Thermoplastic polyolefin low-smoke halogen-free flame-retardant automobile wire insulation material and preparation method thereof

Abstract

The application discloses a thermoplastic polyolefin low-smoke halogen-free flame-retardant automobile wire insulating material, and belongs to the technical field of automobile insulating wires. The insulating material is composed of a flame-retardant master batch and polypropylene with a mass ratio of (2-5):(5-9), wherein the flame-retardant master batch comprises the following components in parts by weight: 20-45 parts of a thermoplastic elastomer, 10-15 parts of maleic anhydride-styrene grafted polypropylene, 10-20 parts of silane coupling agent modified ammonium polyphosphate, 0.5-2.5 parts of an antioxidant, and 0.5-2 parts of a lubricant. The automobile wire insulating material does not contain halogen elements, generates low smoke and is non-toxic when burning, can obviously improve the flame-retardant property of the insulating material, and can greatly improve the mechanical property of the insulating material.

Description

Technical Field

[0001] This application relates to the field of automotive insulation technology, specifically to a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material and its preparation method. Background Technology

[0002] The rapid development of new energy vehicles has spurred the growth of numerous related industries. Currently, most insulation materials used in new energy vehicle wiring harnesses are polyolefins, which possess advantages such as low relative density, good chemical resistance, high mechanical strength, resistance to humidity, and good dielectric and high-frequency insulation properties. However, they are prone to decomposition and combustion at high temperatures, exhibiting poor flammability. Therefore, flame retardants are typically added to improve their flame-retardant performance. Chinese patent CN 110283380A discloses a thermoplastic polypropylene automotive low-voltage insulation wire material and its preparation method. This insulation material uses polypropylene as a base material, decabromodiphenyl ethane as a flame retardant, and incorporates polyolefins, ethylene-octene copolymers, ethylene-vinyl acetate copolymers grafted with maleic anhydride, and other components in a closed-mixing process. While this insulation material exhibits high flame-retardant efficiency, the flame retardant is a halogen-containing product, which produces a large amount of toxic fumes during combustion. Aluminum hydroxide or magnesium hydroxide, as common halogen-free flame retardants, can be added to the aforementioned insulating materials to obtain halogen-free flame-retardant automotive wire insulation. However, to achieve optimal flame-retardant efficiency, the amount of aluminum hydroxide or magnesium hydroxide added is usually large, and the addition of a large number of inorganic particles can severely deteriorate the mechanical properties of the automotive wire. Therefore, how to obtain a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation with both excellent flame-retardant and mechanical properties is a problem that urgently needs to be solved. Summary of the Invention

[0003] To address the problems in the prior art, this application provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material. This insulation material is halogen-free, environmentally friendly and non-toxic, and has excellent mechanical and flame-retardant properties.

[0004] In a first aspect, this application provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material, employing the following technical solution:

[0005] A thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material is composed of a flame-retardant masterbatch and polypropylene in a mass ratio of (2-5):(5-9). The flame-retardant masterbatch includes the following components by weight: 20-45 parts thermoplastic elastomer, 10-15 parts maleic anhydride-styrene-grafted polypropylene, 10-20 parts silane coupling agent modified ammonium polyphosphate, 0.5-2.5 parts antioxidant, and 0.5-2 parts lubricant.

[0006] By adopting the above-mentioned scheme, the automotive wire insulation material of this application does not contain halogen elements, produces low smoke and is non-toxic when burned, and by designing the formula composition, the components in the system are evenly dispersed, which can not only significantly improve the flame retardant performance of the insulation material, but also greatly improve the mechanical properties of the insulation material, and reduce the amount of flame retardant added.

[0007] Preferably, the thermoplastic elastomer is composed of TPU and SEBS in a mass ratio of 4:6. TPU not only synergistically strengthens polypropylene with SEBS, but also synergistically interacts with silane coupling agent-modified ammonium polyphosphate during combustion, resulting in better heat insulation, oxygen barrier properties, and charring ability.

[0008] Preferably, the maleic anhydride-styrene-grafted polypropylene is a modified polypropylene obtained by melt grafting maleic anhydride and styrene onto polypropylene. Through the anchoring force between maleic anhydride and polar groups such as silaneoxy groups, and the van der Waals forces between styrene groups, polypropylene groups, and polypropylene and thermoplastic elastomers, maleic anhydride-styrene-grafted polypropylene can play a good bridging role in the entire insulation system, improving the compatibility between components in the system, enhancing the dispersibility of components in the system, thereby improving the toughness and tensile strength of automotive wire insulation.

[0009] More preferably, when using maleic anhydride and styrene to melt-graft polypropylene, styrene, maleic anhydride, polypropylene, and dicumyl peroxide are first mixed in a mass ratio of 100:3:3:0.3, and then melt-reacted through a twin-screw extruder. Specifically, styrene, maleic anhydride, polypropylene, and dicumyl peroxide are mixed in a mass ratio of 100:3:3:0.3, and melt-reacted through a twin-screw extruder at 190°C for 8 minutes. After extrusion, granulation yields the target maleic anhydride-styrene-grafted polypropylene.

[0010] Preferably, the silane coupling agent modified ammonium polyphosphate is KH560 modified ammonium polyphosphate. Ammonium polyphosphate decomposes upon heating, absorbing heat from the surface of the burning material. Simultaneously, this decomposition produces non-flammable gases such as ammonia and acids. The non-flammable gases, mixed with oxygen, reduce the oxygen concentration in the air, blocking the supply of oxygen needed for combustion. The acids, adhering to the surface of the burning material, promote the formation of a char layer during combustion, creating a heat-insulating, oxygen-barrier, and smoke-suppressing barrier. The inventors discovered that, compared to regular ammonium polyphosphate, KH560-modified ammonium polyphosphate decomposes at lower temperatures. Automotive wire insulation materials containing KH560-modified ammonium polyphosphate promote earlier and denser char layer formation during combustion. Furthermore, KH560 itself contains excellent flame-retardant elements such as Si and N, ensuring good flame-retardant performance even with reduced KH560-modified ammonium polyphosphate usage. In addition, the silanoxy groups and long organic chains in KH560 significantly improve the interfacial interaction between ammonium polyphosphate and the polymer system, further enhancing the toughness and tensile strength of the automotive wire insulation material.

[0011] More preferably, the KH560-modified ammonium polyphosphate is processed under anhydrous conditions. Specifically, anhydrous conditions can be achieved by using anhydrous ethanol as the reaction solvent. More specifically, a mixture of KH560 and ethanol is added to a mixture of ammonium polyphosphate and ethanol, with a molar ratio of KH560 to ammonium polyphosphate of 3:1. The mixture is stirred at 60°C for 1 hour, filtered, and dried to obtain the target KH560-modified ammonium polyphosphate.

[0012] Preferably, the antioxidant is any one of antioxidant 1010, antioxidant DLTP, antioxidant 1035, and antioxidant MB.

[0013] Preferably, the lubricant is any one of polyethylene wax, butyl stearate, and silicone masterbatch.

[0014] Secondly, this application provides a method for preparing the above-mentioned thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material, using the following technical solution:

[0015] The preparation method of the above-mentioned thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material includes the following steps:

[0016] S1. Weigh each raw material according to the formula amount, and put the thermoplastic elastomer, maleic anhydride-styrene-grafted polypropylene, antioxidant and lubricant into a mixer and stir evenly.

[0017] S2, after the raw materials in step S1 are stirred evenly, add silane coupling agent modified ammonium polyphosphate and continue stirring evenly;

[0018] S3 is granulated in an internal mixer, and after the mixing is completed, it is granulated by hot cutting and air cooling with a single screw to obtain flame retardant masterbatch;

[0019] S4. After the flame retardant masterbatch from step S3 is mixed evenly with polypropylene resin, it is extruded by a twin-screw extruder, then granulated by water stripping and drying to obtain the target insulating material.

[0020] Polypropylene resin has a high melting point and is prone to crystallization. Hot-cutting and air-cooling granulation can cause particle agglomeration. The inventors discovered that by first preparing a flame-retardant masterbatch from raw materials other than polypropylene, and then mixing the polypropylene with the masterbatch and granulating it using a twin-screw water-cooling process, particle agglomeration is significantly reduced, as is dust in the workshop. By adopting the above solution, this application can improve the particle agglomeration phenomenon that occurs in the existing polypropylene insulation material production process, and prepare a low-smoke, halogen-free flame-retardant automotive wiring insulation material with excellent flame-retardant and mechanical properties.

[0021] Preferably, the mixing temperature in step S3 is 160-170°C, and the mixing time is 15-20 minutes. Detailed Implementation

[0022] The present application will now be described in detail with reference to the embodiments. The scope of protection of this application is not limited to the following embodiments.

[0023] Unless otherwise specified, the raw materials involved in this application (polypropylene, TPU, SEBS, maleic anhydride, styrene, maleic anhydride-grafted polypropylene, KH560, KH550, KH570, ammonium polyphosphate, antioxidant 1010, polyethylene wax, etc.) can be obtained through ordinary commercial means.

[0024] Preparation Example

[0025] Preparation Example 1

[0026] This preparation example provides a KH560 modified ammonium polyphosphate. The preparation steps of KH560 modified ammonium polyphosphate are as follows: a mixture of KH560 and ethanol is added to a mixture of ammonium polyphosphate and ethanol, wherein the molar ratio of KH560 to ammonium polyphosphate is 3:1. The mixture is stirred at 60°C for 1 hour, filtered, and dried to obtain the target KH560 modified ammonium polyphosphate.

[0027] Preparation Example 2

[0028] This preparation example provides a KH550 modified ammonium polyphosphate. The only difference between this preparation example and Preparation Example 1 is that an equal amount of KH550 is used to replace KH560.

[0029] Preparation Example 3

[0030] This preparation example provides a KH570 modified ammonium polyphosphate. The only difference between this preparation example and Preparation Example 1 is that an equal amount of KH570 is used to replace KH560.

[0031] Preparation Example 4

[0032] This preparation example provides a KH560 modified magnesium hydroxide, the only difference between its preparation steps and those of Preparation Example 1 is that an equal amount of magnesium hydroxide is used to replace ammonium polyphosphate.

[0033] Preparation Example 5

[0034] This preparation example provides a method for preparing maleic anhydride-styrene-grafted polypropylene, the steps of which are as follows: styrene, maleic anhydride, polypropylene and dicumyl peroxide are mixed in a mass ratio of 100:3:3:0.3, and the mixture is melted and reacted at 190°C for 8 minutes using a twin-screw extruder. After extrusion, the mixture is granulated to obtain the target maleic anhydride-styrene-grafted polypropylene.

[0035] Example

[0036] Example 1

[0037] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material A, which is composed of a flame-retardant masterbatch and polypropylene in a mass ratio of 3:8. The flame-retardant masterbatch includes the following components by weight: 35 parts thermoplastic elastomer (TPU and SEBS in a mass ratio of 4:6), 13 parts maleic anhydride-styrene-grafted polypropylene, 15 parts KH560 modified ammonium polyphosphate, 1.5 parts antioxidant 1010, and 1 part polyethylene wax.

[0038] In this embodiment, the maleic anhydride-styrene grafted polypropylene is the maleic anhydride-styrene grafted polypropylene provided in Preparation Example 5, and the KH560 modified ammonium polyphosphate is the KH560 modified ammonium polyphosphate provided in Preparation Example 1.

[0039] The preparation method of the above-mentioned insulating material A includes the following steps:

[0040] S1. Weigh each raw material according to the above formula, and put the thermoplastic elastomer, maleic anhydride-styrene-grafted polypropylene, antioxidant and lubricant into a mixer and stir evenly.

[0041] S2, after the raw materials in step S1 are stirred evenly, add silane coupling agent modified ammonium polyphosphate and continue stirring evenly;

[0042] S3 is mixed in an internal mixer at about 165°C for 18 minutes. After the mixing is completed, it is granulated by hot cutting and air cooling with a single screw to obtain flame retardant masterbatch.

[0043] S4. After the flame retardant masterbatch from step S3 is mixed evenly with polypropylene resin, it is extruded by a twin-screw extruder, then granulated by water stripping and drying to obtain the target insulation material A.

[0044] Example 2

[0045] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material B, which differs from Example 1 only in that KH550 modified ammonium polyphosphate is replaced by an equal mass of KH560 modified ammonium polyphosphate. The KH550 modified ammonium polyphosphate used in this embodiment is the same as that provided in Preparation Example 2.

[0046] The preparation method of automotive wire insulation material B in this embodiment is the same as that in embodiment 1.

[0047] Example 3

[0048] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material C, which differs from Example 1 only in that KH570 modified magnesium hydroxide is used to replace KH560 modified ammonium polyphosphate by mass. In this embodiment, the KH570 modified ammonium polyphosphate is the same as the KH550 modified ammonium polyphosphate provided in Preparation Example 3.

[0049] The preparation method of automotive wire insulation material C in this embodiment is the same as that in Embodiment 1.

[0050] Example 4

[0051] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material D, which differs from Embodiment 1 only in that the thermoplastic elastomer is TPU.

[0052] Example 5

[0053] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material E, which differs from Embodiment 1 only in that the thermoplastic elastomer is SEBS.

[0054] Example 6

[0055] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material F, which differs from Embodiment 1 only in that the thermoplastic elastomer is composed of TPU and SEBS in a mass ratio of 1:1.

[0056] Example 7

[0057] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material G, which is composed of a flame-retardant masterbatch and polypropylene in a mass ratio of 3:8. The flame-retardant masterbatch includes the following components by weight: 20 parts thermoplastic elastomer (TPU and SEBS in a mass ratio of 4:6), 10 parts maleic anhydride-styrene-grafted polypropylene, 10 parts KH560 modified ammonium polyphosphate, 0.5 parts antioxidant 1010, and 0.5 parts polyethylene wax.

[0058] In this embodiment, the maleic anhydride-styrene grafted polypropylene is the maleic anhydride-styrene grafted polypropylene provided in Preparation Example 5, and the KH560 modified ammonium polyphosphate is the KH560 modified ammonium polyphosphate provided in Preparation Example 1.

[0059] The preparation method of automotive wire insulation material G in this embodiment is the same as that in Embodiment 1.

[0060] Example 8

[0061] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material H, which is composed of a flame-retardant masterbatch and polypropylene in a mass ratio of 3:8. The flame-retardant masterbatch includes the following components by weight: 45 parts thermoplastic elastomer (TPU and SEBS in a mass ratio of 4:6), 15 parts maleic anhydride-styrene-grafted polypropylene, 20 parts KH560 modified ammonium polyphosphate, 2.5 parts antioxidant 1010, and 2 parts polyethylene wax.

[0062] In this embodiment, the maleic anhydride-styrene grafted polypropylene is the maleic anhydride-styrene grafted polypropylene provided in Preparation Example 5, and the KH560 modified ammonium polyphosphate is the KH560 modified ammonium polyphosphate provided in Preparation Example 1.

[0063] The preparation method of automotive wire insulation material H in this embodiment is the same as that in embodiment 1.

[0064] Example 9

[0065] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material I, which is composed of a flame-retardant masterbatch and polypropylene in a mass ratio of 2:5. The flame-retardant masterbatch includes the following components by weight: 35 parts thermoplastic elastomer (TPU and SEBS in a mass ratio of 4:6), 13 parts maleic anhydride-styrene-grafted polypropylene, 15 parts KH560 modified ammonium polyphosphate, 1.5 parts antioxidant 1010, and 1 part polyethylene wax.

[0066] In this embodiment, the maleic anhydride-styrene grafted polypropylene is the maleic anhydride-styrene grafted polypropylene provided in Preparation Example 5, and the KH560 modified ammonium polyphosphate is the KH560 modified ammonium polyphosphate provided in Preparation Example 1.

[0067] The preparation method of automotive wire insulation material I in this embodiment is the same as that in embodiment 1.

[0068] Example 10

[0069] This embodiment provides a thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material J, which is composed of a flame-retardant masterbatch and polypropylene in a mass ratio of 5:9. The flame-retardant masterbatch includes the following components by weight: 35 parts thermoplastic elastomer (TPU and SEBS in a mass ratio of 4:6), 13 parts maleic anhydride-styrene-grafted polypropylene, 15 parts KH560 modified ammonium polyphosphate, 1.5 parts antioxidant 1010, and 1 part polyethylene wax.

[0070] In this embodiment, the maleic anhydride-styrene grafted polypropylene is the maleic anhydride-styrene grafted polypropylene provided in Preparation Example 5, and the KH560 modified ammonium polyphosphate is the KH560 modified ammonium polyphosphate provided in Preparation Example 1.

[0071] The preparation method of automotive wire insulation material J in this embodiment is the same as that in embodiment 1.

[0072] Comparative Example 1

[0073] This comparative example provides an automotive wire insulation material K, which differs from Example 1 only in that maleic anhydride-styrene-grafted polypropylene is replaced by maleic anhydride-grafted polypropylene of equal mass.

[0074] The preparation method of the automotive wire insulation material in this comparative example is the same as that in Example 1.

[0075] Comparative Example 2

[0076] This comparative example provides an automotive wire insulation material L, which differs from Example 1 only in that it uses an equal mass of ammonium polyphosphate to replace KH560 modified ammonium polyphosphate.

[0077] The preparation method of the automotive wire insulation material in this comparative example is the same as that in Example 1.

[0078] Comparative Example 3

[0079] This comparative example provides an automotive wire insulation material M, which differs from Example 1 only in that KH560 modified ammonium polyphosphate is replaced by KH560 modified magnesium hydroxide by mass.

[0080] The preparation method of the automotive wire insulation material in this comparative example is the same as that in Example 1.

[0081] Test case

[0082] The automotive wire insulation materials prepared in Examples 1-6 and Comparative Examples 1-3 were tested for tensile strength and elongation at break according to standard GB / T 1040, oxygen index according to standard GB / T 2406, and volume resistivity at 20°C according to standard GB / T 1410. The results are shown in Table 1.

[0083] Table 1

[0084]

[0085] As can be seen from Table 1, the oxygen index, tensile strength, elongation at break and volume resistivity at 20℃ of insulation material A are significantly higher than those of insulation materials K, L and M. This indicates that, in the insulation material system of this application, the insulation material using KH560 modified ammonium polyphosphate and maleic anhydride-styrene grafted polypropylene has the best mechanical properties and flame retardant properties. This may be because, on the one hand, compared to maleic anhydride-grafted polypropylene, the presence of styrene in maleic anhydride-styrene-grafted polypropylene not only increases the grafting rate of maleic anhydride onto polypropylene and increases the anchoring points with KH560 modified ammonium polyphosphate, but also increases the van der Waals forces with polypropylene and thermoplastic elastomers while increasing steric hindrance. This allows maleic anhydride-styrene-grafted polypropylene to play a better bridging role in the insulation system, fully improving the compatibility of the components in the system and enhancing the overall performance of the insulation material. On the other hand, when ammonium polyphosphate is used as a flame retardant for insulation materials, the char layer formed on the surface of the burning material is very loose and has many pores, while the automotive wire insulation material using KH560 modified ammonium polyphosphate can form a relatively dense char layer on its surface when burning.

[0086] As shown in Table 1, the elongation at break and oxygen index of insulation materials B and C are lower than those of insulation material A. This indicates that, in the insulation material system of this application, the insulation material using KH560 modified ammonium polyphosphate as a flame retardant has the best mechanical and flame retardant properties. Table 1 also shows that the oxygen index of insulation material D is slightly higher than that of insulation material A, while its elongation at break is significantly lower. The elongation at break of insulation material E is slightly higher than that of insulation material A, while its oxygen index is significantly lower. This may be because the presence of TPU in the system promotes the formation of a dense char layer on the surface of the combustible material, but the contribution of TPU to the toughening of polypropylene is far less than that of SEBS. Furthermore, the inventors discovered during their research that if TPU and SEBS are simply mixed and used in insulation materials, TPU and SEBS are not well compatible in the insulation material system. This will affect the dispersibility of each component in the insulation material system, thereby affecting the mechanical properties and flame retardant properties of the insulation material. The inventors of this application avoided the above problems through a large number of research experiments and compatibility verifications in the formulation design. This can also be seen from the comparison of oxygen index, tensile strength, elongation at break and volume resistivity at 20°C of insulation material A and insulation material F.

[0087] It is understood that the above detailed description of this application is for illustrative purposes only and is not intended to limit the technical solutions described in the embodiments of this application. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to this application to achieve the same technical effect; as long as the usage requirements are met, they are all within the protection scope of this application.

Claims

1. A thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material, characterized in that, It is composed of a flame retardant masterbatch and polypropylene in a mass ratio of (2~5):(5~9), wherein the flame retardant masterbatch includes the following components by weight: 20~45 parts thermoplastic elastomer, 10~15 parts maleic anhydride-styrene grafted polypropylene, 10~20 parts silane coupling agent modified ammonium polyphosphate, 0.5~2.5 parts antioxidant, and 0.5~2 parts lubricant; The thermoplastic elastomer is composed of TPU and SEBS in a mass ratio of 4:

6.

2. The thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material as described in claim 1, characterized in that, The maleic anhydride-styrene grafted polypropylene is a modified polypropylene produced by melt grafting maleic anhydride and styrene onto polypropylene.

3. The thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material as described in claim 2, characterized in that, When using maleic anhydride and styrene to melt-graft polypropylene, styrene, maleic anhydride, polypropylene and dicumyl peroxide are first mixed in a mass ratio of 100:3:3:0.3 and then melt-reacted through a twin-screw extruder.

4. The thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material as described in claim 1, characterized in that, The silane coupling agent modified ammonium polyphosphate is KH560 modified ammonium polyphosphate.

5. The thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material as described in claim 4, characterized in that, KH560 modified ammonium polyphosphate was processed under anhydrous conditions.

6. The thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material as described in claim 1, characterized in that, The antioxidant is any one of antioxidant 1010, antioxidant DLTP, antioxidant 1035, and antioxidant MB.

7. The thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material as described in claim 1, characterized in that, The lubricant is any one of polyethylene wax, butyl stearate, or silicone masterbatch.

8. A method for preparing the thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material according to any one of claims 1 to 7, comprising the following steps: S1. Weigh each raw material according to the formula amount, and put the thermoplastic elastomer, maleic anhydride-styrene-grafted polypropylene, antioxidant and lubricant into a mixer and stir evenly. S2, after the raw materials in step S1 are stirred evenly, add silane coupling agent modified ammonium polyphosphate and continue stirring evenly; S3 is granulated in an internal mixer, and after the mixing is completed, it is granulated by hot cutting and air cooling with a single screw to obtain flame retardant masterbatch; S4. After the flame retardant masterbatch from step S3 is mixed evenly with polypropylene resin, it is extruded by a twin-screw extruder, then granulated by water stripping and drying to obtain the target insulating material.

9. The preparation method of the thermoplastic polyolefin low-smoke halogen-free flame-retardant automotive wire insulation material as described in claim 8, characterized in that, In step S3, the mixing temperature is 160~170℃ and the mixing time is 15~20 minutes.

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