Flame-retardant rat-proof cable and production method thereof

Abstract

The invention relates to the technical field of cable production, and discloses a flame-retardant rat-proof cable, which comprises a conductor, and a conductor shielding layer, an insulating layer, a fireproof layer and a sheath layer which are sequentially coated outside the conductor. The invention provides a production method which comprises the following steps: S1, preparing raw materials; s2, sheath layer material mixing; s3, extruding a conductor shielding layer; s4, extruding an insulating layer; s5, wrapping a fireproof layer; and S6, extruding a sheath layer. According to the present invention, the natural plant extract and the inorganic nanoparticle compound with the specific ratio are introduced as the rat-proof additive, such that the special odor of the natural plant extract is adopted to effectively repel the rats so as to reduce the possibility of approaching and biting the cable, and the dual rat-proof mechanism of the odor repelling and the physical protection is achieved; the problem that the rat-proof performance of the cable is reduced due to the plasticizing effect of the flame retardant is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of cable production, in particular to a flame-retardant and rat-proof cable and a production method thereof. Background Art

[0002] During long-term operation, cables may generate high temperatures due to overload, short circuit, poor contact, etc., which may cause fires. In some old buildings, due to the continuous increase of electrical equipment, cables are in high-load operation for a long time, which can easily lead to aging and damage of the insulation layer, generating electric sparks, and thus causing fires. In some industrial sites, such as refineries and chemical plants, there are flammable and explosive gases or liquids. Once the cable catches fire, it is very easy to cause a large-scale explosion accident. Therefore, the requirements for flame retardancy in existing cables are getting higher and higher.

[0003] After searching, the Chinese patent number CN105206344B discloses a flame retardant and corrosion resistant power cable, including a conductor, a conductor shielding layer coated on the outside of the conductor, an insulating layer coated on the outside of the conductor shielding layer, a fire resistant layer coated on the outside of the insulating layer, a sheath layer coated on the outside of the fire resistant layer, and the sheath layer is made of EPDM rubber material. The raw materials of EPDM rubber material include: EPDM rubber, chlorosulfonated polyethylene, phenyltrimethoxysilane, dilauroyl peroxide, modified composite fiber, calcium carbonate, zinc borate, montmorillonite, tricresyl phosphate, ammonium polyphosphate, antioxidant, etc. The invention is corrosion resistant, flame retardant, and has excellent thermal stability.

[0004] However, in actual use, phosphate substances have a certain plasticizing effect, and the function of plasticizers is to insert between polymer molecular chains, weaken the interaction force between molecular chains, make the molecular chains easier to slide, thereby increasing the flexibility of the material. When phosphate phosphorus flame retardants are added to the wire matrix, they will have a similar effect to plasticizers, making the wires softer, especially when tricresyl phosphate is added as a flame retardant to polyvinyl chloride (PVC) wires. As the amount of addition increases, the hardness of the PVC wire will gradually decrease, thus becoming softer, making it easier to be bitten through by rats, reducing the rat-proof performance. In some underground cable trenches, tunnels and other environments, due to the relatively closed space and frequent rat activities, the probability of cables being damaged by rats is higher. Based on this, the present invention designs a flame-retardant and rat-proof cable and a production method thereof to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a flame retardant and rat-proof cable and a production method thereof, which solves the problem in the background technology that flame retardants reduce the rat-proof performance.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A flame-retardant and rat-proof cable comprises a conductor and a conductor shielding layer, an insulating layer, a fire-resistant layer and a sheath layer which are sequentially coated outside the conductor, wherein the sheath layer is made of an improved rubber material and comprises the following raw materials in parts by weight:

[0008] 45-65 parts of EPDM rubber;

[0009] Chlorosulfonated polyethylene 10-20 parts;

[0010] 4-7 parts of phenyltrimethoxysilane;

[0011] 2-4 parts of dilauroyl peroxide;

[0012] 20-30 parts of modified composite fiber, wherein the modified composite fiber is a mixture of surface-treated glass fiber and aramid fiber, and the mass ratio of the glass fiber to the aramid fiber is 3:2-2:3;

[0013] Calcium carbonate 12-22 parts;

[0014] 8-15 parts of zinc borate;

[0015] 5-10 parts of montmorillonite;

[0016] 10-20 parts of flame retardant, which is halogen-free and has no plasticizing effect. Its decomposition temperature ranges from 300 to 350°C at high temperatures. It can form a continuous and dense carbon layer when burning, and the thermal conductivity of the carbon layer is less than 0.1W / (m·K);

[0017] 2-5 parts of antioxidant;

[0018] The rodent-proof additive is 5-10 parts, which is a compound of natural plant extract and inorganic nanoparticles, wherein the natural plant extract accounts for 60%-80% of the weight of the compound, and the average particle size of the inorganic nanoparticles is 50-100nm.

[0019] Preferably, in the modified composite fiber, a silane coupling agent is used for surface treatment, and its content in the modified composite fiber is 2%-5%, so as to enhance the interface bonding force between the fiber and the rubber matrix.

[0020] It can be seen from the above technical scheme that the modified composite fiber is made of glass fiber and aramid fiber mixed in a mass ratio of 3:2-2:3. Glass fiber has the characteristics of high strength and high modulus, which can provide basic mechanical support for the cable sheath and enhance its tensile strength and rigidity. Aramid fiber is known for its excellent toughness and wear resistance, which can effectively improve the tear resistance and friction resistance of the sheath material. When the cable is stretched or squeezed externally, the glass fiber can withstand most of the tensile stress and prevent the sheath from being broken; while the aramid fiber can absorb the impact energy and avoid the sheath rupture caused by local stress concentration, thereby significantly improving the overall mechanical properties of the cable sheath and extending the service life of the cable. Due to the complementary properties of glass fiber and aramid fiber, they are evenly dispersed in the sheath material, so that the externally applied stress can be evenly transmitted and distributed throughout the material. When the cable is subjected to external force, there will be no excessive local stress, which effectively avoids cracks and breakage caused by stress concentration, and further enhances the cable sheath's resistance to various mechanical external forces.

[0021] The surface of the modified composite fiber is treated with a silane coupling agent, and the content of the silane coupling agent in the modified composite fiber is 2%-5%. The silane coupling agent molecule has a special structure, one end of which can react chemically with the hydroxyl groups on the surface of the glass fiber and aramid fiber to form a chemical bond; the other end can react or interact with the active groups in the rubber matrix such as EPDM rubber, greatly enhancing the interfacial bonding between the fiber and the rubber matrix.

[0022] Preferably, the conductor shielding layer is made of a semi-conductive shielding material, and its volume resistivity is between 10^(-3)-10^(-1)Ω·m, which can effectively make the electric field uniform.

[0023] Preferably, the insulating layer is made of cross-linked polyethylene material with a cross-linking degree of not less than 80%, a dielectric constant of 2.2-2.5, and a dielectric loss tangent of not more than 0.002; and the thickness of the insulating layer is 1.5-2.5 mm.

[0024] Preferably, the fire-resistant layer is formed by wrapping mica tape, and the wrapping overlap rate of the mica tape is 30%-50%. It can maintain the integrity of the cable for not less than 90 minutes at a high temperature of 950-1000°C; the unit area mass of the mica tape of the fire-resistant layer is 150-250g / m 2 .

[0025] It can be seen from the above technical solution that the insulation layer is made of cross-linked polyethylene material, which can effectively prevent current leakage and ensure the stable transmission of current in the conductor. Good insulation performance not only helps to maintain the normal operation of the cable, but also prevents fires caused by electric sparks generated by leakage, and also avoids electrical failures caused by insulation failure, indirectly improving the safety and stability of the cable.

[0026] The fire-resistant layer is made of mica tape wrapped with an overlap rate of 30%-50%. The mass per unit area of ​​the mica tape is 150-250g / m 2 At high temperatures of 950-1000°C, the integrity of the cable can be maintained for no less than 90 minutes. When a fire occurs, the fire-resistant layer can withstand high temperatures, delaying the damage of the flames to the internal conductors, insulation layers and other structures, ensuring that the cable can still transmit power or signals normally within a certain period of time, buying precious time for personnel evacuation, fire rescue, etc.

[0027] Preferably, the inorganic nanoparticles in the rodent-proof additive are nano-titanium dioxide or nano-zinc oxide, which have a complete crystal structure, a crystallinity of not less than 90%, and a specific surface area of ​​50-100 m 2 / g, synergistically with natural plant extracts to resist the risk of rats biting through due to softening of the sheath material.

[0028] Through the above technical scheme, it can be known that the natural plant extracts in the rat-proofing additives, such as peppermint oil, camphor oil, lavender oil or neem oil, will continue to emit a special smell. Rats have a keen sense of smell and are extremely sensitive and uncomfortable with these smells. They will instinctively avoid cables emitting such smells, thereby reducing the possibility of actively gnawing on the cables, thereby achieving rat-proofing from a behavioral level.

[0029] The inorganic nanoparticles are nano-titanium dioxide or nano-zinc oxide, with a complete crystal structure, a crystallinity of not less than 90%, and a specific surface area of ​​50-100m 2 / g. They are evenly dispersed in the sheath material. Due to their extremely small particle size and large specific surface area, they can fully contact and interact with the rubber matrix, significantly improving the hardness and strength of the sheath material. Even if mice try to gnaw the cable, it is difficult to bite through, providing physical anti-rat protection.

[0030] The odor repellent reduces the number of rats approaching the cable, while the enhanced hardness of the sheath provides effective resistance when rats try to gnaw on it. The two work together to effectively compensate for the decline in rodent-proofing performance due to the possible softening of the sheath material, ensuring that the cable has good rodent-proofing capabilities in all environments.

[0031] Preferably, the antioxidant is a compound of a hindered phenol antioxidant and a phosphite antioxidant, and the mass ratio of the two is 2:1-3:1.

[0032] Through the above technical solution, it can be known that hindered phenol antioxidants can capture free radicals generated by oxidation and other factors during the use of cables. Free radicals are the key factor leading to the aging of polymer materials. Hindered phenol antioxidants react with free radicals to form stable compounds, thereby interrupting the free radical chain reaction and slowing down the aging of cable materials. The common hindered phenol antioxidant 2,6-di-tert-butyl-p-cresol (BHT) can react with free radicals R· to generate stable products, preventing free radicals from further inducing aging reactions such as breakage and cross-linking of rubber molecular chains.

[0033] Cable materials will produce hydroperoxides under the action of oxygen and heat. These hydroperoxides are unstable and will decompose to produce new free radicals, accelerating the aging process. Phosphite antioxidants can reduce hydroperoxides to alcohols, thereby inhibiting the decomposition of hydroperoxides and reducing the generation of free radicals. Common triphenyl phosphite can react with hydroperoxide ROOH and convert it into alcohol ROH, thereby playing an antioxidant role.

[0034] Preferably, the flame retardant is selected from a combination of aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:1.2. The flame retardant can quickly form a continuous and dense carbon layer when burning, and the thermal conductivity of the carbon layer is lower than 0.08W / (m·K), and will not release hydrogen halide and its related halogenated harmful gases, and has no plasticizing effect.

[0035] Through the above technical scheme, it can be known that the flame retardant synergy of aluminum hydroxide and magnesium hydroxide: this cable uses a composition of aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:1.2 as a flame retardant. When the high temperature reaches 300-350℃, the two undergo a decomposition reaction. When aluminum hydroxide decomposes, it absorbs a large amount of heat to generate aluminum oxide. This process consumes heat, reduces the temperature around the cable, and slows down the thermal decomposition rate of the cable material. At the same time, magnesium hydroxide decomposes to generate magnesium oxide, and the generated aluminum oxide and magnesium oxide form a continuous and dense carbon layer on the surface of the cable.

[0036] The carbon layer has excellent thermal insulation performance, with a thermal conductivity of less than 0.08W / (m·K), forming an efficient thermal insulation barrier, effectively preventing external heat from entering the cable, inhibiting the decomposition and combustion of combustible substances inside the cable, and thus achieving flame retardancy. In addition, this flame retardant system will not release harmful gases such as hydrogen halides, is environmentally friendly and safe, and also avoids corrosion problems caused by halogenated gases.

[0037] Preferably, the natural plant extract is selected from at least one of peppermint oil, camphor oil, lavender oil and neem oil, which emits an odor that makes mice uncomfortable and inhibits mice from gnawing; the inorganic nanoparticles are selected from at least one of silicon dioxide, aluminum oxide, zinc oxide and titanium dioxide, and the average particle size of the inorganic nanoparticles is preferably 60-90nm to enhance the hardness of the sheath material.

[0038] A production method is provided, comprising the following steps:

[0039] Step S1, raw material preparation: weighing ethylene propylene diene monomer rubber, chlorosulfonated polyethylene, phenyl trimethoxy silane, dilauroyl peroxide, modified composite fiber, calcium carbonate, zinc borate, montmorillonite, flame retardant, antioxidant and rodent-proof additive according to the weight parts of claim 1; pretreating the modified composite fiber, soaking it in a solution containing a silane coupling agent for 2-4 hours, and then drying it at 80-100° C. for 3-5 hours;

[0040] Step S2, mixing the sheath layer materials: putting the weighed EPDM rubber and chlorosulfonated polyethylene into an internal mixer, mixing at 80-100° C. for 5-10 minutes; sequentially adding phenyltrimethoxysilane, dilauroyl peroxide, pretreated modified composite fiber, calcium carbonate, zinc borate, montmorillonite, flame retardant, antioxidant and rodent-proof additive, and continuing mixing for 15-25 minutes, controlling the temperature at 100-120° C., to obtain a mixed rubber for the sheath layer;

[0041] Step S3, extrusion of conductor shielding layer: putting the semi-conductive shielding material into an extruder, and extruding the conductor shielding layer on the surface of the conductor through the extruder, the extrusion temperature is controlled at 150-180° C., and the extrusion speed is 10-20 m / min;

[0042] Step S4, extrusion of insulating layer: putting the cross-linked polyethylene material into another extruder, and after preheating treatment, extruding the insulating layer outside the conductor shielding layer, the preheating temperature is 80-100°C, the extrusion temperature is 180-220°C, the extrusion speed is 8-15m / min, and then cross-linking treatment is performed, the cross-linking temperature is 150-170°C, and the cross-linking time is 10-20 minutes;

[0043] Step S5, wrapping the fire-resistant layer: wrapping the mica tape outside the insulation layer through a wrapping machine to form a fire-resistant layer, the wrapping speed is 5-10m / min, and the wrapping overlap rate is controlled to be 30%-50%;

[0044] Step S6, extrusion of the sheath layer: the mixed rubber of the sheath layer obtained in step S2 is put into an extruder, and the sheath layer is extruded outside the fire-resistant layer. The extrusion temperature is controlled at 130-160° C. and the extrusion speed is 6-10 m / min, and finally the flame-retardant and rat-proof cable is obtained.

[0045] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0046] 1. The present invention, by introducing a natural plant extract and an inorganic nanoparticle complex in a specific ratio as a rodent-proof additive, not only utilizes the special smell of the natural plant extract to effectively repel mice and reduce the possibility of their approaching and gnawing the cable, but also the addition of inorganic nanoparticles significantly enhances the hardness and wear resistance of the sheath material, making it difficult for mice to penetrate even if they try to gnaw, thereby realizing a dual rodent-proof mechanism of odor repellency and physical protection, and effectively solving the problem of decreased rodent-proof performance of cables due to the plasticizing effect of flame retardants.

[0047] 2. The present invention uses a halogen-free flame retardant that does not have a plasticizing effect. It can quickly form a continuous and dense carbon layer when burning. The carbon layer has an extremely low thermal conductivity, which effectively isolates heat transfer and prevents further combustion of the internal materials of the cable without releasing harmful halogenated gases. This ensures the flame retardant safety of the cable and avoids the plasticizing effect that may be caused by traditional phosphate flame retardants, thereby maintaining the mechanical strength and hardness of the cable.

[0048] 3. The present invention adopts a modified composite fiber formed by mixing surface-treated glass fiber and aramid fiber, and combines a silane coupling agent to enhance the interfacial bonding between the fiber and the rubber matrix, thereby significantly improving the tensile strength, rigidity, tear resistance and friction resistance of the cable sheath layer, making the cable more tough and durable when facing external forces, and extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a structural diagram of a flame-retardant and rat-proof cable of the present invention;

[0050] Figure 2 It is a content composition diagram of a flame retardant and rat-proof cable of the present invention;

[0051] Figure 3 The present invention is a production flow chart of a flame-retardant and rat-proof cable.

[0052] Among them: 1. Conductor; 2. Conductor shielding layer; 3. Insulation layer; 4. Fire-resistant layer; 5. Sheath layer. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] See also Figure 1-Figure 3In an embodiment of the present invention, a flame-retardant and rat-proof cable comprises a conductor 1 and a conductor shielding layer 2, an insulating layer 3, a fire-resistant layer 4 and a sheath layer 5 which are sequentially coated on the outside of the conductor 1, wherein the sheath layer 5 is made of an improved rubber material, and comprises the following raw materials by weight:

[0055] 45-65 parts of EPDM rubber;

[0056] Chlorosulfonated polyethylene 10-20 parts;

[0057] 4-7 parts of phenyltrimethoxysilane;

[0058] 2-4 parts of dilauroyl peroxide;

[0059] 20-30 parts of modified composite fiber, which is a mixture of surface-treated glass fiber and aramid fiber, with a mass ratio of glass fiber to aramid fiber of 3:2-2:3;

[0060] Calcium carbonate 12-22 parts;

[0061] 8-15 parts of zinc borate;

[0062] 5-10 parts of montmorillonite;

[0063] 10-20 parts of flame retardant, which is halogen-free and has no plasticizing effect. Its decomposition temperature ranges from 300 to 350°C at high temperatures. It can form a continuous and dense carbon layer when burning, and the thermal conductivity of the carbon layer is less than 0.1W / (m·K);

[0064] 2-5 parts of antioxidant;

[0065] The rodent-proof additive is 5-10 parts, which is a compound of natural plant extract and inorganic nanoparticles, wherein the natural plant extract accounts for 60%-80% of the weight of the compound, and the average particle size of the inorganic nanoparticles is 50-100nm.

[0066] In the modified composite fiber, a silane coupling agent is used for surface treatment, and its content in the modified composite fiber is 2%-5% to enhance the interface bonding force between the fiber and the rubber matrix.

[0067] The conductor shielding layer 2 is made of semi-conductive shielding material, and its volume resistivity is between 10^(-3)-10^(-1)Ω·m, which can effectively make the electric field uniform.

[0068] The insulating layer 3 is made of cross-linked polyethylene material, with a cross-linking degree of not less than 80%, a dielectric constant of 2.2-2.5, and a dielectric loss tangent value of not more than 0.002; the thickness of the insulating layer 3 is 1.5-2.5 mm.

[0069] The fire-resistant layer 4 is made of mica tape wrapped with an overlap rate of 30%-50%. It can maintain the integrity of the cable for no less than 90 minutes at a high temperature of 950-1000°C; the unit area mass of the mica tape of the fire-resistant layer 4 is 150-250g / m 2 .

[0070] The working principle of the embodiment of the present invention is as follows: the insulating layer 3 is made of cross-linked polyethylene material, which can effectively prevent current leakage and ensure the stable transmission of current in the conductor. Good insulation performance not only helps to maintain the normal operation of the cable, but also prevents fires caused by electric sparks generated by leakage, and also avoids electrical failures caused by insulation failure, indirectly improving the safety and stability of the cable.

[0071] The fireproof layer 4 is formed by wrapping mica tape, the wrapping overlap rate is 30%-50%, and the unit area mass of the mica tape is 150-250g / m 2 At a high temperature of 950-1000℃, the integrity of the cable can be maintained for no less than 90 minutes. When a fire occurs, the fire-resistant layer 4 can withstand the high temperature and delay the damage of the flame to the internal conductor, insulation layer 4 and other structures, ensuring that the cable can still transmit power or signals normally within a certain period of time, buying precious time for personnel evacuation, fire rescue, etc.

[0072] See also Figure 1-Figure 3 In the embodiment of the present invention, the inorganic nanoparticles in the rodent-proof additive are nano-titanium dioxide or nano-zinc oxide, which have a complete crystal structure, a crystallinity of not less than 90%, and a specific surface area of ​​50-100m 2 / g, synergistically with natural plant extracts to resist the risk of rats biting through due to softening of the sheath material.

[0073] The antioxidant is a compound of a hindered phenol antioxidant and a phosphite antioxidant, and the mass ratio of the two is 2:1-3:1.

[0074] The flame retardant is selected from a combination of aluminum hydroxide and magnesium hydroxide, with a mass ratio of 1:1.2. The flame retardant can quickly form a continuous and dense carbon layer during combustion, and the thermal conductivity of the carbon layer is lower than 0.08W / (m·K), and will not release hydrogen halide and related halogenated harmful gases, and has no plasticizing effect.

[0075] The natural plant extract is selected from at least one of peppermint oil, camphor oil, lavender oil and neem oil, which emits an odor that makes mice uncomfortable and inhibits mice from gnawing; the inorganic nanoparticles are selected from at least one of silicon dioxide, aluminum oxide, zinc oxide and titanium dioxide, and the average particle size of the inorganic nanoparticles is preferably 60-90nm to enhance the hardness of the sheath material.

[0076] The working principle of the embodiment of the present invention is: a composition of aluminum hydroxide and magnesium hydroxide in a mass ratio of 1:1.2 is used as a flame retardant. When the high temperature reaches 300-350°C, the two undergo a decomposition reaction. When aluminum hydroxide decomposes, it absorbs a large amount of heat to generate aluminum oxide. This process consumes heat, reduces the temperature around the cable, and slows down the thermal decomposition rate of the cable material. At the same time, magnesium hydroxide decomposes to generate magnesium oxide, and the generated aluminum oxide and magnesium oxide form a continuous and dense carbon layer on the surface of the cable. The carbon layer has excellent thermal insulation properties, with a thermal conductivity of less than 0.08W / (m·K), forming an efficient thermal insulation barrier, effectively preventing external heat from entering the interior of the cable, and inhibiting the decomposition and combustion of combustible materials inside the cable, thereby achieving flame retardancy, and this flame retardant system will not release harmful gases such as hydrogen halides, is environmentally friendly and safe, and also avoids corrosion and other problems caused by halogenated gases.

[0077] Natural plant extracts in rat-proofing additives, such as peppermint oil, camphor oil, lavender oil or neem oil, will continue to emit a special smell. Rats have a keen sense of smell and are extremely sensitive and uncomfortable with these smells. They will instinctively avoid cables that emit such smells, thereby reducing the possibility of actively gnawing on the cables, thus achieving rat-proofing at a behavioral level.

[0078] The inorganic nanoparticles in the rodent-proof additive are nano-titanium dioxide or nano-zinc oxide, which have a complete crystal structure, a crystallinity of not less than 90%, and a specific surface area of ​​50-100m 2 / g, synergistically with natural plant extracts to resist the risk of rats biting through due to softening of the sheath material.

[0079] See also Figure 1-Figure 3 In an embodiment of the present invention, a flame retardant and rat-proof cable provides a production method, comprising the following steps:

[0080] Step S1, raw material preparation: weighing ethylene propylene diene monomer rubber, chlorosulfonated polyethylene, phenyl trimethoxy silane, dilauroyl peroxide, modified composite fiber, calcium carbonate, zinc borate, montmorillonite, flame retardant, antioxidant and rodent-proof additive according to the weight parts of claim 1; pretreating the modified composite fiber, soaking it in a solution containing a silane coupling agent for 2-4 hours, and then drying it at 80-100° C. for 3-5 hours;

[0081] Step S2, mixing the materials of the sheath layer 5: putting the weighed EPDM rubber and chlorosulfonated polyethylene into an internal mixer, mixing at 80-100° C. for 5-10 minutes; sequentially adding phenyltrimethoxysilane, dilauroyl peroxide, pretreated modified composite fiber, calcium carbonate, zinc borate, montmorillonite, flame retardant, antioxidant and rodent-proof additive, and continuing mixing for 15-25 minutes, with the temperature controlled at 100-120° C., to obtain a mixed rubber of the sheath layer 5;

[0082] Step S3, extrusion of the conductor shielding layer 2: putting the semi-conductive shielding material into the extruder, and extruding the conductor shielding layer 2 on the surface of the conductor 1 through the extruder, the extrusion temperature is controlled at 150-180° C., and the extrusion speed is 10-20 m / min;

[0083] Step S4, extrusion of the insulating layer 3: putting the cross-linked polyethylene material into another extruder, and after preheating treatment, extruding the insulating layer 3 outside the conductor shielding layer 2, the preheating temperature is 80-100°C, the extrusion temperature is 180-220°C, the extrusion speed is 8-15m / min, and then cross-linking treatment is performed, the cross-linking temperature is 150-170°C, and the cross-linking time is 10-20 minutes;

[0084] Step S5, wrapping the fire-resistant layer 4: wrapping the mica tape around the insulating layer 3 through a wrapping machine to form the fire-resistant layer 4, with a wrapping speed of 5-10 m / min and a wrapping overlap rate of 30%-50%;

[0085] Step S6, extrusion of the sheath layer 5: the mixed rubber of the sheath layer 5 obtained in step S2 is put into the extruder, and the sheath layer 5 is extruded outside the fire-resistant layer 4. The extrusion temperature is controlled at 130-160°C and the extrusion speed is 6-10m / min, and finally a flame-retardant and rat-proof cable is obtained.

[0086] The working principle of the embodiment of the present invention is: in step S1, the raw material ratio is based on: according to the weight parts specified in claim 1, accurately weigh EPDM rubber, chlorosulfonated polyethylene, phenyltrimethoxysilane, dilauroyl peroxide, modified composite fiber, calcium carbonate, zinc borate, montmorillonite, flame retardant, antioxidant and rodent-proof additive. EPDM rubber and chlorosulfonated polyethylene are the main rubber raw materials of the sheath layer 5, which give the sheath good flexibility, weather resistance and mechanical strength, and provide basic support for the overall structure of the cable. Phenyltrimethoxysilane can improve the compatibility of fillers and rubber matrix, enhance the bonding force between the components, and improve the overall performance of the sheath layer 5. Dilauroyl peroxide, as a vulcanizing agent, promotes cross-linking of rubber molecular chains in subsequent processing and optimizes the physical and mechanical properties of rubber.

[0087] The modified composite fiber is pretreated by soaking it in a solution containing a silane coupling agent for 2-4 hours. During this process, the active groups in the silane coupling agent molecules react chemically with the groups on the surface of the modified composite fiber to form a chemical bond. It is then dried at 80-100°C for 3-5 hours to further stabilize the chemical bond. After this treatment, the organic group at the other end of the silane coupling agent can better interact with the rubber matrix in subsequent mixing, greatly enhancing the interfacial bonding force between the modified composite fiber and the rubber matrix. This not only helps to improve the mechanical properties of the sheath layer 5, but also has a positive impact on the overall durability and stability of the cable.

[0088] In step S2, the weighed EPDM rubber and chlorosulfonated polyethylene are put into an internal mixer. The main purpose of this stage is to make the two rubber matrices preliminarily and evenly mixed, so as to create favorable conditions for the subsequent addition and dispersion of other components. This temperature range can ensure that the rubber has appropriate fluidity and is convenient for mixing operations, and can also avoid premature vulcanization or performance degradation of the rubber due to excessively high temperature.

[0089] Phenyltrimethoxysilane, dilauroyl peroxide, pretreated modified composite fiber, calcium carbonate, zinc borate, montmorillonite, flame retardant, antioxidant and rodent-proof additive are added in sequence. As the ingredients are gradually added, the mechanical action of the internal mixer causes them to be evenly dispersed in the rubber matrix. In this temperature range, dilauroyl peroxide decomposes to produce free radicals, which triggers a cross-linking reaction between rubber molecular chains to form a three-dimensional network structure. This structural change significantly improves the strength, elasticity and heat resistance of the rubber. At the same time, fillers such as calcium carbonate, zinc borate and montmorillonite are evenly distributed in the rubber matrix, playing the role of reinforcing materials and synergistic flame retardancy. The pretreated modified composite fiber is closely integrated into it by virtue of the enhanced interface bonding force with the rubber matrix, further strengthening the mechanical properties of the sheath layer 5. The uniform dispersion of flame retardants, antioxidants and rodent-proof additives gives the cable flame retardant, anti-aging and rodent-proof properties, respectively, ensuring that the sheath layer 5 can effectively protect the internal structure and meet the use requirements of the cable in different environments.

[0090] In step S3, the semi-conductive shielding material is put into the extruder, and the conductor shielding layer 2 is extruded on the surface of the conductor 1 by the extruder at an extrusion temperature of 150-180°C and an extrusion speed of 10-20m / min. Within this temperature range, the semi-conductive shielding material has good fluidity and can be evenly and tightly coated on the surface of the conductor 1. The main function of the conductor shielding layer 2 is to homogenize the electric field distribution on the surface of the conductor 1 to prevent local discharge caused by electric field concentration. Accurately controlling the extrusion temperature and speed ensures the uniformity of the thickness of the conductor shielding layer 2 and the degree of close fit with the conductor 1, thereby effectively playing its role in homogenizing the electric field, ensuring the electrical safety performance of the cable, and providing basic conditions for the stable operation of subsequent layers.

[0091] In step S4, the cross-linked polyethylene material is put into another extruder to extrude the insulating layer 3 outside the conductor shielding layer 2. The preheating treatment allows the cross-linked polyethylene material to reach a suitable processing temperature and improve its fluidity so that it can be evenly and densely coated outside the conductor shielding layer 2 during the extrusion process. This extrusion temperature range ensures that the cross-linked polyethylene material has good plasticity during extrusion, ensuring the molding quality of the insulating layer (3).

[0092] After extrusion, the cross-linking reaction forms chemical bonds between the linear polyethylene molecular chains to construct a three-dimensional network structure. This structural transformation significantly improves the heat resistance, mechanical strength and electrical insulation performance of the insulating layer 3. The cross-linked insulating layer 3 can stably withstand the working voltage and temperature during the long-term operation of the cable, effectively prevent current leakage, ensure the safety and stability of power transmission, and provide a reliable insulation foundation for the subsequent fire-resistant layer 4 and sheath layer 5.

[0093] In step S5, a wrapping machine is used to wrap the mica tape around the insulating layer 3 at a wrapping speed to form a fire-resistant layer 4. The mica tape has excellent high temperature resistance. When a fire occurs, the mica component in the mica tape will expand at high temperature to form a heat insulation barrier, which effectively prevents heat from being transferred to the inside of the cable. The wrapping speed and overlap rate are precisely controlled to ensure that the thickness of the fire-resistant layer 4 is uniform and complete, so that the cable can maintain its integrity for no less than 90 minutes in a high temperature environment. This enables the cable to continue to provide power or signal transmission in a fire scene, buying valuable time for personnel evacuation, fire rescue, etc., and is a key structural layer to ensure that the cable can still work normally under extreme conditions.

[0094] In step S6, the sheath layer 5 rubber compound obtained in step S2 is put into an extruder, and the sheath layer 5 is extruded outside the fire-resistant layer 4 at a speed of 6-10m / min at an extrusion temperature of 130-160°C. This temperature range ensures that the rubber compound has good fluidity and can be evenly coated outside the fire-resistant layer 4, while avoiding the adverse effect of excessive temperature on the performance of each component in the rubber compound. The extruded sheath layer 5 tightly wraps the internal layers, not only providing mechanical protection for the cable to prevent external physical damage, but also achieving flame retardant, rat-proof and other functions by virtue of its unique raw material formula and structure. Through this series of precisely controlled production steps, each structural layer cooperates with each other, and finally a flame retardant and rat-proof cable with excellent comprehensive performance is manufactured to meet the use requirements in various complex environments.

[0095] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit thereof, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A flame-retardant and rat-proof cable, characterized in that: The invention comprises a conductor (1), and a conductor shielding layer (2), an insulating layer (3), a fire-resistant layer (4) and a sheath layer (5) which are sequentially coated on the outside of the conductor (1), wherein the sheath layer (5) is made of an improved rubber material and comprises the following raw materials in parts by weight: 45-65 parts of EPDM rubber; Chlorosulfonated polyethylene 10-20 parts; 4-7 parts of phenyltrimethoxysilane; 2-4 parts of dilauroyl peroxide; 20-30 parts of modified composite fiber, wherein the modified composite fiber is a mixture of surface-treated glass fiber and aramid fiber, and the mass ratio of the glass fiber to the aramid fiber is 3:2-2:3; Calcium carbonate 12-22 parts; 8-15 parts of zinc borate; 5-10 parts of montmorillonite; 10-20 parts of flame retardant, which is halogen-free and has no plasticizing effect. Its decomposition temperature ranges from 300 to 350°C at high temperatures. It can form a continuous and dense carbon layer when burning, and the thermal conductivity of the carbon layer is less than 0.1W / (m·K); 2-5 parts of antioxidant; The rodent-proofing additive is 5-10 parts, which is a compound of natural plant extracts and inorganic nanoparticles, wherein the natural plant extracts account for 60%-80% of the weight of the compound, and the average particle size of the inorganic nanoparticles is 50-100nm.

2. The flame-retardant and rat-proof cable according to claim 1, characterized in that: In the modified composite fiber, a silane coupling agent is used for surface treatment, and the content of the silane coupling agent in the modified composite fiber is 2%-5%, so as to enhance the interface bonding force between the fiber and the rubber matrix.

3. The flame-retardant and rat-proof cable according to claim 1, characterized in that: The conductor shielding layer (2) is made of a semi-conductive shielding material, and its volume resistivity is between 10^(-3)-10^(-1)Ω·m, which can effectively make the electric field uniform.

4. The flame-retardant and rat-proof cable according to claim 1, characterized in that: The insulating layer (3) is made of cross-linked polyethylene material, with a cross-linking degree of not less than 80%, a dielectric constant of 2.2-2.5, and a dielectric loss tangent value of not more than 0.002; the thickness of the insulating layer (3) is 1.5-2.5 mm.

5. The flame-retardant and rat-proof cable according to claim 1, characterized in that: The fire-resistant layer (4) is formed by wrapping mica tape, and the wrapping overlap rate of the mica tape is 30%-50%. It can maintain the integrity of the cable for not less than 90 minutes at a high temperature of 950-1000°C; the unit area mass of the mica tape of the fire-resistant layer (4) is 150-250g / m 2 .

6. The flame-retardant and rat-proof cable according to claim 1, characterized in that: The inorganic nanoparticles in the rodent-proof additive are nano titanium dioxide or nano zinc oxide, which have a complete crystal structure, a crystallinity of not less than 90%, and a specific surface area of ​​50-100 m 2 / g, synergistically with natural plant extracts to resist the risk of rats biting through due to softening of the sheath material.

7. The flame-retardant and rat-proof cable according to claim 1, characterized in that: The antioxidant is a compound of a hindered phenol antioxidant and a phosphite antioxidant, and the mass ratio of the two is 2:1-3:

1.

8. The flame-retardant and rat-proof cable according to claim 1, characterized in that: The flame retardant is selected from a combination of aluminum hydroxide and magnesium hydroxide, with a mass ratio of 1:1.

2. The flame retardant can quickly form a continuous and dense carbon layer when burning, and the thermal conductivity of the carbon layer is lower than 0.08W / (m·K), and will not release hydrogen halide and related halogenated harmful gases, and has no plasticizing effect.

9. The flame-retardant and rat-proof cable according to claim 1, characterized in that: The natural plant extract is selected from at least one of peppermint oil, camphor oil, lavender oil and neem oil, which emits an odor that makes mice uncomfortable and inhibits mice from gnawing; the inorganic nanoparticles are selected from at least one of silicon dioxide, aluminum oxide, zinc oxide and titanium dioxide, and the average particle size of the inorganic nanoparticles is preferably 60-90nm to enhance the hardness of the sheath material.

10. A flame-retardant and rat-proof cable according to any one of claims 1 to 9, providing a production method, characterized in that: The following steps are involved: Step S1, raw material preparation: weighing ethylene propylene diene monomer rubber, chlorosulfonated polyethylene, phenyl trimethoxy silane, dilauroyl peroxide, modified composite fiber, calcium carbonate, zinc borate, montmorillonite, flame retardant, antioxidant and rodent-proof additive according to the weight parts of claim 1; pretreating the modified composite fiber, soaking it in a solution containing a silane coupling agent for 2-4 hours, and then drying it at 80-100° C. for 3-5 hours; Step S2, mixing the materials of the sheath layer (5): weighing EPDM rubber and chlorosulfonated polyethylene into an internal mixer, mixing at 80-100° C. for 5-10 minutes; sequentially adding phenyltrimethoxysilane, dilauroyl peroxide, pretreated modified composite fiber, calcium carbonate, zinc borate, montmorillonite, flame retardant, antioxidant and rodent-proof additive, and continuing mixing for 15-25 minutes, with the temperature controlled at 100-120° C., to obtain a mixed rubber of the sheath layer (5); Step S3, extrusion of the conductor shielding layer (2): putting the semi-conductive shielding material into an extruder, and extruding the conductor shielding layer (2) on the surface of the conductor (1) through the extruder, the extrusion temperature is controlled at 150-180° C., and the extrusion speed is 10-20 m / min; Step S4, extrusion of the insulating layer (3): the cross-linked polyethylene material is put into another extruder, and after preheating treatment, the insulating layer (3) is extruded outside the conductor shielding layer (2), the preheating temperature is 80-100° C., the extrusion temperature is 180-220° C., the extrusion speed is 8-15 m / min, and then cross-linking treatment is performed, the cross-linking temperature is 150-170° C., and the cross-linking time is 10-20 minutes; Step S5, wrapping the fire-resistant layer (4): wrapping the mica tape around the insulating layer (3) through a wrapping machine to form a fire-resistant layer (4), with a wrapping speed of 5-10 m / min and a wrapping overlap rate controlled at 30%-50%; Step S6, extrusion of the sheath layer (5): the mixed rubber of the sheath layer (5) obtained in step S2 is put into an extruder, and the sheath layer (5) is extruded outside the fire-resistant layer (4). The extrusion temperature is controlled at 130-160° C. and the extrusion speed is 6-10 m / min, and finally the flame-retardant and rat-proof cable is obtained.

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