Insulating Material for New Energy Vehicle Wiring Harness with Flame Retardant Characteristics and Its Preparation Method

Abstract

The present invention relates to the technical field of new energy vehicle wiring harnesses, and specifically to a flame-retardant insulating material for new energy vehicle wiring harnesses and a preparation method thereof. In the present invention, ethylenediamine and phytic acid are reacted to synthesize phytic acid amide. Then, Zn-Al-LDHs are synthesized on the surface of phytic acid amide to obtain phytic acid amide-LDHs. Finally, carboxyl silicone oil is used to treat phytic acid amide-LDHs to obtain a flame retardant with excellent flame retardant performance and good compatibility with polyvinyl chloride resin. Moreover, by using polyvinyl chloride resin, flame retardant, and EVA resin as raw materials, a flame-retardant insulating material suitable for new energy vehicle wiring harnesses is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicle wiring harnesses, and specifically to a flame-retardant new energy vehicle wiring harness insulating material and a preparation method thereof. Background Technique

[0002] An automotive wiring harness is the main body for signal transmission in an automobile and plays a crucial role in automobile design and use. The wiring harness mainly consists of electric wires and cables, contact parts made of metal materials, connecting parts, and wrapping and fixing parts. The automotive wiring harness connects various electronic components on the vehicle. It not only needs to accurately transmit various signals, but also ensure the reliability of the connected circuit and requires a certain anti-interference ability.

[0003] With the continuous improvement of people's demands for automobiles, the requirements for the power performance, safety, and comfort of automobiles are also getting higher and higher. While improving the comprehensive performance of automobiles, problems such as the increasing complexity of the wiring harness main body and the decline in system reliability have emerged in the automotive wiring harness. Especially for the high-voltage wiring harness used for connecting the battery and the motor inside a new energy vehicle, the current transmission is frequent and the heating temperature is relatively high, exceeding the long-term allowable working temperature of the cable. When the cable is used under long-term load, over time, the cable material ages more severely, resulting in cracking and threatening people's safety. In order to improve the safety of wiring harness use, flame retardants are often added to endow the wiring harness with flame retardant properties. However, the addition of flame retardants will reduce the mechanical properties of the wiring harness, limit the application of the wiring harness, and shorten the service life of the wiring harness. Therefore, it is necessary to develop a new energy vehicle wiring harness insulating material with both flame retardancy and mechanical properties. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a flame-retardant new energy vehicle wiring harness insulating material and a preparation method thereof.

[0005] A flame-retardant new energy vehicle wiring harness insulating material comprises the following raw materials:

[0006] Polyvinyl chloride resin;

[0007] Flame retardant;

[0008] EVA resin.

[0009] Preferably, the flame-retardant new energy vehicle wiring harness insulating material comprises the following raw materials by mass parts:

[0010] 100 parts of polyvinyl chloride resin;

[0011] 4 - 10 parts of flame retardant;

[0012] 2 - 5 parts of EVA resin.

[0013] Further preferably, the insulating material for new energy vehicle wiring harness with flame retardant properties comprises the following raw materials by mass parts:

[0014] 100 parts of polyvinyl chloride resin;

[0015] 4 - 10 parts of flame retardant;

[0016] 2 - 5 parts of EVA resin;

[0017] 18 - 20 parts of filler;

[0018] 1 - 1.5 parts of high melting point polyethylene wax;

[0019] 0.1 - 0.16 parts of antioxidant.

[0020] The filler is at least one of calcium carbonate, carbon fiber, ceramic microspheres, and silicone powder.

[0021] The antioxidant is at least one of phenolic antioxidants, organophosphorus antioxidants, and aromatic amine antioxidants.

[0022] The preparation method of the flame retardant comprises the following steps:

[0023] S1 Mix ethylenediamine and ethanol according to the volume ratio of (0.1 - 0.5):100, and stir evenly to obtain an ethylenediamine - alcohol solution; subsequently, take 5 - 6 parts of 70wt% phytic acid aqueous solution and 90 - 100 parts of ethylenediamine - alcohol solution by mass parts, mix them, react at 50 - 70°C for 8 - 14h, centrifuge to take the precipitate, wash, and dry to obtain phytic acid amine.

[0024] S2 Mix 3 - 4 parts of the phytic acid amine prepared in step S1 and 90 - 100 parts of water by mass parts, stir at 35 - 45°C for 1 - 2h to obtain a phytic acid amine suspension; mix 4 - 5 parts of Zn(NO3)2·6H2O and 3 - 4 parts of Al(NO3)3·9H2O, and dissolve them with 45 - 55 parts of water to obtain a bimetallic ion solution; add the above bimetallic ion solution to the phytic acid amine suspension at 50 - 70°C and stir for 4 - 6h, adjust the pH to 9.5 - 10.0 with 20wt% ammonia water to obtain a reaction solution; finally, transfer the reaction solution to a hydrothermal reaction kettle, react at 75 - 85°C for 8 - 12h, cool to room temperature, filter, wash, and dry to obtain the flame retardant.

[0025] Preferably, the preparation method of the flame retardant comprises the following steps:

[0026] S1 Mix ethylenediamine and ethanol in a volume ratio of (0.1 - 0.5):100, and stir evenly to obtain an ethylenediamine - alcohol solution; Subsequently, take 5 - 6 parts by mass of a 70wt% phytic acid aqueous solution and 90 - 100 parts by mass of the ethylenediamine - alcohol solution, mix them, react at 50 - 70°C for 8 - 14 h, centrifuge to obtain the precipitate, wash and dry it to obtain phytic acid amide;

[0027] S2 Take 3 - 4 parts by mass of the phytic acid amide prepared in step S1 and 90 - 100 parts by mass of water, stir at 35 - 45°C for 1 - 2 h to obtain a phytic acid amide suspension; Mix 4 - 5 parts of Zn(NO3)2·6H2O and 3 - 4 parts of Al(NO3)3·9H2O, and dissolve them with 45 - 55 parts of water to obtain a bimetallic ion solution; Add the above bimetallic ion solution to the phytic acid amide suspension at 50 - 70°C and stir for 4 - 6 h, adjust the pH to 9.5 - 10.0 with 20wt% ammonia water to obtain a reaction solution; Finally, transfer the reaction solution to a hydrothermal reaction kettle, react at 75 - 85°C for 8 - 12 h, cool to room temperature, filter, wash and dry to obtain phytic acid amide - LDHs;

[0028] S3 Take 4 - 6 parts by mass of the phytic acid amide - LDH obtained in step S2 and add it to 10 - 50 parts by mass of carboxyl silicone oil, stir at 70 - 90°C for 1 - 2 h, centrifuge to obtain the precipitate, wash and dry it to obtain the flame retardant.

[0029] The present invention also provides a preparation method of a new - energy vehicle wire harness insulating material with flame - retardant properties, including the following steps: Mix 100 parts of polyvinyl chloride resin, 4 - 10 parts of flame retardant, 2 - 5 parts of EVA resin, 18 - 20 parts of filler, 1 - 1.5 parts of high - melting - point polyethylene wax, and 0.1 - 0.16 parts of antioxidant, and granulate them in a twin - screw extruder to obtain the new - energy vehicle wire harness insulating material with flame - retardant properties.

[0030] The temperature of the feeding zone of the twin - screw extruder is 120 - 130°C; the temperature of the middle zone is 170 - 180°C; the temperature of the discharging zone is 160 - 170°C.

[0031] The present invention uses polyvinyl chloride resin as the basic raw material, and modifies it with a flame retardant and EVA resin to obtain a new - energy vehicle wire harness insulating material with excellent flame - retardant performance and toughness.

[0032] Aiming at the two problems that traditional flame retardants have a single flame - retardant form, poor flame - retardant performance, poor compatibility with resins, uneven dispersion, and are prone to cause a decline in the mechanical properties of materials, the present invention synthesizes a new type of flame retardant.

[0033] First of all, the present invention uses zinc-aluminum layered double hydroxide as the base material of the flame retardant. It has a layered structure like hydrotalcite, and the voids between the cationic layers can accommodate various anions. The layered structure of Zn-Al-LDHs endows it with good physical isolation performance. During the combustion of the material, the layered structure can form a barrier to prevent the propagation of flames and heat, thereby slowing down the combustion rate. When Zn-Al-LDHs decomposes upon heating, it releases gases such as water and carbon dioxide. These gases can dilute the oxygen concentration in the combustion zone, reduce the flame temperature, and thus slow down the combustion process. In addition, Zn-Al-LDHs absorbs heat during combustion and converts it into chemical energy or transfers it to the surrounding environment, reducing the temperature of the combustion zone and thus slowing down the combustion process. Therefore, compared with traditional flame retardants such as magnesium hydroxide, Zn-Al-LDHs has more excellent flame retardant performance. However, its defect is that it has poor compatibility with the resin, is prone to uneven dispersion, resulting in a decline in the mechanical properties of the material, and at the same time has a higher cost.

[0034] Therefore, in order to further improve its flame retardancy, reduce costs, and weaken the impact of Zn-Al-LDHs on the mechanical properties of polyvinyl chloride resin. The present invention first reacts ethylenediamine with phytic acid to synthesize phytic acid amine, and then conducts the synthesis reaction of Zn-Al-LDHs in the phytic acid amine suspension, so that Zn-Al-LDHs is synthesized on the surface of phytic acid amine to obtain phytic acid amine-LDHs. The present invention finds that it has more excellent flame retardancy than Zn-Al-LDHs and phytic acid amine. The present invention believes that since phytic acid amine has both phosphate groups and amino groups at the same time, the phosphorus-based chemical substances (P· and HPO·) formed during combustion can capture free radicals and terminate the chain reaction, thereby preventing the combustion reaction in the gas phase. In addition, nitrogen-containing compounds will release non-combustible gases, increase the height of the carbon layer, increase the distance between the fire source and the polyvinyl chloride matrix, and at the same time the nitrogen-containing non-combustible gases can also dilute the concentration of combustible gases and oxygen, preventing the combustion reaction in the gas phase. Therefore, it also has good flame retardancy. And when we load Zn-Al-LDHs on the surface of phytic acid amine, not only does it simultaneously exert the flame retardant properties of both, but Zn-Al-LDHs also helps phytic acid amine form a thicker "carbon layer" to prevent the contact of flames and combustible gases with polyvinyl chloride. This further improves its flame retardant performance.

[0035] Furthermore, the present invention finds that the compatibility of Zn-Al-LDHs, phytic acid amide, and phytic acid amide-LDHs with polyvinyl chloride resin is relatively poor. Therefore, the present invention finally treats phytic acid amide-LDHs with carboxyl silicone oil. Carboxyl silicone oil is an organosilicon compound containing carboxyl functional groups, and it has good compatibility with polyvinyl chloride resin. To a certain extent, this improves the compatibility between phytic acid amide-LDHs and polyvinyl chloride resin, which is beneficial to weakening the influence of Zn-Al-LDHs on the mechanical properties of polyvinyl chloride resin.

[0036] Furthermore, the present invention finds that adding a small amount of EVA resin is beneficial to further improving the dispersibility of the flame retardant prepared by the present invention in polyvinyl chloride. The Chinese name of EVA resin is ethylene-vinyl acetate copolymer, which is composed of a copolymer of ethylene and vinyl acetate. EVA resin and its elastomeric derivatives can be compatible with a variety of polymers or mineral powders, and its composite materials have excellent electrical and mechanical properties.

[0037] Advantages of the present invention:

[0038] The present invention uses ethylenediamine and phytic acid to synthesize phytic acid amide, then synthesizes Zn-Al-LDHs on the surface of phytic acid amide to obtain phytic acid amide-LDHs, and finally treats phytic acid amide-LDHs with carboxyl silicone oil to obtain a flame retardant with excellent flame retardant performance and good compatibility with polyvinyl chloride resin. And using polyvinyl chloride resin, flame retardant, and EVA resin as raw materials, an insulating material with flame retardant properties suitable for new energy vehicle wiring harnesses is obtained. Specific embodiments

[0039] Polyvinyl chloride resin: Model: SG-5, Zhengzhou Xigui Chemical Co., Ltd.

[0040] EVA resin: Grade: EA28150, Houyi International Trade (Shanghai) Co., Ltd.

[0041] High melting point polyethylene wax: Product number: P25101245, Shandong Yousuo Chemical Technology Co., Ltd.

[0042] Phytic acid: CAS number: 83-86-3.

[0043] Carboxyl silicone oil: Product number: MY 2520, Anhui Mingyi Silicon Industry Co., Ltd.

[0044] Example 1

[0045] An insulating material for new energy vehicle wiring harnesses with flame retardant properties, by mass, includes the following raw materials:

[0046] 100 parts of polyvinyl chloride resin;

[0047] 6 parts of flame retardant;

[0048] 4 parts of EVA resin;

[0049] 19 parts of filler;

[0050] 1.2 parts of high melting point polyethylene wax;

[0051] 0.14 part of antioxidant.

[0052] The filler is calcium carbonate.

[0053] The antioxidant is phenolic antioxidant 1010.

[0054] The preparation method of the flame retardant includes the following steps:

[0055] S1 Mix ethylenediamine and ethanol according to a volume ratio of 0.2:100, and stir evenly to obtain an ethylenediamine-ethanol solution; Subsequently, take 5.94 parts of a 70 wt% phytic acid aqueous solution and 100 parts of the ethylenediamine-ethanol solution by mass, mix them, place them at 60 °C for reaction for 12 h, centrifuge to obtain the precipitate, wash and dry to obtain phytic acid amine;

[0056] S2 Take 3.8 parts of the phytic acid amine prepared in step S1 and 100 parts of water by mass, stir at 40 °C for 1 h to obtain a phytic acid amine suspension; Mix 4.5 parts of Zn(NO3)2·6H2O and 3.7 parts of Al(NO3)3·9H2O, and dissolve them with 50 parts of water to obtain a bimetallic ion solution; Add the above bimetallic ion solution to the phytic acid amine suspension at 60 °C and stir for 5 h, adjust the pH to 10.0 with 20 wt% ammonia water to obtain a reaction solution; Finally, transfer the reaction solution to a hydrothermal reaction kettle, react at 80 °C for 10 h, cool to room temperature, centrifuge to obtain the precipitate, wash and dry to obtain phytic acid amine-LDHs;

[0057] S3 Take 5 parts of the phytic acid amine-LDH obtained in step S2 and add it to 20 parts of carboxyl silicone oil, stir at 80 °C for 1 h, centrifuge to obtain the precipitate, wash and dry to obtain the flame retardant.

[0058] Example 2

[0059] A new energy vehicle wiring harness insulating material with flame retardant properties, by mass, includes the following raw materials:

[0060] 100 parts of polyvinyl chloride resin;

[0061] 6 parts of flame retardant;

[0062] 4 parts of EVA resin;

[0063] 19 parts of filler;

[0064] 1.2 parts of high melting point polyethylene wax;

[0065] 0.14 part of antioxidant.

[0066] The filler is calcium carbonate.

[0067] The antioxidant is phenolic antioxidant 1010.

[0068] The preparation method of the flame retardant includes the following steps:

[0069] S1 Mix ethylenediamine and ethanol according to a volume ratio of 0.2:100, and stir evenly to obtain an ethylenediamine-ethanol solution; Subsequently, take 5.94 parts of a 70wt% phytic acid aqueous solution and 100 parts of the ethylenediamine-ethanol solution by mass, mix them, react at 60°C for 12h, centrifuge to obtain the precipitate, wash and dry it to obtain phytic acid amine;

[0070] S2 Take 3.8 parts of the phytic acid amine prepared in step S1 and 100 parts of water by mass, stir at 40°C for 1h to obtain a phytic acid amine suspension; Mix 4.5 parts of Zn(NO3)2·6H2O and 3.7 parts of Al(NO3)3·9H2O, and dissolve them with 50 parts of water to obtain a bimetallic ion solution; Add the above bimetallic ion solution to the phytic acid amine suspension at 60°C and stir for 5h, adjust the pH to 10.0 with 20wt% ammonia water to obtain a reaction solution; Finally, transfer the reaction solution to a hydrothermal reaction kettle, react at 80°C for 10h, cool to room temperature, centrifuge to obtain the precipitate, wash and dry it to obtain the flame retardant.

[0071] Example 3

[0072] A new energy vehicle wire harness insulation material with flame retardant properties, by mass, includes the following raw materials:

[0073] 100 parts of polyvinyl chloride resin;

[0074] 6 parts of flame retardant;

[0075] 4 parts of EVA resin;

[0076] 19 parts of filler;

[0077] 1.2 parts of high melting point polyethylene wax;

[0078] 0.14 part of antioxidant.

[0079] The filler is calcium carbonate.

[0080] The antioxidant is phenolic antioxidant 1010.

[0081] The preparation method of the flame retardant includes the following steps:

[0082] S1 By mass, mix 4.5 parts of Zn(NO3)2·6H2O and 3.7 parts of Al(NO3)3·9H2O, and dissolve them in 50 parts of water to obtain a bimetallic ion solution. Stir the solution at 60 °C for 5 h, adjust the pH to 10.0 with 20 wt% ammonia water to obtain a reaction solution; transfer the reaction solution to a hydrothermal reaction kettle, react at 80 °C for 10 h, cool to room temperature, centrifuge to collect the precipitate, wash and dry it to obtain Zn-Al-LDH;

[0083] S2 By mass, add 5 parts of the Zn-Al-LDH obtained in step S1 to 20 parts of carboxyl silicone oil, stir at 80 °C for 1 h, centrifuge to collect the precipitate, wash and dry it to obtain the flame retardant.

[0084] Example 4

[0085] A new energy vehicle wire harness insulating material with flame retardant properties, by mass, includes the following raw materials:

[0086] 100 parts of polyvinyl chloride resin;

[0087] 6 parts of flame retardant;

[0088] 4 parts of EVA resin;

[0089] 19 parts of filler;

[0090] 1.2 parts of high melting point polyethylene wax;

[0091] 0.14 part of antioxidant.

[0092] The filler is calcium carbonate.

[0093] The antioxidant is phenolic antioxidant 1010.

[0094] The preparation method of the flame retardant includes the following steps:

[0095] By mass, mix 4.5 parts of Zn(NO3)2·6H2O and 3.7 parts of Al(NO3)3·9H2O, and dissolve them in 50 parts of water to obtain a bimetallic ion solution. Stir the solution at 60 °C for 5 h, adjust the pH to 10.0 with 20 wt% ammonia water to obtain a reaction solution; transfer the reaction solution to a hydrothermal reaction kettle, react at 80 °C for 10 h, cool to room temperature, centrifuge to collect the precipitate, wash and dry it to obtain the flame retardant.

[0096] Example 5

[0097] A new energy vehicle wire harness insulating material with flame retardant properties, by mass, includes the following raw materials:

[0098] 100 parts of polyvinyl chloride resin;

[0099] 6 parts of flame retardant;

[0100] 19 parts of filler;

[0101] 1.2 parts of high melting point polyethylene wax;

[0102] 0.14 part of antioxidant.

[0103] The filler is calcium carbonate.

[0104] The antioxidant is phenolic antioxidant 1010.

[0105] The preparation method of the flame retardant includes the following steps:

[0106] S1 Mix ethylenediamine and ethanol according to a volume ratio of 0.2:100, and stir evenly to obtain an ethylenediamine-ethanol solution; Subsequently, take 5.94 parts of 70wt% phytic acid aqueous solution and 100 parts of ethylenediamine-ethanol solution by mass, mix them, react at 60°C for 12h, centrifuge to obtain the precipitate, wash and dry to obtain phytic acid amine;

[0107] S2 By mass, mix 3.8 parts of the phytic acid amine prepared in step S1 and 100 parts of water, stir at 40°C for 1h to obtain a phytic acid amine suspension; Mix 4.5 parts of Zn(NO3)2·6H2O and 3.7 parts of Al(NO3)3·9H2O, and dissolve them with 50 parts of water to obtain a bimetallic ion solution; Add the above bimetallic ion solution to the phytic acid amine suspension at 60°C, stir for 5h, adjust the pH to 10.0 with 20wt% ammonia water to obtain a reaction solution; Finally, transfer the reaction solution to a hydrothermal reaction kettle, react at 80°C for 10h, cool to room temperature, centrifuge to obtain the precipitate, wash and dry to obtain phytic acid amine-LDH;

[0108] S3 By mass, add 5 parts of the phytic acid amine-LDH obtained in step S2 to 20 parts of carboxyl silicone oil, stir at 80°C for 1h, centrifuge to obtain the precipitate, wash and dry to obtain the flame retardant.

[0109] Comparative Example 1

[0110] A new energy vehicle wiring harness insulating material with flame retardant properties, by mass, includes the following raw materials:

[0111] 100 parts of polyvinyl chloride resin;

[0112] 4 parts of EVA resin;

[0113] 19 parts of filler;

[0114] 1.2 parts of high melting point polyethylene wax;

[0115] 0.14 part of antioxidant.

[0116] The filler is calcium carbonate.

[0117] The antioxidant is phenolic antioxidant 1010.

[0118] Comparative Example 2

[0119] A flame-retardant new energy vehicle wire harness insulating material, by mass, comprises the following raw materials:

[0120] 100 parts of polyvinyl chloride resin;

[0121] 6 parts of flame retardant;

[0122] 4 parts of EVA resin;

[0123] 19 parts of filler;

[0124] 1.2 parts of high melting point polyethylene wax;

[0125] 0.14 part of antioxidant.

[0126] The filler is calcium carbonate.

[0127] The antioxidant is phenolic antioxidant 1010.

[0128] The preparation method of the flame retardant comprises the following steps:

[0129] Mix ethylenediamine and ethanol in a volume ratio of 0.2:100 and stir evenly to obtain an ethylenediamine alcohol solution; subsequently, take 5.94 parts of a 70wt% phytic acid aqueous solution and 100 parts of the ethylenediamine alcohol solution by mass, mix them, react at 60°C for 12 h, centrifuge to obtain the precipitate, wash and dry to obtain the flame retardant.

[0130] Test Example 1:

[0131] Flame retardancy test:

[0132] (1) Limiting oxygen index test (LOI): Determine its limiting oxygen index with reference to the room temperature test part in GB / T 2406.1-2008 Plastics - Determination of burning behaviour by oxygen index - Part 1. The specimen size is: 120 mm × 10 mm × 4 mm.

[0133] (2) Vertical burning rating test, with reference to the ANST / UL94-2018 standard, the specimen size is: 125 mm × 13 mm × 3 mm. During the test, the burning rating of the material is divided into V-0, V-1, V-2 or NR (unclassified) according to the dripping and burning time.

[0134] Table 1: Flame retardancy test results

[0135] LOI / % UL-94 Example 1 54.9 V-0 Example 2 52.7 V-0 Example 3 48.2 V-0 Example 4 47.3 V-0 Example 5 52.1 V-0 Comparative Example 1 42.6 NR Comparative Example 2 46.9 V-1

[0136] Test Example 2

[0137] Elongation at break: Determined with reference to GB / T 1040.2-2022 "Plastics - Determination of tensile properties - Part 2: Test conditions for moulding and extrusion plastics". The test instrument is a universal tensile testing machine. The test conditions are at 25 °C and a tensile rate of 20 mm / min. Each sample is tested more than 5 times.

[0138] Table 2: Results of tensile strength determination

[0139]

[0140]

[0141] As can be seen from Table 1 and Table 2, Example 1 of the present invention has the best flame retardancy and tensile properties. The limiting oxygen index and elongation at break of Example 2 are lower than those of Example 1. This is because the flame retardant used in Example 2 does not use carboxyl silicone oil to treat phytic acid amide-LDHs, and the compatibility between phytic acid amide-LDHs and polyvinyl chloride resin is relatively poor. The carboxyl silicone oil used in the present invention is an organosilicon compound containing carboxyl functional groups, and it has good compatibility with polyvinyl chloride resin. This improves the compatibility between phytic acid amide-LDHs and polyvinyl chloride resin to a certain extent, thereby improving the dispersibility of the flame retardant and weakening the influence of Zn-Al-LDHs on the mechanical properties of polyvinyl chloride resin.

[0142] The flame retardant prepared in Example 3 does not use phytic acid amide as the carrier of Zn-Al-LDHs, and its limiting oxygen index further decreases compared with Example 2. The present invention believes that this is because after loading Zn-Al-LDHs on the surface of phytic acid amide, not only do the flame retardant properties of both play a role simultaneously, but Zn-Al-LDHs also help phytic acid amide form a thicker "carbon layer" to prevent the contact of flame and combustible gas with polyvinyl chloride. This further improves its flame retardant properties. However, the elongation at break is improved compared with Example 2, which further proves that treating phytic acid amide-LDHs with carboxyl silicone oil helps improve the compatibility between the flame retardant and polyvinyl chloride.

[0143] Example 4 only uses Zn-Al-LDHs as the flame retardant, and Comparative Example 2 only uses phytic acid amide as the flame retardant. Their flame retardant properties further decrease compared with Example 3, which also proves that after loading Zn-Al-LDHs on the surface of phytic acid amide, not only do the flame retardant properties of both play a role simultaneously, but their synergy can further improve the flame retardant properties.

[0144] To verify the effect of EVA resin on the performance of the flame-retardant new energy vehicle wire harness insulation material prepared in the present invention, in Example 5, EVA resin was not used as a raw material. Its flame retardancy decreased slightly compared with that of Example 1, and the elongation at break decreased significantly. EVA resin is composed of a copolymer of ethylene and vinyl acetate. EVA resin and its elastomeric derivatives can be compatible with a variety of polymers or mineral powders, and its composite materials have excellent electrical and mechanical properties. The present invention believes that adding EVA resin is beneficial to further improving the dispersibility of the flame retardant prepared in the present invention in polyvinyl chloride.

[0145] In summary, the present invention uses zinc-aluminum layered double hydroxide as the base material of the flame retardant. It has a layered structure like hydrotalcite, and the voids between the cationic layers can accommodate various anions. The layered structure of Zn-Al-LDHs endows it with good physical isolation performance. During the combustion of the material, the layered structure can form an obstacle to prevent the propagation of flames and heat, thereby slowing down the combustion rate. When Zn-Al-LDHs decomposes upon heating, it releases gases such as water and carbon dioxide. These gases can dilute the oxygen concentration in the combustion area and reduce the flame temperature, thereby slowing down the combustion process. In addition, Zn-Al-LDHs absorbs heat during the combustion process and converts it into chemical energy or transfers it to the surrounding environment, reducing the temperature of the combustion area, thereby slowing down the combustion process. Therefore, compared with traditional flame retardants such as magnesium hydroxide, Zn-Al-LDHs has more excellent flame retardancy. However, its defect is that it has poor compatibility with resins and is prone to uneven dispersion, resulting in a decrease in the mechanical properties of the material and a relatively high cost.

[0146] Therefore, in order to further improve its flame retardancy, reduce costs, and at the same time weaken the impact of Zn-Al-LDHs on the mechanical properties of polyvinyl chloride resin. In the present invention, ethylenediamine and phytic acid are first reacted to synthesize phytic acid amide, and then the synthesis reaction of Zn-Al-LDHs is carried out in the phytic acid amide suspension, so that Zn-Al-LDHs are synthesized on the surface of phytic acid amide to obtain phytic acid amide-LDHs. The present invention finds that it has better flame retardancy than Zn-Al-LDHs and phytic acid amide. The present invention believes that since phytic acid amide has both phosphoric acid groups and amino groups, the phosphorus-containing chemical substances (P· and HPO·) formed during the combustion process can capture free radicals and terminate the chain reaction, thereby preventing the combustion reaction in the gas phase. In addition, nitrogen-containing compounds will release non-combustible gases, increase the height of the carbon layer, increase the distance between the fire source and the polyvinyl chloride matrix, and at the same time the nitrogen-containing non-combustible gases can also dilute the concentrations of combustible gases and oxygen, preventing the combustion reaction in the gas phase. Therefore, it also has good flame retardancy. When Zn-Al-LDHs are loaded on the surface of phytic acid amide, not only do the flame retardant properties of both be exerted simultaneously, but Zn-Al-LDHs also help phytic acid amide form a thicker "carbon layer" to prevent the contact of the flame and combustible gases with polyvinyl chloride. This further improves its flame retardancy.

[0147] Furthermore, the present invention finds that the compatibility of Zn-Al-LDHs, phytic acid amide, and phytic acid amide-LDHs with polyvinyl chloride resin is relatively poor. Therefore, in the end, the present invention uses carboxyl silicone oil to treat phytic acid amide-LDHs. Carboxyl silicone oil is an organosilicon compound containing carboxyl functional groups, and it has good compatibility with polyvinyl chloride resin, which to a certain extent improves the compatibility of phytic acid amide-LDHs and polyvinyl chloride resin and is beneficial to weakening the impact of Zn-Al-LDHs on the mechanical properties of polyvinyl chloride resin.

[0148] Furthermore, the present invention finds that adding a small amount of EVA resin is beneficial to further improving the dispersibility of the flame retardant prepared by the present invention in polyvinyl chloride. The Chinese name of EVA resin is ethylene-vinyl acetate copolymer, which is composed of the copolymer of ethylene and vinyl acetate. EVA resin and its elastomeric derivatives can be compatible with a variety of polymers or mineral powders, and its composite materials have excellent electrical properties and mechanical properties.

[0149] Of course, the above are only specific embodiments of the present invention and do not limit the scope of implementation of the present invention. Any equivalent changes or modifications made according to the structure, characteristics, and principles described in the scope of the patent application of the present invention should be included in the scope of the patent application of the present invention.

Claims

1. A new energy vehicle wiring harness insulation material with flame retardant properties, characterized in that, It consists of the following raw materials: 100 parts of polyvinyl chloride resin; 4 - 10 parts of flame retardant; 2 - 5 parts of EVA resin; 18 - 20 parts of filler; 1 - 1.5 parts of high melting point polyethylene wax; 0.1 - 0.16 parts of antioxidant; The preparation method of the flame retardant includes the following steps: S1 Mix ethylenediamine and ethanol according to a volume ratio of (0.1 - 0.5):100, and stir evenly to obtain an ethylenediamine - alcohol solution; Subsequently, by mass, take 5 - 6 parts of a 70wt% phytic acid aqueous solution and 90 - 100 parts of the ethylenediamine - alcohol solution, mix them, place them at 50 - 70 °C for reaction for 8 - 14 h, centrifuge to obtain the precipitate, wash and dry to obtain phytic acid amide; S2 By mass, mix 3 - 4 parts of the phytic acid amide prepared in step S1 and 90 - 100 parts of water, stir at 35 - 45 °C for 1 - 2 h to obtain a phytic acid amide suspension; Mix 4 - 5 parts of Zn(NO3)2·6H2O and 3 - 4 parts of Al(NO3)3·9H2O, and dissolve them with 45 - 55 parts of water to obtain a bimetallic ion solution; At 50 - 70 °C, add the above bimetallic ion solution to the phytic acid amide suspension, stir for 4 - 6 h, adjust the pH to 9.5 - 10.0 with 20wt% ammonia water to obtain a reaction solution; Finally, transfer the reaction solution to a hydrothermal reaction kettle, react at 75 - 85 °C for 8 - 12 h, cool to room temperature, filter, wash and dry to obtain phytic acid amide - LDHs; S3 By mass, add 4 - 6 parts of the phytic acid amide - LDH obtained in step S2 to 10 - 50 parts of carboxyl silicone oil, stir at 70 - 90 °C for 1 - 2 h, centrifuge to obtain the precipitate, wash and dry to obtain the flame retardant.

2. The insulating material for a new energy vehicle wiring harness with flame retardant properties as described in claim 1, characterized in that, The filler is at least one of calcium carbonate, carbon fiber, ceramic microspheres, and silicone powder.

3. The insulating material for a new energy vehicle wiring harness with flame retardant properties as described in claim 1, characterized in that, The antioxidant is at least one of phenolic antioxidants, organophosphorus antioxidants, and aromatic amine antioxidants.

4. A preparation method of an insulating material for a new energy vehicle wire harness having flame retardant properties as described in any one of claims 1-3, characterized in that, It includes the following steps: Mix 100 parts of polyvinyl chloride resin, 4 - 10 parts of flame retardant, 2 - 5 parts of EVA resin, 18 - 20 parts of filler, 1 - 1.5 parts of high melting point polyethylene wax, and 0.1 - 0.16 parts of antioxidant, and granulate in a twin - screw extruder to obtain the insulating material for new energy vehicle wire harnesses with flame - retardant properties.

5. The preparation method of the insulating material for the new energy vehicle wiring harness with flame retardant properties according to claim 4, characterized in that, The feeding zone temperature of the twin - screw extruder is 120 - 130 °C; the middle zone temperature is 170 - 180 °C; the discharging zone temperature is 160 - 170 °C.

6. The application of the insulating material for new energy vehicle wire harnesses with flame - retardant properties as described in any one of claims 1 - 3 in the technical field of new energy vehicle wire harnesses.

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