Rubber type cable protection sleeve material and preparation method and application thereof

Abstract

The invention relates to a rubber type cable protection sheath material as well as a preparation method and application thereof. The rubber type cable protection sheath material is prepared from the following components in parts by weight: 30 to 70 parts of EVM (Ethylene Vinyl Acetate), 10 to 30 parts of modified EVA (Ethylene Vinyl Acetate), 100 to 150 parts of a flame retardant, 20 to 60 parts of a smoke suppressant, 1 to 5 parts of a carbon forming agent, 1 to 5 parts of a coupling agent, 1 to 15 parts of a cross-linking agent and 1 to 5 parts of a rat and ant resistant agent. According to the invention, through formula design of the cable protection sheath material, the rubber type cable protection sheath material is prepared, and compared with a traditional thermoplastic cable protection sheath material, the rubber type cable protection sheath material has more excellent mechanical properties, oil resistance, cracking resistance, rat and ant resistance and heat resistance. The invention further provides the cable, and the cable has excellent water resistance, flame retardance and molten drop resistance by designing the structure of the cable.

Description

Technical Field

[0001] This invention relates to the field of cable material technology, and in particular to a rubber-type cable protective sheath material, its preparation method, and its application. Background Technology

[0002] The 1500 V DC traction cable is a core power transmission component in urban rail transit systems. It is mainly used as a feeder from the traction substation to the contact network and as a return line from the running rail to the traction substation. Its core function is to stably transmit the converted electrical energy from the traction substation to the contact line and to feed back the loop current introduced into the return box in the ground rail to the main transformer of the traction substation. It is directly related to the safe and stable operation of the rail transit system.

[0003] With the rapid development of urban rail transit, the performance requirements for traction cables in the operating environment are becoming increasingly stringent, especially in terms of high-temperature combustion safety, tolerance to complex environments, and adaptability to special working conditions. Currently, most 1500 V DC traction cables in the rail transit field that meet the requirements of rodent and termite prevention and B1-level combustion performance are manufactured using thermoplastic low-smoke halogen-free flame-retardant oxygen-barrier materials and sheathing materials. Although these products can basically meet the B1-level flame retardancy and basic transmission requirements, they have revealed many technical defects in practical applications and are difficult to adapt to complex operating scenarios.

[0004] First, thermoplastic polyolefin materials have high hardness and insufficient flexibility. When laid or bent in low-temperature environments, the sheath is prone to cracking due to low-temperature embrittlement. In severe cases, this can damage the cable's insulation performance and cause power transmission failures. At the same time, oil stains, lubricating oil, and other media generated during the operation of rail transit trackside equipment can easily corrode thermoplastic polyolefin materials, leading to rapid degradation of material performance, significantly shortening the safe service life of the cable, and increasing operation and maintenance costs and safety risks.

[0005] Secondly, in areas with high incidence of rodent and ant infestations, such as the south, conventional thermoplastic sheathed cables only achieve protection by adding rodent repellents or ant repellents to the material. However, these repellents are prone to migration and volatilization over time, and their protective effect gradually decreases. It is difficult to form a long-term and stable rodent and ant barrier, and the cable sheath is easily eaten and damaged by rodents and ants, affecting the stability of power transmission and even causing safety accidents such as short circuits.

[0006] To address these issues, the industry has experimented with using thermosetting rubber materials as the sheath base material. These materials combine excellent oil resistance and flexibility, effectively avoiding the low-temperature cracking and poor oil resistance of thermoplastic materials. However, new technical challenges have arisen: to ensure that thermosetting rubber sheaths simultaneously meet B1 flammability and rodent / termite repellency requirements, large amounts of flame retardants and rodent / termite repellents must be added to the formulation. However, high additive content significantly damages the mechanical properties of the rubber material, leading to a decrease in key indicators such as tensile strength and elongation at break. Finding a balance between additive dosage and material mechanical properties has become the core bottleneck restricting the compatibility of thermosetting rubber sheaths with this type of cable.

[0007] In addition, existing cable products have the problem of instability in mass production in terms of combustion performance, especially for the requirement of combustion droplets / particles level d0 (requiring no combustion droplets / particles within 1200 s). The droplets generated during the combustion process can easily ignite surrounding combustibles and expand the scope of fire hazards, which cannot fully meet the stringent fire safety requirements of the rail transit sector.

[0008] Therefore, how to provide a DC 1500 V rail transit traction cable that meets the performance requirements of multiple scenarios and is produced stably and reliably has become an urgent problem to be solved. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a rubber-type cable protective sheath material, its preparation method, and its application. By designing a formulation for the cable protective sheath material, a rubber-type cable protective sheath material is obtained, exhibiting superior mechanical properties, oil resistance, crack resistance, rodent and termite resistance, and heat resistance compared to traditional thermoplastic cable protective sheath materials. Furthermore, this invention involves structural design of the cable to give it excellent water resistance, flame retardancy, and anti-dripping properties.

[0010] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a rubber-type cable protective sheath material, which comprises, by weight, 30-70 parts of EVM, 10-30 parts of modified EVA, 100-150 parts of flame retardant, 20-60 parts of smoke suppressant, 1-5 parts of charring agent, 1-5 parts of coupling agent, 1-15 parts of crosslinking agent, and 1-5 parts of rodent and ant repellent.

[0011] Among them, 30-70 portions can be, for example, 30 portions, 35 portions, 40 portions, 45 portions, 50 portions, 55 portions, 60 portions, 65 portions, or 70 portions; 10-30 portions can be, for example, 10 portions, 15 portions, 20 portions, 25 portions, or 30 portions; 100-150 portions can be, for example, 100 portions, 110 portions, 120 portions, 130 portions, 140 portions, or 150 portions; 20-60 portions can be, for example, 20 portions, 30 portions, 40 portions, 50 portions, or 60 portions; 1-15 portions can be, for example, 1 portion, 2 portions, 4 portions, 5 portions, 6 portions, 8 portions, 10 portions, 12 portions, 14 portions, or 15 portions.

[0012] This invention designs a formula for cable protective sheathing materials, using EVM as the rubber matrix to impart excellent insulation, toughness, and oil resistance. Furthermore, it adds functional additives such as flame retardants, charring agents, and rodent repellents to synergistically endow the cable protective sheathing materials with B1-level flammability, rodent repellency, and anti-dripping properties. The addition of modified EVA further improves the dispersion performance of the flame retardants, charring agents, and rodent repellents in the EVM, balancing the functionality of the cable protective sheathing materials without affecting their mechanical properties.

[0013] Preferably, the VA content in the EVM is 45-55%, for example, it can be 45%, 46%, 48%, 50%, 52%, 54% or 55%, etc.

[0014] Preferably, the Mooney viscosity of the EVM is 23-31 MU, for example, it can be 23 MU, 25 MU, 26 MU, 28 MU, 30 MU or 31 MU.

[0015] The Mooney viscosity was tested using a Mooney viscometer in accordance with the GB / T 1232-2016 standard, under the following conditions: L-shaped large rotor, preheating for 1 min, testing for 4 min, and temperature of 100℃.

[0016] This invention limits the VA content in EVM to 45-55% by mass. The lower the VA content in EVM, the worse its oil resistance and flame retardancy; if the VA content is too high, the EVM colloid becomes hard and brittle, its processing performance deteriorates, and it is prone to cracking when bent at low temperatures. Rubber-type cable protective sheathing materials require a certain degree of flexibility; therefore, this invention limits the VA content in EVM to 45-55% by mass, balancing the flexibility, oil resistance, and flame retardancy of EVM.

[0017] This invention further limits the Mooney viscosity of EVM to 23-31 MU. EVM within this Mooney viscosity range can effectively encapsulate the functional additives such as flame retardants, charring agents, and rodent repellents added in this invention. If the EVM viscosity is too low, it cannot completely encapsulate the functional additives, and it is prone to slippage during subsequent processing, resulting in poor additive dispersion and affecting the mechanical properties of its rubber-type cable protective sheath material. If the EVM viscosity is too high, it will affect its processing fluidity, and problems such as rough material extrusion surface and poor dimensional stability will easily occur. At the same time, excessively high viscosity will also aggravate the internal molecular friction and heat generation during processing, which can easily cause local scorching and early cross-linking of the material, thereby reducing the overall processing performance and finished product qualification rate of the sheath material, which is not conducive to continuous industrial production.

[0018] Preferably, the modified EVA comprises maleic anhydride-grafted EVA.

[0019] This invention utilizes maleic anhydride-grafted EVA, which not only improves the dispersion performance of functional additives such as flame retardants, charring agents, and rodent repellents in EVM, but also allows the polar anhydride groups on the maleic anhydride-grafted EVA molecular chain to form strong polar interactions and hydrogen bonds with the vinyl acetate units in the EVM matrix, significantly enhancing their compatibility and interfacial bonding strength. Simultaneously, the anhydride groups can chemically bond and physically adsorb onto the active sites on the surfaces of functional additives such as flame retardants and charring agents, constructing a stable interfacial transition layer between the functional additives and EVM. This effectively reduces interfacial defects and stress concentration, resulting in more uniform stress transmission under external forces, thereby significantly improving tensile strength and elongation at break. Furthermore, the mutually compatible network structure formed by maleic anhydride-grafted EVA and EVM endows the material with excellent elastic recovery capabilities, reducing permanent deformation. The dense cross-linked and polar network structure synergistically constructed by the two also effectively hinders the penetration and swelling of small oil molecules, thus significantly enhancing the material's oil resistance.

[0020] Preferably, the grafting rate of the maleic anhydride-grafted EVA is ≥0.8%, for example, it can be 0.8%, 1%, 1.5%, 2%, 2.5% or 3%, etc.

[0021] Preferably, the melt index of the maleic anhydride-grafted EVA is 1-3 g / 10min, for example, it can be 1 g / 10min, 1.5 g / 10min, 2 g / 10min, 2.5 g / 10min or 3 g / 10min, etc.

[0022] Preferably, the flame retardant comprises aluminum hydroxide and / or magnesium hydroxide.

[0023] Preferably, the flame retardant comprises aluminum hydroxide and magnesium hydroxide.

[0024] Preferably, the flame retardant comprises aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:(1.1-2), for example, it can be 1:1.1, 1:1.2, 1:1.4, 1:1.5, 1:1.6, 1:1.8 or 1:2, etc.

[0025] This invention employs a synergistic flame retardant formulation of aluminum hydroxide and magnesium hydroxide, achieving flame retardancy through endothermic decomposition, dilution of combustible gases, and formation of a ceramicized char layer. If aluminum hydroxide is not added to the rubber-type cable protection sheath formulation, the smoke output after combustion increases significantly, the oxygen index decreases, the char layer formed by bundled combustion is not dense, it is easily burned through, and the cost increases. If magnesium hydroxide is not added to the rubber-type cable protection sheath formulation, the flame-retardant and heat-resistant layer weakens, the strength and density of the char layer decrease, and the residue after combustion is easily pulverized and detached.

[0026] Preferably, the smoke suppressant comprises zinc borate.

[0027] Preferably, the char-forming agent comprises dipentaerythritol.

[0028] The rubber-type cable protective sheath formulation provided by this invention includes a smoke suppressant and a charring agent. The smoke suppressant primarily suppresses smoke and promotes charring of the rubber-type cable protective sheath during combustion, achieving the technical effects of anti-dripping and forming a glassy coating at high temperatures. The charring agent provides gas-phase flame retardancy and rapid charring. If the rubber-type cable protective sheath formulation does not include a smoke suppressant, the smoke density will increase significantly, making it prone to dripping, burn-through, and flame propagation during flame retardancy. The char layer after combustion will be discontinuous and easily detach. If the formulation does not include a charring agent and relies solely on inorganic powders (flame retardants) for flame retardancy, the flame retardant efficiency will be insufficient, requiring a significant increase in the amount of flame retardant. However, this will lead to problems such as the rubber-type cable protective sheath becoming hard and brittle, deteriorating extrusion performance and mechanical properties, and worsening oxygen index. This invention preferably uses dipentaerythritol as the charring agent, which has excellent charring efficiency, better thermal stability, less odor, and stable compatibility with EVM.

[0029] Preferably, the coupling agent comprises a silane coupling agent.

[0030] Preferably, the crosslinking agent comprises any one or a combination of at least two of dicumyl peroxide, triallyl isocyanurate, trimethylolpropane trimethacrylate, or N,N'-m-phenylenebismaleimide.

[0031] Preferably, the crosslinking agent is a combination of dicumyl peroxide, triallyl isocyanurate, trimethylolpropane trimethacrylate, and N,N'-m-phenylenebismaleimide.

[0032] Preferably, the mass ratio of dicumyl peroxide, triallyl isocyanurate, trimethylolpropane trimethacrylate and N,N'-m-phenylenebismaleimide is 1:(0.5-1.5):(1-2):(1-2).

[0033] Among them, 0.5-1.5 can be, for example, 0.5, 0.6, 0.8, 1, 1.2, 1.4 or 1.5; 1-2 can be, for example, 1, 1.2, 1.4, 1.5, 1.6, 1.8 or 2.

[0034] This invention uses a combination of dicumyl peroxide, triallyl isocyanurate, trimethylolpropane trimethacrylate, and N,N'-m-phenylenebismaleimide as a crosslinking agent. This composite crosslinking system can effectively overcome the defects of low crosslinking efficiency, poor mechanical properties, and insufficient heat aging resistance caused by the filling of flame retardants in cable protection sheaths. It significantly improves the crosslinking density, structural compactness, and mechanical strength of the material, enhances the rodent and insect infestation resistance and long-term stability of the cable protection sheath, and enables the product to simultaneously meet the requirements of low smoke, halogen-free, flame retardant, rodent and insect infestation resistance, and excellent mechanical and heat resistance properties. If dicumyl peroxide is used alone, problems such as insufficient crosslinking, low mechanical strength, poor rodent and termite repellency, and easy aging and failure are likely to occur. If dicumyl peroxide and triallyl isocyanurate crosslinking agent system is used, although the crosslinking density is improved, there are defects such as slow vulcanization rate, weak interfacial bonding force, and still unsatisfactory rodent and termite repellency and heat resistance. The dicumyl peroxide and trimethylolpropane trimethacrylate crosslinking agent system has a fast crosslinking speed, but poor heat resistance, easy heat deformation, and poor rodent and termite repellency. The dicumyl peroxide and N,N'-m-phenylenebismaleimide crosslinking agent system has good heat resistance, but low crosslinking efficiency, slow vulcanization, and difficulty in meeting the mechanical strength requirements. Any binary crosslinking system can only improve the performance locally, but cannot simultaneously meet the comprehensive requirements of high-filled halogen-free flame retardant system for high strength, high heat resistance, rodent and termite repellency, low smoke halogen-free, and long-term use stability.

[0035] Preferably, the rodent repellent includes any one or a combination of at least two of the following: cyclooctene rodent repellents, camphor oil rodent repellents, synthetic capsaicin rodent repellents, or bifenthrin rodent repellents.

[0036] Preferably, the rodent repellent comprises a combination of DH-600, a synthetic capsaicin rodent repellent, and EX1001 termite repellent.

[0037] In the rubber-type cable protection sheath material formula provided by this invention, multiple rodent and termite repellent components work synergistically. DH-600 is mainly for rodent repellency, while also being effective against termites. It has the best effect on rodents, is heat resistant, and is easy to extrude. The synthetic capsaicin rodent and termite repellent is a super-strong irritant and repellent material that is effective against both rodents and termites. It is fast-acting and environmentally friendly. EX1001 is a professional termite repellent. The combination of the three components forms a three-dimensional protection system that provides dual protection against rodents and termites and rapid repulsion.

[0038] Preferably, the rubber-type cable protective sheath material further includes, by weight, any one or a combination of at least two of the following: 1-10 parts lubricant, 1-5 parts anti-aging agent, 1-10 parts pigment, or 1-5 parts release agent.

[0039] Among them, 1-10 portions can be, for example, 1 portion, 2 portions, 4 portions, 5 portions, 6 portions, 8 portions, or 10 portions; 1-5 portions can be, for example, 1 portion, 2 portions, 3 portions, 4 portions, or 5 portions.

[0040] Preferably, the lubricant comprises microcrystalline wax.

[0041] Preferably, the anti-aging agent includes hindered phenolic anti-aging agents.

[0042] Preferably, the pigment includes carbon black.

[0043] Preferably, the release agent includes EVM release agent.

[0044] In a second aspect, the present invention provides a method for preparing the rubber-type cable protective sheath material as described in the first aspect, the method comprising the following steps: The components of the rubber-type cable protective sheath are mixed to obtain the rubber-type cable protective sheath.

[0045] Thirdly, the present invention provides a cable comprising an outer protective sheath made of the rubber-type cable protective sheath material described in the first aspect.

[0046] Preferably, the cable includes, in sequence, an isolation wrapping tape, an insulation layer, a water-blocking wrapping tape, a flame-retardant wrapping tape, an oxygen-barrier layer, and an outer protective sheath disposed outside the cable core.

[0047] Preferably, the material of the isolation strap includes non-woven fabric.

[0048] Preferably, the thickness of the isolation tape is 0.1-0.4 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm or 0.4 mm, etc.

[0049] Preferably, the overlap rate of the isolation strap is 10-30%, for example, it can be 10%, 15%, 20%, 25% or 30%, etc.

[0050] Preferably, the insulating layer is made of ethylene propylene rubber.

[0051] Preferably, the thickness of the insulating layer is 2.0-2.6 mm, for example, it can be 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm or 2.6 mm, etc.

[0052] Preferably, the thickness of the water-blocking tape is 0.1-0.4 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm or 0.4 mm, etc.

[0053] Preferably, the overlap rate of the water-blocking tape is 10-50%, for example, it can be 10%, 20%, 30%, 40% or 50%.

[0054] The water-blocking tape used in this invention was purchased from Nantong Cyber ​​Communication Co., Ltd. It uses polyester non-woven fabric as the base material, and sodium polyacrylate superabsorbent resin is uniformly dispersed, coated on both sides and firmly attached to the surface of the polyester non-woven fabric with the help of an adhesive, so that the superabsorbent resin and the base material form a stable bond, thereby giving the water-blocking tape excellent water absorption, water retention and insulation properties.

[0055] Preferably, the thickness of the flame-retardant tape is 0.1-0.4 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm or 0.4 mm, etc.

[0056] Preferably, the overlap rate of the flame-retardant tape is 10-50%, for example, it can be 10%, 15%, 20%, 25%, 30%, 40% or 50%, etc.

[0057] The flame-retardant wrapping tape used in this invention was purchased from Yangzhou Gaoxin Cable Materials Co., Ltd. It uses halogen-free fiber cloth as the base material, and mixes halogen-free flame retardant, inorganic filler and environmentally friendly binder. The mixture is coated on both sides and firmly attached to the surface of the halogen-free fiber cloth, giving the flame-retardant wrapping tape excellent flame-retardant properties, mechanical properties and environmental friendliness.

[0058] Preferably, the thickness of the oxygen barrier layer is 1-3 mm, for example, it can be 1 mm, 1.5 mm, 2 mm, 2.5 mm or 3 mm.

[0059] The oxygen barrier material described in this invention includes a high flame-retardant, halogen-free, low-smoke flame-retardant rubber-type oxygen barrier material, purchased from Jiangsu Hengtong Power Cable Co., Ltd. (WDZB1-XH-90(GY)).

[0060] Preferably, the thickness of the outer protective sleeve is 1-3 mm, for example, it can be 1 mm, 1.5 mm, 2 mm, 2.5 mm or 3 mm, etc.

[0061] Preferably, the oxygen barrier layer and the outer protective sleeve form an oxygen barrier layer-outer protective sleeve composite structure.

[0062] Preferably, the oxygen barrier layer-outer protective sleeve composite structure is prepared by a double-layer co-extrusion process.

[0063] This invention relates to a cable structure design that sequentially incorporates an insulating wrapping tape, an insulation layer, a water-blocking wrapping tape, a flame-retardant wrapping tape, an oxygen-barrier layer, and an outer protective sheath around the cable core. The cable core is composed of multiple strands of annealed tin-plated copper single wires, and its composition, performance, and appearance must comply with the requirements of GB / T 3956-2008 "Conductors of Cables". The cable core surface is smooth, free of burrs, sharp edges, protruding or broken single wires that could damage the insulation, and its resistance value meets the requirements of GB / T 3956-2008 "Conductors of Cables". An insulating wrapping tape is extruded over the cable core to bind the flexible cable core and ensure the cable's roundness. The water-blocking tape serves both as insulation and water resistance. When the outer protective sheath is damaged, the highly absorbent components in the water-blocking tape quickly absorb moisture and expand dozens of times, forming a dense gel that fills the gap between the cable insulation layer and the flame-retardant tape. This prevents moisture from migrating longitudinally and penetrating laterally, and also avoids moisture aging of the insulation layer and corrosion and rusting of the cable core. The water-blocking tape also has the functions of buffering and shock absorption, and shielding electromagnetic interference. It can effectively reduce the risk of faults such as short circuits and signal attenuation, ensure the stability of power or communication transmission, and significantly extend the service life of cables in harsh environments.

[0064] The present invention also employs a double-layer co-extrusion one-time extrusion process to prepare an oxygen barrier layer-outer protective sheath composite structure. This preparation method firmly bonds the oxygen barrier layer and the outer protective sheath together. During combustion tests, the outer protective sheath is not easy to fall off, which can effectively improve the cable's resistance to dripping.

[0065] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention has developed a rubber-type cable protective sheath material by designing a formula for the cable protective sheath material. Compared with traditional thermoplastic cable protective sheath materials, it has better mechanical properties, oil resistance, crack resistance, rodent and ant resistance and heat resistance. It is suitable for DC1500V DC cables.

[0066] (2) The present invention also provides a cable in which the oxygen barrier layer and the outer protective sheath are both made of rubber material and are composited by a double-layer co-extrusion process, so that the two layers of the oxygen barrier layer and the outer protective sheath are firmly composited together. When the combustion test is carried out, the outer protective sheath is not easy to fall off and has excellent anti-dripping properties.

[0067] (3) The cable protective sheath provided by this invention has excellent rodent and termite resistance. Before oil immersion, the tensile strength can reach 9.8-12.5MPa, the elongation at break before oil immersion can reach 320-494%, the change rate of tensile strength after oil immersion is only -6~-10%, the change rate of elongation at break after oil immersion is only -8~-22%, and the Shore hardness can reach 68-78 HA. The rubber-type cable protective sheath has no cracks after testing according to GB / T2951.31-2008. The cable provided by this invention has excellent flame retardancy and anti-dripping properties. The flame retardancy can reach the B1 standard of GB / T 31247-2014, and the anti-dripping property can reach the d0 standard of GB / T 31247-2014. The DC resistance of the conductor of the cable provided by this invention meets the requirements of GB / T 3956-2008 "Conductors of Cables". The maximum allowable operating temperature is greater than 90℃, the short-circuit allowable temperature is greater than 250℃, and the maximum duration is greater than 5. s has excellent electrical conductivity and flame retardancy. Attached Figure Description

[0068] Figure 1 This is a schematic diagram of the cross-sectional structure of the cable provided by the present invention; Among them, 1-cable core, 2-isolation wrapping tape, 3-insulation layer, 4-water-blocking wrapping tape, 5-flame-retardant wrapping tape, 6-oxygen barrier layer, and 7-outer protective sleeve. Detailed Implementation

[0069] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0070] The specific information of the materials used in the following specific embodiments of the present invention is as follows: EVM, Yihuaping EVM 500HV, purchased from Shanghai Tianliu Cable Materials Co., Ltd.; Maleic anhydride-grafted EVA, UE4003, purchased from Shanghai Xuerkai New Materials Co., Ltd. Aluminum hydroxide, Al-40, purchased from Shanghai Weijie Cable Materials Co., Ltd. Magnesium hydroxide was purchased from Yantai Aifuer Flame Retardant Technology Co., Ltd. Smoke suppressant, zinc borate; Carbon-forming agent, dipentaerythritol; Coupling agent, KH550; Crosslinking agent: dicumyl peroxide; Crosslinking agent, triallyl isocyanurate; Crosslinking agent, trimethylolpropane trimethacrylate; Crosslinking agent, N,N'-m-phenylenebismaleimide; Rodent and ant repellent, DH-600, purchased from Leitai Biotechnology; Rodent and ant repellent, M-17, purchased from Qingdao Haike New Materials Co., Ltd.; Rodent and ant repellent, EX1001, purchased from Raytek Biotechnology; Lubricant, microcrystalline wax; Anti-aging agent, XH-3, purchased from Taizhou Xubang New Material Development Co., Ltd.; Pigments, carbon black; EVM mold release agent, ROCESS 18D, purchased from Wuxi Norman Polymer Materials Co., Ltd. The isolation tape, made of non-woven fabric, was purchased from Yangzhou Gaoxin Cable Materials Co., Ltd. Ethylene propylene rubber, purchased from Jiangsu Hengtong Power Cable Co., Ltd.; Water-blocking tape, purchased from Nantong Cyber ​​Communication Co., Ltd.; Flame-retardant wrapping tape, purchased from Yangzhou Gaoxin Cable Materials Co., Ltd. High flame retardant, halogen-free, low-smoke flame retardant rubber-type oxygen barrier material (WDZB1-XH-90(GY)) was purchased from Jiangsu Hengtong Power Cable Co., Ltd.

[0071] Example 1 This embodiment provides a rubber-type cable protective sheath material and its preparation method. The rubber-type cable protective sheath material comprises, by weight, the following: 50 parts EVM, 20 parts maleic anhydride-grafted EVA, 50 parts aluminum hydroxide, 80 parts magnesium hydroxide, 40 parts zinc borate, 2 parts dipentaerythritol, 2 parts coupling agent KH-550, 1 part dicumyl peroxide, 1 part triallyl isocyanurate, 1.5 parts trimethylolpropane trimethacrylate, 1.5 parts N,N'-m-phenylenebismaleimide, 1 part rodenticide DH-600, 0.5 parts synthetic capsaicin rodenticide, 0.5 parts rodenticide EX1001, 5 parts microcrystalline wax, 3 parts anti-aging agent XH-3, 5 parts carbon black, and 3 parts EVM release agent.

[0072] The preparation method includes: mixing the components of the rubber-type cable protective sheath to obtain the rubber-type cable protective sheath.

[0073] Example 2 This embodiment provides a rubber-type cable protective sheath material and its preparation method. The rubber-type cable protective sheath material comprises, by weight, the following: 30 parts EVM, 10 parts maleic anhydride-grafted EVA, 60 parts aluminum hydroxide, 90 parts magnesium hydroxide, 60 parts zinc borate, 5 parts dipentaerythritol, 1 part coupling agent KH-550, 1 part dicumyl peroxide, 0.5 parts triallyl isocyanurate, 1 part trimethylolpropane trimethacrylate, 1 part N,N'-m-phenylenebismaleimide, 2 parts rodenticide DH-600, 1 part rodenticide synthetic capsaicin, 2 parts rodenticide EX1001, 2 parts microcrystalline wax, 1 part anti-aging agent XH-3, 1 part carbon black, and 1 part EVM release agent.

[0074] The preparation method includes: mixing the components of the rubber-type cable protective sheath to obtain the rubber-type cable protective sheath.

[0075] Example 3 This embodiment provides a rubber-type cable protective sheath material and its preparation method. The rubber-type cable protective sheath material comprises, by weight, the following: 70 parts EVM, 30 parts maleic anhydride-grafted EVA, 35 parts aluminum hydroxide, 75 parts magnesium hydroxide, 20 parts zinc borate, 1 part dipentaerythritol, 5 parts coupling agent KH-550, 2 parts dicumyl peroxide, 3 parts triallyl isocyanurate, 2 parts trimethylolpropane trimethacrylate, 2 parts N,N'-m-phenylenebismaleimide, 0.5 parts rodenticide DH-6000, 1 part synthetic capsaicin rodenticide, 0.5 parts rodenticide EX1001, 7 parts microcrystalline wax, 4 parts anti-aging agent XH-3, 7 parts carbon black, and 4 parts EVM release agent.

[0076] The preparation method includes: mixing the components of the rubber-type cable protective sheath to obtain the rubber-type cable protective sheath.

[0077] Example 4 This embodiment provides a rubber-type cable protective sheath material and its preparation method. The difference from Embodiment 1 is that the amount of maleic anhydride-grafted EVA is adjusted to 10 parts by weight, while the rest is the same as in Embodiment 1.

[0078] Example 5 This embodiment provides a rubber-type cable protective sheath material and its preparation method. The difference from Embodiment 1 is that the amount of maleic anhydride-grafted EVA is adjusted to 30 parts by weight, while the rest is the same as in Embodiment 1.

[0079] Example 6 This embodiment provides a rubber-type cable protective sheath material and its preparation method. The difference from Embodiment 1 is that the rubber-type cable protective sheath material includes, by weight, the following: 50 parts EVM, 20 parts maleic anhydride-grafted EVA, 50 parts aluminum hydroxide, 80 parts magnesium hydroxide, 40 parts zinc borate, 2 parts dipentaerythritol, 2 parts coupling agent KH-550, 2.5 parts dicumyl peroxide, 2.5 parts triallyl isocyanurate, 1 part rodenticide DH-600, 0.5 parts synthetic capsaicin rodenticide, 0.5 parts rodenticide EX1001, 5 parts microcrystalline wax, 3 parts anti-aging agent XH-3, 5 parts carbon black, and 3 parts EVM release agent.

[0080] Comparative Example 1 This comparative example provides a rubber-type cable protective sheath material and its preparation method. The rubber-type cable protective sheath material comprises, by weight, the following: 50 parts EVM, 50 parts aluminum hydroxide, 80 parts magnesium hydroxide, 40 parts zinc borate, 2 parts dipentaerythritol, 2 parts coupling agent KH-550, 1 part dicumyl peroxide, 1 part triallyl isocyanurate, 1.5 parts trimethylolpropane trimethacrylate, 1.5 parts N,N'-m-phenylenebismaleimide, 1 part rodenticide DH-600, 0.5 parts synthetic capsaicin rodenticide, 0.5 parts rodenticide EX1001, 5 parts microcrystalline wax, 3 parts anti-aging agent XH-3, 5 parts carbon black, and 3 parts EVM release agent.

[0081] The preparation method includes: mixing the components of the rubber-type cable protective sheath to obtain the rubber-type cable protective sheath.

[0082] Comparative Example 2 This comparative example provides a rubber-type cable protective sheath material and its preparation method. The rubber-type cable protective sheath material comprises, by weight, the following: 50 parts EVM, 20 parts maleic anhydride-grafted EVA, 50 parts aluminum hydroxide, 80 parts magnesium hydroxide, 40 parts zinc borate, 2 parts coupling agent KH-550, 1 part dicumyl peroxide, 1 part triallyl isocyanurate, 1.5 parts trimethylolpropane trimethacrylate, 1.5 parts N,N'-m-phenylenebismaleimide, 1 part rodenticide DH-600, 0.5 parts synthetic capsaicin rodenticide, 0.5 parts rodenticide EX1001, 5 parts microcrystalline wax, 3 parts anti-aging agent XH-3, 5 parts carbon black, and 3 parts EVM release agent.

[0083] The preparation method includes: mixing the components of the rubber-type cable protective sheath to obtain the rubber-type cable protective sheath.

[0084] Comparative Example 3 This comparative example provides a rubber-type cable protective sheath material and its preparation method. The difference from Example 1 is that the amount of maleic anhydride-grafted EVA is adjusted to 5 parts by weight, while the rest are the same as in Example 1.

[0085] Comparative Example 4 This comparative example provides a rubber-type cable protective sheath material and its preparation method. The difference from Example 1 is that the amount of maleic anhydride-grafted EVA is adjusted to 35 parts by weight, while the rest are the same as in Example 1.

[0086] Application Example 1 This application example provides a cable and a method for its fabrication, such as... Figure 1 The cable includes, in sequence, an isolation wrapping tape 2, an insulation layer 3, a water-blocking wrapping tape 4, a flame-retardant wrapping tape 5, an oxygen barrier layer 6, and an outer protective sleeve 7 made of the rubber-type cable protective sheath material provided in Example 1, which are disposed outside the cable core 1.

[0087] The preparation method includes: The cable core uses 0.4 mm tin-plated copper monofilaments. Thirty tin-plated copper monofilaments are bundled into copper strands using a high-speed wire bundling machine, and then further twisted together with 50 strands of annealed tin-plated copper strands. An insulating tape with a thickness of 0.2 mm and an overlap of 20% is wrapped around the outside of the cable core. After wrapping the insulating tape, ethylene propylene rubber is extruded onto the outside of the cable core using an extrusion machine to form an insulation layer with a thickness of 2.3 mm. This insulation layer is then vulcanized through a vulcanization pipe at a steam pressure of 10 MPa and a traction speed of 5 m / min. A water-blocking tape with a thickness of 0.2 mm and an overlap of 30% is wrapped around the surface of the insulation layer. Finally, a flame-retardant tape with a thickness of 0.2 mm is wrapped around the surface of the water-blocking tape. mm, the overlap rate of the water-blocking tape is 30%; a double-layer co-extrusion process is adopted to co-extrude the high flame-retardant halogen-free low-smoke flame-retardant rubber-type oxygen barrier material and the rubber-type cable protective sheath material provided in Example 1 onto the cable core after wrapping with flame-retardant tape. The thickness of the oxygen barrier layer is 2 mm, the thickness of the outer protective sheath is 2 mm, and then vulcanization is carried out through a vulcanization pipe with a steam pressure of 10 MPa, a traction speed of 5 m / min, and a cooling water level ratio of 30% in the vulcanization pipe.

[0088] Application Examples 1-6 and Comparative Application Examples 1-4 Application Examples 1-6 and Comparative Application Examples 1-4 each provide a cable and its preparation method. The difference from Application Example 1 is that the rubber-type cable protective sheath material provided in Example 1 is replaced with the rubber-type cable protective sheath material provided in Examples 1-6 and Comparative Examples 1-4.

[0089] Test methods The rubber-type cable protective sheath materials provided in the examples and comparative examples were subjected to sheet vulcanization using a flat vulcanizing apparatus (pressed at 170°C for 15 min at a pressure of 18 MPa) to prepare separate outer protective sheath test pieces, and the following performance tests were performed: (1) Rodent and termite resistance: Tested in accordance with JB / T 10696.10-2011 and JB / T 10696.9-2011; (2) Oil resistance: Tested according to GB / T 1690-2010; (3) Tensile strength (MPa): Tested according to GB / T 2941-2025; (4) Elongation at break (%): Tested in accordance with GB / T 2941-2025; (5) Shore A (HA): Tested according to GB / T 39693.4-2025; (6) Crack resistance: Tested according to GB / T 2951.31-2008; The cables provided in the corresponding use cases and comparative application examples underwent the following performance tests: (7) Flammability: Tested in accordance with GB / T 31247-2014; (8) Resistance to dripping: The level of burning drips / particles shall be tested in accordance with GB / T 31247-2014.

[0090] The test results are shown in Tables 1 and 2: Table 1 Table 2 The test results show that: (1) As can be seen from Examples 1 to 6, the present invention has prepared a rubber-type cable protective sheath material by designing the formula of the cable protective sheath material. It has excellent mechanical properties, oil resistance, crack resistance, rodent and termite resistance and heat resistance. The tensile strength before oil immersion can reach 9.8-12.5 MPa, the elongation at break before oil immersion can reach 320-494%, the change rate of tensile strength after oil immersion is only -6 to -10%, the change rate of elongation at break after oil immersion is only -8 to -22%, and the Shore hardness can reach 68-78 HA. The rubber-type cable protective sheath material showed no cracks after being tested according to GB / T 2951.31-2008. As can be seen from Application Examples 1 to 6, the cable provided by the present invention has excellent flame retardancy and anti-dripping properties. The flame retardancy can reach the B1 standard of GB / T 31247-2014, and the anti-dripping properties can reach the d0 standard of GB / T 31247-2014.

[0091] (2) As can be seen from Examples 1 and 4-5 and Comparative Examples 1 and 3-4, by further limiting the addition and amount of maleic anhydride-grafted EVA, the introduction of maleic anhydride-grafted EVA can effectively improve the dispersion performance of functional additives such as flame retardants in EVM, and improve the overall performance of rubber-type cable protective sheath material. The rubber-type cable protective sheath material prepared by using maleic anhydride-grafted EVA and EVM in combination also exhibits better tensile properties, resilience and oil resistance. If too little maleic anhydride-grafted EVA is added, it is difficult to fully improve the interfacial bonding effect between functional additives such as flame retardants and EVM matrix. The functional additives are prone to agglomeration and uneven dispersion, resulting in a decrease in the mechanical properties of the material, a decrease in resilience, and the oil resistance cannot achieve the ideal effect. If too much maleic anhydride-grafted EVA is added, it will cause the system to be too polar and the melt viscosity to be too high. This is not only not conducive to processing and molding, but also affects the cross-linking structure of the material, which leads to a decrease in mechanical properties such as tensile strength and elongation at break. At the same time, it will increase the material cost and is not conducive to industrial production application.

[0092] (3) As can be seen from Examples 1 and 6, the present invention optimizes the formulation of the crosslinking agent and uses a combination of dicumyl peroxide, triallyl isocyanurate, trimethylolpropane trimethacrylate and N,N'-m-phenylenebismaleimide as the crosslinking agent. This composite crosslinking system can effectively overcome the defects of low crosslinking efficiency, poor mechanical properties and insufficient heat aging resistance caused by the filling of flame retardants in cable protection sheaths. It significantly improves the crosslinking density, structural compactness and mechanical strength of the material, enhances the anti-rodent and anti-insect performance and long-term stability of cable protection sheaths, and enables the product to simultaneously meet the requirements of low smoke, halogen-free, flame retardant, anti-rodent and anti-insect and excellent mechanical and heat resistance properties.

[0093] (4) As can be seen from Example 1 and Comparative Example 2, the present invention introduces a carbonizing agent into the rubber-type cable protective sheath formulation. The addition of the carbonizing agent makes the rubber-type cable protective sheath have excellent carbonization efficiency, better thermal stability, less odor, and effectively improves the cable's resistance to dripping.

[0094] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A rubber-type cable protective sheath material, characterized in that, The rubber-type cable protective sheath material comprises, by weight, 30-70 parts EVM, 10-30 parts modified EVA, 100-150 parts flame retardant, 20-60 parts smoke suppressant, 1-5 parts charring agent, 1-5 parts coupling agent, 1-15 parts crosslinking agent, and 1-5 parts rodent and ant repellent.

2. The rubber-type cable protective sheath material according to claim 1, characterized in that, The mass content of VA in the EVM is 45-55%; Preferably, the Mooney viscosity of the EVM is 23-31 MU.

3. The rubber-type cable protective sheath material according to claim 1 or 2, characterized in that, The modified EVA includes maleic anhydride-grafted EVA; Preferably, the grafting rate of the maleic anhydride-grafted EVA is ≥0.8%; Preferably, the melt index of the maleic anhydride-grafted EVA is 1-3 g / 10min.

4. The rubber-type cable protective sheath material according to any one of claims 1-3, characterized in that, The flame retardant includes aluminum hydroxide and / or magnesium hydroxide; Preferably, the flame retardant comprises aluminum hydroxide and magnesium hydroxide; Preferably, the flame retardant comprises aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:(1.1-2). Preferably, the smoke suppressant comprises zinc borate; Preferably, the char-forming agent comprises dipentaerythritol; Preferably, the coupling agent comprises a silane coupling agent; Preferably, the crosslinking agent comprises any one or a combination of at least two of dicumyl peroxide, triallyl isocyanurate, trimethylolpropane trimethacrylate, or N,N'-m-phenylenebismaleimide; Preferably, the crosslinking agent is a combination of dicumyl peroxide, triallyl isocyanurate, trimethylolpropane trimethacrylate and N,N'-m-phenylenebismaleimide; Preferably, the mass ratio of dicumyl peroxide, triallyl isocyanurate, trimethylolpropane trimethacrylate, and N,N'-m-phenylenebismaleimide is 1:(0.5-1.5):(1-2):(1-2); Preferably, the rodent repellent includes any one or a combination of at least two of the following: cyclooctene rodent repellents, camphor oil rodent repellents, synthetic capsaicin rodent repellents, or bifenthrin rodent repellents.

5. The rubber-type cable protective sheath material according to any one of claims 1-4, characterized in that, The rubber-type cable protective sheath material further includes, by weight, any one or a combination of at least two of the following: 1-10 parts lubricant, 1-5 parts anti-aging agent, 1-10 parts pigment, or 1-5 parts release agent.

6. The rubber-type cable protective sheath material according to claim 5, characterized in that, The lubricant includes microcrystalline wax; Preferably, the anti-aging agent includes hindered phenolic anti-aging agents; Preferably, the pigment includes carbon black; Preferably, the release agent includes EVM release agent.

7. A method for preparing a rubber-type cable protective sheath as described in any one of claims 1-6, characterized in that, The preparation method includes the following steps: The components of the rubber-type cable protective sheath are mixed to obtain the rubber-type cable protective sheath.

8. A cable, characterized in that, The cable includes an outer protective sheath made of the rubber-type cable protective sheath material as described in any one of claims 1-6.

9. The cable according to claim 8, characterized in that, The cable includes, in sequence, an isolation wrapping tape, an insulation layer, a water-blocking wrapping tape, a flame-retardant wrapping tape, an oxygen-barrier layer, and an outer protective sheath disposed outside the cable core.

10. The cable according to claim 8 or 9, characterized in that, The thickness of the isolation strap is 0.1-0.4 mm; Preferably, the overlap rate of the isolation strap is 10-30%; Preferably, the thickness of the insulating layer is 2.0-2.6 mm; Preferably, the thickness of the water-blocking tape is 0.1-0.4 mm; Preferably, the overlap rate of the water-blocking tape is 10-50%; Preferably, the thickness of the flame-retardant wrapping tape is 0.1-0.4 mm; Preferably, the overlap rate of the flame-retardant strap is 10-50%; Preferably, the thickness of the oxygen barrier layer is 1-3 mm; Preferably, the thickness of the outer protective sleeve is 1-3 mm; Preferably, the oxygen barrier layer and the outer protective sleeve form an oxygen barrier layer-outer protective sleeve composite structure; Preferably, the oxygen barrier layer-outer protective sleeve composite structure is prepared by a double-layer co-extrusion process.

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