A low-smoke halogen-free flame-retardant fire-resistant cable material

Abstract

The application discloses a low-smoke halogen-free flame-retardant fire-resistant cable material, which comprises the following components in parts by mass: low-density polyethylene (LDPE) 80-120 parts, magnesium stearate 1-3 parts, magnesium hydroxide 10-20 parts, aluminum hydroxide 10-20 parts, microencapsulated red phosphorus 5-15 parts, a compatilizer 3-7 parts, a silane coupling agent 1-3 parts, and an antioxidant 0.5-2 parts. The low-smoke halogen-free flame-retardant fire-resistant cable material of the application combines inorganic flame retardants, magnesium stearate and the silane coupling agent to improve the dispersibility and stability of the flame retardants in the LDPE matrix, and to strengthen the flame-retardant performance. Meanwhile, the introduction of the microencapsulated red phosphorus and the compatilizer optimizes the mechanical performance of the material. Overall, the cable material of the application has the advantages of flame retardation, environmental protection, fire resistance, stability and good mechanical performance, and is suitable for being used as a cable insulation and sheath material.

Description

Technical Field

[0001] This invention relates to a cable material, and more particularly to a low-smoke, halogen-free, flame-retardant, and fire-resistant cable material. Background Technology

[0002] Cables are an indispensable element in modern life and industrial production, widely used in communications, power transmission, control systems, and many other fields. However, secondary disasters caused by burning cables in fires pose a significant threat to public safety. Therefore, strict requirements are placed on the flame-retardant properties of cable materials.

[0003] Traditional flame-retardant cables primarily use materials containing halogenated substances, such as polyvinyl chloride (PVC). While these materials exhibit excellent flame-retardant properties, they release large amounts of halogen gases during combustion, including toxic and harmful gases such as hydrogen chloride and chlorides. This not only pollutes the environment but also poses a threat to human health. Furthermore, these gases react with water to form acidic substances, which may corrode equipment, increasing maintenance costs and repair difficulties.

[0004] While existing low-smoke halogen-free flame-retardant cables can reduce the generation of toxic and harmful gases to some extent, their flame-retardant performance is less than satisfactory compared to traditional halogen-containing flame-retardant materials. Their poor flame-retardant properties fail to meet the stringent requirements of high-risk environments. This is because the flame-retardant properties of most low-smoke halogen-free flame-retardant materials primarily come from the charred layer formed during combustion, and the formation rate and stability of this charred layer are often insufficient to prevent the rapid spread of fire.

[0005] In summary, existing flame-retardant cable materials have two main problems: first, traditional halogenated flame-retardant materials produce toxic and harmful gases during combustion, posing a serious threat to the environment and human health; second, existing low-smoke halogen-free flame-retardant materials have insufficient flame-retardant performance and cannot meet strict flame-retardant requirements.

[0006] Therefore, developing a cable material with excellent flame retardant properties, while also being environmentally friendly, halogen-free, and low-smoke, has become an important research topic in cable materials. This invention addresses this problem by proposing a low-smoke, halogen-free, flame-retardant, and fire-resistant cable material to solve the aforementioned issues in the prior art.

[0007] Currently, the development of low-smoke halogen-free flame-retardant cable materials still faces significant challenges. Although some low-smoke halogen-free materials, such as silicon-based and alkyd materials, have been used in cable manufacturing, these materials often have insufficient flame-retardant properties and poor mechanical properties under high-temperature conditions, easily leading to cable damage during use. While flexible materials such as polyurethane (PU) and polypropylene (PP) have good mechanical properties, they produce a large amount of smoke when burning, and their flame-retardant properties are also unsatisfactory.

[0008] Furthermore, even some cable materials that are advertised as low-smoke and halogen-free often still produce a certain amount of harmful fumes during actual use, especially in enclosed spaces. These fumes can obstruct escape routes and increase the risk of fire. Current technology does not offer an effective solution to this problem. Summary of the Invention

[0009] To address the aforementioned technical deficiencies, this invention proposes a novel low-smoke halogen-free flame-retardant and fire-resistant cable material. The aim is to provide a cable material that possesses both excellent flame-retardant properties and characteristics such as low smoke, halogen-free, environmental friendliness, and fire resistance. Under fire conditions, it can limit the spread of flames, reduce the generation of toxic fumes, and further reduce the threat of fire to personnel and equipment. Simultaneously, its excellent flexibility ensures the cable's performance and stability in various environments.

[0010] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0011] This invention provides a low-smoke, halogen-free, flame-retardant, and fire-resistant cable material, comprising the following components: low-density polyethylene (LDPE), magnesium stearate, magnesium hydroxide, aluminum hydroxide, microencapsulated red phosphorus, compatibilizer, silane coupling agent, and antioxidant.

[0012] Preferably, a low-smoke, halogen-free, flame-retardant, and fire-resistant cable material comprises the following components, in parts by weight:

[0013] Low-density polyethylene (LDPE) 50-150 parts

[0014] 1-10 parts magnesium stearate

[0015] 5-35 parts of magnesium hydroxide,

[0016] 5-35 parts aluminum hydroxide

[0017] Microencapsulated red phosphorus 3-20 parts,

[0018] 2-10 parts compatibilizer

[0019] 1-6 parts of silane coupling agent

[0020] Antioxidant 0.2-3 parts.

[0021] Preferably, a low-smoke, halogen-free, flame-retardant, and fire-resistant cable material comprises the following components, in parts by weight:

[0022] Low-density polyethylene (LDPE) 80-120 parts

[0023] 1-3 parts magnesium stearate

[0024] 10-20 parts magnesium hydroxide,

[0025] 10-20 parts aluminum hydroxide,

[0026] Microencapsulated red phosphorus 5-15 parts,

[0027] 3-7 parts compatibilizer

[0028] 1-3 parts of silane coupling agent

[0029] Antioxidant 0.5-2 parts.

[0030] The compatibilizer can be a block type compatibilizer, a grafted type compatibilizer, a copolymer type compatibilizer, an anhydride type compatibilizer, an epoxy type compatibilizer, or an oxazoline type compatibilizer. Through extensive experimentation, the inventors have determined that the most suitable compatibilizer for the system of this invention is at least one of POE-g-MAH compatibilizer, a polyethylene-styrene / acrylonitrile graft copolymer, and an epoxy-modified PS-grafted PMMA compatibilizer. The preferred compatibilizer is a combination of POE-g-MAH compatibilizer and a polyethylene-styrene / acrylonitrile graft copolymer in a mass ratio of (1-3):(1-3).

[0031] Preferably, the low-smoke halogen-free flame-retardant and fire-resistant cable material further includes 1-3 parts of diphenylsilanediol.

[0032] In some other embodiments, the cable material may further contain other additives, such as stabilizers, UV absorbers, mildew inhibitors, and preservatives, with the total mass fraction of these additives being between 0 and 10.

[0033] In addition, in some solutions, the cable material can be further processed, for example, by extrusion, molding, blown film, injection molding and other processes to form the required cable cover layer to meet different application requirements.

[0034] In some solutions, the cable material can be applied to various types of cables, including but not limited to power cables, communication cables, data cables, coaxial cables, etc.

[0035] This invention also provides a method for preparing the above-mentioned low-smoke halogen-free flame-retardant and fire-resistant cable material, comprising the following steps:

[0036] First, magnesium hydroxide, aluminum hydroxide, magnesium stearate, and silane coupling agent are mixed to obtain a modified inorganic flame retardant;

[0037] The modified inorganic flame retardant, low-density polyethylene (LDPE), microencapsulated red phosphorus, compatibilizer, and antioxidant are then mixed and extruded.

[0038] Preferably, a method for preparing a low-smoke halogen-free flame-retardant fire-resistant cable material includes the following steps:

[0039] First, mix magnesium hydroxide, aluminum hydroxide, magnesium stearate and silane coupling agent, and stir at a stirring speed of 400-600 rpm for 1-3 hours to obtain a modified inorganic flame retardant.

[0040] The modified inorganic flame retardant, low-density polyethylene (LDPE), microencapsulated red phosphorus, compatibilizer, and antioxidant are then mixed and melt-mixed for 10-15 minutes on a twin-screw extruder at 135-145°C, and then granulated or directly molded.

[0041] During the experiment, the inventors discovered that changing the order in which magnesium stearate and the silane coupling agent were added had a significant impact on the performance of the final product. Mixing magnesium hydroxide and aluminum hydroxide first with the silane coupling agent and then with magnesium stearate improved both the flame retardant and mechanical properties.

[0042] Accordingly, the present invention also provides another method for preparing a low-smoke halogen-free flame-retardant and fire-resistant cable material, comprising the following steps:

[0043] First, magnesium hydroxide, aluminum hydroxide and silane coupling agent are mixed evenly, and then mixed with magnesium stearate to obtain a modified inorganic flame retardant.

[0044] The modified inorganic flame retardant, low-density polyethylene (LDPE), microencapsulated red phosphorus, compatibilizer, and antioxidant are then mixed and extruded.

[0045] The advantages of the low-smoke, halogen-free, flame-retardant, and fire-resistant cable material of this invention are as follows:

[0046] Using halogen-free flame retardants, the environmental performance is outstanding: This invention uses halogen-free flame retardants, which effectively avoids the harmful halogenated compounds that may be produced when traditional flame retardants burn, in line with modern environmental protection concepts.

[0047] Significant flame retardant effect: By modifying the inorganic flame retardant and using microencapsulated red phosphorus (MRP), the cable material of the present invention has an excellent flame retardant effect.

[0048] High stability and excellent mechanical properties: Through the rational design of the formula and preparation process, this invention enables the inorganic flame retardant to be evenly distributed in the polyethylene matrix. In addition, the introduction of compatibilizer effectively improves the stability and mechanical properties of the material.

[0049] The process is simple and the cost is low: the cable material of the present invention has a simple preparation process, which does not require complicated equipment and high energy consumption conditions, thus reducing production costs.

[0050] Therefore, the low-smoke halogen-free flame-retardant and fire-resistant cable material and its preparation method provided by this invention are a new type of cable material that is environmentally friendly, safe, and economical with broad application prospects. Detailed Implementation

[0051] A low-smoke, halogen-free, flame-retardant, and fire-resistant cable material comprises the following components, in parts by weight:

[0052] Low-density polyethylene (LDPE) 80-120 parts

[0053] 1-3 parts magnesium stearate

[0054] 10-20 parts magnesium hydroxide,

[0055] 10-20 parts aluminum hydroxide,

[0056] Microencapsulated red phosphorus 5-15 parts,

[0057] 3-7 parts compatibilizer

[0058] 1-3 parts of silane coupling agent

[0059] Antioxidant 0.5-2 parts.

[0060] The preparation method of the above-mentioned low-smoke halogen-free flame-retardant fire-resistant cable material includes the following steps:

[0061] (1) First, mix magnesium hydroxide, aluminum hydroxide, magnesium stearate and silane coupling agent, and stir at a stirring speed of 400-600 rpm for 1-3 hours to obtain modified inorganic flame retardant.

[0062] Inorganic flame retardants, such as metal hydroxides, have high surface energy, which can lead to uneven dispersion in polymers and affect the overall performance of the material. This is because high surface energy increases the attraction between powder particles, making them more prone to agglomeration. To address this issue, this invention employs a surface modification method. The purpose of surface modification is to introduce groups compatible with polymers onto the surface of the inorganic flame retardant metal hydroxide, thereby improving the dispersibility of the flame retardant in the polymer and thus enhancing the material's processing and mechanical properties. In this invention, the inventors use magnesium stearate and a silane coupling agent for surface modification. Magnesium stearate can form a coating layer on the surface of the inorganic flame retardant, which reduces the attraction between flame retardant particles, thereby reducing agglomeration. The silane coupling agent can form an interface with good compatibility with the polymer on the surface of the inorganic flame retardant, further improving the dispersibility of the flame retardant in the polymer. The combined use of these two modifiers can effectively improve the dispersibility of flame retardant metal hydroxides in the polymer LDPE, thereby improving the processing performance and mechanical properties of the material.

[0063] (2) The modified inorganic flame retardant, low-density polyethylene (LDPE), microencapsulated red phosphorus, compatibilizer and antioxidant are then mixed and melt-mixed for 10-15 minutes on a twin-screw extruder at 135-145℃, and then granulated or directly molded.

[0064] Low-density polyethylene (LDPE) serves as the main matrix of this invention, providing the cable with excellent mechanical and electrical properties. Furthermore, the high degree of freedom in the chain structure of LDPE contributes to its good flexibility and processability. Microencapsulated red phosphorus, as part of the flame retardant, is an effective phosphorus-based flame retardant. Its mechanism of action primarily involves releasing phosphoric acid during combustion, which reacts with free radicals in the combustion reaction, preventing the combustion chain reaction. Microencapsulation technology prevents red phosphorus from reacting with oxygen and moisture in the environment at room temperature, improving its stability and safety. The compatibilizer promotes interfacial adhesion between the flame retardant and LDPE, effectively improving the dispersibility and stability of the flame retardant in the LDPE matrix. It also improves the material's mechanical properties. Antioxidants are mainly used to prevent oxidative degradation of LDPE during processing and use, thereby maintaining the material's long-term stability and performance.

[0065] The purpose of this step is to mix the raw materials and form a molded material through extrusion. During extrusion, the components of the raw materials are thoroughly mixed under the strong shearing action of the twin-screw extruder, resulting in a homogeneous mixture. The extruder temperature is controlled at 135-145℃ to melt the LDPE, but to avoid decomposition or excessive flow due to excessive temperature. The mixing time of 10-15 minutes is set with reference to typical process conditions. This time needs to be long enough to ensure thorough mixing of the raw materials, but not too long to prevent degradation caused by prolonged exposure to high temperatures. Direct molding refers to using an extruder to directly extrude the mixture into the desired shape, such as cable sheaths. Granulation involves cutting the extruded mixture into granules for easy storage and transportation, and also allows for further processing when needed.

[0066] Preferably, the low-smoke halogen-free flame-retardant fire-resistant cable material also contains 1-3 parts of diphenylsilanediol. The presence of diphenylsilanediol optimizes the polymer's flowability and tensile strength, thereby improving the finished product's elongation at break and tensile strength. Furthermore, diphenylsilanediol possesses excellent heat resistance, enhancing the material's thermal stability and resistance to heat aging. In addition, diphenylsilanediol exhibits superior electrical insulation properties, further improving the cable material's electrical insulation performance.

[0067] In the following examples:

[0068] Low-density polyethylene (LDPE), Sinopec Yanshan 1C7A general-purpose grade low-density polyethylene (LDPE).

[0069] Magnesium stearate, Linghu Xinwang Company Magnesium stearate with product number yzsm.

[0070] Magnesium hydroxide, Grade I laser-cut magnesium hydroxide with a particle size D(50) / μm of 0.5-1.5 provided by Weifang Kaibo Magnesium Salt Co., Ltd.

[0071] Aluminum hydroxide, grade AH-3, with a particle size of 800-10000, provided by Hefei Zhongke Flame Retardant New Materials Co., Ltd.

[0072] Microencapsulated red phosphorus, 2000 mesh YMRP-90 (item number 8) coated red phosphorus flame retardant provided by Jining Yimin Chemical Co., Ltd.

[0073] POE-g-MAH compatibilizer, model XY-310, provided by Dongguan Xingyuan Chemical Co., Ltd.

[0074] Epoxy-modified PS grafted PMMA compatibilizer, trade name Reseda GP 300 provided by Toa Chemicals, Japan.

[0075] The polyethylene-styrene / acrylonitrile graft was a polyethylene-styrene / acrylonitrile graft of grade modiperA1401 provided by Nippon Oils & Fats Co., Ltd.

[0076] Silane coupling agent, Kangjin Chemical provides KH-560 (γ-glycidyl etheroxypropyltrimethoxysilane) with product number 0795.

[0077] Diphenylsilanediol, CAS No. 947-42-2, is diphenylsilanediol supplied by Wuhan Adoma New Energy Co., Ltd.

[0078] Example 1

[0079] A low-smoke, halogen-free, flame-retardant cable material is composed of the following components, in parts by weight:

[0080] 100 parts of low-density polyethylene (LDPE)

[0081] 2 parts magnesium stearate

[0082] 15 parts magnesium hydroxide,

[0083] 15 parts aluminum hydroxide,

[0084] 10 parts of microencapsulated red phosphorus,

[0085] 5 parts of POE-g-MAH compatibilizer

[0086] 2 parts silane coupling agent

[0087] 1 part of 1010 antioxidant.

[0088] The preparation method of the above-mentioned low-smoke halogen-free flame-retardant cable material includes the following steps:

[0089] (1) First, mix magnesium hydroxide, aluminum hydroxide, magnesium stearate and silane coupling agent evenly, and then stir at a stirring speed of 500 rpm for 2 hours to obtain modified inorganic flame retardant.

[0090] (2) The modified inorganic flame retardant, low-density polyethylene (LDPE), microencapsulated red phosphorus, POE-g-MAH compatibilizer and antioxidant 1010 obtained in the above steps are mixed evenly and melt-mixed on a twin-screw extruder at 140°C for 12 minutes. Then, the mixture is extruded and the standard sample is obtained by using an injection molding machine with the corresponding mold according to the relevant standards.

[0091] The low-smoke halogen-free flame-retardant cable material of this embodiment uses a halogen-free flame retardant, which is both environmentally friendly and has excellent flame-retardant effects. Modified inorganic flame retardants, magnesium hydroxide and aluminum hydroxide, work together with magnesium stearate and silane coupling agents to effectively improve the dispersibility and stability of the flame retardant in the LDPE matrix, thereby enhancing the material's flame-retardant performance. The addition of microencapsulated red phosphorus and POE-g-MAH compatibilizer not only improves the flame-retardant effect but also optimizes the material's mechanical properties. Overall, the cable material of this invention features good flame retardancy, is environmentally friendly and halogen-free, has high stability, and possesses good mechanical and electrical properties, making it highly suitable as insulation and sheathing materials for cables.

[0092] Comparative Example 1

[0093] The magnesium stearate in Example 1 was replaced with an equal amount of stearic acid, and all other conditions were the same.

[0094] Example 2

[0095] The formulation of Example 2 is exactly the same as that of Example 1, the difference being in the preparation method. The preparation method of the low-smoke halogen-free flame-retardant cable material includes the following steps:

[0096] (1) First, mix magnesium hydroxide, aluminum hydroxide and silane coupling agent evenly, then stir at a stirring speed of 500 rpm for 1 hour, then add magnesium stearate and stir at a stirring speed of 500 rpm for 1 hour to obtain modified inorganic flame retardant.

[0097] (2) The modified inorganic flame retardant, low-density polyethylene (LDPE), microencapsulated red phosphorus, POE-g-MAH compatibilizer and antioxidant 1010 obtained in the above steps are mixed evenly and melt-mixed on a twin-screw extruder at 140°C for 12 minutes. Then, the mixture is extruded and the standard sample is obtained by using an injection molding machine with the corresponding mold according to the relevant standards.

[0098] Example 3

[0099] The formulation of Example 3 is exactly the same as that of Example 1, the difference being in the preparation method. The preparation method of the low-smoke halogen-free flame-retardant cable material includes the following steps:

[0100] (1) First, mix magnesium hydroxide, aluminum hydroxide and magnesium stearate evenly, then stir at a stirring speed of 500 rpm for 1 hour, then add silane coupling agent and stir at a stirring speed of 500 rpm for 1 hour to obtain modified inorganic flame retardant.

[0101] (2) The modified inorganic flame retardant, low-density polyethylene (LDPE), microencapsulated red phosphorus, POE-g-MAH compatibilizer and antioxidant 1010 obtained in the above steps are mixed evenly and melt-mixed on a twin-screw extruder at 140°C for 12 minutes. Then, the mixture is extruded and the standard sample is obtained by using an injection molding machine with the corresponding mold according to the relevant standards.

[0102] Example 4

[0103] A low-smoke, halogen-free, flame-retardant cable material is composed of the following components, in parts by weight:

[0104] 100 parts of low-density polyethylene (LDPE)

[0105] 2 parts magnesium stearate

[0106] 15 parts magnesium hydroxide,

[0107] 15 parts aluminum hydroxide,

[0108] 10 parts of microencapsulated red phosphorus,

[0109] 5 parts of POE-g-MAH compatibilizer

[0110] 2 parts silane coupling agent

[0111] Two parts of diphenylsilanediol;

[0112] 1 part of 1010 antioxidant.

[0113] The preparation method of the above-mentioned low-smoke halogen-free flame-retardant cable material includes the following steps:

[0114] (1) First, mix magnesium hydroxide, aluminum hydroxide and silane coupling agent evenly, then stir at a stirring speed of 500 rpm for 1 hour, then add magnesium stearate and stir at a stirring speed of 500 rpm for 1 hour to obtain modified inorganic flame retardant.

[0115] (2) The modified inorganic flame retardant, low-density polyethylene (LDPE), microencapsulated red phosphorus, POE-g-MAH compatibilizer, diphenylsilanediol and antioxidant 1010 obtained in the above steps are mixed evenly and melt-mixed on a twin-screw extruder at 140°C for 12 minutes. Then, the mixture is extruded and the standard sample is obtained by using an injection molding machine with the corresponding mold according to the relevant standards.

[0116] Example 5

[0117] The POE-g-MAH compatibilizer in Example 4 was replaced with an equal amount of epoxy-modified PS-grafted PMMA compatibilizer, while all other conditions remained the same.

[0118] Example 6

[0119] Replace “5 parts of POE-g-MAH compatibilizer” in Example 4 with “3 parts of POE-g-MAH compatibilizer and 2 parts of epoxy-modified PS grafted PMMA compatibilizer”, with all other conditions remaining the same.

[0120] Example 7

[0121] The POE-g-MAH compatibilizer in Example 4 was replaced with an equal amount of polyethylene and styrene / acrylonitrile graft, while all other conditions remained the same.

[0122] Example 8

[0123] Replace “5 parts of POE-g-MAH compatibilizer” in Example 4 with “3 parts of POE-g-MAH compatibilizer and 2 parts of the grafted product of polyethylene and styrene / acrylonitrile”, with all other conditions remaining the same.

[0124] Test Example 1

[0125] The oxygen index was determined according to the test method in GB / T 2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test". Type I specimens were used in this test.

[0126] The vertical flammability rating was determined according to the test method in GB / T 2408-2021, "Determination of Burning Performance of Plastics - Horizontal and Vertical Methods". A 3.0 mm wide specimen was used as the sample in the test.

[0127] The tensile strength was determined according to the test method of GB / T 1040-2006.

[0128] The elongation at break was determined according to the test method in GB / T 1040-2006. A type 1A standard specimen was used in the test, and the experimental speed was set to 50 mm / min.

[0129] Table 1: Cable Material Performance Test Table

[0130] Example 1 Comparative Example 1 Example 2 Example 3 Example 4 Oxygen index, % 29.4 28.1 30.2 28.8 30.6 Vertical flammability rating V-0 V-0 V-0 V-0 V-0 Tensile strength, MPa 14.5 13.2 14.8 14.1 15.2 Elongation at break, % 320 285 345 305 365

[0131] Table 2: Cable Material Performance Test Table

[0132]

[0133]

[0134] Comparing Example 1 and Comparative Example 1, it can be seen that:

[0135] Magnesium stearate has better advantages over stearic acid, mainly due to its interaction with magnesium hydroxide and aluminum hydroxide.

[0136] Magnesium stearate is a compound formed from stearic acid and magnesium ions. It is formed by two stearic acid anions sharing a magnesium ion. In this process, the carboxylic acid group of stearic acid binds to the magnesium ion. The magnesium ion is divalent, carrying two charges, thus enabling it to bind with two stearic acid ions to form stable magnesium stearate. Unlike stearic acid, magnesium stearate contains magnesium ions, which theoretically can form chemical bonds with the surface hydroxyl groups of magnesium hydroxide and aluminum hydroxide, thereby improving the dispersibility of the flame retardant in the polyethylene matrix. The formation of these chemical bonds is more stable than the physical adsorption of stearic acid because chemical bonds involve the sharing or transfer of electrons, while physical adsorption mainly relies on intermolecular van der Waals forces. Therefore, the use of magnesium stearate results in a tighter bond between the flame retardant and the matrix, leading to better dispersibility. Furthermore, the presence of magnesium stearate also improves the thermal stability of the flame retardant. This is because magnesium ions can prevent stearic acid molecules from agglomerating during heating, thus maintaining the stability of the flame retardant at high temperatures and improving the flame-retardant effect of the material.

[0137] In summary, magnesium stearate binds more tightly to magnesium hydroxide and aluminum hydroxide than stearic acid, which can better improve the dispersibility of flame retardants in the polyethylene matrix, thereby enhancing the flame retardant effect.

[0138] Comparing Examples 1-3, it can be seen that:

[0139] The difference between Examples 1-3 lies in the order of mixing the silane coupling agent and magnesium stearate. In Example 1, magnesium hydroxide, aluminum hydroxide, silane coupling agent, and magnesium stearate are added and mixed simultaneously; in Example 2, magnesium hydroxide and aluminum hydroxide are mixed with the silane coupling agent first, and then magnesium stearate is mixed; in Example 3, magnesium hydroxide and aluminum hydroxide are mixed with magnesium stearate first, and then silane coupling agent is mixed.

[0140] In Example 2, magnesium hydroxide, aluminum hydroxide, and a silane coupling agent were first mixed, followed by the addition of magnesium stearate. This sequence may help the silane coupling agent to better adsorb onto the surfaces of magnesium hydroxide and aluminum hydroxide, thereby improving the dispersibility of the nanofiller and its compatibility with the polyethylene matrix. This may improve flame retardant properties because the silane coupling agent enhances the thermal stability of magnesium hydroxide and aluminum hydroxide, reduces free radicals generated during heating, and slows down the thermal degradation rate of polyethylene, thus improving flame retardant performance. Furthermore, the dispersibility of the nano-flame retardant in the matrix also affects the electrical properties of the cable material. Better-dispersed nanoparticles can form a more uniform insulation layer, thereby improving the insulation performance of the cable. As for mechanical properties, when the nano-flame retardant is more uniformly dispersed in the polyethylene matrix, it can enhance the tensile strength, abrasion resistance, and impact resistance of the cable material.

[0141] In Example 3, magnesium hydroxide, aluminum hydroxide, and magnesium stearate were mixed first, and then a silane coupling agent was added. This difference may affect the interaction between the silane coupling agent and the nanoparticles, thereby affecting the dispersion of the flame retardant in the polyethylene matrix. When the silane coupling agent cannot be sufficiently adsorbed onto the surface of the nanoparticles, the bonding between particles may not be tight enough during mixing, thus affecting the dispersion of the flame retardant in the polyethylene matrix. This difference in dispersion may lead to a reduction in the flame retardant effect. First, when the nano-flame retardant is unevenly dispersed in the matrix, it may not be able to form a complete protective layer during combustion, slowing down the pyrolysis of polyethylene and thus reducing the flame retardant performance. In addition, unevenly dispersed nano-flame retardants may cause a decrease in the electrical properties of the cable material. Unevenly dispersed flame retardants may lead to uneven resistance, affecting the insulation performance of the cable. Second, unevenly dispersed nano-flame retardants may affect the mechanical properties of the cable material. Unevenly dispersed nanoparticles may form local stress concentrations, reducing the tensile strength, abrasion resistance, and impact resistance of the cable material.

[0142] Comparing Example 2 and Example 4, it can be seen that:

[0143] Diphenylsilanediol itself does not have significant flame retardancy and does not directly affect the flame retardant properties of materials. However, it indirectly improves flame retardancy by enhancing the dispersibility and stability of the flame retardant in the polyethylene matrix.

[0144] Diphenylsilanediol can improve the flowability and tensile strength of polymers, thereby increasing the elongation at break and tensile strength of finished products. Diphenylsilanediol has good heat resistance, which can improve the thermal stability and heat resistance of materials. Diphenylsilanediol also has excellent electrical insulation properties, which can improve the electrical insulation of cable materials.

[0145] Comparative Examples 5 and 4:

[0146] Replacing the POE-g-MAH compatibilizer with an epoxy-modified PS grafted PMMA compatibilizer improves mechanical properties while maintaining essentially the same flame retardant properties.

[0147] Improved Mechanical Properties: In Example 5, the compatibilizer was replaced by epoxy-modified PS grafted PMMA instead of POE-g-MAH. Since PS and PMMA have superior hardness and mechanical properties compared to POE, the use of this compatibilizer improves the overall hardness and mechanical properties of the composite material. Furthermore, the epoxy groups can form chemical bonds between polyethylene (LDPE) and the flame retardant, thereby improving the dispersion of the flame retardant in the polyethylene matrix and enhancing the tensile strength and abrasion resistance of the composite material.

[0148] The flame retardant properties remain essentially unchanged: Although epoxy-modified PS grafted PMMA and POE-g-MAH have different chemical structures, they can both act as effective compatibilizers, improving the dispersibility of flame retardants in LDPE. Magnesium stearate, magnesium hydroxide, aluminum hydroxide, and microencapsulated red phosphorus, as flame retardants, generate non-combustible gases through hydration and thermal decomposition, preventing the combustion of the polyethylene matrix. This process is not significantly affected by the type of compatibilizer used; therefore, the flame retardant properties are essentially unaffected by compatibilizer substitution.

[0149] Improved electrical insulation performance: The presence of epoxy-modified PS grafted PMMA compatibilizer improves the dispersion of flame retardant in LDPE, reduces microscopic defects in the cable, and thus improves the electrical insulation performance of the cable.

[0150] Comparative Examples 7 and 4:

[0151] The mechanical properties are improved by replacing the POE-g-MAH compatibilizer with a grafted polyethylene and styrene / acrylonitrile, while the flame retardant properties remain basically unchanged.

[0152] In Example 7, the POE-g-MAH compatibilizer was replaced by a polyethylene-styrene / acrylonitrile graft copolymer. The polyethylene-styrene / acrylonitrile graft copolymer is a copolymer formed by grafting polyethylene with a polymer containing styrene and acrylonitrile units. This compatibilizer contains both a polyethylene structure similar to the matrix LDPE and a polar structure similar to rigid flame retardants (such as magnesium hydroxide and aluminum hydroxide), thus effectively improving the interfacial compatibility between LDPE and the flame retardant.

[0153] Improved Mechanical Properties: Compared to POE-g-MAH, styrene / acrylonitrile grafts of polyethylene may exhibit better hardness and tensile strength due to the more complex structure of the grafts, which allows for the formation of more physical cross-linking points within the material. Therefore, the addition of this compatibilizer can effectively improve the mechanical properties of LDPE, including hardness, tensile strength, and abrasion resistance.

[0154] The flame retardant properties remain essentially unchanged: the role of the polyethylene-styrene / acrylonitrile graft compound in the material is mainly to improve the compatibility between LDPE and the flame retardant, while having virtually no impact on the combustion-inhibiting mechanism of the flame retardant itself. Magnesium stearate, magnesium hydroxide, aluminum hydroxide, and microencapsulated red phosphorus, as flame retardants, primarily function by absorbing heat through hydrothermal hydration or thermal decomposition to generate non-combustible gases, thus inhibiting the combustion process. This process is largely independent of the type of compatibilizer used; therefore, the flame retardant properties are essentially unaffected by compatibilizer replacement.

[0155] Impact on electrical insulation performance: Grafting polyethylene with styrene / acrylonitrile can improve the dispersion of flame retardants in LDPE and reduce microscopic defects in the material, thereby improving the electrical insulation performance of the cable.

[0156] Comparing Examples 8 and 4 / 7:

[0157] POE-g-MAH compatibilizer and the grafted polyethylene with styrene / acrylonitrile work synergistically to significantly improve mechanical properties.

[0158] POE-g-MAH exhibits excellent toughness and flexibility due to the high chain mobility of the polyether ester group in its molecular chain, which effectively absorbs external impact forces and prevents material breakage. Simultaneously, the maleic anhydride moiety forms a microscopic interpenetrating network structure within the polyethylene matrix, enhancing the material's cohesiveness and improving its impact strength and ductility. In the grafted polyethylene with styrene / acrylonitrile, the microphase separation structure formed between the hard segment (styrene / acrylonitrile) and the soft segment (polyethylene) allows for physical cross-linking through hard segment interactions under stress, increasing the material's hardness and tensile strength.

[0159] When these two compatibilizers are present simultaneously, POE-g-MAH and the polyethylene-styrene / acrylonitrile graft may form a composite network structure at the microscopic level. The elastic network of POE-g-MAH can absorb external forces, while the hard segment network of the polyethylene-styrene / acrylonitrile graft can prevent the slippage of polymer chains. This dual-network structure retains, to a certain extent, both the toughness and flexibility of POE-g-MAH and the hardness and tensile strength of the polyethylene-styrene / acrylonitrile graft. Therefore, this synergistic effect can improve the hardness and tensile strength of the material while maintaining its good flexibility, thereby significantly improving the mechanical properties of the material.

[0160] Test Example 2: Electrical Performance

[0161] Volume resistivity: The volume resistivity was measured at 20℃ in accordance with GB / T15662-1995 "Test Method for Volume Resistivity of Conductive and Antistatic Plastics".

[0162] Table 3 Resistivity Test Results

[0163] <![CDATA[Volume Resistivity / 10 14 Ω·M]]> Example 1 14.5 Example 4 16.2

[0164] Comparing Example 1 and Example 4, it can be seen that:

[0165] Diphenylsilanediol can improve the flowability and tensile strength of polymers, thereby increasing the elongation at break and tensile strength of finished products. Diphenylsilanediol has good heat resistance, which can improve the thermal stability and heat resistance of materials. Diphenylsilanediol also has excellent electrical insulation properties, which can improve the electrical insulation of cable materials.

[0166] The low-smoke halogen-free flame-retardant fire-resistant cable material of this invention also possesses excellent fire resistance. Firstly, this novel low-smoke halogen-free flame-retardant fire-resistant cable material exhibits significant fire resistance. This means that under fire conditions, it not only effectively limits the spread of flames and the generation of smoke, but more importantly, it maintains its structural integrity and functional performance during a fire. This allows the cable to continue performing its power or data transmission functions even during a fire, reducing the damage to power and communication systems caused by the fire and improving public safety and equipment reliability. Secondly, due to the material's excellent fire resistance, it can significantly improve the safety of equipment and systems using such cables. This is crucial for critical facilities that need to maintain operation in fire or high-temperature environments, such as fire alarm systems, emergency evacuation lighting systems, and power and communication infrastructure.

[0167] Furthermore, because this cable material maintains its structural and functional properties under fire conditions, it helps prevent the spread of flames to other parts of the building through the cable system. This is especially important in large buildings and facilities, where cables are typically distributed throughout the building. Finally, the use of this fire-resistant cable material can reduce the time and cost of facility restoration after a fire. Because the cables retain their function during a fire, facilities may require little or no cable replacement and repair work after a fire.

[0168] In summary, the fire resistance of this new low-smoke halogen-free flame-retardant fire-resistant cable material brings significant advantages and application value, providing higher safety, reducing the threat of fire to personnel and equipment, and reducing the cost and time of facility restoration after a fire.

Claims

1. A low smoke, halogen-free, flame retardant, fire resistant cable material characterized in that, Comprise the following components, its mass fraction is: Low density polyethylene LDPE 80-120 parts, Magnesium stearate 1-3 parts, Magnesium hydroxide 10-20 parts, Aluminum hydroxide 10-20 parts, Microencapsulated red phosphorus 5-15 parts, Compatibilizer 3-7 parts, Silane coupling agent 1-3 parts, Diphenylsilanediol 1-3 parts, Antioxidant 0.5-2 parts; The silane coupling agent is γ-glycidyl ether oxygen propyl trimethoxysilane; Prepared by the following method: First, magnesium hydroxide, aluminum hydroxide and silane coupling agent are mixed uniformly, then mixed with magnesium stearate, to obtain modified inorganic flame retardant; Then the modified inorganic flame retardant, low density polyethylene LDPE, microencapsulated red phosphorus, compatibilizer, diphenylsilanediol and antioxidant are mixed and extruded.

2. A low smoke, halogen-free, flame retardant, fire resistant cable material as set forth in Claim 1 wherein, The compatibilizer is POE-g-MAH compatibilizer, the graft of polyethylene and styrene / acrylonitrile is combined according to the mass ratio (1-3):(1-3).

3. A process for the preparation of a low smoke, halogen-free, flame retardant, fire resistant cable material as claimed in claim 1 or 2, characterised in that, Comprise the following steps: First, magnesium hydroxide, aluminum hydroxide and silane coupling agent are mixed uniformly, then mixed with magnesium stearate, to obtain modified inorganic flame retardant; Then the modified inorganic flame retardant, low density polyethylene LDPE, microencapsulated red phosphorus, compatibilizer, diphenylsilanediol and antioxidant are mixed and extruded.

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