Preparation method of halogen-free environment-friendly flame-retardant PVC cable

Abstract

The invention relates to a halogen-free environment-friendly flame-retardant PVC cable and a preparation method thereof, and belongs to the technical field of PVC cables. The invention provides a halogen-free environment-friendly flame-retardant PVC cable which is prepared by the following steps: compounding PVC, an ATBC plasticizer and epoxidized soybean oil to obtain a material I, compounding the material I, a La-Zn composite rare earth stabilizer, polyether silicone oil and silicon carbide nanowires to obtain a material II, and performing extrusion molding to obtain the halogen-free environment-friendly flame-retardant PVC cable. And compounding the material II, a diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate and coupling agent surface modified charcoal to obtain a material III, compounding the material III and a borate cross-linking agent to obtain a mixture, finally extruding the mixture on the surface of the armored wire core, and cooling and molding. The diatomite-ammonium polyphosphate composite flame retardant, the zinc borate and the calcium stannate are adopted to replace a traditional halogen-containing flame retardant, toxic halogen hydride gas is prevented from being released during combustion, the environment-friendly requirement is met, and on the basis, the components are compounded to synergistically exert the flame-retardant effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of PVC cables, and relates to a preparation method of a halogen-free environmentally friendly flame-retardant PVC cable. Background Art

[0002] Cables are an essential infrastructure in modern society and are widely used in multiple fields such as power transmission, communication networks, and control systems. According to different functions and structures, cables can be classified into types such as network cables, electric wires, and power cables, mainly used to achieve the efficient transmission of electrical energy and information. Their normal operation is directly related to the smoothness and safety of social production and life. Although traditional cables have important functions in applications, they also have many deficiencies in use. For example, traditional cables often use halogen-containing materials, which are prone to releasing toxic gases in fires, seriously affecting personal safety and environmental protection. In addition, the flame-retardant effect of some cables is insufficient and cannot effectively inhibit the spread of fire, thus potentially causing greater property losses and casualties in high-temperature or fire situations. These problems not only affect the safety and reliability of cables but also pose challenges to the sustainable development of the industry. Summary of the Invention

[0003] The purpose of the present invention is to provide a preparation method of a halogen-free environmentally friendly flame-retardant PVC cable. The present invention uses a diatomite-ammonium polyphosphate composite flame retardant, zinc borate, and calcium stannate to replace traditional halogen-containing flame retardants, avoiding the release of toxic hydrogen halide gas during combustion and meeting environmental protection requirements. On this basis, through the compounding of each component, the flame-retardant effect is synergistically exerted.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A preparation method of a halogen-free environmentally friendly flame-retardant PVC cable, the preparation method of the PVC cable comprising the following steps:

[0006] Step 1: Mix PVC, ATBC plasticizer, and epoxidized soybean oil to obtain Material 1;

[0007] Step 2: Add a La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires to Material 1 and mix to obtain Material 2;

[0008] Step 3: Mix Material 2, a diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate, and coupling agent surface-modified biochar to obtain Material 3;

[0009] Step 4: Add a borate crosslinking agent to Material 3 and process to obtain a mixed material;

[0010] Step 5: Extrude the mixed material on the surface of an armored wire core and cool and form.

[0011] Further, the mass ratio of PVC, ATBC plasticizer, and epoxidized soybean oil in Step 1 is 1:0.26 - 0.3:0.06 - 0.08; the mixing method is to heat to 93 - 97°C and then stir at a speed of 600 - 800 rpm for 5 - 7 min.

[0012] Further, the mass ratio of Material 1, La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires in Step 2 is 13.2 - 13.8:0.3 - 0.5:0.11 - 0.13:0.04 - 0.06; the mixing method is to stir at a speed of 800 - 900 rpm for 4 - 6 min.

[0013] Further, the preparation method of the La-Zn composite rare earth stabilizer in Step 2 includes the following steps:

[0014] Step X1: Mix lanthanum nitrate and zinc nitrate in a mass ratio of 1:3 - 4, and then at 60 - 80°C and a speed of 300 - 500 rpm, dropwise add ammonia water with a mass concentration of 25 - 28 wt% at a dropping rate of 2 - 5 mL / min to adjust the pH to 8 - 10. After reaching the pH value, let it stand for 2 - 3 h, filter to obtain the La-Zn hydroxide coprecipitate;

[0015] Step X2: Calcinate the La-Zn hydroxide coprecipitate at 800 - 900°C for 3 - 4 h to obtain the La-Zn composite oxide;

[0016] Step X3: Mix KH-550, absolute ethanol, and deionized water in a volume ratio of 1:4 - 5:1, stir at room temperature for 25 - 35 min, and dropwise add 0.1 M acetic acid solution to adjust the pH to 4 - 5 to obtain the silane solution;

[0017] Step X4: Mix the La-Zn composite oxide and the silane solution in a mass ratio of 1:6 - 10, stir at 50 - 60°C at a speed of 200 - 400 rpm for 2 - 4 h, filter, precipitate and dry, and keep warm at 120 - 130°C for 1 - 1.2 h to obtain the composite rare earth stabilizer.

[0018] Further, the preparation method of the diatomite-ammonium polyphosphate composite flame retardant in Step 3 includes the following steps:

[0019] Step Y1: Calcinate diatomite at 340 - 360°C for 1.5 - 2.5 h to obtain activated diatomite;

[0020] Step Y2: Mix the activated diatomite, ammonium polyphosphate, and absolute ethanol in a mass ratio of 1:0.66 - 0.7:4.5 - 5.1, ball mill for 2 - 3 h, and spray dry to obtain it.

[0021] Further, the mixing method is as follows: divide the diatomite-ammonium polyphosphate into the first batch, the second batch and the third batch. Add the first batch and the second batch to the second material, and stir for 2-3 minutes after each addition. After each stirring, leave a 2-minute interval. While adding the third batch, add zinc borate, calcium stannate and coupling agent surface-modified biochar. Raise the temperature to 102-108 °C and stir for 6-10 minutes. Then raise the temperature to 108-112 °C and increase the rotation speed to 950-1050 rpm, and stir for 8-12 minutes.

[0022] Further, the mass ratio of the first batch, the second batch and the third batch is 9.5-10.1:1.18-1.22:0.64-0.68; the mass ratio of the first batch and the second material is 1:7.8-8.2; the mass ratio of the third batch, zinc borate, calcium stannate and coupling agent surface-modified biochar is 1:5.8-6.2:3.5-4.5:5.2-5.4.

[0023] Further, the preparation method of the coupling agent surface-modified biochar in step three includes the following steps:

[0024] Step Z1: In an anaerobic atmosphere, carbonize rice husks at 600-620 °C for 2.2-2.6 hours to obtain biochar powder;

[0025] Step Z2: Mix the biochar powder and a KH-550 ethanol solution with a mass concentration of 1.5-2.5 wt% of KH-550 according to a ratio of 1:10-12 g / mL. Set the ultrasonic frequency to 35-45 kHz, the ultrasonic power to 100-200 W, the ultrasonic temperature to 60 °C, and ultrasonicate for 1.8-2.2 hours to obtain a mixture;

[0026] Step Z3: Purify the mixture to obtain the product.

[0027] Further, the mass ratio of the third material and the borate crosslinking agent in step four is 17.3-17.5:0.38-0.42; the treatment method is to cool down to 85-95 °C and stir for 3-7 minutes, and discharge the material after the temperature drops to 60 °C.

[0028] Further, the water temperature used for cooling in step five is 20-30 °C, and the water pressure is 0.2-0.4 MPa.

[0029] Advantages of the present invention:

[0030] (1) The present invention uses a diatomite-ammonium polyphosphate composite flame retardant, zinc borate and calcium stannate to replace traditional halogen-containing flame retardants, avoiding the release of toxic hydrogen halide gas during combustion and meeting the requirements of environmental protection.

[0031] (2) The present invention calcines and activates the surface of diatomite, utilizes the porous structure of diatomite to adsorb ammonium polyphosphate, delays its decomposition, and prolongs the flame retardant action time; ammonium polyphosphate decomposes when heated to generate polyphosphoric acid, which promotes the formation of a carbon layer. The present invention adds the flame retardant in batches to ensure the uniform dispersion of the flame retardant and avoid agglomeration; on this basis, zinc borate catalyzes carbon formation, calcium stannate inhibits ignition, and forms a gas-phase - condensed-phase synergistic flame retardancy with ammonium polyphosphate; further, the coupling agent surface-modifies biochar to form a dense carbon layer at high temperature, isolating oxygen and heat, and simultaneously adsorbing free radicals generated during combustion; in addition, the present invention uses a La-Zn composite rare earth stabilizer to improve thermal stability, and the silanization treatment helps to enhance the compatibility with PVC and reduce thermal degradation during processing; each component exerts a flame retardant effect synergistically through specific processing. Detailed implementation manners

[0032] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in combination with embodiments, details the specific implementation manners, structures, features, and their effects of the present invention as follows.

[0033] Example 1

[0034] A preparation method of a halogen-free environmentally friendly flame retardant PVC cable. The preparation method of the PVC cable in this example comprises the following steps:

[0035] Step 1: Mix PVC, ATBC plasticizer, and epoxidized soybean oil to obtain Material 1;

[0036] Step 2: Add a La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires to Material 1 and mix to obtain Material 2;

[0037] Step 3: Mix Material 2, diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate, and coupling agent surface-modified biochar to obtain Material 3;

[0038] Step 4: Add a borate crosslinking agent to Material 3 and process to obtain a mixed material;

[0039] Step 5: Extrude the mixed material on the surface of an armored wire core and cool to form.

[0040] In Step 1 of this example, the mass ratio of PVC, ATBC plasticizer, and epoxidized soybean oil is 1:0.26:0.06; the mixing method is to heat to 93°C and stir at a speed of 600 rpm for 5 minutes.

[0041] In Step 2 of this example, the mass ratio of Material 1, La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires is 13.2:0.3:0.11:0.04; the mixing method is to stir at a speed of 800 rpm for 4 minutes.

[0042] The preparation method of the La-Zn composite rare earth stabilizer in step two of this embodiment includes the following steps:

[0043] Step X1: Mix lanthanum nitrate and zinc nitrate according to a mass ratio of 1:3, and then at 60 °C and a rotation speed of 300 rpm, dropwise add ammonia water with a mass concentration of 25 wt% at a dropping rate of 2 mL / min to adjust the pH to 8. After reaching the pH value, let it stand for 3 h, filter to obtain a La-Zn hydroxide coprecipitate;

[0044] Step X2: Calcinate the La-Zn hydroxide coprecipitate at 800 °C for 4 h to obtain a La-Zn composite oxide;

[0045] Step X3: Mix KH-550, absolute ethanol, and deionized water according to a volume ratio of 1:4:1, stir at room temperature for 25 min, and dropwise add 0.1 M acetic acid solution to adjust the pH to 4 to obtain a silane solution;

[0046] Step X4: Mix the La-Zn composite oxide and the silane solution according to a mass ratio of 1:6, stir at 50 °C at 200 rpm for 4 h, filter, precipitate and dry, and keep it at 120 °C for 1.2 h to obtain a composite rare earth stabilizer.

[0047] The preparation method of the diatomite-ammonium polyphosphate composite flame retardant in step three of this embodiment includes the following steps:

[0048] Step Y1: Calcinate diatomite at 340 °C for 2.5 h to obtain activated diatomite;

[0049] Step Y2: Mix the activated diatomite, ammonium polyphosphate, and absolute ethanol according to a mass ratio of 1:0.66:4.5, ball mill for 2 h, and spray dry to obtain it.

[0050] In this embodiment, the mixing method is as follows: Divide the diatomite-ammonium polyphosphate into the first batch, the second batch, and the third batch. Add the first batch and the second batch to material two, stir for 2 min after adding the first batch and the second batch respectively, and there is an interval of 2 min after each stirring. While adding the third batch, add zinc borate, calcium stannate, and coupling agent surface-modified biochar, raise the temperature to 102 °C, stir for 6 min, then raise the temperature to 108 °C and increase the rotation speed to 950 rpm, and stir for 12 min.

[0051] In this embodiment, the mass ratio of the first batch, the second batch, and the third batch is 9.5:1.18:0.64; the mass ratio of the first batch to material two is 1:7.8; the mass ratio of the third batch, zinc borate, calcium stannate, and coupling agent surface-modified biochar is 1:5.8:3.5:5.2.

[0052] The preparation method of the coupling agent surface-modified biochar in step three of this embodiment includes the following steps:

[0053] Step Z1: In an oxygen-free atmosphere, rice husks are carbonized at 600 °C for 2.6 h to obtain biochar powder;

[0054] Step Z2: The biochar powder and a KH-550 ethanol solution with a mass concentration of 1.5 wt% of KH-550 are mixed at a ratio of 1:10 g / mL. The ultrasonic frequency is set to 35 kHz, the ultrasonic power is 100 W, the ultrasonic temperature is 60 °C, and ultrasonic treatment is carried out for 2.2 h to obtain a mixed material;

[0055] Step Z3: Purify the mixed material to obtain the product.

[0056] In step four of this embodiment, the mass ratio of material three to the borate cross-linking agent is 17.3:0.38; the treatment method is to cool down to 85 °C and stir for 7 min, and then discharge the material after the temperature drops to 60 °C.

[0057] In step five of this embodiment, the water temperature used during cooling is 20 °C and the water pressure is 0.4 MPa.

[0058] Example 2

[0059] A preparation method of a halogen-free environmentally friendly flame-retardant PVC cable. The preparation method of the PVC cable in this embodiment includes the following steps:

[0060] Step one: Mix PVC, ATBC plasticizer, and epoxidized soybean oil to obtain material one;

[0061] Step two: Add La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires to material one and mix to obtain material two;

[0062] Step three: Mix material two, diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate, and coupling agent surface-modified biochar to obtain material three;

[0063] Step four: Add a borate cross-linking agent to material three and process to obtain a mixed material;

[0064] Step five: Extrude the mixed material on the surface of the armored wire core and cool it to form.

[0065] In step one of this embodiment, the mass ratio of PVC, ATBC plasticizer, and epoxidized soybean oil is 1:0.27:0.068; the mixing method is to heat up to 94 °C and stir at a speed of 640 rpm for 6.7 min.

[0066] In Step 2 of this embodiment, the mass ratio of Material 1, La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires is 13.4:0.36:0.118:0.043; the mixing method is to stir at a speed of 820 rpm for 5.5 min.

[0067] The preparation method of the La-Zn composite rare earth stabilizer in Step 2 of this embodiment includes the following steps:

[0068] Step X1: Mix lanthanum nitrate and zinc nitrate in a mass ratio of 1:3.2, and at 68 °C and a rotation speed of 350 rpm, dropwise add ammonia water with a mass concentration of 26 wt% at a dropping rate of 3 mL / min to adjust the pH to 8.5. After reaching the pH value, let it stand for 2.8 h, filter to obtain a La-Zn hydroxide coprecipitate;

[0069] Step X2: Calcinate the La-Zn hydroxide coprecipitate at 820 °C for 3.6 h to obtain a La-Zn composite oxide;

[0070] Step X3: Mix KH-550, absolute ethanol, and deionized water in a volume ratio of 1:4.2:1, stir at room temperature for 28 min, and dropwise add 0.1 M acetic acid solution to adjust the pH to 4.3 to obtain a silane solution;

[0071] Step X4: Mix the La-Zn composite oxide and the silane solution in a mass ratio of 1:7, stir at 52 °C at 250 rpm for 3.5 h, filter, precipitate and dry, and keep warm at 122 °C for 1.05 h to obtain a composite rare earth stabilizer.

[0072] The preparation method of the diatomite-ammonium polyphosphate composite flame retardant in Step 3 of this embodiment includes the following steps:

[0073] Step Y1: Calcinate diatomite at 345 °C for 2.2 h to obtain activated diatomite;

[0074] Step Y2: Mix the activated diatomite, ammonium polyphosphate, and absolute ethanol in a mass ratio of 1:0.67:4.7, ball mill for 2.2 h, and spray dry to obtain it.

[0075] In Step 3 of this embodiment, the mixing method is to divide the diatomite-ammonium polyphosphate into the first batch, the second batch, and the third batch. Add the first batch and the second batch to Material 2, stir for 2.2 min after adding the first batch and the second batch respectively, with an interval of 2 min after each stirring. While adding the third batch, add zinc borate, calcium stannate, and coupling agent surface-modified biochar, raise the temperature to 104 °C, stir for 9 min, then raise the temperature to 109 °C and increase the rotation speed to 980 rpm, and stir for 11 min.

[0076] The mass ratio of the first batch, the second batch and the third batch in this embodiment is 9.6:1.19:0.65; the mass ratio of the first batch to the second material is 1:7.9; the mass ratio of the third batch, zinc borate, calcium stannate and the coupling agent surface-modified biochar is 1:5.9:3.8:5.25.

[0077] The preparation method of the coupling agent surface-modified biochar in step three of this embodiment includes the following steps:

[0078] Step Z1: In an oxygen-free atmosphere, rice husks are carbonized at 608 °C for 2.5 h to obtain biochar powder;

[0079] Step Z2: The biochar powder and a KH-550 ethanol solution with a mass concentration of 1.8 wt% of KH-550 are mixed at a ratio of 1:10.6 g / mL. The ultrasonic frequency is set to 38 kHz, the ultrasonic power is 120 W, the ultrasonic temperature is 60 °C, and ultrasonic treatment is carried out for 2.1 h to obtain a mixed material;

[0080] Step Z3: Purify the mixed material to obtain the product.

[0081] In step four of this embodiment, the mass ratio of the third material to the borate crosslinking agent is 17.35:0.39; the treatment method is to cool down to 88 °C and stir for 4 min, and discharge the material after the temperature drops to 60 °C.

[0082] In step five of this embodiment, the water temperature used for cooling is 22 °C and the water pressure is 0.4 MPa.

[0083] Example 3

[0084] A preparation method of a halogen-free environmentally friendly flame-retardant PVC cable. The preparation method of the PVC cable in this embodiment includes the following steps:

[0085] Step one: Mix PVC, ATBC plasticizer and epoxidized soybean oil to obtain the first material;

[0086] Step two: Add La-Zn composite rare earth stabilizer, polyether silicone oil and silicon carbide nanowires to the first material and mix to obtain the second material;

[0087] Step three: Mix the second material, diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate and the coupling agent surface-modified biochar to obtain the third material;

[0088] Step four: Add a borate crosslinking agent to the third material and process to obtain a mixed material;

[0089] Step five: Extrude the mixed material on the surface of the armored wire core and cool and form.

[0090] In Step 1 of this embodiment, the mass ratio of PVC, ATBC plasticizer, and epoxidized soybean oil is 1:0.28:0.07; the mixing method is to heat to 95°C and then stir at 700 rpm for 6 min.

[0091] In Step 2 of this embodiment, the mass ratio of Material 1, La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires is 13.5:0.4:0.12:0.05; the mixing method is to stir at 850 rpm for 5 min.

[0092] The preparation method of the La-Zn composite rare earth stabilizer in Step 2 of this embodiment includes the following steps:

[0093] Step X1: Mix lanthanum nitrate and zinc nitrate in a mass ratio of 1:3.5, and then at 70°C and 400 rpm, adjust the pH to 9 by dropping ammonia water with a mass concentration of 26.5 wt% at a dropping rate of 3.5 mL / min. After reaching the pH value, let it stand for 2.5 h, filter to obtain La-Zn hydroxide coprecipitate;

[0094] Step X2: Calcinate the La-Zn hydroxide coprecipitate at 850°C for 3.5 h to obtain La-Zn composite oxide;

[0095] Step X3: Mix KH-550, absolute ethanol, and deionized water in a volume ratio of 1:4.5:1, stir at room temperature for 30 min, and adjust the pH to 4.5 by dropping 0.1 M acetic acid solution to obtain a silane solution;

[0096] Step X4: Mix the La-Zn composite oxide and the silane solution in a mass ratio of 1:8, stir at 55°C at 300 rpm for 3 h, filter, precipitate and dry, and keep warm at 125°C for 1.1 h to obtain the composite rare earth stabilizer.

[0097] The preparation method of the diatomite-ammonium polyphosphate composite flame retardant in Step 3 of this embodiment includes the following steps:

[0098] Step Y1: Calcinate diatomite at 350°C for 2 h to obtain activated diatomite;

[0099] Step Y2: Mix the activated diatomite, ammonium polyphosphate, and absolute ethanol in a mass ratio of 1:0.68:4.8, ball mill for 2.5 h, and spray dry to obtain the product.

[0100] In step three of this embodiment, the mixing method is as follows: The diatomite-ammonium polyphosphate is divided into the first batch, the second batch, and the third batch. Add the first batch and the second batch to Material Two, and stir for 2.5 minutes after each addition. After each stirring ends, there is an interval of 2 minutes. While adding the third batch, add zinc borate, calcium stannate, and coupling agent surface-modified biochar. Raise the temperature to 105 °C and stir for 8 minutes. Then raise the temperature to 110 °C and increase the rotation speed to 1000 rpm, and stir for 10 minutes.

[0101] In this embodiment, the mass ratio of the first batch, the second batch, and the third batch is 9.8:1.2:0.66; the mass ratio of the first batch to Material Two is 1:8; the mass ratio of the third batch, zinc borate, calcium stannate, and coupling agent surface-modified biochar is 1:6:4:5.3.

[0102] The preparation method of the coupling agent surface-modified biochar in step three of this embodiment includes the following steps:

[0103] Step Z1: In an oxygen-free atmosphere, carbonize rice husks at 610 °C for 2.4 hours to obtain biochar powder;

[0104] Step Z2: Mix the biochar powder and a KH-550 ethanol solution with a mass concentration of 2 wt% of KH-550 according to a ratio of 1:11 g / mL. Set the ultrasonic frequency to 40 kHz, the ultrasonic power to 150 W, and the ultrasonic temperature to 60 °C, and ultrasonicate for 2 hours to obtain a mixture;

[0105] Step Z3: Purify the mixture to obtain the product.

[0106] In step four of this embodiment, the mass ratio of Material Three to the borate cross-linking agent is 17.4:0.4; the treatment method is to cool down to 90 °C and stir for 5 minutes, and discharge the material after the temperature drops to 60 °C.

[0107] In this embodiment, the water temperature used for cooling in step five is 26 °C, and the water pressure is 0.3 MPa.

[0108] Example 4

[0109] A preparation method of a halogen-free environmentally friendly flame-retardant PVC cable. The preparation method of the PVC cable in this embodiment includes the following steps:

[0110] Step One: Mix PVC, ATBC plasticizer, and epoxidized soybean oil to obtain Material One;

[0111] Step Two: Add La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires to Material One and mix to obtain Material Two;

[0112] Step 3: Mix Material 2, diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate, and coupling agent surface-modified biochar to obtain Material 3;

[0113] Step 4: Add a borate crosslinking agent to Material 3 and process to obtain a mixed material;

[0114] Step 5: Extrude the mixed material on the surface of the armored wire core and cool it to form a shape.

[0115] In this embodiment, the mass ratio of PVC, ATBC plasticizer, and epoxidized soybean oil in Step 1 is 1:0.29:0.075; the mixing method is to heat up to 96 °C and then stir at a speed of 750 rpm for 5.5 min.

[0116] In this embodiment, the mass ratio of Material 1, La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires in Step 2 is 13.6:0.45:0.125:0.056; the mixing method is to stir at a speed of 860 rpm for 4.5 min.

[0117] The preparation method of the La-Zn composite rare earth stabilizer in Step 2 of this embodiment includes the following steps:

[0118] Step X1: Mix lanthanum nitrate and zinc nitrate in a mass ratio of 1:3.6, and then at 75 °C and a rotation speed of 450 rpm, dropwise add ammonia water with a mass concentration of 27 wt% at a dropping rate of 4 mL / min to adjust the pH to 9.4. After reaching the pH value, let it stand for 2.2 h, filter to obtain a La-Zn hydroxide coprecipitate;

[0119] Step X2: Calcinate the La-Zn hydroxide coprecipitate at 870 °C for 3.2 h to obtain a La-Zn composite oxide;

[0120] Step X3: Mix KH-550, absolute ethanol, and deionized water in a volume ratio of 1:4.6:1, stir at room temperature for 32 min, and dropwise add 0.1 M acetic acid solution to adjust the pH to 4.7 to obtain a silane solution;

[0121] Step X4: Mix the La-Zn composite oxide and the silane solution in a mass ratio of 1:6 - 10, stir at 58 °C at a speed of 350 rpm for 2.4 h, filter, precipitate and dry, and keep warm at 128 °C for 1.16 h to obtain a composite rare earth stabilizer.

[0122] The preparation method of the diatomite-ammonium polyphosphate composite flame retardant in Step 3 of this embodiment includes the following steps:

[0123] Step Y1: Calcinate diatomite at 355 °C for 1.8 h to obtain activated diatomite;

[0124] Step Y2: Mix activated diatomaceous earth, ammonium polyphosphate, and absolute ethanol in a mass ratio of 1:0.69:5, then ball mill for 2.8 h and spray dry to obtain the product.

[0125] In step three of this example, the mixing method is as follows: Divide the diatomaceous earth - ammonium polyphosphate into the first batch, the second batch, and the third batch. Add the first batch and the second batch to material two, and stir for 2.6 min after each addition. After each stirring ends, leave a 2 - minute interval. While adding the third batch, add zinc borate, calcium stannate, and coupling agent - modified biochar. Raise the temperature to 106°C and stir for 7 min, then raise the temperature to 111°C and increase the rotation speed to 1020 rpm, and stir for 9 min.

[0126] In this example, the mass ratio of the first batch, the second batch, and the third batch is 9.9:1.21:0.67; the mass ratio of the first batch to material two is 1:8.1; the mass ratio of the third batch, zinc borate, calcium stannate, and coupling agent - modified biochar is 1:6.1:4.2:5.36.

[0127] The preparation method of the coupling agent - modified biochar in step three of this example includes the following steps:

[0128] Step Z1: In an oxygen - free atmosphere, carbonize rice husks at 615°C for 2.3 h to obtain biochar powder.

[0129] Step Z2: Mix the biochar powder and a KH - 550 ethanol solution with a mass concentration of 2.2 wt% of KH - 550 in a ratio of 1:11.2 g / mL. Set the ultrasonic frequency to 42 kHz, the ultrasonic power to 180 W, and the ultrasonic temperature to 60°C, and ultrasonicate for 1.9 h to obtain a mixture.

[0130] Step Z3: Purify the mixture to obtain the product.

[0131] In step four of this example, the mass ratio of material three to the borate cross - linker is 17.45:0.41; the treatment method is to cool to 92°C and stir for 4 min, and then discharge the material after the temperature drops to 60°C.

[0132] In step five of this example, the water temperature for cooling is 28°C and the water pressure is 0.2 MPa.

[0133] Example 5

[0134] A preparation method of a halogen - free environmentally friendly flame - retardant PVC cable. The preparation method of the PVC cable in this example includes the following steps:

[0135] Step one: Mix PVC, ATBC plasticizer, and epoxy soybean oil to obtain material one.

[0136] Step 2: Add La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires to Material 1, and mix to obtain Material 2;

[0137] Step 3: Mix Material 2, diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate, and coupling agent surface-modified biochar to obtain Material 3;

[0138] Step 4: Add borate crosslinking agent to Material 3 and process to obtain a mixture;

[0139] Step 5: Extrude the mixture onto the surface of the armored wire core and cool to form.

[0140] In Step 1 of this example, the mass ratio of PVC, ATBC plasticizer, and epoxidized soybean oil is 1:0.3:0.08; the mixing method is to heat to 97 °C and then stir at 800 rpm for 5 min.

[0141] In Step 2 of this example, the mass ratio of Material 1, La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires is 13.8:0.5:0.13:0.06; the mixing method is to stir at 900 rpm for 4 min.

[0142] The preparation method of the La-Zn composite rare earth stabilizer in Step 2 of this example includes the following steps:

[0143] Step X1: Mix lanthanum nitrate and zinc nitrate in a mass ratio of 1:4, and at 80 °C and 500 rpm, dropwise add ammonia water with a mass concentration of 28 wt% at a dropping rate of 5 mL / min to adjust the pH to 10. After reaching the pH value, let it stand for 2 h, filter to obtain La-Zn hydroxide coprecipitate;

[0144] Step X2: Calcinate the La-Zn hydroxide coprecipitate at 900 °C for 3 h to obtain La-Zn composite oxide;

[0145] Step X3: Mix KH-550, absolute ethanol, and deionized water in a volume ratio of 1:5:1, stir at room temperature for 35 min, and dropwise add 0.1 M acetic acid solution to adjust the pH to 5 to obtain a silane solution;

[0146] Step X4: Mix the La-Zn composite oxide and the silane solution in a mass ratio of 1:6 - 10, stir at 60 °C at 400 rpm for 2 h, filter, precipitate and dry, and keep warm at 130 °C for 1 h to obtain the composite rare earth stabilizer.

[0147] The preparation method of the diatomite-ammonium polyphosphate composite flame retardant in Step 3 of this example includes the following steps:

[0148] Step Y1: Calcinate diatomite at 360 °C for 1.5 h to obtain activated diatomite;

[0149] Step Y2: Mix the activated diatomite, ammonium polyphosphate, and absolute ethanol in a mass ratio of 1:0.7:5.1, then ball mill for 3 h and spray dry to obtain the product.

[0150] In this example, in Step 3, the mixing method is as follows: Divide the diatomite-ammonium polyphosphate composite flame retardant into the first batch, the second batch, and the third batch. Add the first batch and the second batch to Material 2, stir for 3 min after each addition, with a 2-min interval between each stirring end. While adding the third batch, add zinc borate, calcium stannate, and coupling agent surface-modified biochar. Raise the temperature to 108 °C and stir for 6 min, then raise the temperature to 112 °C and increase the rotation speed to 1050 rpm, and stir for 8 min.

[0151] In this example, the mass ratio of the first batch, the second batch, and the third batch is 10.1:1.22:0.68; the mass ratio of the first batch to Material 2 is 1:8.2; the mass ratio of the third batch, zinc borate, calcium stannate, and coupling agent surface-modified biochar is 1:6.2:4.5:5.4.

[0152] In this example, the preparation method of the coupling agent surface-modified biochar in Step 3 includes the following steps:

[0153] Step Z1: In an anaerobic atmosphere, carbonize rice husks at 620 °C for 2.2 h to obtain biochar powder;

[0154] Step Z2: Mix the biochar powder and a KH-550 ethanol solution with a mass concentration of 2.5 wt% of KH-550 in a ratio of 1:12 g / mL, set the ultrasonic frequency to 45 kHz, the ultrasonic power to 200 W, and the ultrasonic temperature to 60 °C, and ultrasonicate for 1.8 h to obtain a mixed material;

[0155] Step Z3: Purify the mixed material to obtain the product.

[0156] In this example, in Step 4, the mass ratio of Material 3 to the borate crosslinking agent is 17.5:0.42; the treatment method is to cool to 95 °C and stir for 3 min, and discharge the material after the temperature drops to 60 °C.

[0157] In this example, the water temperature used for cooling in Step 5 is 30 °C and the water pressure is 0.2 MPa.

[0158] Example 6

[0159] On the basis of Example 3, remove the diatomite-ammonium polyphosphate composite flame retardant in Step 3 and replace it with an equal weight of zinc borate, and keep other conditions the same as in Example 3.

[0160] Example 7

[0161] On the basis of Example 3, zinc borate in Step 3 was removed and replaced with an equal weight of calcium stannate, and other conditions were the same as those in Example 3.

[0162] Example 8

[0163] On the basis of Example 3, calcium stannate in Step 3 was removed and replaced with an equal weight of biochar surface-modified with a coupling agent, and other conditions were the same as those in Example 3.

[0164] Example 9

[0165] On the basis of Example 3, the biochar surface-modified with a coupling agent in Step 3 was removed and replaced with an equal weight of diatomite-ammonium polyphosphate composite flame retardant, and other conditions were the same as those in Example 3.

[0166] Comparative Example 1

[0167] On the basis of Example 3, with other conditions remaining the same, the preparation method of the PVC cable was changed to the following steps:

[0168] Step 1: Mix PVC, ATBC plasticizer, and epoxidized soybean oil to obtain Material 1;

[0169] Step 2: Add La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires to Material 1 and mix to obtain Material 2;

[0170] Step 3: Add diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate, and biochar surface-modified with a coupling agent to Material 2, stir at a speed of 850 rpm for 5 min, heat up to 105 °C, stir for 8 min, then heat up to 110 °C and increase the speed to 1000 rpm, and stir for 10 min to obtain Material 3;

[0171] Step 4: Add borate crosslinking agent to Material 3 and process to obtain a mixture;

[0172] Step 5: Extrude the mixture on the surface of the armored wire core and cool to form.

[0173] Comparative Example 2

[0174] On the basis of Example 3, with other conditions remaining the same, the preparation method of the PVC cable was changed to the following steps:

[0175] Step 1: Mix PVC, ATBC plasticizer, and epoxidized soybean oil to obtain Material 1;

[0176] Step 2: Add La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires to Material 1 and mix to obtain Material 2;

[0177] Step 3: Add diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate, and coupling agent surface-modified biochar to Material 2, stir at a speed of 850 rpm for 5 min, heat up to 110 °C, and stir at a speed of 1000 rpm for 18 min to obtain Material 3;

[0178] Step 4: Add borate crosslinking agent to Material 3 and process to obtain a mixture;

[0179] Step 5: Extrude the mixture on the surface of the armored wire core and cool it to form.

[0180] Comparative Example 3

[0181] On the basis of Example 3, while keeping other conditions the same, change the preparation method of the PVC cable to the following steps:

[0182] Step 1: Mix PVC, ATBC plasticizer, and epoxidized soybean oil to obtain Material 1;

[0183] Step 2: Divide the diatomite-ammonium polyphosphate into the first batch, the second batch, and the third batch. Add the first batch and the second batch to Material 1, stir for 2.5 min after each addition, with an interval of 2 min after each stirring. While adding the third batch, add zinc borate, calcium stannate, and coupling agent surface-modified biochar, heat up the temperature to 105 °C, stir for 8 min, then heat up to 110 °C and increase the speed to 1000 rpm, and stir for 10 min to obtain Material 2;

[0184] Step 3: Add La-Zn composite rare earth stabilizer, polyether silicone oil, and silicon carbide nanowires to Material 2 and mix to obtain Material 3; the mixing method is to stir at a speed of 850 rpm for 5 min;

[0185] Step 4: Add borate crosslinking agent to Material 3 and process to obtain a mixture;

[0186] Step 5: Extrude the mixture on the surface of the armored wire core and cool it to form.

[0187] Comparative Example 4

[0188] On the basis of Example 3, while keeping other conditions the same, change the preparation method of the PVC cable to the following steps:

[0189] PVC, ATBC plasticizer, epoxidized soybean oil, La-Zn composite rare earth stabilizer, polyether silicone oil, silicon carbide nanowires, diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate and coupling agent surface-modified biochar were mixed, then heated to 110 °C and stirred at 1000 rpm for 34 min. Then, borate crosslinking agent was added, and the temperature was lowered to 90 °C and stirred for 5 min. After the temperature dropped to 60 °C, the mixture was discharged and extruded onto the surface of the armored wire core and cooled to form a shape.

[0190] Comparative Example 5

[0191] On the basis of Example 3, with other conditions remaining the same, the preparation method of the diatomite-ammonium polyphosphate composite flame retardant was changed to the following steps:

[0192] Diatomite, ammonium polyphosphate, and absolute ethanol were mixed in a mass ratio of 1:0.68:4.8, then ball-milled for 2.5 h and spray-dried to obtain the product.

[0193] Comparative Example 6

[0194] On the basis of Example 3, with other conditions remaining the same, the coupling agent surface-modified biochar was replaced with biochar, and the preparation method of the biochar was as follows:

[0195] In an oxygen-free atmosphere, rice husks were carbonized at 610 °C for 2.4 h to obtain biochar.

[0196] Taking the PVC cables prepared in Examples 1-9 and Comparative Examples 1-6 as samples, their flame retardant properties were tested according to GB / T18380.32-2022, and the results are recorded in Table 1 below.

[0197] Table 1

[0198]

[0199]

[0200] As can be seen from Table 1, the halogen-free environmentally friendly flame retardant PVC cables prepared by the present invention have good flame retardant properties and have good application prospects in types of cables such as network cables, electric wires, and power cables.

[0201] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content within the scope of the technical solution of the present invention to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the technical solution content of the present invention, any indirect modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a halogen-free environmentally friendly flame-retardant PVC cable, characterized in that: The preparation method of the PVC cable comprises the following steps: Step 1: Mix PVC, ATBC plasticizer and epoxidized soybean oil to obtain Material 1; Step 2: Add La-Zn composite rare earth stabilizer, polyether silicone oil and silicon carbide nanowires to Material 1 and mix to obtain Material 2; Step 3: Mix Material 2, diatomite-ammonium polyphosphate composite flame retardant, zinc borate, calcium stannate and coupling agent surface-modified biochar to obtain Material 3; Step 4: Add borate crosslinking agent to Material 3 and process to obtain a mixture; Step 5: Extrude the mixture on the surface of the armored wire core and cool it to form.

2. The preparation method of a halogen-free environmentally friendly flame-retardant PVC cable according to claim 1, characterized in that: In Step 1, the mass ratio of the PVC, ATBC plasticizer and epoxidized soybean oil is 1:0.26-0.3:0.06-0.08; the mixing method is to heat to 93-97°C and then stir at a speed of 600-800 rpm for 5-7 min.

3. The preparation method of a halogen-free environmentally friendly flame-retardant PVC cable according to claim 1, characterized in that: In Step 2, the mass ratio of Material 1, La-Zn composite rare earth stabilizer, polyether silicone oil and silicon carbide nanowires is 13.2-13.8:0.3-0.5:0.11-0.13:0.04-0.06; the mixing method is to stir at a speed of 800-900 rpm for 4-6 min.

4. The preparation method of a halogen-free environmentally friendly flame-retardant PVC cable according to claim 1, characterized in that: The preparation method of the La-Zn composite rare earth stabilizer in Step 2 comprises the following steps: Step X1: Mix lanthanum nitrate and zinc nitrate according to a mass ratio of 1:3-4, and then dropwise add ammonia water with a mass concentration of 25-28 wt% at a dropping rate of 2-5 mL / min at 60-80°C and a speed of 300-500 rpm to adjust the pH to 8-10. After reaching the pH value, stand for 2-3 h, filter to obtain La-Zn hydroxide coprecipitate; Step X2: Calcinate the La-Zn hydroxide coprecipitate at 800-900°C for 3-4 h to obtain La-Zn composite oxide; Step X3: Mix KH-550, absolute ethanol and deionized water according to a volume ratio of 1:4-5:1, stir at room temperature for 25-35 min, and dropwise add 0.1 M acetic acid solution to adjust the pH to 4-5 to obtain a silane solution; Step X4: Mix the La-Zn composite oxide and the silane solution according to a mass ratio of 1:6-10, stir at 50-60°C at a speed of 200-400 rpm for 2-4 h, filter, precipitate and dry, and keep warm at 120-130°C for 1-1.2 h to obtain the composite rare earth stabilizer.

5. The preparation method of a halogen-free environmentally friendly flame-retardant PVC cable according to claim 1, characterized in that: The preparation method of the diatomite-ammonium polyphosphate composite flame retardant in Step 3 comprises the following steps: Step Y1: Calcinate diatomite at 340-360°C for 1.5-2.5 h to obtain activated diatomite; Step Y2: Mix the activated diatomite, ammonium polyphosphate and absolute ethanol according to a mass ratio of 1:0.66-0.7:4.5-5.1, ball mill for 2-3 h, and spray dry to obtain it.

6. The preparation method of a halogen-free environmentally friendly flame-retardant PVC cable according to claim 1, characterized in that: The mixing method described in Step 3 is as follows: Divide the diatomite-ammonium polyphosphate into the first batch, the second batch, and the third batch. Add the first batch and the second batch to Material 2, and stir for 2 - 3 minutes after each addition. After each stirring ends, leave a 2-minute interval. While adding the third batch, add zinc borate, calcium stannate, and coupling agent surface-modified biochar. Raise the temperature to 102 - 108 °C and stir for 6 - 10 minutes. Then raise the temperature to 108 - 112 °C and increase the rotation speed to 950 - 1050 rpm, and stir for 8 - 12 minutes.

7. The preparation method of a halogen-free environmentally friendly flame-retardant PVC cable according to claim 6, characterized in that: The mass ratio of the first batch, the second batch, and the third batch is 9.5 - 10.1:1.18 - 1.22:0.64 - 0.68; the mass ratio of the first batch to Material 2 is 1:7.8 - 8.2; the mass ratio of the third batch, zinc borate, calcium stannate, and coupling agent surface-modified biochar is 1:5.8 - 6.2:3.5 - 4.5:5.2 - 5.

4.

8. The preparation method of a halogen-free environmentally friendly flame-retardant PVC cable according to claim 1, characterized in that: The preparation method of the coupling agent surface-modified biochar described in Step 3 includes the following steps: Step Z1: In an anaerobic atmosphere, carbonize rice husks at 600 - 620 °C for 2.2 - 2.6 hours to obtain biochar powder. Step Z2: Mix the biochar powder and a KH-550 ethanol solution with a mass concentration of KH-550 of 1.5 - 2.5 wt% at a ratio of 1:10 - 12 g / mL. Set the ultrasonic frequency to 35 - 45 kHz, the ultrasonic power to 100 - 200 W, the ultrasonic temperature to 60 °C, and ultrasonicate for 1.8 - 2.2 hours to obtain a mixed material. Step Z3: Purify the mixed material to obtain the product.

9. The preparation method of a halogen-free environmentally friendly flame-retardant PVC cable according to claim 1, characterized in that: The mass ratio of Material 3 to the borate crosslinking agent in Step 4 is 17.3 - 17.5:0.38 - 0.42; the processing method is to cool to 85 - 95 °C and stir for 3 - 7 minutes, and discharge the material after the temperature drops to 60 °C.

10. The preparation method of a halogen-free environmentally friendly flame-retardant PVC cable according to claim 1, characterized in that: The water temperature used during cooling in Step 5 is 20 - 30 °C, and the water pressure is 0.2 - 0.4 MPa.

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