Detection equipment and method for low-smoke halogen-free cable

Abstract

The invention relates to the technical field of low-smoke halogen-free cable detection, and discloses a low-smoke halogen-free cable detection method, which comprises: S1, preparing a cable coating material according to an initial preparation condition, and assembling the cable coating material and a cable part component to obtain a low-smoke halogen-free cable, the carbon source compound is used for improving the flame retardance of the low-smoke halogen-free cable; s2, performing a combustion experiment on the low-smoke halogen-free cable, and synchronously detecting performance indexes including smoke density, harmful gas emission and high temperature resistance; and S3, feeding back the obtained performance index to S1, adjusting the initial preparation condition to obtain an improved preparation condition, and obtaining the improved cable coating material according to the improved preparation condition. According to the detection equipment and method for the low-smoke halogen-free cable, the material optimization period is shortened, the comprehensive flame-retardant safety performance of the low-smoke halogen-free cable can be more accurately improved, and it is ensured that a final product meets the safety and environment-friendly requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of low-smoke zero-halogen cable detection, and in particular to a detection device and method for low-smoke zero-halogen cables. Background Art

[0002] Low-smoke halogen-free cables have become the preferred cable type for places with extremely stringent fire safety requirements, such as modern buildings, rail transit, ships, nuclear power plants, and data centers, because they can significantly reduce the release of toxic smoke and corrosive halogen gases when burned. In these densely populated or confined spaces, the combustion products of cable materials in fires are key factors threatening the safety of people's lives (suffocation, poisoning) and equipment safety (corrosion). Stringent and multi-dimensional comprehensive requirements are placed on the flame retardancy, low smoke properties (low transmittance loss), halogen-free properties (low acid gas release), and high temperature resistance (how long the circuit integrity can be maintained) of low-smoke halogen-free cables.

[0003] Currently, the performance of low-smoke, halogen-free halogen-free cables is primarily evaluated by measuring smoke density, halogen acid gas emissions, and vertical / bundled burning flame retardancy. However, the existing testing process typically follows a one-way, fragmented model. Material developers design formulations and processes based on experience or theory to produce samples. Testers then conduct independent combustion performance tests according to standards, ultimately producing a report on whether the specific sample meets the performance standards. However, there is a significant feedback lag and disconnect between test results and the material preparation process. While performance test data (such as high smoke density, excessive levels of certain harmful gases, or insufficient high-temperature resistance) may reveal issues, it is difficult to efficiently and accurately track and directly guide immediate, targeted adjustments to material preparation conditions (for example, how to specifically change the type, dosage, dispersion process, or synergistic effects of the carbon source compound with other components). This requires multiple, lengthy trial-and-error cycles, significantly prolonging the material optimization cycle and making precise and efficient adjustments that require a balance between low smoke, low toxicity, and high flame retardancy difficult and costly. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a low-smoke zero-halogen cable detection device and method, which solves the problems raised in the above background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: Please refer to Figure 1 , design a detection method for low smoke zero halogen cables, including: S1. preparing a cable coating material according to the initial preparation conditions, assembling the cable coating material and some cable components to obtain a low-smoke zero-halogen cable, wherein the cable coating material includes a carbon source compound, and the carbon source compound is used to improve the flame retardancy of the low-smoke zero-halogen cable; S2. Conduct combustion tests on low-smoke halogen-free cables and simultaneously test performance indicators, including smoke density, harmful gas emissions, and high-temperature resistance. S3. Feeding back the obtained performance indicators to S1, adjusting the initial preparation conditions to obtain improved preparation conditions, and obtaining an improved cable coating material based on the improved preparation conditions.

[0006] Optionally, the cable components include a conductor core wire and an insulation layer, and the carbon source compound is at least one of polyacrylonitrile particles, polymethacrylate particles and natural polysaccharide particles.

[0007] Optionally, S1 specifically includes: S11, providing a polyolefin material, a flame retardant additive, a filler, and a carbon source compound, sequentially adding the flame retardant additive and the filler to the polyolefin material and mixing them to obtain a premix, and heat-treating the carbon source compound to obtain carbonized particles; S12, gradiently melting and blending the carbonized particles with the premix, so that the carbon shells between the carbonized particles melt and interlock to form a flame retardant network, thereby obtaining a cable coating material; S13. The cable sheathing material, the conductor core wire and the insulation layer are assembled by three-layer co-extrusion to produce a low-smoke halogen-free cable, wherein the inner layer is the conductor core wire, the middle layer is the insulation layer, and the outer layer is the sheathing layer formed by the cable sheathing material.

[0008] Optionally, S11 specifically includes: S111. Providing a polyolefin material, a flame retardant additive, a filler, and polyacrylonitrile particles, placing the polyolefin material into a mixer, and sequentially adding the flame retardant additive and the filler to obtain a premix, wherein the polyolefin material is at least one of polyethylene or cross-linked polyethylene, the flame retardant additive includes a phthalate plasticizer, a light stabilizer, and a flame retardant, and the filler is at least one of zinc borate, silicone masterbatch, bauxite, and silica; S112, placing polyacrylonitrile particles in a pyrolysis furnace, introducing nitrogen, and heating to 250° C. at a rate of 10° C. / min for 30 minutes to form a cross-linked skeleton structure, thereby obtaining pre-oxidized particles; S113. Transfer the pre-oxidized particles to a rotary tube furnace for deep carbonization. After nitrogen is introduced into the rotary tube furnace, the temperature is increased to 600°C at a gradient rate of 3°C / min and kept at this temperature for t minutes, where t = 0.2×(temperature - 500) minutes. Argon is introduced into the rotary tube furnace to exhaust nitrogen, and the furnace is cooled to room temperature at a rate of 10°C / min to obtain carbonized particles.

[0009] Optionally, S12 specifically includes: S121, adding the premix to a twin-screw extruder, adjusting the temperature of the twin-screw extruder to 160-170° C. and the screw speed to 200 rpm, so that the premix is ​​melted to form a matrix phase; S122, adding carbonized particles to the twin-screw extruder at a mass ratio of 2:8 of carbonized particles to premix, adjusting the temperature of the twin-screw extruder to 200-205° C. and the screw speed to 500 rpm to soften the carbon shell of the carbonized particles; S123, raising the temperature of the twin-screw extruder to 210-215° C. and injecting a transition metal catalyst to cause C—C bonds to recombine and interlock between the carbon shells of the catalytically softened carbonized particles to form a flame-retardant network, thereby obtaining a flame-retardant melt; S124. The flame retardant melt extruded from the twin-screw extruder is subjected to water-cooling pelletizing to obtain a cable coating material, wherein the water temperature of the water-cooling pelletizing is 25±1°C.

[0010] Optionally, S2 specifically includes: S21. Place the low-smoke zero-halogen cable horizontally at a fixed position of the cone calorimeter in the test chamber, and ignite the cable sheathing material of the low-smoke zero-halogen cable using a flame spray gun; S22. When the flame of the flame spray gun contacts the cable sheath material of the low-smoke halogen-free cable, smoke density, harmful gas emissions, and high-temperature resistance are obtained through testing. The smoke density is obtained by measuring the relative optical density using a smoke density chamber, the harmful gas emissions are obtained by measuring the total amount of CO / HCN released using a gas analyzer, and the peak value of the heat release rate curve is obtained by measuring the peak value using a cone calorimeter. The high-temperature resistance is obtained by integrating the results. S23, after the flame of the flame spray gun is extinguished and cooled to room temperature, the carbon residue of the cable sheathing material is collected, the ash is removed by ultrasonic cleaning, and the carbon residue rate is obtained after weighing, and the average thickness of the carbon shell in the carbon residue layer is measured; S24. The obtained specific optical density, total CO / HCN release, peak value of heat release rate curve, residual carbon rate and average thickness of carbon shell in the residual carbon layer are integrated as performance indicators.

[0011] Optionally, S3 specifically includes: S31. Determine whether the performance index meets the improvement conditions. If so, adjust the initial preparation conditions to obtain the improved preparation conditions and execute step S32. If not, obtain the improved cable coating material. Among them, improving conditions and adjusting initial preparation conditions include increasing the deep carbonization temperature by 20-40°C and extending the holding time by 10-20 minutes when the specific optical density exceeds the specific optical threshold or the peak of the heat release rate curve exceeds the thermal peak threshold; When the specific optical density exceeds the threshold and the residual carbon rate is normal, reduce the pre-oxidation temperature by 10-30°C and extend the pre-treatment temperature time by 15-30 minutes; When the residual carbon rate is lower than the residual carbon threshold or the average thickness of the carbon shell in the residual carbon layer is lower than the carbon shell thickness threshold, the additional holding time is 15 minutes when the deep carbonization temperature is raised to 420℃.

[0012] Optionally, S3 also includes: S32. Repeat S1 according to the improved preparation conditions to obtain an adjusted cable coating material, and then perform S2 and S31 on the adjusted cable coating material.

[0013] A low-smoke zero-halogen cable detection device is characterized by adopting the low-smoke zero-halogen cable detection method as described above.

[0014] The present invention provides a low-smoke zero-halogen cable detection device and method, which has the following beneficial effects: A low-smoke, halogen-free cable testing device and method first prepares a cable sheathing material containing a carbon source compound for improving flame retardancy according to initially set preparation conditions. This material is then assembled with other cable components into a low-smoke, halogen-free cable. A combustion test is then conducted on the finished cable, while key indicators such as smoke density, harmful gas emissions, and high-temperature resistance are monitored in real time. Performance indicator data obtained from the combustion test is then fed back into the initial preparation stage, whereby preparation conditions are adjusted and optimized to form an improved preparation scheme. Ultimately, this improved scheme is applied to produce a cable sheathing material with improved performance. This closed-loop optimization mechanism significantly improves R&D efficiency and the targeted performance of material properties. Simultaneously monitoring indicators during the combustion test allows for direct and quantitative assessment of the cable's key safety performance in fire scenarios. More importantly, the test results are fed back in real time and used to adjust preparation conditions, enabling targeted improvements based on actual performance data. This not only avoids the blindness of trial-and-error methods and shortens the material optimization cycle, but also precisely improves the comprehensive flame retardant safety performance of the low-smoke, halogen-free cable, ensuring that the final product meets safety and environmental requirements and that the performance of the low-smoke, halogen-free cable sheathing material is targeted. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The figure is a flow chart of a method for detecting low-smoke zero-halogen cables according to one embodiment of the present invention. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative work shall fall within the scope of protection of the present invention.

[0017] The present invention provides a technical solution: a method for detecting low-smoke halogen-free cables, comprising: S1. Prepare a cable coating material according to the initial preparation conditions, assemble the cable coating material and some cable components to obtain a low-smoke halogen-free cable, wherein the cable coating material includes a carbon source compound, and the carbon source compound is used to improve the flame retardancy of the low-smoke halogen-free cable. According to the preset initial preparation conditions, that is, the material formula ratio, the mixing temperature range and the extrusion speed parameters, prepare a cable coating material containing the carbon source compound. The compound decomposes at high temperature to absorb heat and promote the formation of a dense carbon layer, which is the core mechanism for improving the flame retardancy of the cable. Subsequently, the cable coating material is assembled with the conductor core wire, the insulation layer (such as cross-linked polyethylene) and other components of the cable into a complete low-smoke halogen-free cable; S2. Conduct a combustion test on the low-smoke, zero-halogen cable and simultaneously test performance indicators, including smoke density, harmful gas emissions, and high-temperature resistance. This step simultaneously quantifies three core safety indicators through standardized combustion tests. Dynamic monitoring of the combustion process and reverse analysis of the residual carbon structure comprehensively evaluate the fire safety performance of the low-smoke, zero-halogen cable. S3. Feeding the obtained performance indicators back to S1, adjusting the initial preparation conditions to obtain improved preparation conditions, obtaining an improved cable coating material based on the improved preparation conditions, and feeding the performance indicator data back to the preparation end. By dynamically adjusting the carbon source compound treatment process (such as pre-oxidation / carbonization parameters), a targeted improvement and continuous optimization of the flame retardant performance is achieved; First, a cable sheathing material containing a carbon source compound for flame retardancy enhancement was prepared according to the initial preparation conditions. This material was then assembled with other cable components into a low-smoke, halogen-free cable. The finished cable was then subjected to a combustion test, with key indicators such as smoke density, harmful gas emissions, and high-temperature resistance monitored in real time. The performance data obtained from the combustion test was then fed back into the initial preparation stage, allowing the preparation conditions to be adjusted and optimized to form an improved preparation plan. Ultimately, this improved plan was applied to produce a cable sheathing material with even better performance. This closed-loop optimization mechanism significantly improved R&D efficiency and the targeted performance of the material. The simultaneous monitoring of indicators during the combustion test enabled a direct and quantitative assessment of the cable's key safety performance in fire scenarios. More importantly, the real-time feedback of the test results, used to adjust the preparation conditions, enabled targeted improvements based on actual performance data. This not only avoided the blindness of the trial-and-error method and shortened the material development cycle, but also precisely improved the cable's comprehensive flame retardant and safety performance, ensuring that the final product met strict safety and environmental requirements and ensuring the targeted performance improvement of the low-smoke, halogen-free cable sheathing material.

[0018] In this embodiment, as a preferred embodiment, the cable components include a conductor core wire and an insulation layer, and the carbon source compound is at least one of polyacrylonitrile particles, polymethacrylate particles and natural polysaccharide particles. The cable components are a basic structure that clearly includes a conductor core wire (such as a copper / aluminum core) and an insulation layer (such as cross-linked polyethylene), and the two constitute the conductive and insulating core of the low-smoke halogen-free cable. On this basis, a functional carbon source compound is introduced as a key component of the coating material, specifically selected from at least one of polyacrylonitrile particles, polymethacrylate particles or natural polysaccharide particles. The carbon source compound is converted into carbonized particles with a cross-linked skeleton through a directional carbonization process (such as pre-oxidation of polyacrylonitrile, followed by gradient temperature increase and deep carbonization), and a dense flame retardant network is formed through the interlocking of the carbon shell during the melt blending process.

[0019] In this embodiment, as a preferred solution, S1 specifically includes: S11. Provide polyolefin materials, flame retardant additives, fillers and carbon source compounds, add flame retardant additives and fillers to the polyolefin materials in sequence and mix them to obtain a premix, heat-treat the carbon source compound to obtain carbonized particles, provide polyolefin base material (such as polyethylene / cross-linked polyethylene), flame retardant additives (including plasticizers, light stabilizers and flame retardants), fillers (zinc borate / silicon dioxide), add them to the mixer in sequence to form a homogeneous premix, convert the carbon source compound into carbonized particles with a cross-linked skeleton through staged heat treatment, and provide core functional units for the construction of the flame retardant network. The polyolefin base material (such as polyethylene / cross-linked polyethylene) accounts for 50-70% of the premix mass, the flame retardant additives (including plasticizers, light stabilizers and flame retardants) The flame retardant (such as aluminum hydroxide / magnesium hydroxide) accounts for 15-25% of the mass of the premix, the main flame retardant (such as aluminum hydroxide / magnesium hydroxide) accounts for 60-70% of the mass of the flame retardant additive, that is, 9-17.5% of the mass of the premix, the plasticizer (phthalate) accounts for 15-20% of the mass of the flame retardant additive, that is, 2.25-5% of the mass of the premix, the light stabilizer (such as hindered amine) accounts for 10-15% of the mass of the flame retardant additive, that is, 1.5-3.75% of the mass of the premix, the filler (zinc borate / silicon dioxide) accounts for 10-20% of the mass of the premix, and the filler is preferably a composite of zinc borate and silicon dioxide, zinc borate: silicon dioxide = 2:1, for example, 15% filler = 10% zinc borate + 5% silicon dioxide; The carbon source compound is processed separately from the premix. For example, polyacrylonitrile particles account for 15-25% of the cable sheath material mass, while the premix accounts for 75-85% of the cable sheath material mass. S12, gradient melting and blending the carbonized particles with the premix, so that the carbon shells between the carbonized particles melt and interlock to form a flame retardant network, thereby obtaining a cable coating material. The carbonized particles melt and interlock to form a continuous flame retardant network, thereby improving the fire retardant properties of the cable coating material; S13. The cable sheathing material, the conductor core wire and the insulation layer are assembled by three-layer co-extrusion to produce a low-smoke halogen-free cable, wherein the inner layer is the conductor core wire, the middle layer is the insulation layer, and the outer layer is the coating layer formed by the cable sheathing material, wherein the inner layer: the conductor core wire (such as a copper core, with a cross-sectional area of ​​1.5-240mm²), the middle layer: the insulation layer (such as cross-linked polyethylene, with a cross-sectional thickness of 0.8-3.0mm), and the outer layer: a flame-retardant coating layer formed by the cable sheathing material (with a cross-sectional thickness of 1.0-2.5mm). The coating layer is the outermost layer directly exposed to the fire source, and its continuous flame-retardant network constructed by carbonized particles can quickly respond to fire and form a carbon layer to protect the internal structure.

[0020] In this embodiment, as a preferred solution, S11 specifically includes: S111. Providing a polyolefin material, a flame retardant additive, a filler, and polyacrylonitrile particles, placing the polyolefin material into a mixer, and sequentially adding the flame retardant additive and the filler to obtain a premix, wherein the polyolefin material is at least one of polyethylene or cross-linked polyethylene, the flame retardant additive includes a phthalate plasticizer, a light stabilizer, and a flame retardant, and the filler is at least one of zinc borate, silicone masterbatch, bauxite, and silica, and the filler is preferably a composite of zinc borate and silica, with a ratio of zinc borate to silica of 2:1, for example, 15% filler = 10% zinc borate + 5% silica; Provide polyethylene material, accounting for 60% of the total weight of the premix, as the basis for the mechanical properties of the coating material. After the base material is placed in a mixer, add phthalate plasticizer accounting for 5% of the total weight of the premix, light stabilizer accounting for 2% of the total weight of the premix, main flame retardant accounting for 15% of the total weight of the premix, and filler (composite of zinc borate and silicon dioxide) accounting for 18% of the total weight of the premix in sequence. Stir at high speed at 80°C for 20 minutes to form a premix without agglomeration, thus obtaining a flame-retardant and smoke-suppressing premix. S112. Place polyacrylonitrile particles in a pyrolysis furnace, introduce nitrogen, and heat the mixture to 250°C at a rate of 10°C / min for pre-oxidation for 30 minutes to form a cross-linked skeleton structure, thereby obtaining pre-oxidized particles. Place the polyacrylonitrile particles in a pyrolysis furnace, introduce nitrogen to remove oxygen, and heat the mixture to 250°C at a rate of 10°C / min (to avoid violent decomposition). Maintain the temperature for 30 minutes. In the 250°C constant temperature section, polyacrylonitrile molecules undergo a cyclization reaction to form a heat-resistant ladder-shaped cross-linked skeleton, which helps to increase the residual carbon rate. S113. Transfer the pre-oxidized particles to a rotary tube furnace for deep carbonization. After nitrogen is introduced into the rotary tube furnace, the temperature is gradually increased to 600°C at a rate of 3°C / min, and the temperature is kept for t minutes, where t=0.2×(temperature-500) minutes. Argon is introduced into the rotary tube furnace to expel nitrogen, and the furnace is cooled to room temperature at a rate of 10°C / min to obtain carbonized particles. The pre-oxidized particles are transferred to a rotary tube furnace, and the temperature is slowly increased to 600°C at a rate of 3°C / min under nitrogen (to prevent cracking of the carbon layer), and the temperature is kept at 600°C for t=0.2×(600-500)=20 minutes. For every 100°C increase, 20 minutes is required to complete the growth of graphite microcrystals. Argon is then introduced to replace nitrogen (to avoid the formation of high-temperature nitrides), and the furnace is slowly cooled to room temperature at a rate of 10°C / min to obtain carbonized particles with a residual carbon rate ≥80% and a carbon shell thickness ≥5μm, thereby realizing the directional conversion of polyacrylonitrile particles to highly dense carbonized particles.

[0021] In this embodiment, as a preferred solution, S12 specifically includes: S121. Add the premix to a twin-screw extruder. Adjust the temperature of the twin-screw extruder to 160-170°C and the screw speed to 200 rpm to melt the premix and form a matrix phase. Add the premix to the twin-screw extruder and set the temperature to 160-170°C, slightly higher than the polyethylene melting point of 135°C, to ensure complete melting but avoid thermal degradation. Control the screw speed to 200 rpm (medium shear speed) to evenly disperse the flame retardant additive / filler in the polyethylene melt to form a continuous matrix phase. Through precise temperature control (160-170°C) and moderate shear (200 rpm), the premix is ​​melted and homogenized, providing a carrier for the dispersion of carbonized particles. S122. Add carbonized particles to the twin-screw extruder at a mass ratio of 2:8. Adjust the twin-screw extruder temperature to 200-205°C and the screw speed to 500 rpm to soften the carbon shell of the carbonized particles. Add the carbonized particles to the premix at a mass ratio of 2:8 (i.e., carbonized particles account for 20% of the cable sheathing material). Add the carbonized particles to the molten premix matrix and heat it to 200-205°C (close to the glass transition point of the carbon shell, promoting softening but not decomposition). The softened carbonized particles are embedded in the molten premix matrix to form a "hard core and soft shell" transition structure, laying the foundation for the flame retardant network interlocking. S123. After the twin-screw extruder temperature is raised to 210-215°C, a transition metal catalyst is injected. After the carbonized particles have been catalytically softened, C-C bonds are recombined and interlocked between the carbon shells to form a flame-retardant network, thereby obtaining a flame-retardant melt. After the temperature is further raised to 210-215°C (above the softening point of the carbon shell), a transition metal catalyst (such as nickel acetylacetonate, added in an amount of 0.5-1.0 wt%) is injected to catalytically soften the active carbon atoms on the surface of the carbon shell. Under high shear (500 rpm) of the screw, C-C bonds are recombined between the particles to form a three-dimensional interlocking network (the residual carbon rate is further improved). S124. The flame retardant melt extruded from the twin-screw extruder is subjected to water-cooling pelletizing to obtain cable coating material, wherein the water temperature of the water-cooling pelletizing is 25±1°C, the extruded flame retardant melt is passed through a water cooling tank, the water temperature is controlled at 25±1°C, the interlocking structure is locked by rapid cooling, and cylindrical coating material particles with a diameter of 2-3mm and a length of 3-5mm are obtained by pelletizing with a rotating blade, cold water quenching is performed to prevent grain growth and maintain the dispersed state of carbonized particles, and the interlocking network morphology is solidified by rapid cooling pelletizing to ensure stable transmission of flame retardant properties in subsequent cable extrusion.

[0022] In this embodiment, as a preferred solution, S2 specifically includes: S21. Place the low-smoke zero-halogen cable horizontally in a fixed position of the cone calorimeter in the test chamber. Ignite the cable sheathing material of the low-smoke zero-halogen cable using a flame spray gun. Fix the cable to be tested horizontally in the cone calorimeter test chamber with the sheath facing upward. Use a methane flame spray gun (flow rate 650±10mL / min, flame temperature 1100℃) to vertically ignite the sheathing surface at a distance of 50mm to ensure the repeatability and comparability of the combustion test. S22. When the flame of the flame spray gun contacts the cable sheath material of the low-smoke halogen-free cable, smoke density, harmful gas emissions, and high-temperature resistance are obtained through testing. The smoke density is obtained by measuring the relative optical density using a smoke density chamber, the harmful gas emissions are obtained by measuring the total amount of CO / HCN released using a gas analyzer, and the peak value of the heat release rate curve is obtained by measuring the peak value using a cone calorimeter. The high-temperature resistance is obtained by integrating the results. The transmittance was recorded in real time using a smoke density chamber, and the maximum specific optical density (OD) was calculated. The unit was dimensionless, and the specific optical density threshold requirement was: OD ≤ 150. The total CO / HCN release was measured using an FTIR gas analyzer (mg / g), with CO ≤ 1000 and HCN ≤ 150. The peak heat release rate (kW / m²) was collected using a cone calorimeter, with a heat release threshold of: < 100 kW / m². S23. After the flame of the flame spray gun is extinguished and cooled to room temperature, the carbon residue of the cable sheathing material is collected, ultrasonically cleaned to remove ash, and then weighed to obtain the carbon residue rate. The average thickness of the carbon shell in the carbon residue layer is also measured. After cooling, the carbon residue of the sheathing layer is scraped off and ultrasonically cleaned with ethanol (40 kHz / 30 min) to remove ash. The carbon residue rate = (mass of carbon residue after cleaning / mass of original sheathing layer) × 100%. The carbon residue rate threshold is: carbon residue rate ≥ 35%. The carbon layer thickness (unit: μm) of the interlocking carbon layer in the carbon residue layer is measured at 10 randomly selected points using a scanning electron microscope. The average value is used to obtain the average carbon layer thickness. The carbon shell thickness threshold is: the average carbon shell thickness ≥ 5 μm. S24. The obtained specific optical density, total CO / HCN release, peak value of heat release rate curve, residual carbon rate and average thickness of carbon shell in the residual carbon layer are integrated as performance indicators.

[0023] In this embodiment, as a preferred solution, S3 specifically includes: S31. Determine whether the performance index meets the improvement conditions. If so, adjust the initial preparation conditions to obtain the improved preparation conditions and execute step S32. If not, obtain the improved cable coating material. Among them, improving conditions and adjusting initial preparation conditions include increasing the deep carbonization temperature by 20-40°C and extending the holding time by 10-20 minutes when the specific optical density exceeds the specific optical threshold or the peak of the heat release rate curve exceeds the thermal peak threshold; When the specific optical density exceeds the threshold and the residual carbon rate is normal, reduce the pre-oxidation temperature by 10-30°C and extend the pre-treatment temperature time by 15-30 minutes; When the residual carbon rate is lower than the residual carbon threshold or the average thickness of the carbon shell in the residual carbon layer is lower than the carbon shell thickness threshold, the additional holding time is 15 minutes when the deep carbonization temperature is raised to 420℃.

[0024] In this embodiment, as a preferred solution, S3 further includes: S32. Repeat S1 according to the improved preparation conditions to obtain an adjusted cable coating material, and then perform S2 and S31 on the adjusted cable coating material.

[0025] The present invention also provides a low-smoke zero-halogen cable detection device, which is characterized by adopting the low-smoke zero-halogen cable detection method as described above.

[0026] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for detecting low-smoke halogen-free cables, characterized in that: include: S1. preparing a cable coating material according to the initial preparation conditions, assembling the cable coating material and some cable components to obtain a low-smoke zero-halogen cable, wherein the cable coating material includes a carbon source compound, and the carbon source compound is used to improve the flame retardancy of the low-smoke zero-halogen cable; S2. Conduct combustion tests on low-smoke halogen-free cables and simultaneously test performance indicators, including smoke density, harmful gas emissions, and high-temperature resistance. S3. Feeding back the obtained performance indicators to S1, adjusting the initial preparation conditions to obtain improved preparation conditions, and obtaining an improved cable coating material based on the improved preparation conditions.

2. The method for detecting low-smoke zero-halogen cables according to claim 1, wherein: The cable components include a conductor core wire and an insulation layer, and the carbon source compound is at least one of polyacrylonitrile particles, polymethacrylate particles and natural polysaccharide particles.

3. The method for detecting low-smoke zero-halogen cables according to claim 2, wherein: S1 specifically includes: S11, providing a polyolefin material, a flame retardant additive, a filler, and a carbon source compound, sequentially adding the flame retardant additive and the filler to the polyolefin material and mixing them to obtain a premix, and heat-treating the carbon source compound to obtain carbonized particles; S12, gradiently melting and blending the carbonized particles with the premix, so that the carbon shells between the carbonized particles melt and interlock to form a flame retardant network, thereby obtaining a cable coating material; S13. The cable sheathing material, the conductor core wire and the insulation layer are assembled by three-layer co-extrusion to produce a low-smoke halogen-free cable, wherein the inner layer is the conductor core wire, the middle layer is the insulation layer, and the outer layer is the sheathing layer formed by the cable sheathing material.

4. The method for detecting low-smoke zero-halogen cables according to claim 3, wherein: S11 specifically includes: S111. Providing a polyolefin material, a flame retardant additive, a filler, and polyacrylonitrile particles, placing the polyolefin material into a mixer, and sequentially adding the flame retardant additive and the filler to obtain a premix, wherein the polyolefin material is at least one of polyethylene or cross-linked polyethylene, the flame retardant additive includes a phthalate plasticizer, a light stabilizer, and a flame retardant, and the filler is at least one of zinc borate, silicone masterbatch, bauxite, and silica; S112, placing polyacrylonitrile particles in a pyrolysis furnace, introducing nitrogen, and heating to 250° C. at a rate of 10° C. / min for 30 minutes to form a cross-linked skeleton structure, thereby obtaining pre-oxidized particles; S113. Transfer the pre-oxidized particles to a rotary tube furnace for deep carbonization. After nitrogen is introduced into the rotary tube furnace, the temperature is increased to 600°C at a gradient rate of 3°C / min and kept at this temperature for t minutes, where t = 0.2×(temperature - 500) minutes. Argon is introduced into the rotary tube furnace to exhaust nitrogen, and the furnace is cooled to room temperature at a rate of 10°C / min to obtain carbonized particles.

5. The method for detecting low-smoke zero-halogen cables according to claim 4, characterized in that: S12 specifically includes: S121, adding the premix to a twin-screw extruder, adjusting the temperature of the twin-screw extruder to 160-170° C. and the screw speed to 200 rpm, so that the premix is ​​melted to form a matrix phase; S122, adding carbonized particles to the twin-screw extruder at a mass ratio of 2:8 of carbonized particles to premix, adjusting the temperature of the twin-screw extruder to 200-205° C. and the screw speed to 500 rpm to soften the carbon shell of the carbonized particles; S123, raising the temperature of the twin-screw extruder to 210-215° C. and injecting a transition metal catalyst to cause C—C bonds to recombine and interlock between the carbon shells of the catalytically softened carbonized particles to form a flame-retardant network, thereby obtaining a flame-retardant melt; S124. The flame retardant melt extruded by the twin-screw extruder is subjected to water-cooling pelletizing to obtain a cable sheathing material, wherein the water temperature of the water-cooling pelletizing is 25±1°C.

6. The method for detecting low-smoke zero-halogen cables according to claim 5, characterized in that: S2 specifically includes: S21. Place the low-smoke zero-halogen cable horizontally at a fixed position of the cone calorimeter in the test chamber, and ignite the cable sheathing material of the low-smoke zero-halogen cable using a flame spray gun; S22. When the flame of the flame spray gun contacts the cable sheath material of the low-smoke halogen-free cable, smoke density, harmful gas emissions, and high-temperature resistance are obtained through testing. The smoke density is obtained by measuring the relative optical density using a smoke density chamber, the harmful gas emissions are obtained by measuring the total amount of CO / HCN released using a gas analyzer, and the peak value of the heat release rate curve is obtained by measuring the peak value using a cone calorimeter. The high-temperature resistance is obtained by integrating the results. S23, after the flame of the flame spray gun is extinguished and cooled to room temperature, the carbon residue of the cable sheathing material is collected, the ash is removed by ultrasonic cleaning, and the carbon residue rate is obtained after weighing, and the average thickness of the carbon shell in the carbon residue layer is measured; S24. The obtained specific optical density, total CO / HCN release, peak value of heat release rate curve, residual carbon rate and average thickness of carbon shell in the residual carbon layer are integrated as performance indicators.

7. The method for detecting low-smoke zero-halogen cables according to claim 6, characterized in that: S3 specifically includes: S31. Determine whether the performance index meets the improvement conditions. If so, adjust the initial preparation conditions to obtain the improved preparation conditions and execute step S32. If not, obtain the improved cable coating material. Among them, improving conditions and adjusting initial preparation conditions include increasing the deep carbonization temperature by 20-40°C and extending the holding time by 10-20 minutes when the specific optical density exceeds the specific optical threshold or the peak of the heat release rate curve exceeds the thermal peak threshold; When the specific optical density exceeds the threshold and the residual carbon rate is normal, reduce the pre-oxidation temperature by 10-30°C and extend the pre-treatment temperature time by 15-30 minutes; When the residual carbon rate is lower than the residual carbon threshold or the average thickness of the carbon shell in the residual carbon layer is lower than the carbon shell thickness threshold, the additional holding time is 15 minutes when the deep carbonization temperature is raised to 420℃.

8. The method for detecting low-smoke zero-halogen cables according to claim 7, wherein: S3 also includes: S32. Repeat S1 according to the improved preparation conditions to obtain an adjusted cable coating material, and then perform S2 and S31 on the adjusted cable coating material.

9. A low-smoke zero-halogen cable detection device, characterized by: A low-smoke zero-halogen cable detection method as described in any one of claims 1 to 8 is used.

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