Silane-crosslinked halogen-free low-smoke flame-retardant polyolefin electronic wire material, preparation method and application

Abstract

The invention relates to the technical field of electronic wire materials, and discloses a silane crosslinked halogen-free low-smoke flame-retardant polyolefin electronic wire material, a preparation method and application, the silane crosslinked halogen-free low-smoke flame-retardant polyolefin electronic wire material comprises the following components: 60-70% of ethylene-vinyl acetate copolymer matrix; 1.5%-2.5% of a silane cross-linking agent; 15%-20% of a flame retardant system; 5%-8% of a charring agent; 0.2%-0.5% of an antioxidant; and 0.3%-0.7% of a lubricant. The silane cross-linking agent is vinyl trimethoxy silane, the flame-retardant system is formed by compounding magnesium aluminum hydroxide, zinc borate and phosphate, and the charring agent is isopropyl phenyl phosphate. And a flame-retardant system compounded by zinc borate, magnesium aluminum hydroxide and phosphate is adopted, so that the technical effects of VW-1 flame-retardant grade, low smoke and no toxicity are achieved. The problems of insufficient flame retardant property and poor environmental protection property are solved, and the applicability of the material in a high-safety application scene is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic wire materials, specifically to a silane cross-linked halogen-free low-smoke flame-retardant polyolefin electronic wire material, a preparation method and an application thereof. Background Art

[0002] With the rapid development of the electronic equipment and cable industries, the performance requirements for electronic wire materials are constantly increasing. The cable materials in the existing market generally adopt a halogenated flame retardant system. Although such materials have a high flame retardancy efficiency, they will release a large amount of toxic gases and thick smoke during combustion, seriously endangering human health and polluting the environment. To meet the increasingly strict environmental protection requirements, halogen-free low-smoke flame-retardant materials have gradually become a research and development hotspot. However, the technical level of existing halogen-free flame-retardant materials still has obvious limitations.

[0003] Most of the existing halogen-free flame-retardant polyolefin materials use magnesium-aluminum hydroxide as the main flame retardant. This material inhibits combustion by decomposing and absorbing heat. However, due to its single flame retardant mechanism, it is difficult to simultaneously meet the requirements of high-efficiency flame retardancy and low-smoke environmental protection in practical applications. In addition, its flame retardancy efficiency rapidly decays at high temperatures. Especially for the flame retardancy requirements that need to reach the VW-1 level, the performance often fails to meet the requirements. This defect limits the application of halogen-free flame-retardant materials in high-safety and high-reliability fields.

[0004] On the other hand, the existing flame-retardant polyolefin materials also have deficiencies in heat resistance. Traditional flame retardants such as magnesium-aluminum hydroxide have poor stability at high temperatures, which easily leads to a decline in the mechanical properties of the material and an accelerated aging rate. Although some studies have tried to introduce zinc borate as an auxiliary flame retardant, due to the unreasonable proportion design (such as too high or too low), there is a lack of effective synergistic effect in the flame retardant system, resulting in the failure to significantly improve the thermal aging performance of the material. Therefore, how to reasonably optimize the component ratio of the flame retardant system so that the material has excellent heat resistance while meeting high flame retardancy is a major difficulty in the current technology.

[0005] In addition, with the integration and complexity of modern electronic equipment, higher requirements are put forward for the electromagnetic shielding performance of cable materials. However, most of the existing halogen-free flame-retardant materials lack conductive functions and are difficult to effectively suppress electromagnetic interference. This technical defect directly affects the application of the materials in the field of high-frequency signal transmission. While traditional shielding materials (such as metal shielding layers) have good electromagnetic shielding performance, they will significantly increase the weight of the material and are not suitable for equipment with high lightweight requirements.

[0006] The prior art still has problems in terms of processing performance. Traditional char-forming agents (such as melamine) are prone to decomposition and gas release during processing, resulting in poor material fluidity, low molding quality, and easy appearance of bubbles and defects on the surface of the sheet. In addition, the low fluidity also limits the processing ability of complex-shaped cables, affecting production efficiency and the consistency of product performance. Therefore, how to select a suitable char-forming agent to improve the processing fluidity and surface quality of the material is the key to enhancing the processing performance of halogen-free flame-retardant materials.

[0007] Therefore, the present invention proposes a silane-crosslinked halogen-free low-smoke flame-retardant polyolefin electronic wire material, a preparation method and an application thereof to solve the deficiencies of the prior art. Summary of the Invention

[0008] In view of the deficiencies of the prior art, the present invention provides a silane-crosslinked halogen-free low-smoke flame-retardant polyolefin electronic wire material, a preparation method and an application thereof, aiming to solve the deficiencies of the existing halogen-free low-smoke flame-retardant polyolefin materials in terms of flame retardancy, heat resistance, electromagnetic shielding performance and processing performance. Through the silane-crosslinked halogen-free low-smoke flame-retardant polyolefin electronic wire material with high efficiency in flame retardancy, low smoke and environmental protection, high temperature resistance, easy processing and electromagnetic shielding performance, it meets the comprehensive requirements of modern electronic devices and cables for material performance.

[0009] To achieve the above objectives, the present invention is realized through the following technical solutions: The silane-crosslinked halogen-free low-smoke flame-retardant polyolefin electronic wire material comprises the following components: 60%-70% of ethylene-vinyl acetate copolymer matrix; 1.5%-2.5% of silane crosslinking agent; 15%-20% of flame-retardant system; 5%-8% of char-forming agent; 0.2%-0.5% of antioxidant; 0.3%-0.7% of lubricant.

[0010] Ethylene-vinyl acetate copolymer (EVA) is used as the matrix material, which has excellent flexibility and processing performance, and can simultaneously provide a basis for uniform dispersion of flame-retardant additives. The silane crosslinking agent forms a network structure through crosslinking reaction, significantly improving the heat resistance and mechanical properties of the material. The flame-retardant system and the char-forming agent act synergistically to rapidly form an oxygen isolation layer and a carbonized protective layer during combustion, reducing the release of combustible gases. The antioxidant and the lubricant respectively extend the service life of the material and improve the processing fluidity, making it have comprehensive advantages.

[0011] Preferably, the silane crosslinking agent is vinyltrimethoxysilane.

[0012] Due to its excellent reactivity, vinyltrimethoxysilane undergoes chemical cross-linking with the EVA matrix to form a polymer with a three-dimensional network structure. This cross-linked network not only endows the material with good thermal stability and mechanical strength but also significantly improves its chemical corrosion resistance. This silane cross-linking process has strong controllability, enabling efficient reactions at low concentrations and avoiding the deterioration of material properties.

[0013] Preferably, the flame retardant system is composed of a compound of magnesium-aluminum hydroxide, zinc borate, and phosphate, where zinc borate accounts for 25% - 35% of the flame retardant system, and magnesium-aluminum hydroxide and phosphate are mixed in a mass ratio of 6:4 to 8:2.

[0014] The compound design of the flame retardant system is based on the synergistic effect of the three flame retardants. Magnesium-aluminum hydroxide decomposes endothermically to lower the surface temperature of the material and simultaneously releases water vapor to dilute combustible gases; zinc borate forms a zinc oxide protective layer during combustion, effectively isolating oxygen; phosphate promotes the carbonization of the matrix to form a dense carbon layer. The optimization of the ratio of the three ensures that the material has a stable flame retardant effect at different combustion stages, which can not only improve the VW-1 grade flame retardancy but also meet the requirements for long-term use at high temperatures.

[0015] Preferably, the charring agent is tris(isopropylphenyl) phosphate.

[0016] As a charring agent, tris(isopropylphenyl) phosphate releases phosphoric acid during decomposition, significantly improving the carbonization ability of the material. The generated carbonized layer has high density and can effectively block heat conduction and oxygen penetration. In addition, this charring agent can play a role at the initial stage of combustion, cooperate with the flame retardant system to form a multiple protection mechanism, reduce the release of smoke and toxic gases, and enhance the flame retardant persistence of the material.

[0017] Preferably, the antioxidant is 1,3,5-trimethyl-2,4,6-(tert-butyl)-s-triazine.

[0018] This antioxidant inhibits thermal-oxidative degradation by scavenging free radicals, preventing the deterioration of material properties during processing and use. The stable triazine ring in its molecular structure has excellent thermal stability and can still maintain antioxidant activity at high temperatures, thereby extending the durability of the material, especially being particularly remarkable in a long-term high-temperature environment.

[0019] Preferably, the lubricant is calcium stearate.

[0020] Calcium stearate is an efficient internal lubricant that can reduce the friction of the material during melt processing, improve fluidity, and reduce die wear. In addition, its stable chemical properties avoid adverse reactions between the lubricant and other components, ensuring the mechanical properties and processing and molding quality of the final material.

[0021] Preferably, the electronic wire material further includes conductive carbon black, and the addition amount of the conductive carbon black is 2% of the total weight.

[0022] With its unique nano-scale structure, the conductive carbon black forms a conductive network in the material. This network can not only effectively shield electromagnetic waves, but also improve the mechanical strength and thermal stability of the material to a certain extent. The addition amount of 2% has been optimized to ensure the shielding efficiency while avoiding the problem of decreased fluidity caused by too high a concentration.

[0023] A preparation method of a silane-crosslinked halogen-free low-smoke flame-retardant polyolefin electronic wire material includes the following steps: (1) Weigh an ethylene-vinyl acetate copolymer matrix, a silane crosslinking agent, a flame-retardant system, a charring agent, an antioxidant, and a lubricant according to a mass ratio; (2) Uniformly mix the above components through a high-speed mixer to ensure that each component is fully dispersed, and the mixing time is 10 to 15 minutes; (3) Extrude and pelletize the mixed material through a melt extruder within a suitable temperature range; (4) Carry out a crosslinking reaction on the pelletized material through a silane hydrolysis initiator. The hydrolysis initiator is an organic compound containing a hydrolysis group. The reaction time is 10 to 15 minutes, and the reaction temperature is 140°C to 160°C, so that the material forms a crosslinked network structure.

[0024] Preferably, the melt extrusion temperature range of the mixed material is 150°C to 200°C, and the extruder rotates at 20 - 30 rpm for operation to ensure uniform mixing of the material and obtain uniform particles after extrusion.

[0025] Mix evenly: Weigh an EVA matrix, a silane crosslinking agent, a flame-retardant system, a charring agent, an antioxidant, and a lubricant according to a ratio, and use a high-speed mixer for sufficient mixing to ensure uniform distribution of each component.

[0026] Melt extrusion: Melt-extrude the mixed material at a temperature of 150°C to 200°C. At this time, the material should be operated through an extruder rotating at 20 - 30 rpm to ensure uniform mixing of the material during extrusion.

[0027] Crosslinking reaction: The extruded material undergoes a crosslinking reaction through a silane hydrolysis initiator. The reaction temperature is controlled at 140°C to 160°C, and the reaction time is 10 to 15 minutes. This reaction causes the crosslinking agent to react with the EVA matrix to form a strong three-dimensional network structure.

[0028] The mixing uniformity step ensures sufficient contact between the components, providing conditions for the subsequent cross-linking reaction. The melt extrusion process not only ensures the uniformity of the material but also avoids thermal degradation through appropriate temperature and rotation speed, creating optimal conditions for the cross-linking reaction. In the cross-linking reaction stage, through the action of the hydrolysis initiator, the silane cross-linking agent reacts with the functional groups of the EVA matrix to form a three-dimensional cross-linked structure, thus significantly improving the heat resistance and mechanical strength of the material.

[0029] Preferably, the silane cross-linked halogen-free low-smoke flame-retardant polyolefin electronic wire material is applied, and the electronic wire material is suitable for working in high-temperature environments and meets the VW-1 flame-retardant performance standard.

[0030] The material can work stably at a high temperature of 125 °C, thanks to the synergistic effect of the silane cross-linking and flame-retardant systems. The achievement of the VW-1 flame-retardant performance depends on the decomposition effect of the flame-retardant system and the charring agent, and this design significantly improves the safety of the material under fire conditions.

[0031] The present invention provides a silane cross-linked halogen-free low-smoke flame-retardant polyolefin electronic wire material, a preparation method, and an application. It has the following beneficial effects: 1. The present invention adopts a flame-retardant system composed of a combination of zinc borate, magnesium aluminum hydroxide, and phosphate, achieving the technical effects of VW-1 flame-retardant grade and low smoke and non-toxicity. Compared with the technical solution in the prior art that uses magnesium aluminum hydroxide alone, resulting in low flame-retardant efficiency and large amounts of smoke, it solves the problems of insufficient flame-retardant performance and poor environmental protection, and significantly improves the applicability of the material in high-safety application scenarios.

[0032] 2. By optimizing the proportion of zinc borate to 25%-35%, the present invention enhances the stability of the flame-retardant system at high temperatures, achieving better antioxidant and thermal aging properties. Compared with the deficiency in the prior art where the low content of zinc borate cannot form an effective protective layer, it overcomes the problem of rapid aging of the material in high-temperature environments, significantly extending its service life under the condition of 125 °C high temperature.

[0033] 3. The present invention innovatively introduces 2% of conductive carbon black, endowing the material with excellent electromagnetic shielding effectiveness and achieving the effect of electromagnetic interference suppression in high-frequency signal transmission. Compared with traditional electronic wire materials without conductive components, it solves the shortcoming of poor shielding performance in complex electromagnetic environments, and at the same time expands the multifunctional application of the material, meeting the requirements of modern electronic devices for high-performance materials.

[0034] 4. The present invention uses triisopropylphenyl phosphate as the charring agent, which not only improves the melt fluidity of the flame-retardant material but also improves the stability during the processing process, achieving better molding performance. Compared with the problems of poor fluidity and many bubbles caused by using traditional melamine charring agents, it completely solves the process defects in production and improves the overall performance of the product surface quality and mechanical properties. Brief Description of the Drawings

[0035] Figure 1 It is a schematic flow chart of the method of the present invention. Detailed Embodiments

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] Please refer to the attached Figure 1 :[[]] Embodiment

[0038] Take 65% ethylene-vinyl acetate copolymer matrix (EVA), 1.8% vinyltrimethoxysilane crosslinking agent, 17% flame retardant system (where zinc borate accounts for 30%, and the rest is a 7:3 mixture of magnesium aluminum hydroxide and phosphate), 6% tris(isopropylphenyl) phosphate charring agent, 0.35% 1,3,5-trimethyl-2,4,6-(tert-butyl)-s-triazine antioxidant, and 0.5% calcium stearate lubricant.

[0039] Add the above components to a high-speed mixer and mix for 10 minutes to make them evenly dispersed.

[0040] Use a twin-screw extruder to carry out extrusion granulation at an extrusion temperature of 170 °C, with a rotation speed of 25 rpm, to obtain uniform particles.

[0041] Use a silane hydrolysis initiator to carry out a crosslinking reaction at 145 °C for 12 minutes to obtain an electron wire material with a crosslinked network structure.

[0042] Embodiment 2: Take 60% EVA matrix, 2% vinyltrimethoxysilane crosslinking agent, 18% flame retardant system (zinc borate accounts for 35%, and the rest is a 6:4 mixture of magnesium aluminum hydroxide and phosphate), 8% tris(isopropylphenyl) phosphate charring agent, 0.3% antioxidant, and 0.7% calcium stearate lubricant.

[0043] Weigh all raw materials in proportion and put them into a mixer to mix evenly. The mixing time is controlled within 15 minutes.

[0044] Extrude and granulate the mixture through a single-screw extruder at 180 °C, with the rotation speed of the extruder being 28 rpm to ensure uniform particles.

[0045] After the particles are treated with a silane hydrolysis initiator, they are crosslinked at 160 °C for 10 minutes to form a high-strength crosslinked network structure.

[0046] Example 3: Take 62% EVA matrix, 2.2% vinyltrimethoxysilane crosslinking agent, 17.5% flame retardant system (30% zinc borate, and the remaining magnesium-aluminum hydroxide and phosphate are mixed at a ratio of 7:3), 6% charring agent, 0.3% antioxidant, 0.5% lubricant, and 2% conductive carbon black.

[0047] Put all the raw materials into a mixing device and mix at high speed for 12 minutes to ensure the uniform dispersion of the conductive carbon black.

[0048] Extrude and pelletize at 190°C through a twin-screw extruder with a rotation speed of 20 rpm. The pellets are smooth and non-caking after extrusion.

[0049] The pellets are crosslinked for 15 minutes at 155°C by a silane hydrolysis initiator to form a complete crosslinked network structure.

[0050] Example 4: Take 70% EVA matrix, 1.5% vinyltrimethoxysilane crosslinking agent, 15% flame retardant system (28% zinc borate, and the remaining is a mixture of magnesium-aluminum hydroxide and phosphate at a ratio of 8:2), 6% tris(isopropylphenyl) phosphate charring agent, 0.4% antioxidant, 0.6% lubricant, and 0.5% processing aid (such as low molecular weight polyethylene).

[0051] Weigh the raw materials according to the ratio and put them into a mixer to mix at low speed for 10 minutes to make the particles uniform.

[0052] Pelletize at 160°C through a single-screw extruder with a rotation speed of 30 rpm. There are no bubbles on the surface of the pellets, and they are smooth and crack-free.

[0053] Treat with a silane hydrolysis initiator and crosslink at 140°C for 10 minutes to obtain a uniform crosslinked network material.

[0054] Comparative Example 1: It is basically the same as Example 1, except that 17% of the flame retardant system uses only magnesium-aluminum hydroxide as the flame retardant component.

[0055] Comparative Example 2: It is basically the same as Example 2, except that the proportion of zinc borate in 18% of the flame retardant system is adjusted to 15%.

[0056] Comparative Example 3: It is basically the same as Example 3, except that 2% of the conductive carbon black is not added.

[0057] Comparative Example 4: It is basically the same as Example 4, except that 6% of the charring agent uses the traditional charring agent melamine.

[0058] Experiment 1: Flame Retardancy Performance Test Purpose of the experiment: To verify the effect of the compound design of the flame retardant system on the VW-1 flame retardant grade performance.

[0059] Experimental steps: Sample preparation: Sample of Example 1: After being prepared according to the formula, it was extruded into a standard cable sheath sheet with a thickness of 1.6 mm. The flame retardant system includes a compound design of magnesium-aluminum hydroxide, zinc borate and phosphate.

[0060] Sample of Comparative Example 1: After being prepared according to the formula, it was extruded into a sheet with a thickness of 1.6 mm. Only magnesium-aluminum hydroxide was used in the flame retardant system, and no compound optimization was carried out.

[0061] Test preparation: The samples were cut into specified sizes, 150 mm in length and 13 mm in width.

[0062] The samples were fixed on the vertical fixture of the UL94 VW-1 combustion test device to ensure that the samples were suspended vertically.

[0063] Flame retardancy test: A 500 W flame was used to directly contact the bottom of the sample for 15 seconds, and then the flame was removed, and it was recorded whether the sample self-extinguished.

[0064] The combustion was repeated 5 times, with an interval of 15 seconds each time.

[0065] Record the combustion time, whether it self-extinguished, the damaged length of the sample and the amount of smoke.

[0066] Data recording: Compare the performances of Example 1 and Comparative Example 1 in the test, and focus on observing the differences in self-extinguishing time and damaged length.

[0067] Comparison of VW-1 Flame Retardancy Performance Test Data in Experiment 1 Sample Combustion times Self-extinguishing time (seconds) Damaged length (mm) Smoke volume (visual inspection) Toxic odor (visual inspection) Example 1 1 2.5 25 Low No obvious odor Example 1 2 2.8 27 Low No obvious odor Example 1 3 3.1 30 Low No obvious odor Example 1 4 2.9 28 Low No obvious odor Example 1 5 3.0 29 Low No obvious odor Comparative Example 1 1 6.5 45 High Irritating odor Comparative Example 1 2 6.3 43 High Irritating odor Comparative Example 1 3 6.8 47 High Irritating odor Comparative Example 1 4 6.6 46 High Irritating odor Comparative Example 1 5 6.7 48 High Irritating odor The compound optimization of the flame retardant system has played a significant role. By introducing zinc borate and phosphate, the self-extinguishing time of the material in Example 1 was significantly shortened after the flame contact, and the damaged length was significantly reduced at the same time. In contrast, only magnesium-aluminum hydroxide was used in Comparative Example 1, lacking the synergistic flame retardant effect, showing a longer combustion time and a larger damage range. This difference shows that the compound design of the flame retardant system is not a simple physical superposition, but there is a unique synergistic effect.

[0068] During the combustion process of the material, zinc borate can rapidly decompose to produce an inorganic oxide layer, which plays a role in isolating oxygen, while phosphate promotes char formation in the initial stage of combustion. The actions of these two substances are connected in terms of time with that of magnesium-aluminum hydroxide, enabling the material to maintain strong flame retardancy at different combustion stages. In Comparative Example 1, due to the uneven decomposition rate of the single flame retardant at high temperatures, the flame spread could not be inhibited in a timely manner, resulting in much poorer combustion performance than that of the examples.

[0069] From the test results, the smoke volume and toxic odor of Example 1 are both low, which is another major advantage of the zinc borate and phosphate compound system. Different from the halogen flame retardant system, this combination avoids the release of toxic gases during the combustion process, meeting the requirements of environmental protection and safety. At the same time, the low-smoke characteristic also reduces the risk of decreased visibility in a fire, adding more safety to practical applications. This characteristic makes it more competitive in the field of high-temperature electronic cables.

[0070] Experiment 2: High-temperature heat resistance performance test Experiment purpose: To explore the influence of the proportion of zinc borate in the flame retardant system on the heat resistance performance of the material.

[0071] Experiment steps: Sample preparation: Sample of Example 2: Zinc borate accounts for 35% in the flame retardant system, and the rest is a 6:4 mixture of magnesium-aluminum hydroxide and phosphate. After preparation, it is pressed into a thin sheet with a thickness of 2 mm for testing.

[0072] Sample of Comparative Example 2: Zinc borate accounts for 15% in the flame retardant system, and the rest is a 6:4 mixture of magnesium-aluminum hydroxide and phosphate. After preparation, it is pressed into a thin sheet of the same specification.

[0073] Test conditions: According to the IEC 60811-1-2 standard, the samples are placed in a constant-temperature oven at 150 °C for heat aging test.

[0074] The samples are taken out every 24 hours, and a tensile testing machine is used to measure their tensile strength and elongation at break.

[0075] Each group is measured 5 times, and the average value is taken.

[0076] Record data: During the test, record the appearance changes of the samples (such as surface cracking, color change) and mechanical properties (retention rates of tensile strength and elongation at break).

[0077] Comparison of high-temperature heat resistance performance test data in Experiment 2 Sample Aging time (hours) Tensile strength retention rate (%) Elongation at break retention rate (%) Surface change condition Example 2 0 100 100 None Example 2 24 98 96 Slightly discolored Example 2 48 94 92 No obvious change Example 2 72 89 88 Tiny cracks Example 2 96 83 81 More obvious cracks Comparative Example 2 0 100 100 None Comparative Example 2 24 92 90 Slightly discolored Comparative Example 2 48 78 75 Cracks begin to appear Comparative Example 2 72 63 60 Cracks expand, obvious aging Comparative Example 2 96 50 47 Surface cracking is severe The proportion of zinc borate in the flame retardant system significantly affects the stability of the material under high-temperature aging conditions. Experiments show that the high proportion of zinc borate (35%) in Example 2 can better resist oxidation and degradation under high temperature. The proportion of zinc borate in the sample of Comparative Example 2 is relatively low, only 15%, which fails to effectively form a protective layer, resulting in an accelerated aging rate. The rapid decline in tensile strength and elongation at break fully reflects the performance shortcoming of the low-proportion flame retardant system in the thermal aging environment.

[0078] Zinc borate decomposes at high temperature to form zinc oxide and water vapor. This reaction can not only absorb heat but also generate a dense oxide film on the material surface, playing a role in heat insulation and anti-oxidation. At the same time, the synergistic effect with magnesium-aluminum hydroxide and phosphate significantly reduces the degradation rate of the overall flame retardant system at high temperature. When the content of zinc borate is low, the formation of the oxide film is insufficient, the synergistic effect weakens, and the internal structure of the material is more vulnerable to high-temperature damage.

[0079] Experimental data also reveals the close connection between surface cracking and internal property degradation during high-temperature aging. Due to the formation of a stronger oxidation barrier, Example 2 can maintain surface stability in the initial stage of aging. The surface cracks of Comparative Example 2 rapidly expand after 48 hours of aging, directly leading to a rapid decline in the elongation at break of the material. This phenomenon indicates that the proportion optimization of each component in the flame retardant system is not randomly adjusted, and the proportion of zinc borate can reflect its special protection function within a certain range.

[0080] Experiment 3: Electromagnetic shielding performance test Experimental purpose: To verify the influence of conductive carbon black on the electromagnetic shielding performance of the material.

[0081] Experimental procedure: Sample preparation: Sample of Example 3: The addition amount of conductive carbon black is 2%, and after preparation, it is extruded into a cable sheath layer with a diameter of 2 mm.

[0082] Sample of Comparative Example 3: Conductive carbon black is not added, and the proportion of the remaining components is the same as that of Example 3. After preparation, it is extruded into a sheath layer of the same specification.

[0083] Testing method: According to the ASTM D4935 standard, the sample is cut into circular test pieces with a diameter of 10 cm for electromagnetic shielding effectiveness (SE) testing.

[0084] The test piece is installed in the electromagnetic shielding effectiveness test device, and electromagnetic shielding effectiveness measurement is carried out using electromagnetic waves with a frequency range of 30 MHz to 1 GHz.

[0085] Record the shielding effectiveness (unit: dB) at different frequencies. Each sample is tested 3 times and the average value is taken.

[0086] Data record: Compare the shielding effectiveness curves of the samples in Comparative Example 3 and Example 3 at each frequency point to analyze the contribution of conductive carbon black to the shielding performance.

[0087] Experimental data of electromagnetic shielding effectiveness test for Experiment 3 Sample Test frequency (MHz) Shielding effectiveness (dB) Time 1 Time 2 Time 3 Average value Example 3 30 48.2 47.8 48.5 48.2 48.2 Example 3 300 57.1 56.8 57.5 57.0 57.1 Example 3 600 61.9 61.5 62.2 61.8 61.9 Example 3 900 59.3 59.0 59.6 59.3 59.3 Comparative Example 3 30 16.7 16.5 16.8 16.6 16.7 Comparative Example 3 300 22.3 22.0 22.5 22.3 22.3 Comparative Example 3 600 25.8 25.5 26.0 25.8 25.8 Comparative Example 3 900 23.1 22.8 23.3 23.2 23.1 The role of conductive carbon black in enhancing the shielding performance is very significant. In the high-frequency band (such as 600 MHz and above), the shielding effectiveness of the sample in Example 3 is far better than that of Comparative Example 3 without adding conductive carbon black. The presence of conductive carbon black not only enhances the internal conductivity of the material but also significantly reduces the transmittance of electromagnetic waves by forming a continuous conductive network. The low shielding performance of Comparative Example 3 indicates that effective electromagnetic shielding cannot be achieved only by relying on other flame retardant components.

[0088] The dispersion of conductive carbon black in the material is the key to its performance. In Example 3, conductive carbon black forms a dense conductive path through good mixing with the matrix. When electromagnetic waves pass through, the material can effectively absorb or reflect them, forming an efficient shield. In contrast, Comparative Example 3 lacks conductive components, and there are not enough electron freedoms inside the material, resulting in the direct penetration of electromagnetic waves and unable to meet the shielding requirements.

[0089] In addition, the experimental data also reveals the law of the change of shielding effectiveness with frequency. In the high-frequency band, the shielding effectiveness of Example 3 decreases, which is related to the absorption mechanism of conductive carbon black. Although the reflection performance remains high, the absorption efficiency is limited at specific frequencies. However, this slight decrease has little impact on the application scenarios of the vast majority of electronic cables. Therefore, the optimized design of conductive carbon black not only achieves a significant improvement in shielding performance but also endows the material with multifunctionality, making it have a broader application prospect in high-frequency communication and high-security fields.

[0090] Experiment 4: Processing fluidity and molding performance test Experimental purpose: To study the influence of the type of charring agent on the processing fluidity and molding performance of the material.

[0091] Experimental steps: Sample preparation: Sample of Example 4: The charring agent is triisopropylphenyl phosphate, and after preparation, it is extruded into a sheet with a thickness of 2 mm.

[0092] Sample of Comparative Example 4: The charring agent is melamine, and the proportion of the remaining components is the same as that of Example 4, and it is prepared into a sheet with the same specifications.

[0093] Testing method: Melt flow rate test: Using a melt flow rate tester, in accordance with ISO 1133 standard, test the melt flow rate (MFR) of two groups of samples at 190 °C under a load of 2.16 kg, and record the fluidity data.

[0094] Molding performance test: Extrude the samples into sheets through a single-screw extruder, observe whether there are bubbles, delamination or non-uniform flow phenomena during the extrusion process, and at the same time check the flatness of the sheet surface.

[0095] Mechanical property test: Conduct tensile strength and elongation at break tests on the extruded sheets to evaluate the stability of the mechanical properties after molding.

[0096] Experimental data on the comparison of processing fluidity and molding performance in Experiment 4 Sample Test item Test times Data 1 Data 2 Data 3 Average value Example 4 Melt flow rate (g / 10 min) 3 9.2 9.1 9.4 9.2 Example 4 Extrusion surface flatness score 3 9 8 9 8.7 Example 4 Sheet tensile strength (MPa) 3 24.5 25.0 24.8 24.8 Comparative Example 4 Melt flow rate (g / 10 min) 3 7.8 8.0 7.7 7.8 Comparative Example 4 Extrusion surface flatness score 3 6 5 6 5.7 Comparative Example 4 Sheet tensile strength (MPa) 3 21.2 21.5 21.0 21.2 The processing fluidity of materials is crucial for actual production. Experiments show that the triphenyl phosphate charring agent used in Example 4 significantly increases the melt flow rate of the material. In contrast, when traditional melamine is used in Comparative Example 4, the flow rate decreases, and this difference directly reflects the different effects of the charring agent on the matrix viscosity in the high-temperature molten state. The molecular structure of triphenyl phosphate is more likely to be evenly dispersed with the matrix, thereby reducing internal friction and making the processing process smoother.

[0097] Moreover, the flatness of the extruded sheet surface has an important impact on the quality of end applications. The sheet surface of Example 4 is smooth and has no obvious bubbles, while in Comparative Example 4, due to the relatively fast decomposition rate of melamine at high temperatures, gas is generated during the processing, resulting in damage to the sheet surface quality. This phenomenon further verifies the necessity of optimizing the charring agent formulation to improve processing performance. The stability during material molding is closely related to the flow performance. Insufficient fluidity will lead to an increase in surface defects of the product and at the same time affect the mechanical properties.

[0098] Finally, the test results of mechanical properties also show that the charring agent has an important impact on the comprehensive properties of the material. The samples of Example 4 maintained high tensile strength and uniformity after molding, while the samples of Comparative Example 4 had a significant decrease in tensile strength due to non-uniform processing. This shows that the optimized charring agent not only improves the processing fluidity of the material but also enhances the integrity of the material structure, providing a reliable basis for its promotion in the field of high-performance electronic wire materials.

[0099] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Silane cross-linked halogen-free low-smoke flame-retardant polyolefin electronic wire material, characterized in that: The composition includes the following ingredients: Ethylene-vinyl acetate copolymer matrix 60%-70%; Silane crosslinker 1.5%-2.5%; Flame retardant system 15%-20%; Carbon-forming agent 5%-8%; Antioxidant 0.2%-0.5%; Lubricant 0.3%-0.7%.

2. The silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material according to claim 1, characterized in that: The silane crosslinking agent is vinyltrimethoxysilane.

3. The silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material according to claim 1, characterized in that: The flame retardant system is compounded by magnesium aluminum hydroxide, zinc borate and phosphate, wherein the zinc borate accounts for 25%-35% of the flame retardant system, and the magnesium aluminum hydroxide and the phosphate are mixed in a mass ratio of 6:4 to 8:

2.

4. The silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material according to claim 1, characterized in that: The carbon-forming agent is triisopropylphenyl phosphate.

5. The silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material according to claim 1, characterized in that: The antioxidant is 1,3,5-trimethyl-2,4,6-(tert-butyl)-s-triazine.

6. The silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material according to claim 1, characterized in that: The lubricant is calcium stearate.

7. The silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material according to claim 1, characterized in that: The electronic wire material also includes conductive carbon black, and the added amount of the conductive carbon black is 2% of the total weight.

8. A method for preparing a silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material, for preparing the silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) Weigh the ethylene-vinyl acetate copolymer matrix, silane crosslinking agent, flame retardant system, carbon forming agent, antioxidant and lubricant according to the mass ratio; (2) The above ingredients are uniformly mixed using a high-speed mixer to ensure that each component is fully dispersed. The mixing time is 10 to 15 minutes; (3) Extruding and granulating the mixed materials through a melt extruder within a suitable temperature range; (4) The granulated material is subjected to a cross-linking reaction using a silane hydrolysis initiator, where the hydrolysis initiator is an organic compound containing a hydrolyzable group. The reaction time is 10 to 15 minutes and the reaction temperature is 140° C. to 160° C., so that the material forms a cross-linked network structure.

9. The method for preparing the silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material according to claim 8, characterized in that: The melt extrusion temperature of the mixed material is in the range of 150° C. to 200° C., and the rotation speed of the extruder is 20-30 rpm to obtain uniform particles after extrusion.

10. An application of the silane cross-linked halogen-free, low-smoke, flame-retardant polyolefin electronic wire material according to any one of claims 1 to 7, characterized in that: The electronic wire material is suitable for working in a high temperature environment and meets the VW-1 flame retardant performance standard.

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