Halogen-free flame-retardant insulating material as well as preparation method and application thereof

Abstract

The invention relates to a halogen-free flame-retardant insulating material as well as a preparation method and application thereof. The halogen-free flame-retardant insulating material is prepared from the following raw materials in parts by weight: 5 to 10 parts of polyethylene resin, 15 to 30 parts of elastomer, 35 to 45 parts of halogen-free flame-retardant filler, 25 to 35 parts of white carbon black, 0.3 to 0.8 part of cross-linking agent, 1 to 2 parts of anti-aging agent, 2 to 3 parts of lubricating agent and 0.3 to 1 part of anti-ultraviolet agent. The halogen-free flame-retardant insulating material provided by the invention can reach the flame-retardant grade of FT-4 grade, is good in flame-retardant effect and excellent in mechanical property, and can meet the performance requirement of UL44 standard.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of insulating materials, in particular to a halogen-free flame-retardant insulating material and a preparation method and application thereof. BACKGROUND

[0002] Polyolefin materials are widely used in the field of wire and cable due to their excellent electrical properties, low temperature resistance, comprehensive mechanical properties, etc. With the increasing demand for flame retardance of wire and cable, the application of halogen-free flame-retardant polyolefin materials is gradually becoming mainstream.

[0003] However, the traditional polyolefin cable material has low burning grade, large smoke emission and many harmful gases, etc. In order to ensure that the wire and cable can be safely and effectively used for a long time, it is necessary to improve the flame retardance and mechanical properties.

[0004] Therefore, it is necessary to develop a halogen-free flame-retardant insulating material with high flame retardance and good mechanical properties. SUMMARY

[0005] To solve the above technical problems, the present application provides a halogen-free flame-retardant insulating material and a preparation method and application thereof. The halogen-free flame-retardant insulating material can reach FT-4 grade of flame retardance, has good flame retardance effect and excellent mechanical properties, and can meet the performance requirements of UL44 standard.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a halogen-free flame retardant insulating material, which comprises the following components in parts by weight: 5 to 10 parts of polyethylene resin (for example, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts or 9.5 parts, etc.), 15 to 30 parts of elastomer (for example, 17 parts, 19 parts, 21 parts, 23 parts, 25 parts, 27 parts or 29 parts, etc.), 35 to 45 parts of halogen-free flame retardant filler (for example, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 43 parts or 44 parts, etc.), 25 to 35 parts of white carbon black (for example, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, etc.), 3 parts or 34 parts, etc.), 0.3-0.8 parts of a cross-linking agent (for example, 0.35 parts, 0.4 parts, 0.45 parts, 0.5 parts, 0.55 parts, 0.6 parts, 0.65 parts, 0.7 parts or 0.75 parts, etc.), 1-2 parts of an antioxidant (for example, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts or 1.9 parts, etc.), 2-3 parts of a lubricant (for example, 2.1 parts, 2.2 parts, 2.3 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts, 2.8 parts or 2.9 parts, etc.), and 0.3-1 part of an anti-ultraviolet agent (for example, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts or 0.9 parts, etc.).

[0008] In the present invention, the halogen-free flame retardant insulation material prepared by compounding polyethylene resin, elastomer, halogen-free flame retardant filler, white carbon black, cross-linking agent, antioxidant, lubricant and anti-ultraviolet agent can achieve FT-4 grade flame retardancy, has good flame retardancy effect and excellent mechanical properties, and can meet the performance requirements of UL44 standard.

[0009] Preferably, the polyethylene resin comprises low density polyethylene.

[0010] Preferably, the melt index of the low-density polyethylene is 3 to 8 g / 10 min, for example, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min, 5.5 g / 10 min, 6 g / 10 min, 6.5 g / 10 min, 7 g / 10 min or 7.5 g / 10 min.

[0011] Preferably, the elastomer comprises polyolefin elastomer (POE) and / or thermoplastic polyurethane elastomer (TPU).

[0012] Preferably, the mass ratio of the polyolefin elastomer to the thermoplastic polyurethane elastomer is (1-1.5):1, for example, 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1 or 1.45:1.

[0013] Preferably, the halogen-free flame retardant filler comprises aluminum hydroxide.

[0014] Preferably, the aluminum hydroxide includes a first aluminum hydroxide and a second aluminum hydroxide.

[0015] Preferably, the D50 particle size of the first aluminum hydroxide is 3-5 μm, for example, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm, 4.0 μm, 4.2 μm, 4.4 μm, 4.6 μm or 4.8 μm.

[0016] Preferably, the D50 particle size of the second aluminum hydroxide is 10-15 μm, for example, 10.5 μm, 11 μm, 11.5 μm, 12 μm, 12.5 μm, 13 μm, 13.5 μm, 14 μm or 14.5 μm.

[0017] Preferably, the mass ratio of the first aluminum hydroxide to the second aluminum hydroxide is (1.5-2.5):1, for example, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1 or 2.4:1, etc.

[0018] In the present invention, the halogen-free flame retardant filler is preferably a first aluminum hydroxide with a D50 particle size of 3 to 5 μm and a second aluminum hydroxide with a D50 particle size of 10 to 15 μm, which are added in a mass ratio of (1.5 to 2.5):1, and the flame retardant properties and mechanical properties of the prepared halogen-free flame retardant insulation material are better.

[0019] Preferably, the crosslinking agent comprises triallyl isocyanurate and / or trimethylolpropane trimethacrylate.

[0020] Preferably, the crosslinking agent includes triallyl isocyanurate and trimethylolpropane trimethacrylate.

[0021] Preferably, the mass ratio of triallyl isocyanurate to trimethylolpropane trimethacrylate is 1:(2.5-3.5), for example, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3.0, 1:3.1, 1:3.2, 1:3.3 or 1:3.4.

[0022] Preferably, the antioxidant includes any one or a combination of at least two of 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N-phenyl-α-aniline, N-phenyl-β-naphthylamine or N-phenyl-N'-isopropyl-p-phenylenediamine.

[0023] Preferably, the lubricant includes any one of stearic acid, zinc stearate, calcium stearate or polyethylene wax, or a combination of at least two thereof.

[0024] Preferably, the anti-ultraviolet agent includes any one of 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole or 2-(2-hydroxy-5-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, or a combination of at least two thereof.

[0025] Preferably, the halogen-free flame-retardant insulating material further comprises 0.5 to 2 parts by weight of a coupling agent, for example, 0.7 parts by weight, 0.9 parts by weight, 1.1 parts by weight, 1.3 parts by weight, 1.5 parts by weight, 1.7 parts by weight or 1.9 parts by weight.

[0026] Preferably, the coupling agent is a silane coupling agent.

[0027] Preferably, the silane coupling agent includes any one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane or γ-(methacryloyloxy)propyltrimethoxysilane, or a combination of at least two thereof, and more preferably γ-(methacryloyloxy)propyltrimethoxysilane.

[0028] In the present invention, when the coupling agent is preferably a combination of bis(dioctyloxypyrophosphate)ethylene titanate and γ-(methacryloyloxy)propyltrimethoxysilane, the mechanical properties and flame retardant properties of the prepared halogen-free flame retardant insulating material are better.

[0029] In a second aspect, the present invention provides a method for preparing a halogen-free flame-retardant insulating material as described in the first aspect, the preparation method comprising the following steps: mixing a polyethylene resin, an elastomer, a halogen-free flame-retardant filler, white carbon black, a cross-linking agent, an antioxidant, a lubricant, an anti-ultraviolet agent and optionally a coupling agent, and extruding to obtain the halogen-free flame-retardant insulating material.

[0030] Preferably, the preparation method comprises the following steps:

[0031] (1) A halogen-free flame retardant filler, white carbon black and a coupling agent are mixed to obtain a modified filler.

[0032] (2) The modified filler, polyethylene resin, elastomer, cross-linking agent, antioxidant, lubricant and anti-ultraviolet agent prepared in step (1) are mixed and extruded to obtain the halogen-free flame retardant insulating material.

[0033] Preferably, the extrusion temperature is 100-130°C, such as 105°C, 110°C, 115°C, 120°C or 125°C.

[0034] In a third aspect, the present invention provides a halogen-free flame-retardant insulating layer, which is prepared by cross-linking the halogen-free flame-retardant insulating material described in the first aspect through electron accelerator irradiation.

[0035] In a fourth aspect, the present invention provides a cable, comprising the halogen-free flame-retardant insulation layer as described in the third aspect.

[0036] Illustratively, the cable is prepared by the following method: melt-extrude the halogen-free flame-retardant insulating material as described in the first aspect onto the conductive core of the cable, coat the conductive core of the cable with the halogen-free flame-retardant insulating material, and perform electron accelerator irradiation cross-linking to obtain the cable.

[0037] Compared with the prior art, the present invention has at least the following beneficial effects:

[0038] In the present invention, the halogen-free flame retardant insulating material prepared by compounding polyethylene resin, elastomer, halogen-free flame retardant filler, white carbon black, crosslinking agent, antioxidant, lubricant and anti-ultraviolet agent can achieve FT-4 flame retardant grade, good flame retardant effect and excellent mechanical properties, and can meet the performance requirements of UL44 standard. The tensile strength of the halogen-free flame retardant insulating material is ≥9.3MPa, the elongation at break is ≥223%, the tensile strength of the halogen-free flame retardant insulating material after radiation crosslinking is ≥10.6MPa, the elongation at break is ≥158%, and the cable prepared by the halogen-free flame retardant insulating material has a char height of ≤1.3m in a flame test (FT4). Preferably, the tensile strength of the halogen-free flame retardant insulating material is ≥10.5MPa, the elongation at break is ≥245%, the tensile strength of the halogen-free flame retardant insulating material after radiation crosslinking is ≥12.3MPa, the elongation at break is ≥170%, and the cable prepared by the halogen-free flame retardant insulating material has a char height of ≤1.15m in a flame test (FT4). DETAILED DESCRIPTION

[0039] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0040] Some of the raw materials used in the following examples and comparative examples are as follows:

[0041] Low-density polyethylene: melt index is 4.5g / 10min;

[0042] Polyolefin elastomer: manufacturer is Dow, model number is 8842;

[0043] Thermoplastic polyurethane elastomer: manufacturer is Covestro of Germany, model number is 345X;

[0044] Silica: The manufacturer is Cabot, the model is M-5.

[0045] Example 1

[0046] The present embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof, wherein the halogen-free flame-retardant insulating material comprises the following components in parts by weight: 8 parts of polyethylene resin (low-density polyethylene, melt index of 4.5 g / 10 min), 15 parts of polyolefin elastomer (8842), 12 parts of thermoplastic polyurethane elastomer (345X), 30 parts of a first aluminum hydroxide (D50 particle size of 4 μm), 12 parts of a second aluminum hydroxide (D50 particle size of 12 μm), 30 parts of white carbon black (M-5), 0.4 parts of a crosslinking agent (triallyl isocyanurate and trimethylolpropane trimethacrylate in a mass ratio of 1:3), 1.5 parts of an antioxidant (6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline), 2.5 parts of a lubricant (stearic acid), 0.5 parts of an anti-ultraviolet agent (2-hydroxy-4-n-octyloxybenzophenone), and 1.5 parts of a silane coupling agent (γ-(methacryloyloxy)propyltrimethoxysilane).

[0047] The preparation method comprises the following steps:

[0048] (1) mixing a silane coupling agent and ethanol to form a coupling agent solution, then mixing the coupling agent solution with a first aluminum hydroxide, a second aluminum hydroxide, and white carbon black, and drying to obtain a modified filler;

[0049] (2) The modified filler, polyethylene resin, polyolefin elastomer, thermoplastic polyurethane elastomer, crosslinking agent, antioxidant, lubricant and anti-ultraviolet agent prepared in step (1) are mixed, and extruded into granules using a twin-screw extruder at an extrusion temperature of 120° C. to obtain the halogen-free flame retardant insulating material.

[0050] Example 2

[0051] This embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof. The difference between the embodiment 1 and the embodiment 1 is that the halogen-free flame-retardant insulating material comprises the following components in parts by weight: 6 parts of polyethylene resin (low-density polyethylene, melt index of 4.5g / 10min), 18 parts of polyolefin elastomer (8842), 12 parts of thermoplastic polyurethane elastomer (345X), 22 parts of first aluminum hydroxide (D50 particle size of 3μm), and 22 parts of second aluminum hydroxide. (D50 particle size is 15μm) 13 parts, white carbon black (M-5) 35 parts, crosslinking agent (triallyl isocyanurate and trimethylolpropane trimethacrylate with a mass ratio of 1:2.7) 0.55 parts, antioxidant (N-phenyl-α-aniline) 2 parts, lubricant (zinc stearate) 2 parts, anti-ultraviolet agent (2-hydroxy-4-methoxybenzophenone) 0.3 parts, silane coupling agent (γ-(methacryloyloxy)propyltrimethoxysilane) 1 part.

[0052] Other conditions are the same as in Example 1.

[0053] Example 3

[0054] The embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof, which are different from those in the embodiment 1 in that the halogen-free flame-retardant insulating material comprises the following components in parts by weight: polyethylene resin (low-density polyethylene, melt index 4.5 g / 10 min) 10 parts, polyolefin elastomer (8842) 10 parts, thermoplastic polyurethane elastomer (345X) 10 parts, first aluminum hydroxide (D50 particle size 5 mu m) 30 parts, second aluminum hydroxide (D50 particle size 10 mu m) 15 parts, white carbon black (M-5) 25 parts, crosslinking agent (mass ratio 1:3.3 of triallyl isocyanurate and trimethylolpropane trimethacrylate) 0.52 parts, antioxidant (N-phenyl-N'-isopropyl-p-phenylenediamine) 1 part, lubricant (calcium stearate) 3 parts, ultraviolet resistance agent (2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole) 1 part, and silane coupling agent (gamma-(methacryloyloxy)propyltrimethoxysilane) 2 parts.

[0055] The other conditions are the same as those in the embodiment 1.

[0056] Embodiment 4

[0057] The embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof, which are different from those in the embodiment 1 in that the weight parts of the polyolefin elastomer (8842) are adjusted to 7 parts, and the weight parts of the thermoplastic polyurethane elastomer (345X) are adjusted to 20 parts, and the other conditions are the same as those in the embodiment 1.

[0058] Embodiment 5

[0059] The embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof, which are different from those in the embodiment 1 in that the silane coupling agent (gamma-(methacryloyloxy)propyltrimethoxysilane) is replaced by the same mass of silane coupling agent (gamma-aminopropyltriethoxysilane), and the other conditions are the same as those in the embodiment 1.

[0060] Embodiment 6

[0061] The embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof, which are different from those in the embodiment 1 in that the halogen-free flame-retardant insulating material does not comprise a silane coupling agent.

[0062] The preparation method comprises the following steps: mixing the polyethylene resin, the polyolefin elastomer, the thermoplastic polyurethane elastomer, the first aluminum hydroxide, the second aluminum hydroxide, the white carbon black, the crosslinking agent, the antioxidant, the lubricant and the ultraviolet resistance agent, and extruding and granulating by using a double-screw extruder, so that the temperature of extrusion is 120 DEG C, to obtain the halogen-free flame-retardant insulating material.

[0063] The other conditions are the same as those in the embodiment 1.

[0064] Example 7

[0065] This embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof. The difference between the present embodiment and Example 1 is that the first aluminum hydroxide (D50 particle size is 4 μm) is not added, the weight portion of the second aluminum hydroxide (D50 particle size is 12 μm) is adjusted to 42 parts, and other conditions are the same as those in Example 1.

[0066] Example 8

[0067] This embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof. The difference between the present embodiment and Example 1 is that the second aluminum hydroxide (D50 particle size is 12 μm) is not added, the weight portion of the first aluminum hydroxide (D50 particle size is 4 μm) is adjusted to 42 parts, and other conditions are the same as those in Example 1.

[0068] Example 9

[0069] This embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof. The difference between this embodiment and Example 1 is that the weight fraction of the first aluminum hydroxide (D50 particle size is 4 μm) is adjusted to 31.5 parts, and the weight fraction of the second aluminum hydroxide (D50 particle size is 12 μm) is adjusted to 10.5 parts. Other conditions are the same as those in Example 1.

[0070] Example 10

[0071] This embodiment provides a halogen-free flame-retardant insulating material and a preparation method thereof. The difference between this embodiment and Example 1 is that the weight fraction of the first aluminum hydroxide (D50 particle size is 4 μm) is adjusted to 21 parts, and the weight fraction of the second aluminum hydroxide (D50 particle size is 12 μm) is adjusted to 21 parts. Other conditions are the same as those in Example 1.

[0072] Comparative Example 1

[0073] This comparative example provides a halogen-free flame-retardant insulating material and a preparation method thereof. The difference between it and Example 1 is that the weight fraction of the first aluminum hydroxide (D50 particle size is 4 μm) is adjusted to 20 parts, and the weight fraction of the second aluminum hydroxide (D50 particle size is 12 μm) is adjusted to 8 parts. Other conditions are the same as those in Example 1.

[0074] Comparative Example 2

[0075] This comparative example provides a halogen-free flame-retardant insulating material and a preparation method thereof. The difference between it and Example 1 is that the weight fraction of the first aluminum hydroxide (D50 particle size is 4 μm) is adjusted to 35.7 parts, and the weight fraction of the second aluminum hydroxide (D50 particle size is 12 μm) is adjusted to 14.3 parts. Other conditions are the same as those in Example 1.

[0076] Performance Testing

[0077] (1) Properties before irradiation: Test specimens of the halogen-free flame-retardant insulating materials provided in Examples 1 to 13 and Comparative Examples 1 to 2 were prepared and tested for hardness, tensile strength, and elongation at break;

[0078] Hardness: Tested using a rubber hardness tester (Shore A);

[0079] Tensile strength and elongation at break: tested using a YH-8812WEI material tensile testing machine.

[0080] (2) Post-irradiation properties: Test specimens of the halogen-free flame-retardant insulating materials provided in Examples 1 to 13 and Comparative Examples 1 to 2 were prepared and subjected to electron accelerator irradiation cross-linking at a dose of 200 kGy. Tensile strength and elongation at break were then tested.

[0081] Tensile strength and elongation at break: tested using a YH-8812WEI material tensile testing machine.

[0082] (3) Flame retardant properties: The halogen-free flame-retardant insulating materials provided in Examples 1 to 13 and Comparative Examples 1 to 2 were melt-extruded onto the conductive cores, respectively, to coat the conductive cores with the halogen-free flame-retardant insulating materials, and then subjected to electron accelerator irradiation cross-linking at a dose of 200 kGy to produce a cable having a cross-sectional area of ​​4 mm2 in the conductive cores. 2 , the outer diameter of the cable is 6.1mm, and then the cable is subjected to a vertical burning test (FT4) in accordance with the UL1581-2019 standard to observe the burning height of the cable.

[0083] The test results are shown in Table 1.

[0084] Table 1

[0085]

[0086] It can be seen from the test results in Table 1 that the tensile strength of the halogen-free flame retardant insulating materials provided in Examples 1 to 10 is ≥9.31 MPa, and the elongation at break is ≥223%. The tensile strength of the halogen-free flame retardant insulating materials after irradiation cross-linking is ≥10.63 MPa, and the elongation at break is ≥158%. The prepared cables are subjected to a combustion test (FT4), and the charred height of the cables is ≤1.3 m.

[0087] Compared with Example 1, if the silane coupling agent is not added (Example 6), the mechanical properties and flame retardant properties of the prepared halogen-free flame retardant insulation material are both reduced.

[0088] Compared with Example 1, if the first aluminum hydroxide is not added (Example 7) or the second aluminum hydroxide is not added (Example 8), the mechanical properties and flame retardant properties of the prepared halogen-free flame retardant insulating material are reduced.

[0089] Compared with Example 1, if the mass ratio of the first aluminum hydroxide to the second aluminum hydroxide is too high (Example 9) or too low (Example 10), the mechanical properties and flame retardant properties of the prepared halogen-free flame retardant insulating material are reduced.

[0090] Compared with Example 1, if the weight fraction of the halogen-free flame retardant filler is too low (Comparative Example 1), the mechanical properties and flame retardant properties of the prepared halogen-free flame retardant insulation material are reduced, and the charred height of the cable is greater than 1.5 m.

[0091] Compared with Example 1, if the weight fraction of the halogen-free flame retardant filler is too high (Comparative Example 2), the mechanical properties and flame retardant properties of the prepared halogen-free flame retardant insulating material are reduced, and the tensile strength of the halogen-free flame retardant insulating material after irradiation is less than 10.5 MPa.

[0092] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A halogen-free flame-retardant insulating material, characterized in that: The halogen-free flame-retardant insulating material includes the following components in parts by weight: 5 to 10 parts of polyethylene resin, 15 to 30 parts of elastomer, 35 to 45 parts of halogen-free flame-retardant filler, 25 to 35 parts of white carbon black, 0.3 to 0.8 parts of cross-linking agent, 1 to 2 parts of antioxidant, 2 to 3 parts of lubricant and 0.3 to 1 part of anti-ultraviolet agent.

2. The halogen-free flame-retardant insulating material according to claim 1, characterized in that: The polyethylene resin includes low-density polyethylene; Preferably, the melt index of the low-density polyethylene is 3 to 8 g / 10 min; Preferably, the elastomer comprises a polyolefin elastomer and / or a thermoplastic polyurethane elastomer; Preferably, the mass ratio of the polyolefin elastomer to the thermoplastic polyurethane elastomer is (1-1.5):

1.

3. The halogen-free flame-retardant insulating material according to claim 1 or 2, characterized in that: The halogen-free flame retardant filler includes aluminum hydroxide; Preferably, the aluminum hydroxide includes a first aluminum hydroxide and a second aluminum hydroxide; Preferably, the D50 particle size of the first aluminum hydroxide is 3 to 5 μm; Preferably, the D50 particle size of the second aluminum hydroxide is 10 to 15 μm; Preferably, the mass ratio of the first aluminum hydroxide to the second aluminum hydroxide is (1.5-2.5):

1.

4. The halogen-free flame-retardant insulating material according to any one of claims 1 to 3, characterized in that: The crosslinking agent includes triallyl isocyanurate and / or trimethylolpropane trimethacrylate.

5. The halogen-free flame-retardant insulating material according to any one of claims 1 to 4, characterized in that: The antioxidant includes any one or a combination of at least two of 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N-phenyl-α-aniline, N-phenyl-β-naphthylamine or N-phenyl-N'-isopropyl-p-phenylenediamine; Preferably, the lubricant comprises any one or a combination of at least two of stearic acid, zinc stearate, calcium stearate or polyethylene wax; Preferably, the anti-ultraviolet agent includes any one of 2-hydroxy-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole or 2-(2-hydroxy-5-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, or a combination of at least two thereof.

6. The halogen-free flame-retardant insulating material according to any one of claims 1 to 5, characterized in that: The halogen-free flame-retardant insulating material further comprises 0.5 to 2 parts by weight of a coupling agent; Preferably, the coupling agent comprises a silane coupling agent; Preferably, the silane coupling agent includes any one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane or γ-(methacryloyloxy)propyltrimethoxysilane, or a combination of at least two thereof.

7. A method for preparing a halogen-free flame-retardant insulating material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: mixing polyethylene resin, elastomer, halogen-free flame retardant filler, white carbon black, cross-linking agent, antioxidant, lubricant, anti-ultraviolet agent and optionally coupling agent, and extruding to obtain the halogen-free flame retardant insulating material.

8. The preparation method according to claim 7, characterized in that The preparation method comprises the following steps: (1) mixing a halogen-free flame retardant filler, white carbon black, and a coupling agent to obtain a modified filler; (2) The modified filler, polyethylene resin, elastomer, cross-linking agent, antioxidant, lubricant and anti-ultraviolet agent prepared in step (1) are mixed and extruded to obtain the halogen-free flame retardant insulating material.

9. A halogen-free flame-retardant insulating layer, characterized in that: The halogen-free flame-retardant insulating layer is prepared by cross-linking the halogen-free flame-retardant insulating material according to any one of claims 1 to 6 through electron accelerator irradiation.

10. A cable, characterized in that: The cable comprises the halogen-free flame-retardant insulation layer according to claim 9.

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