Flame-retardant polyethylene cable material and high-performance flame-retardant cable

Abstract

The invention discloses a flame-retardant polyethylene cable material and a high-performance flame-retardant cable. The flame-retardant polyethylene cable material comprises the following components in parts by weight: high-density polyethylene, an ethylene-octylene copolymer, a composite flame retardant, an organic silicon master batch, a compatilizer, a red phosphorus master batch and a carbon black master batch. According to the flame-retardant polyethylene cable material provided by the invention, the components such as the HDPE, the ethylene-octylene copolymer and the composite flame retardant are reasonably proportioned, so that the synergistic optimization of flame retardance and mechanical properties is realized. On one hand, the composite flame retardant and the red phosphorus master batch can significantly improve the flame retardant property of the cable sheath, and inhibit combustion and reduce the smoke release amount when a fire occurs, so that the use safety is improved; and on the other hand, the introduction of the ethylene-octylene copolymer, the organic silicon master batch and the compatilizer effectively improves the flexibility and the mechanical property of the material, and avoids the mechanical property problem caused by directly adding the flame retardant traditionally.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric wire and cable, and particularly relates to a flame-retardant polyethylene cable material and a high-performance flame-retardant cable. BACKGROUND

[0002] At present, the materials used for cable sheaths are mostly organic polymers, including polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), ethylene-vinyl acetate (EVA) and the like, wherein high-density polyethylene (HDPE) has the advantages of low price, excellent electrical insulation and mechanical properties and the like, and is a commonly used material for cable sheaths.

[0003] However, HDPE is a flammable material and will continue to burn after ignition. At the same time, it will release a large amount of smoke during the combustion process, which poses a serious threat to life and property safety, so it is necessary to modify the flame retardance of HDPE materials. However, the addition of a flame retardant directly in HDPE will seriously affect the mechanical properties of the composite material. Therefore, the research on the flame-retardant and mechanical property modification of HDPE has become an inevitable trend. SUMMARY

[0004] To solve the technical problems existing in the prior art, the purpose of the present application is to provide a flame-retardant polyethylene cable material and a high-performance flame-retardant cable.

[0005] The purpose of the present application is achieved by the following technical solutions.

[0006] In a first aspect, the present application provides a flame-retardant polyethylene cable material for the sheath of an electric wire and cable, which comprises the following components in parts by weight:

[0007]

[0008] In combination with the first aspect, the present application further provides a first preferred embodiment of the first aspect, and specifically, the flame-retardant polyethylene cable material is composed of the following components in parts by weight:

[0009]

[0010]

[0011] In combination with the first aspect, the present application further provides a second preferred embodiment of the first aspect, and specifically, the composite flame retardant is an intumescent flame-retardant composite material, and the intumescent flame-retardant composite material comprises iron oxide, zinc borate, sepiolite and modified ammonium polyphosphate.

[0012] In combination with the first aspect, the present application further provides a third preferred embodiment of the first aspect, and specifically, the preparation method of the modified ammonium polyphosphate is as follows:

[0013] Ammonium polyphosphate is dispersed in a mixture of anhydrous ethanol and deionized water, the mass ratio of anhydrous ethanol and deionized water is 2:1, and 20g of ammonium polyphosphate is added per 100ml of mixed solution;

[0014] Ammonia water is added to adjust the PH of the mixed solution to 10;

[0015] Phenyltrimethoxysilane and tetraethyl orthosilicate are added to the mixed solution, and the mixed solution is stirred uniformly with a glass cup, the mass ratio of the ammonium polyphosphate, phenyltrimethoxysilane and tetraethyl orthosilicate is 5:1:1;

[0016] The mixed solution is stirred and reacted at 40°C for 3h, and then filtered and washed with anhydrous ethanol;

[0017] The washed powder is placed in a Soxhlet extractor and extracted with anhydrous ethanol for 24h, and then dried in an electric heating air drying oven to obtain the modified ammonium polyphosphate powder.

[0018] In combination with the first aspect, the application further provides a fourth preferred embodiment of the first aspect, and specifically, the organic silicone master batch is composed of the following components in parts by weight:

[0019]

[0020] In the second aspect, the application further provides a high-performance flame-retardant cable, which comprises a composite core, a first flame-retardant wrapping tape layer, an isolation layer, a first water-blocking layer, a second flame-retardant wrapping tape layer, a metal braided layer, a second water-blocking layer, an inner sheath, a third flame-retardant wrapping tape layer, a metal sheath layer and an outer sheath arranged in sequence from inside to outside.

[0021] The isolation layer and the outer sheath are both formed by extrusion coating of the flame-retardant polyethylene cable material described in the first aspect and the first to fourth specific embodiments of the first aspect.

[0022] In combination with the second aspect, the application further provides a first preferred embodiment of the second aspect, and specifically, the inner sheath is a ceramicized polyolefin material extrusion coated on the second flame-retardant wrapping tape layer.

[0023] In combination with the second aspect, the application further provides a second preferred embodiment of the second aspect, and specifically, the ceramicized polyolefin material comprises the following components in parts by weight:

[0024]

[0025] In combination with the second aspect, the application further provides a third preferred embodiment of the second aspect, and specifically, the composite flame retardant of the ceramicized polyolefin material is an intumescent flame-retardant composite material, and the intumescent flame-retardant composite material comprises iron oxide, zinc borate, sepiolite and modified ammonium polyphosphate.

[0026] Compared with the prior art, the present application has at least the following beneficial effects:

[0027] The present application provides a flame-retardant polyethylene cable material for the sheath of electric wires and cables, which comprises the following components in parts by weight: high-density polyethylene, ethylene-octene copolymer, composite flame retardant, silicone master batch, compatibilizer, red phosphorus master batch and carbon black master batch.

[0028] The flame-retardant polyethylene cable material provided by the present application realizes the synergistic optimization of flame-retardant performance and mechanical properties by reasonably matching high-density polyethylene (HDPE), ethylene-octene copolymer and composite flame retardant and other components. On the one hand, the composite flame retardant and the red phosphorus master batch can significantly improve the flame-retardant performance of the cable sheath, inhibit combustion and reduce the amount of smoke released when a fire occurs, thereby improving the safety in use; on the other hand, the introduction of the ethylene-octene copolymer, the silicone master batch and the compatibilizer effectively improves the flexibility and mechanical properties of the material, avoiding the mechanical property problems caused by the traditional direct addition of flame retardants. In addition, the carbon black master batch can enhance the weather resistance and ultraviolet resistance of the material, so that the cable sheath can maintain stable performance in long-term use. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a circuit structure diagram of a high-performance flame-retardant cable of the present application.

[0030] In the figure:

[0031] 100 - composite cable core;

[0032] 200 - first flame-retardant wrapping tape layer;

[0033] 300 - isolation layer;

[0034] 400 - first water-blocking layer;

[0035] 500 - second flame-retardant wrapping tape layer;

[0036] 600 - metal braiding layer;

[0037] 700 - second water-blocking layer;

[0038] 800 - inner sheath;

[0039] 900 - third flame-retardant wrapping tape layer;

[0040] 1000 - metal sheath layer;

[0041] 1100 - outer sheath. DETAILED DESCRIPTION

[0042] For the convenience of understanding the present application, the technical solutions and advantages of the present application are further described in detail below in combination with the drawings and examples. The mechanisms or methods not described in the present application can refer to the prior art. The specific structure and characteristics of the present application are described below by way of example, which should not constitute any limitation on the present application. At the same time, any one of the technical features mentioned below (including implied or disclosed), and any one of the technical features directly shown or implied in the drawings, can continue to be combined or deleted between these technical features, thereby forming more other embodiments that may not be directly or indirectly mentioned in the present application. The preferred embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0043] HDPE is a flammable material that will continue to burn after ignition. At the same time, it will release a large amount of smoke during combustion, posing a serious threat to life and property safety, so HDPE materials need to be flame-retardant modified. However, the direct addition of flame retardants in HDPE will seriously affect the mechanical properties of the composite material. Therefore, the research on the flame-retardant and mechanical performance modification of HDPE has become an inevitable trend.

[0044] Therefore, the present application provides a flame-retardant polyethylene cable material for the sheath of electric wires and cables, which realizes the synergistic optimization of flame-retardant performance and mechanical performance by reasonably matching high-density polyethylene (HDPE), ethylene-octene copolymer and composite flame retardant components.

[0045] The flame-retardant polyethylene cable material provided by the present application comprises the following components in parts by weight:

[0046]

[0047] In the present application, high-density polyethylene (HDPE) is used as the base resin to provide mechanical properties and electrical insulation properties, as well as good processability and heat resistance. Ethylene-octene copolymer improves flexibility and low-temperature resistance, and improves the mechanical properties of the cable. Silicone masterbatch is a multifunctional silicone composite modifier with flame-retardant and smoke-suppressing, lubricating and toughening properties. The compatibilizer is used to improve the compatibility between different polymers and additives, and to improve the mixing uniformity and processing stability. Red phosphorus masterbatch is used as a synergistic flame retardant to improve the flame-retardant performance. Carbon black masterbatch provides ultraviolet aging resistance, and improves the appearance and processing performance.

[0048] In a specific implementation, the composite flame retardant is an intumescent flame-retardant composite material, which comprises iron oxide, zinc borate, sepiolite and modified ammonium polyphosphate.

[0049] In the present embodiment, the iron oxide catalyzes the carbonization reaction during the combustion process, forming a dense carbon layer that insulates oxygen and heat conduction. Zinc borate participates in carbonization and inhibits combustion, playing a synergistic flame-retardant role. Sepiolite absorbs heat to release moisture, improving the thermal stability of the material and assisting in the formation of an expanded carbon layer. Modified ammonium polyphosphate provides a phosphorus-based carbonization agent, enhancing the structure of the expanded carbon layer while releasing inert gas to inhibit the combustion chain reaction.

[0050] In the present application, the simplest way to improve the flame retardancy of polyolefin materials is to add a flame retardant. Among them, the present application selects ammonium polyphosphate, which can be applied to intumescent flame retardants as an acid source and gas source at the same time, and it can effectively inhibit the smoke generated during polymer combustion, in line with the green, environmentally friendly, smoke suppression, and high-efficiency flame-retardant trend. However, ammonium polyphosphate as an inorganic substance added to polyethylene material has poor compatibility, and is easy to absorb moisture in the air, and then migrate to the surface of the material to cause loss, thereby reducing the mechanical properties and flame retardant efficiency of the polymer. Therefore, the present application also modifies the ammonium polyphosphate to improve its hydrophobicity and thermal stability, thereby improving the flame retardant properties of the polyethylene material.

[0051] In a preferred embodiment, the preparation method of the modified ammonium polyphosphate is as follows:

[0052] Disperse ammonium polyphosphate in a mixture of anhydrous ethanol and deionized water, the mass ratio of anhydrous ethanol and deionized water is 2:1, and 20g of ammonium polyphosphate is added per 100ml of mixed solution;

[0053] Add ammonia water to adjust the PH of the mixed solution to 10;

[0054] Add phenyltrimethoxysilane and tetraethyl orthosilicate to the mixed solution, stir uniformly with a glass cup, and the mass ratio of the ammonium polyphosphate, phenyltrimethoxysilane and tetraethyl orthosilicate is 5:1:1;

[0055] Stir the mixed solution at 40℃ for 3h, then filter and wash with anhydrous ethanol;

[0056] Put the washed powder into a Soxhlet extractor and extract it with anhydrous ethanol for 24h, then place it in an electric heating air drying oven, and after drying, the modified ammonium polyphosphate powder is obtained.

[0057] In the present application, the modified ammonium polyphosphate can significantly improve the flame retardant efficiency and smoke suppression performance in the polyethylene matrix, while improving the mechanical properties and thermal stability of the material. Compared with unmodified ammonium polyphosphate, it is more uniformly dispersed in the material and is not easy to migrate to the surface and be lost, thereby ensuring the long-term stability of the flame retardant effect. In addition, the modified ammonium polyphosphate can synergistically act with iron oxide, zinc borate and sepiolite in the intumescent flame retardant to form a high-efficiency intumescent carbon layer, so that the amount of smoke generated during the combustion of the cable material is significantly reduced, in line with the green, environmentally friendly and efficient flame retardant trend. The modified ammonium polyphosphate releases acidic substances and inert gases during combustion, promoting the formation of a dense intumescent carbon layer on the surface of the polymer. This carbon layer can insulate oxygen and heat, reducing the heat transfer speed, thereby delaying the combustion of the polymer.

[0058] In a specific implementation, the silicone masterbatch is composed of the following components by weight fraction:

[0059]

[0060] The silicone masterbatch of the present application takes silicone rubber as the main component, improves the compatibility with the polyethylene matrix through EVA and grafted polyethylene, and at the same time utilizes silica and MQ type silicone resin to enhance the mechanical properties and heat resistance. Barium stearate, silane coupling agent and oligomeric olefin wax further optimize the processability and interfacial bonding, and antioxidants ensure thermal oxidative stability. The overall masterbatch has good flexibility, heat resistance and flame retardant synergistic effect, and can be used as a functional additive component for polyethylene cable material.

[0061] In the present application, silicone rubber as the main component of the masterbatch has high elasticity and heat resistance, and can form an elastic phase in the polyethylene matrix, improving the flexibility and impact resistance of the cable material. EVA (ethylene-vinyl acetate copolymer) improves the flexibility and ductility of the polyethylene matrix, and at the same time improves the compatibility of the masterbatch with the polyethylene matrix, making the mechanical properties more balanced. Maleic anhydride grafted polyethylene and organosilane coupling agent can enhance the interfacial bonding between inorganic fillers (such as silica) in the silicone masterbatch and the polyethylene matrix, making the added silicone masterbatch uniformly dispersed in the polyethylene matrix, avoiding stress concentration, and thus improving the tensile strength and tear resistance. Fumed silica and MQ type silicone resin can enhance the rigidity and heat resistance of the silicone masterbatch, forming a micro-reinforced phase in the cable material, which helps to improve the heat distortion temperature and mechanical strength of the material.

[0062] Example 1

[0063] This example 1 provides a flame-retardant polyethylene cable material for wire and cable sheath, which comprises the following components by weight fraction:

[0064]

[0065] Specifically, the raw material ratio and preparation method of the composite flame retardant and silicone master batch in Example 1 are consistent with the above description.

[0066] Example 2

[0067] The present Example 2 provides a flame-retardant polyethylene cable material for wire and cable sheath, which comprises the following components by weight fraction:

[0068]

[0069] Specifically, the raw material ratio and preparation method of the composite flame retardant and silicone master batch in Example 2 are consistent with the above description.

[0070] Example 3

[0071] The present Example 3 provides a flame-retardant polyethylene cable material for wire and cable sheath, which comprises the following components by weight fraction:

[0072]

[0073]

[0074] Specifically, the raw material ratio and preparation method of the composite flame retardant and silicone master batch in Example 3 are consistent with the above description.

[0075] The product performance test results of the flame-retardant polyethylene cable material of Example 2 are as follows:

[0076] After weighing based on the above ratio, put into the rubber and plastic mixing device, the temperature of each section of the device is 130℃, 135℃, 140℃, the rotation speed is set to 60r / min, after the material temperature reaches 165℃, take out the mixed rubber; Put the rubber into the rubber mixing machine set at 165℃ and continue to mix for 8min, make the sheet; After cutting the sheet, place it in the mold, and press it into a sheet with a thickness of 1mm and 3.2mm on the flat vulcanizing machine, the temperature of the flat vulcanizing machine is 165℃, the pressure is 15MPa, the pressing process is preheating for 10min without pressure, pressure forming for 5min, and pressure cooling for 3min, after cooling, the flame-retardant polyethylene sheet with a thickness of 1mm and 3.2mm is obtained respectively; Cut the flame-retardant polyethylene sheet with a thickness of 1mm into 5 dumbbell-shaped pieces and circular test pieces with a diameter of 100mm, and cut the flame-retardant polyethylene sheet with a thickness of 3.2mm into 125mm×13mm×3.2mm and 125mm×6.5mm×3.2mm for performance testing.

[0077] (1)Mechanical property test: the tensile strength and elongation at break of the flame-retardant PE were tested by using a microcomputer-controlled electronic universal testing machine, which was carried out according to GB / T1040.3-2006, the sample was a dumbbell piece of type 5, the tensile speed was (250±50) mm / min. Each sample was tested for 3 times, and the average value of the 3 data was the final result.

[0078] (2) LOI performance test: the LOI of the flame-retardant polyethylene was tested by using an oxygen index tester, which was carried out according to GB / T2406.2-2009, type IV sample (125mm×6.5mm×3.2mm) was used, and method B-diffusion ignition method was used for ignition. Each sample was tested for 3 times, and the average value of the 3 data was the final result.

[0079] (3) MFR performance test: the flame-retardant polyethylene sheet was cut into small particles, and the melt flow rate was tested by using a melt flow rate tester, which was carried out according to GB / T3682.1-2018, the temperature was 150℃, and the load was 21.6kg. Each sample was tested for 3 times, and the average value of the 3 data was the final result.

[0080] (4) Volume resistivity test: the volume resistivity of the flame-retardant polyethylene sheet was tested by using a high resistance meter, which was carried out according to GB / T1410-2006, the thickness of the test piece was (1.0±0.1) mm, and the test voltage was 1000V. Each sample was tested for 3 times, and the average value of the 3 data was the final result.

[0081] (5) Vertical burning test: the vertical burning performance of the flame-retardant polyethylene sheet was tested by using a horizontal vertical burning test box, which was carried out according to UL94, the sample was a 125mm×13mm×3.2mm sample. Each sample was tested for 3 times, and the worst one of the 3 tests was used as the final result.

[0082] The performance test results of the flame-retardant polyethylene cable material of example 2 are shown in table 1:

[0083] Table 1 Mechanical properties of flame-retardant polyethylene cable material

[0084] Indicators Example Two Flame Retardant Polyethylene Cable Compound Tensile Strength / MPa 18.23 Elongation at Break / % 405.3 MFR / g·(10 min) -1 ]] 2.18 Volume resistivity / x 10 13 Ω·m 9.64 LOI % 32.7 Vertical Burning Rating (3.2 mm) V-0

[0085] As Figure 1 shown, the present application provides a high-performance flame-retardant cable on the basis of the above-mentioned flame-retardant polyethylene cable material, as Figure 1 shown, the preferred structure of the high-performance flame-retardant cable of the present application.

[0086] As Figure 1As shown, the high-performance flame-retardant cable of the present application comprises, from inside to outside, a composite cable core 100, a first flame-retardant wrapping tape layer 200, a separation layer 300, a first water-blocking layer 400, a second flame-retardant wrapping tape layer 500, a metal braid layer 600, a second water-blocking layer 700, an inner sheath 800, a third flame-retardant wrapping tape layer 900, a metal sheath layer 1000, and an outer sheath 1100. Among them, the separation layer and the outer sheath are both extruded by the above-mentioned flame-retardant polyethylene cable material.

[0087] In a specific implementation, the first, second, and third flame-retardant wrapping tape layers are wrapped with mica tape, glass fiber tape, or ceramicized glass fiber tape to improve the overall fire resistance of the cable.

[0088] In a specific implementation, the first and second water-blocking layers can be polyester tape or non-woven fabric tape coated with intumescent water-blocking powder to prevent longitudinal water seepage.

[0089] In a specific implementation, the metal braid layer is woven with tin-plated copper wire or aluminum-magnesium alloy wire, mainly for electromagnetic shielding and mechanical protection. The weaving density of the metal braid layer is not less than 85%. The metal sheath layer can be a corrugated aluminum sheath or a welded copper sheath

[0090] Through the synergistic effect of the above-mentioned material system, the separation layer and the outer sheath have excellent flame-retardant performance, heat resistance, mechanical strength, and anti-aging performance, and can maintain structural stability under complex working conditions such as high temperature, electrical load, and external mechanical stress, thereby significantly improving the safety reliability and service life of the entire cable.

[0091] In a preferred implementation, the inner sheath is an extruded ceramicized polyolefin material covering the second flame-retardant wrapping tape layer.

[0092] In a preferred implementation, the ceramicized polyolefin material includes the following components by weight:

[0093]

[0094]

[0095] In this application, EVA and POE provide matrix toughness and flexibility, ensuring good ductility and strain resistance of the material during extrusion processing and service. LLDPE enhances the mechanical strength and weather resistance of the outer sheath. Wollastonite fibers and glass powder can form an inorganic skeleton in high-temperature combustion, promoting the ceramicization of the material surface, and the composite flame retardant A provides the main flame-retardant and ceramic functions. Antioxidants (selected from 1010 or 168 type) prevent thermal and oxidative aging of polymers during processing and use. Lubricants (selected from stearate) improve extrusion flowability and interfacial compatibility.

[0096] In a specific implementation, the modified nanometer pottery clay is prepared by the following method:

[0097] (1) Raw material mixing: mix the nanometer pottery clay with aminopropyl triethoxysilane to obtain a mixture; wherein the amount of aminopropyl triethoxysilane is 3-5% of the mass of the nanometer pottery clay;

[0098] (2) Heating and stirring: heat the mixture to 50-60℃ and continuously stir for 20-30 minutes;

[0099] (3) Adding nanometer silicon dioxide: add 1.5% of the total mass of the mixture of nanometer silicon dioxide to the mixture after heating and stirring;

[0100] (4) High-speed dispersion: high-speed dispersion treatment is performed on the mixture with the added nanometer silicon dioxide to obtain the modified nanometer pottery clay.

[0101] In the present application, the modified nanometer pottery clay can significantly improve the hardness, strength and toughness of the material due to the nanoscale dispersion and surface modification. The performance of the nanometer pottery clay composite at high temperature is improved, including the increase of hardness and strength. Pressure resistance and impact resistance: the modified nanometer pottery clay enhances the barrier property and air tightness of the material, and has good pressure resistance and impact resistance. Heat sealing performance: it has the characteristics of high heat sealing strength and good heat sealing performance.

[0102] The present application uses modified nanometer pottery clay and wollastonite fibers to synergistically enhance the effect of "micro-filling + interface tackifying + sintering assistance" in the ceramicized polyolefin sheath system. In the ceramicized polyolefin sheath material of the present application, wollastonite fibers mainly exist as macroscopic framework fillers. Its fibrous structure can maintain the overall form at high temperature, providing a continuous support network for the ceramic layer, preventing the material from dripping or collapsing under burning or high temperature conditions, thereby enhancing the mechanical stability of the ceramic layer. The modified nanometer pottery clay is uniformly dispersed between the polyolefin matrix and the wollastonite fibers in the form of nanometer particles, and realizes good interface bonding with polyolefin and grafting compatibilizer through surface modification.

[0103] During the ceramicization process, nanometer pottery clay can fill the gaps between fibers and micro-holes, promote the sintering of glass powder and low-melting flux, and form a dense ceramic network structure. The combination of wollastonite fibers and modified nanometer pottery clay forms a multi-level network structure of macroscopic framework + micro-filling, realizing the synergistic effect of physical support and interface tackifying. This structure can significantly improve the tensile strength, hardness and toughness of the sheath material, while improving the pressure resistance and impact resistance. In addition, the synergistic network hinders heat conduction and flame spread at high temperature, improving the flame retardant performance and fire resistance of the material. The micro-filling effect of nanometer pottery clay also helps to inhibit crack propagation and pore formation, making the ceramic layer more dense and enhancing the heat resistance, insulation and air tightness.

[0104] In summary, the synergistic effect of wollastonite fibers and modified nano-talc not only improves the ceramic performance of the material, but also enhances the mechanical properties, fire resistance and flame retardant properties, while ensuring processing and flexibility, making it suitable for high flame retardant and environmentally friendly cable sheath applications.

[0105] In a specific embodiment, the composite flame retardant of the ceramic polyolefin material is an intumescent flame retardant composite, which includes iron oxide, zinc borate, sepiolite and modified ammonium polyphosphate.

[0106] In this embodiment, iron oxide acts as a catalyst for carbonization, promoting the formation of a carbon layer on the polyolefin matrix at high temperatures. Zinc borate has the effect of smoke suppression and ceramic promotion. Sepiolite fibers, as inorganic skeleton reinforcing agents, can significantly improve the density and crack resistance of the ceramic layer. Modified ammonium polyphosphate is the main intumescent flame retardant, which releases phosphoric acid substances when heated, forming a heat-insulating expanded carbon layer, and promoting the ceramic reaction together with glass powder and wollastonite.

[0107] In this application, the simplest way to improve the flame retardancy of polyolefin materials is to add flame retardants. Among them, the application selects ammonium polyphosphate, which can be used as an acid source and a gas source in intumescent flame retardants. It can effectively suppress the smoke generated during polymer combustion, and meet the green, environmentally friendly, smoke suppression and high efficiency flame retardant trend. However, when ammonium polyphosphate is added to polyolefin materials as an inorganic substance, its compatibility is poor, and it is easy to absorb moisture in the air and then migrate to the surface of the material, causing loss, thereby reducing the mechanical properties and flame retardant efficiency of the polymer. Therefore, the application also modifies ammonium polyphosphate to improve its hydrophobicity and thermal stability, thereby improving the flame retardant properties of the polyolefin material.

[0108] In a preferred embodiment, the preparation method of the modified ammonium polyphosphate is as follows:

[0109] Disperse ammonium polyphosphate in a mixture of anhydrous ethanol and deionized water, the mass ratio of anhydrous ethanol and deionized water is 2:1, and 20g of ammonium polyphosphate is added per 100ml of mixed solution;

[0110] Add ammonia water to adjust the PH of the mixed solution to 10;

[0111] Add phenyltrimethoxysilane and tetraethyl orthosilicate to the mixed solution, stir uniformly with a glass cup, and the mass ratio of ammonium polyphosphate, phenyltrimethoxysilane and tetraethyl orthosilicate is 5:1:1;

[0112] Stir the mixed solution at 40°C for 3h, then filter and wash with anhydrous ethanol;

[0113] The washed powder is placed in a Soxhlet extractor and extracted with anhydrous ethanol for 24 hours, and then dried in an electric heating air drying oven to obtain the modified ammonium polyphosphate powder.

[0114] In the present application, the modified ammonium polyphosphate releases phosphoric acid to form an insulating expansion layer, while absorbing part of the heat and inhibiting the generation of smoke, which conforms to the green and environmentally-friendly trend. The expanded insulating carbon layer is formed on the surface of the polyolefin matrix, which simultaneously acts as an acid source to catalyze the carbonization of the polymer, and cooperates with the wollastonite fibers, sepiolite fibers and glass powder to promote the densification of the ceramicization; the surface modification improves the hydrophobicity and interface compatibility, reduces migration and precipitation, thereby significantly improving the flame retardant performance, smoke suppression effect, high-temperature mechanical strength and long-term stability of the material.

[0115] The product performance detection results of the ceramicized polyolefin material of the present application are as follows:

[0116] The preparation of the ceramicized polyolefin composite material includes three steps. The first step is mixing, which is carried out in an internal mixer. The internal mixer is preheated, and a certain amount of base resin particles and filler powder are weighed in two beakers. When the internal mixer is heated to 160 DEG C, the base resin is poured in. After the base resin is evenly mixed, the powder is slowly added to the internal mixer. After the filler and the base resin are mixed for 20 minutes, they are taken out and cut while hot. The second step is vulcanization, which is carried out in a flat vulcanizing machine. The pressure is set to 10 MPa, and the flat vulcanizing machine is preheated to 160 DEG C. An appropriate amount of mixed and cut material is weighed and stacked into a mold with a corresponding thickness. The flat vulcanizing machine is used for vulcanization. The material is preheated for 10 minutes to melt and remove bubbles. The pressing temperature is 160 DEG C. After 20 minutes of hot pressing and 20 minutes of cold pressing, the formed composite material is cooled to room temperature and taken out.

[0117] (1) Limiting oxygen index test

[0118] The limiting oxygen index sample is injected by a micro injection molding machine using an oxygen index mold, and then the oxygen index at the 50mm mark is marked on the sample when it just burns to the mark after 3 minutes.

[0119] (2) Vertical burning determination (UL 94) test

[0120] The vertical burning sample is injected by a micro injection molding machine using a vertical burning mold, and then placed on a vertical burning tester for vertical burning test. Each group of formula is tested for 5 times.

[0121] (3) Mechanical property test

[0122] The standard GB / T 1040-2006 is adopted for the test, the sample size is dumbbell type (the middle part is 5.5 mm wide) of 125 mm*6 mm*2 mm, the test speed is 50 mm / min, and 5 times of tensile test are performed on each sample.

[0123] After detection, the product performance is shown in Table 1:

[0124] Sample Limiting Oxygen Index / % UL94 Rating Tensile Strength Elongation at Break Ceramified Polyolefin Material 32.7％ V-0 13.58 MPa 132.58％

[0125] The high-performance flame-retardant cable of the application realizes the multiple flame-retardant protection effect of the cable through the synergistic design of the ceramicized polyolefin material of the inner sheath, the isolation layer and the flame-retardant polyethylene cable material of the outer sheath. The outer layer of flame-retardant polyethylene can quickly form a carbonized heat insulation film when subjected to flame, delaying the heat transfer inward and reducing the smoke generation; the inner layer of ceramicized polyolefin undergoes inorganic reaction at high temperature to generate a dense and hard ceramic protective layer, maintaining the integrity of the conductor structure and preventing short circuit. The synergistic effect of the two forms a composite system of "outer layer of flame-retardant smoke suppression and inner layer of ceramic protection", so that the cable has excellent fire resistance, power integrity and low smoke and halogen characteristics under fire conditions, significantly improving the overall safety performance.

[0126] In a specific implementation, the composite cable core includes a plurality of insulated wire cores, each insulated wire core including a conductor and an insulation layer wrapped around the outer surface of the conductor. The insulation layer is polyvinyl chloride sheath material extruded on the conductor. In a specific implementation, the composite cable core includes 3 insulated wire cores, and the conductor is the first conductor structure or the second conductor structure in GB / T 3956.

[0127] In a preferred implementation, an oxygen barrier filler is filled between the composite cable core and the first flame-retardant wrapping tape layer, and the oxygen barrier filler is fire clay that is semi-extruded on the composite cable core.

[0128] In the field, the fire clay for cables uses magnesium hydroxide as the main inorganic flame-retardant matrix, which is used to absorb heat and decompose, release crystal water and generate magnesium oxide layer when heated, thereby reducing the temperature and forming an oxygen barrier. Auxiliary expansion fillers such as expanded vermiculite, sepiolite or expanded graphite make the material expand in volume at high temperature and form a porous heat insulation layer. An appropriate amount of inorganic binder (such as water glass or silica sol) is added to the fire clay to enhance the plasticity and forming strength at room temperature. On the other hand, in order to improve the construction and long-term stability, a small amount of organic modifier or moisture-proof additive (such as silane coupling agent, polyacrylate) can also be added, and inert fillers (such as talc, calcium carbonate) are used to adjust the rheological properties and cost. The overall system can rapidly expand into a shell, absorb heat and isolate oxygen when heated, thereby achieving excellent fireproof sealing and flame-retardant effect.

[0129] Specifically, the raw material composition of the fireproof mortar includes 60-75 parts of magnesium hydroxide as the main fire-retardant matrix, 10-20 parts of expanded vermiculite or sepiolite, 5-10 parts of water glass or silica sol as inorganic binder, 5-10 parts of talc or calcium carbonate to adjust the rheological property and reduce the cost, 1-3 parts of silane coupling agent or polyacrylate organic modifier to improve the interface bonding and moisture resistance, and 2-5 parts of expanded graphite to improve the carbon layer density and thermal insulation property.

[0130] The other structure of the high-performance fire-retardant cable is described in the embodiment and can be known from the prior art.

[0131] In the embodiments of the present application, the terms "first", "second" and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance. The term "at least one" refers to one or more, and the term "multiple" refers to two or more, unless otherwise explicitly limited.

[0132] In the present application, the term "and / or" is only used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0133] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the protection scope of the technical solutions of the embodiments of the present application.

Claims

1. A flame-retardant polyethylene cable material for use as a sheath for wires and cables, characterized in that, The flame-retardant polyethylene cable material comprises the following components in parts by weight:

2. The flame-retardant polyethylene cable material according to claim 1, characterized in that, The flame-retardant polyethylene cable material is composed of the following components in parts by weight:

3. The flame-retardant polyethylene cable material according to claim 2, characterized in that: The composite flame retardant is an intumescent flame retardant composite material, which includes iron oxide, zinc borate, sepiolite, and modified ammonium polyphosphate.

4. The flame-retardant polyethylene cable material according to claim 3, characterized in that, The modified ammonium polyphosphate is prepared as follows: Ammonium polyphosphate was dispersed in a mixture of anhydrous ethanol and deionized water at a mass ratio of 2:1, with 20g of ammonium polyphosphate prepared per 100ml of the mixed solution. Add ammonia to adjust the pH of the mixed solution to 10; Phenylacetyltrimethoxysilane and tetraethyl orthosilicate were added to the mixed solution and stirred evenly with a glass beaker. The mass ratio of ammonium polyphosphate, phenyltrimethoxysilane and tetraethyl orthosilicate was 5:1:

1. The mixed solution was stirred at 40°C for 3 hours, then filtered and washed with anhydrous ethanol. The washed powder was placed in a Soxhlet extractor and extracted with anhydrous ethanol for 24 hours. After drying in an electric heating oven, modified ammonium polyphosphate powder was obtained.

5. The flame-retardant polyethylene cable material according to claim 2, characterized in that, The silicone masterbatch is composed of the following components in parts by weight:

6. A high-performance flame-retardant cable, characterized in that, It includes, from the inside out, a composite cable core, a first flame-retardant wrapping tape layer, an isolation layer, a first water-blocking layer, a second flame-retardant wrapping tape layer, a metal braided layer, a second water-blocking layer, an inner sheath, a third flame-retardant wrapping tape layer, a metal sheath layer, and an outer sheath; Wherein, the isolation layer and the outer sheath are both formed by extrusion of the flame-retardant polyethylene cable material as described in any one of claims 1 to 5.

7. A high-performance flame-retardant cable according to claim 6, characterized in that, The inner sheath is made of ceramicized polyolefin material extruded and covered on the second flame-retardant wrapping tape layer.

8. A high-performance flame-retardant cable according to claim 7, characterized in that, The ceramicized polyolefin material comprises the following components in parts by weight:

9. A high-performance flame-retardant cable according to claim 8, characterized in that: The composite flame retardant of the ceramicized polyolefin material is an intumescent flame retardant composite material, which includes iron oxide, zinc borate, sepiolite, and modified ammonium polyphosphate.

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