Efficient radiation crosslinking halogen-free flame-retardant cable material and preparation method thereof
By combining ethylene-vinyl acetate copolymer and highly branched polyethylene resin with vinyl-terminated hyperbranched polymers, along with crosslinking sensitizers and dual-terminated vinyl silicone oil, the problems of cost and energy consumption in traditional cable materials under high crosslinking degree are solved, achieving efficient crosslinking and improved material performance under low irradiation dose.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HANGZHOU MEILIN PLASTIC IND CO LTD
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional irradiated cross-linked halogen-free flame-retardant cable materials require increased irradiation dose when the cross-linking degree or thickness is high, which leads to increased production costs, high energy consumption and decreased material aging performance, making them unsuitable for ultra-long lifespan and extreme environments.
Using ethylene-vinyl acetate copolymer and highly branched polyethylene resin as the matrix resin, combined with terminal vinyl hyperbranched polymer and crosslinking sensitizer, efficient crosslinking is achieved through low irradiation dose, and double-terminated vinyl silicone oil is added to improve flowability and flexibility.
Achieving high cross-linking at low irradiation doses improves the overall performance of materials, including cross-linking reaction rate, density, flexibility, heat resistance, and surface smoothness, while reducing production costs and energy consumption.
Smart Images
Figure SMS_1 
Figure SMS_2
Abstract
Description
Technical Field
[0001] This application relates to the technical field of cable materials, and in particular to a high-efficiency radiation cross-linked halogen-free flame-retardant cable material and its preparation method. Background Technology
[0002] Irradiated cross-linked halogen-free flame-retardant cable materials are key basic materials for high-performance special cables, playing an important role in complex operating environments requiring high reliability and safety, such as locomotives, rolling stock, and nuclear power plants. These materials must possess multiple properties, including excellent flame retardancy, low smoke density, heat resistance, radiation resistance, mechanical strength, and oil resistance. While traditional irradiated cross-linked polyolefin cable materials possess certain cross-linking efficiency and processing convenience, achieving high cross-linking degrees or greater thicknesses often requires increasing the irradiation dose. This not only increases production costs and energy consumption but also easily triggers irradiation degradation of the polymer matrix, leading to problems such as excessive consumption of antioxidants, decreased material aging performance, and poor uniformity of the cross-linked network, thus limiting their applicability in ultra-long-life cables and cables used in extreme environments.
[0003] Therefore, developing a cable material that can achieve high cross-linking at low radiation doses while also maintaining excellent thermal stability and processing feasibility has become a pressing technical challenge in the high-end cable field. Summary of the Invention
[0004] To improve the crosslinking degree of cable material under low radiation dose, this application provides a high-efficiency radiation crosslinking halogen-free flame-retardant cable material and its preparation method.
[0005] In the first aspect, this application provides a high-efficiency radiation cross-linked halogen-free flame-retardant cable material, which adopts the following technical solution: A high-efficiency radiation crosslinking halogen-free flame-retardant cable material comprises the following raw materials in parts by weight: 15-25 parts of ethylene-vinyl acetate copolymer, 3-8 parts of highly branched polyethylene resin, 0.5-1.5 parts of vinyl-terminated hyperbranched polymer, 12-18 parts of compatibilizer, 35-45 parts of flame retardant, 0.8-1.2 parts of antioxidant, 1-3 parts of radiation resistant agent, and 1.5-3 parts of crosslinking sensitizer.
[0006] By adopting the above technical solution, using ethylene-vinyl acetate copolymer and highly branched polyethylene resin as the matrix resin, the ethylene-vinyl acetate copolymer can provide polarity and flexibility, while the highly branched polyethylene resin, due to its multi-branched structure containing more vinyl groups, can become a sensitive point for irradiation crosslinking. The blending of the two provides a basis for efficient crosslinking.
[0007] Building upon this foundation, a vinyl-terminated hyperbranched polymer was added. This is a key method for achieving efficient crosslinking in this application. Its hyperbranched three-dimensional spherical structure possesses numerous terminal functional groups. Under irradiation, these terminal vinyl groups are activated, forming uniform "micro-crosslinking points" within the matrix, significantly increasing the density of reaction sites and substantially enhancing the crosslinking reaction rate and density. Simultaneously, due to its inherent characteristics as a hyperbranched polymer, the vinyl-terminated hyperbranched polymer exhibits low viscosity. Furthermore, its excellent compatibility with ethylene-vinyl acetate copolymers allows for uniform distribution within the matrix, another crucial factor contributing to its efficient crosslinking. It was also discovered that its spherical, extended-branch structure can encapsulate crosslinking sensitizer molecules to a certain extent. Upon radiation excitation, the crosslinking sensitizer can more rapidly initiate the crosslinking of the vinyl-terminated hyperbranched polymer, further contributing to its efficient crosslinking. Therefore, through the synergistic effect of the various raw materials, the cable material of this application achieves efficient crosslinking under low irradiation doses, improving the overall performance of the cable material.
[0008] Preferably, the terminal vinyl hyperbranched polymer is prepared by reacting terminal amino hyperbranched polyamide with acryloyl chloride.
[0009] By adopting the above technical solution and defining this synthetic route, it is possible to obtain a terminal vinyl hyperbranched polymer containing vinyl groups by reacting terminal amino hyperbranched polyamide with acryloyl chloride. The resulting molecular chain skeleton itself has certain toughness and polarity, and the amide bonds in its molecular structure can also make it more compatible with the matrix resin and improve its dispersibility in the matrix. At the same time, its molecular skeleton may also contribute to the toughness of the final material.
[0010] Preferably, the average molecular weight of the terminal amino hyperbranched polyamide is 900-2200 Da.
[0011] By employing the above technical solution and limiting the molecular weight of the terminal amino hyperbranched polyamide, the overall performance of the resulting cable material can be optimized. When the molecular weight is too low, its effect is not significant; when the molecular weight is too high, it easily leads to increased material brittleness, causing a decline in the overall performance of the material.
[0012] Preferably, the crosslinking sensitizer includes crosslinking sensitizer A and crosslinking sensitizer B, wherein crosslinking sensitizer A is one or more of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and triallyl isocyanurate; and crosslinking sensitizer B is one or more of tri(2-hydroxyethyl) isocyanurate triacrylate and di(trimethylolpropane) tetraacrylate.
[0013] By adopting the above technical solution, crosslinking sensitizer A is a traditional, highly efficient trifunctional monomer. Crosslinking sensitizer B typically has higher functionality (>3) or longer flexible chains. The introduction of component B can synergize with component A and the terminal vinyl hyperbranched polymer. Its technical effects are reflected in: 1) increasing the density of network crosslinking points; 2) the longer molecular chains of component B may introduce appropriate flexible segments into the high crosslinking density network, helping to suppress material embrittlement while increasing the degree of crosslinking, thus balancing toughness and strength.
[0014] Preferably, the mass ratio of the crosslinking sensitizer A to the crosslinking sensitizer B is (1-1.7):(0.3-1).
[0015] By adopting the above technical solution, this ratio is key to optimizing the synergistic effect. If the ratio of A is too high, the network may become too rigid and brittle; if the ratio of B is too high, it may lead to a decrease in crosslinking efficiency or uneconomical costs. This specific ratio range is the optimal balance between "crosslinking efficiency" and "network toughness" verified through experiments, ensuring that the material achieves high crosslinking degree (low thermal elongation) while maintaining excellent elongation at break under low irradiation doses.
[0016] Preferably, the raw materials of the high-efficiency radiation cross-linked halogen-free flame-retardant cable material also include 0.5-1.5 parts by weight of double-ended vinyl silicone oil.
[0017] By adopting the above technical solution, the addition of dual-terminated vinyl silicone oil can further optimize the overall performance of cable materials. Dual-terminated vinyl silicone oil is a reactive, flexible chain segment that can improve the flowability of high-filler (high flame retardant) formulations during processing, reduce extrusion torque, and make processing smoother. The terminal vinyl segments can participate in the radiation crosslinking reaction, introducing flexible siloxane segments into the crosslinking network. This can significantly enhance the material's flexibility, heat resistance, and surface smoothness.
[0018] Preferably, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168.
[0019] By adopting the above technical solutions, it is possible to synergistically prevent thermo-oxidative aging of materials during high-temperature processing and long-term use, thus ensuring the service life of the materials.
[0020] Secondly, this application provides a method for preparing a high-efficiency radiation cross-linked halogen-free flame-retardant cable material, using the following technical solution: A method for preparing a high-efficiency radiation cross-linked halogen-free flame-retardant cable material, comprising the following steps: S1. After mixing all the raw materials evenly, feed them into a twin-screw extruder for extrusion granulation to obtain masterbatch; S2. The prepared masterbatch is extruded through an extruder to produce a cable with a wall thickness of ≤1.5mm. The cable is then irradiated with a dose of 5-10Mrad to obtain a high-efficiency radiation-crosslinked halogen-free flame-retardant cable material.
[0021] By adopting the above technical solution, cables with a wall thickness of ≤1.5mm can achieve efficient radiation cross-linking under low radiation dose, resulting in a high yield and facilitating mass production.
[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. Using ethylene-vinyl acetate copolymer and highly branched polyethylene resin as the matrix resin, the ethylene-vinyl acetate copolymer provides polarity and flexibility, while the highly branched polyethylene resin, due to its multi-branched structure containing more vinyl groups, can become sensitive sites for irradiation crosslinking. The blending of these two provides a foundation for efficient crosslinking. Based on this, a terminal vinyl hyperbranched polymer is added. Its hyperbranched three-dimensional spherical structure has a large number of terminal functional groups. Under irradiation, these terminal vinyl groups are activated, forming uniform "micro-crosslinking points" in the matrix, greatly increasing the density of reaction sites and significantly improving the crosslinking reaction rate and crosslinking density. Simultaneously, the terminal vinyl hyperbranched polymer, due to its inherent characteristics as a hyperbranched polymer, has a low viscosity. Combined with its good compatibility with the ethylene-vinyl acetate copolymer, it can be evenly distributed in the matrix, which is also an important reason for its efficient crosslinking. It was also found that its spherical, branched structure can encapsulate the crosslinking sensitizer molecules to a certain extent. After the crosslinking sensitizer is excited by radiation, it can more quickly initiate the crosslinking of the terminal vinyl hyperbranched polymer, which is also a factor in its efficient crosslinking.
[0023] 2. The addition of dual-terminated vinyl silicone oil further optimizes the overall performance of cable materials. Dual-terminated vinyl silicone oil consists of reactive, flexible segments that improve the flowability of high-filler (high-flame-retardant) formulations during processing, reduce extrusion torque, and make processing smoother. The terminal vinyl groups can participate in radiation crosslinking reactions, introducing flexible siloxane segments into the crosslinking network. This significantly enhances the material's flexibility, heat resistance, and surface smoothness. Detailed Implementation
[0024] The following provides a more detailed description of this application in conjunction with specific details.
[0025] raw material All raw materials used in the preparation examples and embodiments of this application are commercially available products. Among them, the amino-terminated hyperbranched polyamide was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd.; the ethylene-vinyl acetate copolymer was purchased from Sinopec-Beijing Yanshan Petrochemical, model UL00218; the highly branched polyethylene resin was purchased from Japan-Primeval, model SP1071C; the POE-MAH grafting material was purchased from Ningbo Nengzhiguang New Material Technology Co., Ltd., model N129-1; and the double-terminated vinyl silicone oil was purchased from Hubei Longsheng Sihai New Material Co., Ltd.
[0026] Preparation Example Preparation Example 1 A vinyl-terminated hyperbranched polyamide is prepared by the following method: S1. Add 5g of amino-terminated hyperbranched polyamide to 90mL of THF (tetrahydrofuran) and stir until dissolved to obtain solution A; The amino-terminated hyperbranched polyamide is designated HyPer N102 (average molecular weight 920 g / mol), and its amino number is 8 / mol. S2. Add 1.01 equivalents of acryloyl chloride and triethylamine, an acid-binding agent, to 30 mL of THF to obtain solution B; S3. Keep solution A below 10°C using an ice-water bath. Add solution B dropwise to solution A at a uniform rate while stirring. The addition time is 1 hour. After the addition is complete, remove the ice-water bath and continue stirring for 15 hours to ensure complete reaction. Then, remove the solvent by rotary evaporation to obtain the target product, terminal vinyl hyperbranched polyamide. Its molecular structure is detected by NMR. By comparison, the peaks of the two protons of CH2=CH- at δ5.6-6.4 ppm should be sharp and symmetrical, and the signal should basically disappear near δ2.0-3.0 ppm (the chemical shift region of the terminal amino group -NH2) to determine the synthesis of the target product and the completeness of the reaction.
[0027] Preparation Example 2 A vinyl-terminated hyperbranched polyamide differs from Preparation Example 1 in that its amino-terminated hyperbranched polyamide is of type HyPer N103 (average molecular weight of 2100 g / mol), while the remaining steps are the same as in Preparation Example 1. Example
[0028] Examples 1-3 A high-efficiency radiation cross-linked halogen-free flame-retardant cable material, the dosage of each raw material is shown in Table 1, and its preparation method is as follows: S1. Mix the raw materials according to the mass ratio in Table 1, and then feed them into a twin-screw extruder. Control the temperature at 125-130-140-145-150-150-155-155-155℃ and the speed at 150-350r / min. Extrude and granulate to obtain masterbatch. S2. The prepared masterbatch is extruded in an extruder at an extrusion temperature of 160℃ to obtain a 2.5 square millimeter stranded conductor single core wire with a wall thickness of 0.8 mm and an outer diameter of 3.5 mm, thus obtaining a high-efficiency radiation cross-linked halogen-free flame-retardant cable material.
[0029] Among the antioxidants, the mass ratio of antioxidant 1010 to antioxidant 168 is 1:1.
[0030] Table 1. Raw materials and their weight parts in Example 1
[0031] Example 4 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material differs from Example 2 in that its end-vinyl hyperbranched polyamide is derived from Example 2, while the remaining steps are the same as in Example 2.
[0032] Example 5 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material differs from Example 4 in that the amount of end-vinyl hyperbranched polyamide added is 0.5 parts by weight, while the remaining steps are the same as in Example 4.
[0033] Example 6 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material differs from Example 4 in that the amount of end-vinyl hyperbranched polyamide added is 1.5 parts by weight, while the remaining steps are the same as in Example 4.
[0034] Example 7 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material differs from Example 6 in that its raw materials also include 0.5 parts by weight of double-ended vinyl silicone oil, while the remaining steps are the same as in Example 6.
[0035] Example 8 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material differs from Example 6 in that its raw materials also include 1 part by weight of double-ended vinyl silicone oil, while the remaining steps are the same as in Example 6.
[0036] Example 9 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material differs from Example 6 in that its raw materials also include 1.5 parts by weight of double-ended vinyl silicone oil, while the remaining steps are the same as in Example 6.
[0037] Example 10 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material differs from Example 2 in that crosslinking sensitizer B is replaced with an equal mass of crosslinking sensitizer A, while the remaining steps are the same as in Example 2.
[0038] Example 11 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material differs from Example 2 in that crosslinking sensitizer A is replaced with an equal mass of crosslinking sensitizer B, while the remaining steps are the same as in Example 2.
[0039] Comparative Example Comparative Example 1 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material differs from Example 2 in that its raw materials do not contain end-vinyl hyperbranched polyamide, while the remaining steps are the same as in Example 2.
[0040] Comparative Example 2 A high-efficiency radiation crosslinking halogen-free flame-retardant cable material, which differs from Example 6 in that, in the preparation of its end-vinyl hyperbranched polyamide, the end-amino hyperbranched polyamide used is HyPer N101, and the remaining steps are the same as in Example 6. After preparation, since the corresponding end-vinyl hyperbranched polyamide is a liquid with low viscosity, it is easy to precipitate onto the product surface and exhibit an oily surface. Therefore, no further investigation was conducted.
[0041] Performance testing Detection methods / test methods Cable materials were prepared according to the preparation methods of Examples 1-11 and Comparative Example 1, and then tested according to the following testing methods. The test results are shown in Table 2.
[0042] The samples from each embodiment were irradiated and crosslinked at a dose of 6.5 Mrad, and then the following tests were performed.
[0043] Thermal elongation, tensile strength and elongation at break: tested according to the test methods in GB / T2951.11.
[0044] Gel content: Tested according to the test method in JB / T10437.
[0045] Table 2 Test Results
[0046] As can be seen from the test data in Table 1, the gel content of the cable material prepared in this application is 93.2% or higher, with a maximum of 95.7%, indicating that it can be fully cross-linked under low radiation. The thermal elongation is less than 18%, with a minimum of 11%. At the same time, its tensile strength is between 13.5-16.0 MPa, and its elongation at break can reach 171.4-183.2%. This shows that the cable material of this application also has excellent mechanical properties.
[0047] In conjunction with Example 2 and Comparative Example 1, a terminal vinyl hyperbranched polymer was added. This is the key means for efficient crosslinking in this application. Its hyperbranched three-dimensional spherical structure has a large number of terminal functional groups. Under irradiation, these terminal vinyl groups are activated and can form uniform "micro crosslinking points" in the matrix, which greatly increases the density of reaction sites and significantly improves the crosslinking reaction rate and crosslinking density.
[0048] In conjunction with Examples 2 and 4 and Comparative Example 2, the molecular weight of the vinyl-terminated hyperbranched polyamide can optimize the overall performance of the prepared cable material within a certain range. When the molecular weight is small, its effect is not obvious and migration and precipitation are prone to occur. When the molecular weight is too large, it can easily cause increased brittleness of the material and reduce its overall performance.
[0049] Combining Examples 6 and 8-9, the addition of dual-terminated vinyl silicone oil further optimizes the overall performance of the cable material. Dual-terminated vinyl silicone oil, being a reactive, flexible segment, improves the flowability of high-filler (high-flame-retardant) formulations during processing, reduces extrusion torque, and facilitates smoother processing. The terminal vinyl groups can participate in the radiation crosslinking reaction, introducing flexible siloxane segments into the crosslinking network. This significantly enhances the material's flexibility, heat resistance, and surface smoothness.
[0050] Combining Examples 2 and 10-11, it can be seen that crosslinking sensitizer A and crosslinking sensitizer B have a synergistic effect.
[0051] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.
Claims
1. A high-efficiency radiation cross-linked halogen-free flame-retardant cable material, characterized in that: It comprises the following raw materials in parts by weight: 15-25 parts of ethylene-vinyl acetate copolymer, 3-8 parts of highly branched polyethylene resin, 0.5-1.5 parts of terminal vinyl hyperbranched polymer, 12-18 parts of compatibilizer, 35-45 parts of flame retardant, 0.8-1.2 parts of antioxidant, 1-3 parts of radiation protectant, and 1.5-3 parts of crosslinking sensitizer.
2. The high-efficiency radiation cross-linked halogen-free flame-retardant cable material according to claim 1, characterized in that: The terminal vinyl hyperbranched polymer is prepared by reacting terminal amino hyperbranched polyamide with acryloyl chloride.
3. The high-efficiency radiation cross-linked halogen-free flame-retardant cable material according to claim 2, characterized in that: The average molecular weight of the terminal amino hyperbranched polyamide is 900-2200 Da.
4. The high-efficiency radiation cross-linked halogen-free flame-retardant cable material according to claim 1, characterized in that: The crosslinking sensitizer includes crosslinking sensitizer A and crosslinking sensitizer B. Crosslinking sensitizer A is one or more of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, and triallyl isocyanurate. Crosslinking sensitizer B is one or more of tri(2-hydroxyethyl)isocyanurate triacrylate and di(trimethylolpropane) tetraacrylate.
5. The high-efficiency radiation cross-linked halogen-free flame-retardant cable material according to claim 4, characterized in that: The mass ratio of the crosslinking sensitizer A to the crosslinking sensitizer B is (1-1.7):(0.3-1).
6. The high-efficiency radiation cross-linked halogen-free flame-retardant cable material according to claim 1, characterized in that: The raw materials of the high-efficiency radiation cross-linked halogen-free flame-retardant cable material also include 0.5-1.5 parts by weight of double-ended vinyl silicone oil.
7. The high-efficiency radiation cross-linked halogen-free flame-retardant cable material according to claim 1, characterized in that: The antioxidant is a mixture of antioxidant 1010 and antioxidant 168.
8. A method for preparing a high-efficiency radiation cross-linked halogen-free flame-retardant cable material according to any one of claims 1-7, characterized in that: It includes the following steps: S1. After mixing all the raw materials evenly, feed them into a twin-screw extruder for extrusion granulation to obtain masterbatch; S2. The prepared masterbatch is extruded through an extruder to produce a cable with a wall thickness of ≤1.5mm. The cable is then irradiated with a dose of 5-10Mrad to obtain a high-efficiency radiation-crosslinked halogen-free flame-retardant cable material.