation caused by too slow cooling, at the same time keeping the surface of the insulation layer smooth and flat, providing a good base for subsequent plasma activation pretreatment of the insulation layer surface and formation of the double-layer co-extrusion functional sheath, ensuring that the insulation layer and the cold-resistant stable layer can be closely combined, reducing the formation of interlayer voids, thereby reducing the water infiltration channel, supporting the performance of blocking water intrusion and anti-frost heaving of the cable, and improving the overall and stability of the sheath structure.

[0036] Preferably, in the S4 step, the plasma activation uses an atmospheric pressure plasma treatment device, the treatment power is 300-500W, and the treatment gas is a mixed gas of argon and oxygen with a volume ratio of 3:1.

[0037] By using the above technical solution, the plasma activation uses an atmospheric pressure plasma treatment device, a specific treatment power ensures that the device generates plasma with sufficient activity, and the treatment gas is a mixed gas of argon and oxygen, argon provides a stable discharge environment for the plasma, and oxygen participates in the interaction between the plasma and the surface of the insulation layer. Through the bombardment and chemical reaction of the plasma, the weak boundary layer on the surface of the insulation layer is removed, and polar groups are introduced, which improves the surface energy of the insulation layer, makes the surface of the insulation layer and the subsequent extruded cold-resistant stable layer material have better compatibility, thereby enhancing the interfacial bonding force between the insulation layer and the cold-resistant stable layer, reducing the formation of interlayer voids, blocking the path of water infiltration through the interlayer voids, reducing the risk of interlayer peeling of the cable in the process of low-temperature bending and cold-hot cycle, improving the overall and stability of the sheath structure, and supporting the anti-frost heaving performance of the cable.

[0038] Preferably, in the S5 step, the inner-layer extruder of the double-layer co-extrusion machine is used to extrude the cold-resistant stabilizing layer, and the outer-layer extruder is used to extrude the water-stop layer.

[0039] The inner-layer extrusion pressure is 0.8-1.2 MPa, the outer-layer extrusion pressure is 1.0-1.5 MPa, the temperature of the feeding section of the inner-layer extruder is 150-170℃, the temperature of the compression section is 170-190℃, the temperature of the homogenizing section is 180-200℃, the temperature of the die head is 190-210℃, and the screw rotation speed is 40-60 r / min.

[0040] The temperature of the feeding section of the outer-layer extruder is 160-180℃, the temperature of the compression section is 180-200℃, the temperature of the homogenizing section is 190-210℃, the temperature of the die head is 200-220℃, and the screw rotation speed is 30-50 r / min.

[0041] The gradient cooling sequentially passes through a first-level cooling water tank and a second-level cooling water tank, the water temperature of the first-level cooling water tank is 40-50℃, and the cooling time is 3-5 min; the water temperature of the second-level cooling water tank is 20-30℃, and the cooling time is 5-8 min.

[0042] By adopting the above technical solution, the double-layer co-extrusion machine is divided into the inner-layer extruder for extruding the cold-resistant stabilizing layer and the outer-layer extruder for extruding the water-stop layer, so that the two layers of sheaths directly contact and fuse during the forming process; the cooperation of the inner-layer and outer-layer extrusion pressures ensures that the cold-resistant stabilizing layer is closely attached to the insulation layer and the water-stop layer is closely attached to the cold-resistant stabilizing layer, reducing the formation of interlayer gaps; the temperature gradient settings of each section of the inner-layer extruder make the cold-resistant stabilizing layer masterbatch gradually melt, ensuring that the nano-silicon nitride dispersion liquid is uniformly distributed in the molten matrix, and the temperature gradient settings of each section of the outer-layer extruder make the water-stop layer masterbatch fully melt, ensuring that the polytetrafluoroethylene micro-powder is uniformly dispersed, avoiding the enrichment or absence of functional components due to uneven melting; the regulation of the inner-layer and outer-layer screw rotation speeds, in cooperation with the temperature parameters, realizes the stable conveying and uniform extrusion of the molten material, ensuring that the thicknesses of the two layers of sheaths are consistent and the structures are dense; the gradient cooling, through the water temperature difference between the first-level cooling water tank and the second-level cooling water tank, makes the formed double-layer co-extrusion functional sheath gradually cool and solidify, avoiding the generation of internal stress or micro-cracks due to rapid cooling, stabilizing the crystalline structure and size form of the sheath. The interface bonding force between the insulation layer and the cold-resistant stabilizing layer, and between the cold-resistant stabilizing layer and the water-stop layer is strengthened, reducing the water permeation channels and ensuring the uniform distribution of the nano-silicon nitride dispersion liquid and the polytetrafluoroethylene micro-powder, playing a physical barrier role, inhibiting the low-temperature migration and precipitation of cold-resistant additives, and at the same time improving the integrity and stability of the sheath structure, supporting the anti-frost heaving, waterproof, and long-term low-temperature service performance of the cable.

[0043] Preferably, in the S6 step, hot air drying is adopted, the drying temperature is 50-70℃, and the drying time is 10-15 min.

[0044] By adopting the technical scheme, the drying adopts hot air drying, the hot air evaporates the possible residual moisture on the surface and gradient of the cable through heat transfer, ensures complete removal of moisture, avoids ice volume expansion of residual moisture in subsequent low-temperature service environment, causes micro-cracks or interlayer peeling of the double-layer co-extrusion functional sheath, and further reduces the formation of moisture penetration channels, guarantees the structural integrity of the cold-resistant stable layer and the water stop layer, supports the performance of the cable to block water intrusion and resist frost heaving, and at the same time maintains the integrity and stability of the sheath structure, helps the cable to stably serve in the high-cold and high-humidity environment.

[0045] The application provides a heat preservation anti-freezing and cracking cable.

[0046] 1、The application forms a double protection system of physical barrier and structural support by adding nano silicon nitride dispersion liquid in the cold-resistant stable layer and adding polytetrafluoroethylene micro powder in the water stop layer, strengthens the interfacial adhesion of the insulation layer and the cold-resistant stable layer, the cold-resistant stable layer and the water stop layer, reduces the moisture penetration channels formed by interlayer voids, blocks the water intrusion path to the heat preservation layer, and significantly improves the frost heaving damage resistance of the cable.

[0047] 2、The low thermal conductivity and space barrier effect of the nano silicon nitride dispersion liquid can hinder the migration of the cold-resistant additive molecules in the low-temperature environment, and the uniform dispersion of the polytetrafluoroethylene micro powder can fill the small gaps in the sheath, further limit the precipitation channels of the additive, effectively inhibit the low-temperature migration and surface precipitation of the cold-resistant additives such as ethylene-octene copolymer and stearyl methacrylate, and guarantee the cold-resistant performance stability of the cable in long-term low-temperature service.

[0048] 3、The application adds an insulation layer plasma activation step before the double-layer co-extrusion functional sheath is formed, enhances the surface energy of the insulation layer through the plasma effect of argon-oxygen mixed gas, and enhances the interfacial adhesion between the insulation layer and the cold-resistant stable layer; the control of the extrusion pressure of the inner and outer layers in the double-layer co-extrusion process can ensure that the cold-resistant stable layer and the water stop layer are closely attached, can effectively reduce the interlayer peeling risk of the cable in the low-temperature bending and cold-hot cycle process, and improve the integrity and stability of the sheath structure.

[0049] 4、The application realizes the excellent frost heaving resistance, water resistance and cold resistance of the cable through the synergistic modification of the raw material system and the precise regulation of the process parameters, solves the problems of sheath cracking, moisture penetration and performance attenuation of conventional cables in low-temperature and humid environment, meets the power transmission demand in high-cold and high-humidity areas, and improves the environmental adaptability and service life of the cable. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 The application provides a method flowchart. DETAILED DESCRIPTION

[0051] In order to better understand the above technical solutions, the technical solutions of the present application will be described clearly and completely in conjunction with the drawings of the specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0052] Embodiment 1

[0053] The present embodiment provides a heat preservation anti-freezing cable, comprising a conductor, an insulation layer, and a double-layer co-extrusion functional sheath wrapped outside the insulation layer, the double-layer co-extrusion functional sheath comprising a cold-resistant stabilizing layer and a water-stopping layer arranged in sequence.

[0054] The cold-resistant stabilizing layer is composed of the following raw materials in parts by weight: linear low-density polyethylene 30 parts, ethylene-octene copolymer 20 parts, maleic anhydride grafted polyethylene 2 parts, stearyl methacrylate 4 parts, dicumyl peroxide 0.08 parts, hindered phenol antioxidant AO-1010 0.10 parts, phosphite antioxidant AO-168 0.10 parts, and nano silicon nitride dispersion liquid 0.5 parts.

[0055] The water-stopping layer is composed of the following raw materials in parts by weight: linear low-density polyethylene 35 parts, ethylene-octene copolymer 10 parts, maleic anhydride grafted polyethylene 1 part, vinyl trimethoxysilane 2 parts, polyethylene glycol methyl ether methacrylate 2 parts, zinc neodecanoate 0.02 parts, dicumyl peroxide 0.06 parts, hindered phenol antioxidant AO-1010 0.10 parts, phosphite antioxidant AO-168 0.10 parts, and polytetrafluoroethylene micro powder 1 part.

[0056] The preparation method of the heat preservation anti-freezing cable comprises the following steps:

[0057] S1, raw material pretreatment: prepare cold-resistant stabilizing layer masterbatch and water-stopping layer masterbatch respectively;

[0058] The preparation steps of the cold-resistant stabilizing layer masterbatch are as follows: prepare linear low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, stearyl methacrylate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168, and nano silicon nitride dispersion liquid, and put them all into a high-speed mixer for uniform dispersion, then send them into a twin-screw extruder for melt granulation to obtain the cold-resistant stabilizing layer masterbatch;

[0059] The preparation process of the water stop layer master batch is as follows: linear low density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, vinyl trimethoxysilane, polyethylene glycol methyl ether methacrylate, zinc neodecanoate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168 and polytetrafluoroethylene powder are uniformly dispersed in a high-speed mixer, and after mixing is completed, the mixture is sent to a twin-screw extruder for melt granulation to obtain the water stop layer master batch;

[0060] When the cold-resistant stable layer master batch is prepared, the mixing temperature of the high-speed mixer is 85 DEG C, the mixing speed is 800 r / min, and the mixing time is 8 min; the screw temperature of the twin-screw extruder is 165 DEG C, the screw speed is 200 r / min; the solid content of the nano silicon nitride dispersion liquid is 25%;

[0061] When the water stop layer master batch is prepared, the mixing temperature of the high-speed mixer is 80 DEG C, the mixing speed is 700 r / min, and the mixing time is 10 min; the screw temperature of the twin-screw extruder is 170 DEG C, the screw speed is 180 r / min, and the particle size of the polytetrafluoroethylene powder is 5 mu m;

[0062] S2, conductor pretreatment: the conductor is cleaned and dried;

[0063] The cleaning is performed by ultrasonic cleaning, the cleaning frequency is 28 kHz, and the cleaning time is 5 min; the drying is performed by hot air drying, the drying temperature is 60 DEG C, and the drying time is 10 min;

[0064] S3, insulating layer extrusion: the insulating layer is extruded on the outer side of the treated conductor and is cooled and shaped;

[0065] The insulating layer extrusion is realized by a single screw extruder, the temperature of each section of the extruder is set as follows: the feeding section is 100 DEG C, the compression section is 130 DEG C, the homogenizing section is 150 DEG C, and the head temperature is 160 DEG C; the screw speed is 50 r / min, and the traction speed is 10 m / min; after the extrusion is completed, the extrusion is cooled and shaped in a cooling water tank, the cooling water temperature is 20 DEG C, and the cooling time is 5 min;

[0066] S4, insulating layer surface plasma activation pretreatment: the surface of the extruded insulating layer is activated by plasma;

[0067] The plasma activation is performed by an atmospheric pressure plasma treatment device, the treatment power is 300 W, and the treatment gas is a mixed gas of argon and oxygen with a volume ratio of 3:1;

[0068] S5, double-layer co-extrusion functional sheath forming: a double-layer co-extrusion extruder is used to extrude the cold-resistant stable layer and the water stop layer on the outer side of the activated insulating layer in sequence, and then the gradient cooling and shaping are performed;

[0069] The inner layer extruder of the double-layer co-extrusion machine is used for extruding a cold-resistant stabilizing layer, and the outer layer extruder is used for extruding a water stop layer; the inner layer extrusion pressure is 0.8 MPa, the outer layer extrusion pressure is 1.0 MPa, the temperature of the feeding section of the inner layer extruder is 150℃, the temperature of the compression section is 170℃, the temperature of the homogenizing section is 180℃, the temperature of the die head is 190℃, and the screw rotation speed is 40 r / min; the temperature of the feeding section of the outer layer extruder is 160℃, the temperature of the compression section is 180℃, the temperature of the homogenizing section is 190℃, the temperature of the die head is 200℃, and the screw rotation speed is 30 r / min; the gradient cooling sequentially passes through a first cooling water tank and a second cooling water tank, the water temperature of the first cooling water tank is 40℃, and the cooling time is 3 min; the water temperature of the second cooling water tank is 20℃, and the cooling time is 5 min;

[0070] S6, finished product post-treatment: drying treatment is performed on the cable;

[0071] The drying is hot air drying, the drying temperature is 50℃, and the drying time is 10 min.

[0072] Example 2

[0073] The present embodiment provides a heat-preservation anti-freezing and cracking cable, which comprises the following raw material components by weight:

[0074] The cable comprises a conductor, an insulation layer, and a double-layer co-extrusion functional sheath wrapped outside the insulation layer, wherein the double-layer co-extrusion functional sheath comprises a cold-resistant stabilizing layer and a water stop layer arranged in sequence.

[0075] The cold-resistant stabilizing layer is composed of the following raw materials by weight: linear low-density polyethylene 50 parts, ethylene-octene copolymer 40 parts, maleic anhydride grafted polyethylene 5 parts, stearyl methacrylate 10 parts, dicumyl peroxide 0.19 parts, hindered phenol antioxidant AO-1010 0.25 parts, phosphite antioxidant AO-168 0.25 parts, and nano silicon nitride dispersion liquid 1.25 parts.

[0076] The water stop layer is composed of the following raw materials by weight: linear low-density polyethylene 55 parts, ethylene-octene copolymer 27.5 parts, maleic anhydride grafted polyethylene 3.5 parts, vinyl trimethoxysilane 6 parts, polyethylene glycol methyl ether methacrylate 6 parts, zinc neodecanoate 0.11 parts, dicumyl peroxide 0.16 parts, hindered phenol antioxidant AO-1010 0.25 parts, phosphite antioxidant AO-168 0.25 parts, and polytetrafluoroethylene powder 2 parts.

[0077] The preparation method of the above-mentioned heat-preservation anti-freezing and cracking cable comprises the following steps:

[0078] S1, raw material pretreatment: preparing a cold-resistant stabilizing layer master batch and a water stop layer master batch respectively;

[0079] The preparation steps of the cold-resistant stabilizing layer master batch are as follows: linear low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, stearyl methacrylate, dicumyl peroxide, hindered phenolic antioxidant AO-1010, phosphite antioxidant AO-168, and nano silicon nitride dispersion liquid are prepared and uniformly dispersed in a high-speed mixer, and after mixing is completed, they are sent to a twin-screw extruder for melt granulation to obtain the cold-resistant stabilizing layer master batch.

[0080] The preparation process of the water stop layer master batch is as follows: linear low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, vinyl trimethoxysilane, polyethylene glycol methyl ether methacrylate, zinc neodecanoate, dicumyl peroxide, hindered phenolic antioxidant AO-1010, phosphite antioxidant AO-168, and polytetrafluoroethylene micro powder are prepared and uniformly dispersed in a high-speed mixer, and after mixing is completed, they are sent to a twin-screw extruder for melt granulation to obtain the water stop layer master batch.

[0081] When preparing the cold-resistant stabilizing layer master batch, the mixing temperature of the high-speed mixer is 90°C, the mixing speed is 900 r / min, and the mixing time is 10 min; the screw temperature of the twin-screw extruder is 175°C, the screw speed is 225 r / min; and the solid content of the nano silicon nitride dispersion liquid is 30%;

[0082] When preparing the water stop layer master batch, the mixing temperature of the high-speed mixer is 85°C, the mixing speed is 800 r / min, and the mixing time is 12.5 min; the screw temperature of the twin-screw extruder is 180°C, the screw speed is 200 r / min, and the particle size of the polytetrafluoroethylene micro powder is 7.5 μm;

[0083] S2, conductor pretreatment: the conductor is cleaned and dried;

[0084] The cleaning is performed by ultrasonic cleaning, the cleaning frequency is 34 kHz, and the cleaning time is 7.5 min; the drying is performed by hot air drying, the drying temperature is 70°C, and the drying time is 12.5 min;

[0085] S3, insulating layer extrusion coating: the insulating layer is extrusion coated on the outside of the treated conductor and is cooled and shaped;

[0086] The insulating layer extrusion coating is realized by a single-screw extruder, the temperature of each section of the extruder is set as follows: the feeding section is 110°C, the compression section is 140°C, the homogenizing section is 160°C, and the die temperature is 170°C; the screw speed is 65 r / min, and the traction speed is 15 m / min; after the extrusion coating is completed, the insulating layer is cooled and shaped in a cooling water tank, the cooling water temperature is 25°C, and the cooling time is 7.5 min;

[0087] S4, insulating layer surface plasma activation pretreatment: the surface of the extrusion coated insulating layer is activated by plasma;

[0088] The plasma activation adopts an atmospheric pressure plasma processing device, the processing power is 400 W, and the processing gas is a mixed gas of argon and oxygen with a volume ratio of 3:1.

[0089] S5, double-layer co-extrusion functional sheath forming: using a double-layer co-extrusion extruder, a cold-resistant stabilizing layer and a water stop layer are successively extruded and wrapped outside the activated insulation layer, and then gradient cooling is performed for shaping;

[0090] The inner-layer extruder of the double-layer co-extrusion extruder is used for extruding and wrapping the cold-resistant stabilizing layer, and the outer-layer extruder is used for extruding and wrapping the water stop layer; the inner-layer extrusion pressure is 1.0 MPa, the outer-layer extrusion pressure is 1.25 MPa, the temperature of the feeding section of the inner-layer extruder is 160℃, the temperature of the compression section is 180℃, the temperature of the homogenizing section is 190℃, the temperature of the die head is 200℃, and the screw rotation speed is 50 r / min; the temperature of the feeding section of the outer-layer extruder is 170℃, the temperature of the compression section is 190℃, the temperature of the homogenizing section is 200℃, the temperature of the die head is 210℃, and the screw rotation speed is 40 r / min; the gradient cooling successively passes through a first-stage cooling water tank and a second-stage cooling water tank, the water temperature of the first-stage cooling water tank is 45℃, and the cooling time is 4 min; the water temperature of the second-stage cooling water tank is 25℃, and the cooling time is 6.5 min;

[0091] S6, product post-processing: drying treatment is performed on the cable;

[0092] The drying is performed by hot air drying, the drying temperature is 60℃, and the drying time is 12.5 min.

[0093] Example 3

[0094] The embodiment provides a heat preservation anti-freezing and cracking cable, which comprises a conductor, an insulation layer, and a double-layer co-extrusion functional sheath wrapped outside the insulation layer, wherein the double-layer co-extrusion functional sheath comprises a cold-resistant stabilizing layer and a water stop layer arranged in sequence.

[0095] The cold-resistant stabilizing layer is composed of the following raw materials in parts by weight: linear low-density polyethylene 70 parts, ethylene-octene copolymer 60 parts, maleic anhydride grafted polyethylene 8 parts, stearyl methacrylate 16 parts, dicumyl peroxide 0.30 parts, hindered phenol antioxidant AO-1010 0.40 parts, phosphite antioxidant AO-168 0.40 parts, and nano silicon nitride dispersion liquid 2 parts.

[0096] The water-stopping and sealing layer is composed of the following raw materials by weight: linear low density polyethylene 75 parts, ethylene-octene copolymer 45 parts, maleic anhydride grafted polyethylene 6 parts, vinyl trimethoxysilane 10 parts, polyethylene glycol methyl ether methacrylate 10 parts, zinc neodecanoate 0.20 parts, dicumyl peroxide 0.25 parts, hindered phenol antioxidant AO-1010 0.40 parts, phosphite antioxidant AO-168 0.40 parts, and polytetrafluoroethylene micro powder 3 parts.

[0097] The preparation method of the heat-preservation anti-freezing and cracking cable comprises the following steps:

[0098] S1, raw material pretreatment: prepare cold-resistant stabilizing layer masterbatch and water-stopping and sealing layer masterbatch respectively;

[0099] The preparation steps of the cold-resistant stabilizing layer masterbatch are as follows: prepare linear low density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, stearyl methacrylate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168, and nano silicon nitride dispersion liquid, and put them into a high-speed mixer for uniform dispersion, and then put them into a double-screw extruder for melt granulation after mixing is completed to obtain the cold-resistant stabilizing layer masterbatch;

[0100] The preparation process of the water-stopping and sealing layer masterbatch is as follows: prepare linear low density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, vinyl trimethoxysilane, polyethylene glycol methyl ether methacrylate, zinc neodecanoate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168, and polytetrafluoroethylene micro powder, and put them into a high-speed mixer for uniform dispersion, and then put them into a double-screw extruder for melt granulation after mixing is completed to obtain the water-stopping and sealing layer masterbatch;

[0101] During preparation of the cold-resistant stabilizing layer masterbatch, the mixing temperature of the high-speed mixer is 95℃, the mixing speed is 1000r / min, and the mixing time is 12min; the screw temperature of the double-screw extruder is 185℃, the screw speed is 250r / min; and the solid content of the nano silicon nitride dispersion liquid is 35%;

[0102] During preparation of the water-stopping and sealing layer masterbatch, the mixing temperature of the high-speed mixer is 90℃, the mixing speed is 900r / min, and the mixing time is 15min; the screw temperature of the double-screw extruder is 190℃, the screw speed is 220r / min, and the particle size of the polytetrafluoroethylene micro powder is 10μm;

[0103] S2, conductor pretreatment: clean and dry the conductor;

[0104] The cleaning is ultrasonic cleaning, the cleaning frequency is 40kHz, and the cleaning time is 10min; the drying is hot air drying, the drying temperature is 80℃, and the drying time is 15min;

[0105] S3, insulating layer extrusion: extruding an insulating layer outside the processed conductor and cooling and setting;

[0106] The insulating layer extrusion is realized by a single screw extruder, the temperature of each section of the extruder is set as follows: 120℃ for the feeding section, 150℃ for the compression section, 170℃ for the homogenizing section, and 180℃ for the head temperature; the screw rotation speed is 80r / min, and the traction speed is 20m / min; after the extrusion is completed, cooling and setting are performed in a cooling water tank, the cooling water temperature is 30℃, and the cooling time is 10min;

[0107] S4, insulating layer surface plasma activation pretreatment: plasma activation is performed on the surface of the extruded insulating layer;

[0108] The plasma activation is performed by using an atmospheric pressure plasma treatment device, the treatment power is 500W, and the treatment gas is a mixed gas of argon and oxygen with a volume ratio of 3:1;

[0109] S5, double-layer co-extrusion functional sheath forming: a double-layer co-extrusion extruder is used to extrude a cold-resistant stabilizing layer and a water stop layer outside the activated insulating layer in sequence, and then gradient cooling and setting are performed;

[0110] The inner layer extruder of the double-layer co-extrusion extruder is used to extrude the cold-resistant stabilizing layer, and the outer layer extruder is used to extrude the water stop layer; the inner layer extrusion pressure is 1.2MPa, the outer layer extrusion pressure is 1.5MPa, the temperature of the feeding section of the inner layer extruder is 170℃, the temperature of the compression section is 190℃, the temperature of the homogenizing section is 200℃, the head temperature is 210℃, and the screw rotation speed is 60r / min; the temperature of the feeding section of the outer layer extruder is 180℃, the temperature of the compression section is 200℃, the temperature of the homogenizing section is 210℃, the head temperature is 220℃, and the screw rotation speed is 50r / min; the gradient cooling is sequentially performed in a first cooling water tank and a second cooling water tank, the water temperature of the first cooling water tank is 50℃, and the cooling time is 5min; the water temperature of the second cooling water tank is 30℃, and the cooling time is 8min;

[0111] S6, finished product post-treatment: drying treatment is performed on the cable;

[0112] The drying is performed by using hot air drying, the drying temperature is 70℃, and the drying time is 15min.

[0113] Comparative Example 1

[0114] The difference from Example 2 is only that the nano silicon nitride dispersion liquid is not added in the raw material of the cold-resistant stabilizing layer.

[0115] Comparative Example 2

[0116] The difference from Example 2 is only that the polytetrafluoroethylene micro powder is not added in the raw material of the water stop layer.

[0117] Comparative Example 3

[0118] The difference from Example 2 is only that the polytetrafluoroethylene micro powder in the water stop layer is replaced by talc powder of equal weight.

[0119] Comparative Example 4

[0120] The difference from Example 2 is only that the surface plasma activation pretreatment of the insulating layer in the preparation method is omitted.

[0121] Comparative Example 5

[0122] The difference from Example 2 is only that the treatment gas for plasma activation in step S4 is replaced by pure argon gas.

[0123] Comparative Example 6

[0124] The difference from Example 2 is only that the gradient cooling in step S5 is replaced by single cooling water tank cooling.

[0125] Comparative Example 7

[0126] The difference from Example 2 is only that the nano silicon nitride dispersion liquid in the cold-resistant stabilizing layer is replaced by equal weight of silica dispersion liquid.

[0127] Comparative Example 8

[0128] The difference from Example 2 is only that when preparing the cold-resistant stabilizing layer master batch in step S1, the high-speed mixer is not mixed, and all the raw materials are directly put into the twin-screw extruder for melt granulation.

[0129] Comparative Example 9

[0130] The difference from Example 2 is only that the vinyl trimethoxysilane in the water stop layer is replaced by equal weight of vinyl triethoxysilane.

[0131] Experiment One Low Temperature-Immersion Cycle Frost Heave Damage Test

[0132] According to the relevant provisions in GB / T 2423.1-2008 “Electrical and electronic products environmental testing Part 2: Test methods Test A: Low temperature” and GB / T 12706.1-2020 “Power cables of rated voltage 1kV (Um=1.2kV) to 35kV (Um=420kV) - Part 1: Cables of rated voltage 1kV and 3kV”, each of the cable samples of Examples 1-3 and Comparative Examples 1-9 was cut into 3 test pieces with a length of 500 mm, the conductors at both ends were removed, and the sealed end face was placed in an environment of (23±2) °C, humidity (50±5) %RH for 24 h of pretreatment. The pretreated test pieces were completely immersed in deionized water at (23±2) °C, with an immersion pressure of 0.1 MPa, for 24 h to allow the water to fully contact the surface of the sheath; then the test pieces were transferred to a high-low temperature test box, frozen at -40 °C for 12 h, then warmed to 23 °C for 6 h of thawing, to complete one cycle of “immersion-freezing-thawing”, which was continued until the test piece showed sheath cracking, interlayer peeling, or a volume change rate exceeding 5%. The outer diameter and sheath thickness of the test piece before and after the cycle were measured using a vernier caliper, the volume change rate was calculated, and the number of cycles at which the first damage occurred was recorded. Volume change rate = (volume after cycle - volume before cycle) / volume before cycle x 100%.

[0133] Experiment two: low temperature long-term placement of cold-resistant additive migration and precipitation amount test

[0134] According to GB / T 29613.4-2013 “Rubber pyrolysis gas chromatography analysis method Part 4: Identification of polymers (single polymer and copolymer)”, pyrolysis-gas chromatography / mass spectrometry was used to analyze the sheath layer of about 5 g of each of the cable samples of Examples 1-3 and Comparative Examples 1-9, which was ground to a particle size of ≤0.5 mm, dried in a (60±2) °C vacuum drying oven for 4 h, and accurately weighed 20 mg into a pyrolysis instrument. The pyrolysis temperature was set to 500 °C, the pyrolysis time was 30 s, the carrier gas was high-purity helium, and the flow rate was 1.0 mL / min; the chromatographic column was an HP-5MS capillary column, and the column temperature program was: initial temperature 50 °C, holding for 2 min, increasing at 10 °C / min to 300 °C, holding for 10 min; the mass spectrometry detector ion source temperature was 230 °C, the electron impact energy was 70 eV, and the scan range was m / z 30-500. The standard curve was drawn using ethylene-octene copolymer and stearyl methacrylate standards by external standard method, and the total amount of cold-resistant additive precipitated on the surface and inside of the sheath after the sample was placed in an environment of -40 °C for 90 days was quantitatively analyzed.

[0135] Experiment three: combined test of interlayer interface waterproof bonding strength and water permeation amount

[0136] The interlayer adhesion strength test and moisture permeation amount test were performed on the cable samples of Examples 1-3 and Comparative Examples 1-9 according to GB / T 1408.1-2021 "Insulating materials - Determination of electrical strength - Part 1: Test at power frequency" and GB / T 21529-2008 "Determination of water vapour transmission rate of plastics - Electrolytic sensor method". Adhesion strength test: the interlayer peeling sample of insulation layer-cold-resistant stabilizing layer, cold-resistant stabilizing layer-water stop layer was cut off, T-type peeling test was performed by using a tensile testing machine at a stretching rate of 50 mm / min, the maximum peeling force was recorded, and the adhesion strength was calculated, adhesion strength = maximum peeling force / sample width; moisture permeation amount test: the cable sample with a length of 200 mm was cut off, one end was sealed, and a deionized water pressure of 0.2 MPa was applied to the other end, the sample was placed in a-20℃ environment, and the total amount of moisture permeated into the internal part through the sheath layer within 24 h was monitored in real time by using the electrolytic sensor method.

[0137] Table 1 Low temperature-immersion water cycle frost heave damage test data

[0138]

[0139] Table 2 Low temperature long-term storage cold-resistant additive migration and precipitation amount detection test data

[0140]

[0141] Table 3 Interlayer interface waterproof adhesion strength and moisture permeation amount combined test data

[0142]

[0143] From the experimental data of the above examples and comparative examples, the following conclusions are obtained:

[0144] It can be seen from Examples 2 and Comparative Examples 1-9 and Table 1 that the significant effect of blocking the moisture intrusion and frost heave feedback loop. The cycle number of the first damage of Comparative Examples 1-3, 7 and 9 is only 18-25 times, and the volume change rate is 7.0%-9.2%; the cycle damage number of Comparative Examples 4-6 and 8 is 15-23 times, and the volume change rate is 6.8%-10.3%, which are significantly worse than 58 times and 2.1% of Example 2. This shows that the structure support of nano-silicon nitride dispersion liquid and the hydrophobic barrier of polytetrafluoroethylene micro powder form raw material synergy, the plasma activation strengthens the interlayer bonding, and the gradient cooling optimizes the sheath structure, which constitutes process synergy. The two linkages block the moisture penetration path, break the vicious cycle of "moisture intrusion, low temperature frost heaving and structure damage".

[0145] Combining Example 2 and Comparative Examples 1-9 with Table 2, it can be seen that the additive exhibits excellent performance in inhibiting low-temperature migration and precipitation. In Comparative Examples 1, 2, 7, 8, and 9, the additive precipitation amount reached 1.45%-1.92%; in Comparative Examples 3-6, the precipitation amount was 1.12%-1.32%, all significantly higher than the 0.22% in Example 2. This indicates that the low thermal conductivity of the nano-silicon nitride dispersion and the spatial barrier effect of the polytetrafluoroethylene micropowder work synergistically. The high-speed mixing process ensures uniform dispersion of the raw materials, and all three factors work together to inhibit the migration and surface precipitation of additive molecules, preventing the degradation of cold-resistant performance.

[0146] Combining Example 2 and Comparative Examples 1-9 with Table 3, it can be seen that there is a synergistic effect in improving interlayer waterproofing and bonding strength. Comparative Example 4, lacking plasma activation, has an interlayer bonding strength of only 0.7-0.8 N / mm and a 24-hour water penetration of 0.52 g / m². Comparative Examples 1-3 and 7-9 have bonding strengths of 0.7-1.1 N / mm and penetrations of 0.32-0.48 g / m². Comparative Examples 5-6 have bonding strengths of 1.1-1.2 N / mm and penetrations of 0.28-0.30 g / m², all lower than the 2.2-2.3 N / mm and 0.05 g / m² of Example 2. This indicates that plasma activation treatment improves interfacial compatibility, enhances bonding strength, reduces interlayer moisture channels, and works in conjunction with the chemical cross-linking of the waterproofing layer and the physical support of the cold-resistant stabilizing layer, thus strengthening the waterproofing effect and further inhibiting additive migration pathways.

[0147] Combining Examples 2 and Comparative Examples 1-9 with Tables 1-3, it can be seen that the present invention exhibits excellent overall performance in terms of anti-freeze heave, prevention of additive precipitation, and interlayer waterproofing. Comparative Example 1, lacking the nano-silicon nitride dispersion, not only had only 18 cycles of degradation, but also experienced additive precipitation of 1.85% and water penetration of 0.38 g / m². Comparative Example 4, omitting plasma activation, saw a decline in all three core indicators. Comparative Example 8, without the mixing process, had a precipitation rate as high as 1.92% and only 17 cycles of degradation. This demonstrates that the selection of raw materials ensures core functionality, the process design optimizes structural performance, and each link forms a close synergistic chain relationship. The absence or deviation of any key link will lead to a comprehensive decline in the overall performance of the entire system, highlighting the rationality and synergistic necessity of the raw material combination and process design of the present invention.

[0148] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A temperature-maintained anti-icing cable, characterized by, The double-layer co-extrusion functional sheath includes a cold-resistant stabilizing layer and a water stop layer arranged in sequence, and the cold-resistant stabilizing layer is composed of the following raw materials in parts by weight: linear low-density polyethylene 30-70 parts, ethylene-octene copolymer 20-60 parts, maleic anhydride grafted polyethylene 2-8 parts, stearyl methacrylate 4-16 parts, dicumyl peroxide 0.08-0.30 parts, hindered phenol antioxidant AO-1010 0.10-0.40 parts, phosphite antioxidant AO-168 0.10-0.40 parts, and nano silicon nitride dispersion liquid 0.5-2 parts; The water stop layer is composed of the following raw materials in parts by weight: linear low-density polyethylene 35-75 parts, ethylene-octene copolymer 10-45 parts, maleic anhydride grafted polyethylene 1-6 parts, vinyl trimethoxysilane 2-10 parts, polyethylene glycol methyl ether methacrylate 2-10 parts, zinc neodecanoate 0.02-0.20 parts, dicumyl peroxide 0.06-0.25 parts, hindered phenol antioxidant AO-1010 0.10-0.40 parts, phosphite antioxidant AO-168 0.10-0.40 parts, and polytetrafluoroethylene powder 1-3 parts.

2. A method of preparing a temperature-maintaining freeze-preventing cable, characterized by, A heat preservation anti-freezing and cracking cable according to claim 1, comprising the following steps: S1, raw material pretreatment: prepare cold-resistant stabilizing layer masterbatch and water stop layer masterbatch respectively; S2, conductor pretreatment: clean and dry the conductor; S3, insulating layer extrusion: extrude the insulating layer on the outer side of the treated conductor and cool and shape; S4, insulating layer surface plasma activation pretreatment: activate the surface of the extruded insulating layer by plasma; S5, double-layer co-extrusion functional sheath forming: use a double-layer co-extrusion extruder to extrude the cold-resistant stabilizing layer and the water stop layer on the outer side of the activated insulating layer in sequence, and then gradient cool and shape; S6, finished product post-treatment: dry the cable.

3. A method of preparing a temperature-maintaining freeze-preventing cable according to claim 2, characterized in that, In the S1 step, the preparation steps of the cold-resistant stabilizing layer masterbatch are as follows: prepare linear low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, stearyl methacrylate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168, and nano silicon nitride dispersion liquid, and put them into a high-speed mixer for uniform dispersion, and then put them into a double-screw extruder for melt granulation after mixing is completed to obtain the cold-resistant stabilizing layer masterbatch; The preparation process of the water stop layer masterbatch is as follows: prepare linear low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, vinyl trimethoxysilane, polyethylene glycol methyl ether methacrylate, zinc neodecanoate, dicumyl peroxide, hindered phenol antioxidant AO-1010, phosphite antioxidant AO-168, and polytetrafluoroethylene powder, put them into a high-speed mixer for uniform dispersion, and then put them into a double-screw extruder for melt granulation after mixing is completed to obtain the water stop layer masterbatch.

4. A method of preparing a temperature-maintaining freeze-preventing cable according to claim 3, characterized in that, When preparing the cold-resistant stabilizing layer masterbatch, the mixing temperature of the high-speed mixer is 85-95℃, the mixing speed is 800-1000r / min, and the mixing time is 8-12min; The screw temperature of the double screw extruder is 165-185℃, and the screw rotation speed is 200-250r / min; The solid content of the nano-silicon nitride dispersion liquid is 25-35%.

5. A method of preparing a temperature-maintaining freeze-preventing cable according to claim 3, characterized in that, When preparing the water stop layer master batch, the mixing temperature of the high-speed mixer is 80-90℃, the mixing rotation speed is 700-900r / min, and the mixing time is 10-15min; The screw temperature of the double screw extruder is 170-190℃, the screw rotation speed is 180-220r / min, and the particle size of the polytetrafluoroethylene micro powder is 5-10μm.

6. A method of preparing a temperature-maintaining freeze-preventing cable according to claim 2, characterized by, In the S2 step, ultrasonic cleaning is used, the cleaning frequency is 28-40kHz, and the cleaning time is 5-10min; The drying temperature is 60-80℃, and the drying time is 10-15min.

7. A method of preparing a temperature-maintaining freeze-preventing cable according to claim 2, characterized by, In the S3 step, the insulation layer extrusion coating is realized by a single screw extruder, the temperature of each section of the extruder is set as follows: the feeding section is 100-120℃, the compression section is 130-150℃, the homogenization section is 150-170℃, and the die temperature is 160-180℃; the screw rotation speed is 50-80r / min, and the traction speed is 10-20m / min; After the extrusion coating is completed, it is cooled and shaped in a cooling water tank, the cooling water temperature is 20-30℃, and the cooling time is 5-10min.

8. A method of preparing a temperature-maintaining freeze-preventing cable according to claim 2, characterized by, In the S4 step, the plasma activation is realized by using an atmospheric pressure plasma treatment device, the treatment power is 300-500W, and the treatment gas is a mixed gas of argon and oxygen with a volume ratio of 3:

1.

9. A method of preparing a temperature-maintaining freeze-preventing cable according to claim 2, characterized by, In the S5 step, the inner layer extruder of the double-layer co-extrusion extruder is used for extruding the cold-resistant stable layer, and the outer layer extruder is used for extruding the water stop layer. The inner layer extrusion pressure is 0.8-1.2MPa, the outer layer extrusion pressure is 1.0-1.5MPa, the temperature of the feeding section of the inner layer extruder is 150-170℃, the temperature of the compression section is 170-190℃, the temperature of the homogenization section is 180-200℃, the die temperature is 190-210℃, and the screw rotation speed is 40-60r / min; The temperature of the feeding section of the outer layer extruder is 160-180℃, the temperature of the compression section is 180-200℃, the temperature of the homogenization section is 190-210℃, the die temperature is 200-220℃, and the screw rotation speed is 30-50r / min; The gradient cooling successively passes through a primary cooling water tank and a secondary cooling water tank, the water temperature of the primary cooling water tank is 40-50℃, and the cooling time is 3-5min; the water temperature of the secondary cooling water tank is 20-30℃, and the cooling time is 5-8min.

10. A method of preparing a temperature-maintaining freeze-preventing cable according to claim 2, characterized by, In the S6 step, the drying is realized by using hot air drying, the drying temperature is 50-70℃, and the drying time is 10-15min.

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