Self-crosslinking flame-retardant insulating material and preparation method thereof

Abstract

The invention relates to a self-crosslinking flame-retardant insulating material and a preparation method thereof, and belongs to the technical field of insulating material preparation. The self-crosslinking flame-retardant insulating material comprises the following raw materials: polyethylene, modified vinyl silane, an epoxy flame retardant, a water producing agent, a catalyst and an initiator, the modified vinyl silane is prepared from a ring-opening reaction product and a diamine compound through a condensation reaction; the ring-opening reaction product is prepared from an epoxy silane coupling agent and a 2, 2-dimethylolpropionic acid derivative through a reaction; the 2, 2-dimethylolpropionic acid derivative is prepared from 2, 2-dimethylolpropionic acid and acrylic acid through esterification reaction; the epoxy flame retardant is prepared from a hydroxyl-terminated dendritic compound and an epoxidation agent through an epoxidation reaction; the hydroxyl-terminated dendritic compound is prepared from hexachlorocyclotriphosphazene and alkyl binary primary alcohol through a substitution reaction. By introducing the modified vinyl silane and the epoxy flame retardant, a bi-crosslinking interpenetrating network is formed in the obtained material, so that the problems in the background technology are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of insulating material preparation, and in particular relates to a self-crosslinking flame-retardant insulating material and a preparation method thereof. Background Art

[0002] Insulating materials are often used in the field of cable sheath materials. Due to their excellent insulation properties, they can achieve the purpose of cable protection and cable application safety. Common insulating materials are usually made of polymer materials, fillers and additives through melt mixing and molding processes. Among them, common polymer sub-materials include traditional natural rubber, polyvinyl chloride, polyolefins, etc. The aforementioned various polymer materials have their own advantages and disadvantages. Therefore, the development trend of existing insulating materials is to mix different types of polymer materials to form a blended material, so as to give full play to the strengths of each material, overcome the shortcomings of each material, and obtain a sheath material with excellent comprehensive performance. Among them, the self-crosslinking insulating material is an insulating material in which a cross-linked interpenetrating network is formed in the mixed system after the multi-component polymer materials are mixed. This self-crosslinking insulating material greatly improves the insulation and mechanical properties of the obtained material because an interpenetrating network system is formed in the material system. The most commonly used self-crosslinking insulating material is silane crosslinked polyethylene material, which is made of polyethylene and olefin silane by melt mixing and molding. Silane cross-linked polyethylene material overcomes the low temperature resistance of polyethylene and exerts its excellent elastic properties due to the introduction of silane (high temperature resistant polymer material) and the formation of a cross-linked interpenetrating network (material structure enhancement) in the molding material.

[0003] In order to obtain highly flame-retardant silane cross-linked polyethylene materials, it is necessary to introduce flame-retardant fillers into the mixed system of polyethylene and olefin silane. Regardless of whether the introduced flame-retardant fillers are inorganic flame-retardant fillers or organic flame-retardant fillers, the fillers do not participate in cross-linking, and their own spatial effects and steric effects will lead to a decrease in the cross-linking degree in the obtained material, thereby reducing the mechanical properties of the obtained self-cross-linking material. Summary of the invention

[0004] The purpose of the present invention is to provide a self-crosslinking flame-retardant insulating material and a preparation method thereof, so as to solve the problem that the mechanical properties of the crosslinked material are reduced due to the introduction of flame-retardant fillers, so as to obtain a self-crosslinking insulating material with excellent mechanical properties and flame-retardant properties.

[0005] One object of the present invention can be achieved by the following technical solutions:

[0006] The self-crosslinking flame-retardant insulating material comprises the following raw materials in parts by weight: 100 parts of polyethylene, 5-12 parts of modified vinyl silane, 20-35 parts of epoxy flame retardant, 0.05-0.4 parts of water generating agent, 0.1-1 parts of catalyst, and 0.1-0.5 parts of initiator;

[0007] The modified vinyl silane is prepared by a condensation reaction between a ring-opening reaction product and a diamine compound; the ring-opening reaction product is prepared by a reaction between an epoxy silane coupling agent and a 2,2-dimethylol propionic acid derivative; the 2,2-dimethylol propionic acid derivative is prepared by an esterification reaction between 2,2-dimethylol propionic acid and acrylic acid;

[0008] The epoxy flame retardant is prepared by epoxidation reaction of a terminal hydroxyl dendrimer and an epoxidant; and the terminal hydroxyl dendrimer is prepared by substitution reaction of hexachlorocyclotripolyphosphazene and alkyl diol.

[0009] Furthermore, the condensation reaction conditions are: reacting in the presence of a first organic solvent and a condensing agent, the reaction temperature is 70-95° C., and the reaction time is 4-8 hours.

[0010] Furthermore, the reaction conditions of the ring-opening reaction are: reacting in a second organic solvent, the reaction pH is 9-10, the reaction temperature is 50-70° C., and the reaction time is 2-4 h.

[0011] Furthermore, the reaction conditions of the esterification reaction are: reacting in the presence of a third organic solvent and an esterification reaction catalyst, the reaction temperature is 70-95° C., and the reaction time is 3-8 hours.

[0012] Furthermore, the molar ratio of the epoxy silane coupling agent, the 2,2-dimethylol propionic acid derivative, and the diamine compound is 1:1-1.3:1-1.3; the molar ratio of the 2,2-dimethylol propionic acid and acrylic acid is 1:1-1.2.

[0013] Furthermore, the first organic solvent is one of tetrahydrofuran, benzene, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, and dichloromethane.

[0014] Furthermore, the diamine compound is one of 1,4-butanediamine and 1,6-hexanediamine.

[0015] Furthermore, the condensing agent is a mixture of dicyclohexylcarbodiimide (DCC) and 4-N,N-dimethylpyridine (DMAP).

[0016] Furthermore, the second organic solvent is one of tetrahydrofuran, benzene, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, and dichloromethane.

[0017] Preferably, when the first organic solvent and the second organic solvent are the same, when the ring-opening reaction is finished, the condensation reaction is directly carried out without going through the step of removing impurities from the ring-opening reaction product.

[0018] Furthermore, the third organic solvent is one of tetrahydrofuran, benzene, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, and dichloromethane.

[0019] Furthermore, the esterification reaction catalyst is one of concentrated sulfuric acid and p-toluenesulfonic acid with a mass fraction of 98%.

[0020] In the preparation process of modified vinyl silane, double bonds and carboxyl groups are introduced into the silane coupling agent through the ring-opening grafting of epoxy silane coupling agent and 2,2-dihydroxymethyl propionic acid derivative (ring-opening reaction of epoxy group and hydroxyl group), and then amino groups are introduced into the silane coupling agent through the condensation reaction of carboxyl group and amino group in diamine compound, so as to obtain modified vinyl silane containing both double bonds and amino groups.

[0021] The 2,2-dimethylolpropionic acid derivative is obtained by esterification of a hydroxyl group in 2,2-dimethylolpropionic acid and a carboxyl group in acrylic acid, thereby making the obtained 2,2-dimethylolpropionic acid derivative contain a double bond.

[0022] Furthermore, the molecular structural formula of the 2,2-dihydroxymethylpropionic acid derivative is shown below.

[0023]

[0024] Furthermore, the conditions of the epoxidation reaction are: in the fourth organic solvent, the reaction pH is 10.5-11, the reaction temperature is 50-70° C., and the reaction time is 6-10 h.

[0025] Furthermore, the fourth solvent is one of ethanol, tetrahydrofuran, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, benzene and toluene.

[0026] Furthermore, the substitution reaction conditions are: reacting in a fifth organic solvent, an acid absorber and under nitrogen protection, the reaction temperature is 0-10° C., and the reaction time is 1-6 h.

[0027] Further, the fifth organic solvent is one of acetone, dichloromethane, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, benzene and toluene;

[0028] Furthermore, the acid absorber is one of potassium carbonate and sodium carbonate.

[0029] Furthermore, the molar ratio of the hexachlorocyclotripolyphosphazene to the alkyl diol is 1:6-10.

[0030] Furthermore, the number of carbon atoms of the alkyl group in the alkyl diol is greater than or equal to 4, such as 1,4-butanediol, 1,6-hexanediol, 1,7-heptanediol, and the like.

[0031] Preferably, the alkyl diol is 1,12-dodecanediol.

[0032] Furthermore, the molecular structure formula of the hexachlorocyclotripolyphosphazene is shown below.

[0033]

[0034] Furthermore, the molar ratio of the alkyl diol to the epoxidizing agent is 1:2-3.

[0035] Furthermore, the epoxidizing agent is epichlorohydrin.

[0036] In the present invention, the hexachlorocyclotripolyphosphazene is used as the rigid flame retardant core of the terminal hydroxyl dendrimer, and then the terminal hydroxyl dendrimer is obtained through etherification reaction of chlorinated groups and alcoholic hydroxyl groups, wherein the alcoholic hydroxyl compounds are screened, alkyl dihydric primary alcohol is used as the source of alcoholic hydroxyl groups, and flexible alkyl links are introduced outside the rigid flame retardant core, so that the obtained terminal hydroxyl dendrimer has a rigid flame retardant core and a flexible outer chain, and finally the terminal hydroxyl groups of the flexible outer chain are epoxidized to form an epoxy flame retardant.

[0037] Furthermore, the self-crosslinking flame-retardant insulating material further comprises 1-10 parts by weight of an auxiliary agent, wherein the auxiliary agent is one or a mixture of several of the antioxidants and lubricants well known in the art.

[0038] Furthermore, the water producing agent is zinc acetate.

[0039] Furthermore, the catalyst is an organotin catalyst.

[0040] Furthermore, the initiator is a peroxide.

[0041] The second object of the present invention is to provide a method for preparing a self-crosslinking flame retardant insulating material, comprising:

[0042] The polyethylene, modified vinyl silane and initiator are mixed, melt-blended and granulated by a twin-screw extruder to obtain a first material, wherein the extrusion temperature is 170-190° C.;

[0043] The first material, epoxy flame retardant, water generating agent and catalyst are mixed, melt-blended, extruded and molded by a twin-screw extruder to obtain a cross-linked flame retardant insulating material, wherein the extrusion temperature is 180-200°C.

[0044] Beneficial effects of the present invention:

[0045] In the present invention, amino groups, double bonds and tree-shaped epoxy flame retardants in modified vinyl silane are used to form a double cross-linked interpenetrating network in the obtained self-crosslinking flame-retardant insulating material, wherein one cross-linked interpenetrating network is a double bond cross-linked interpenetrating network formed by double bonds and polyethylene in modified vinyl silane through one-step grafting and two-step catalytic cross-linking, and the other cross-linked interpenetrating network is an interpenetrating cross-linked network formed by ring-opening cross-linking between amino groups (derived from modified vinyl silane) in the previous cross-linked network and the terminal epoxy groups of the flexible long chains in the tree-shaped epoxy flame retardant. When the flame retardant is introduced, the cross-linking degree of the obtained material is not reduced, but is improved on the basis of the original self-cross-linking network to form a self-cross-linking network with a rigid flame-retardant core and a flexible long chain. Not only is the mechanical properties of the material further improved, and the technical problems mentioned in the background technology are solved, but the combination of the rigid flame-retardant core and the flexible long chain can coordinately exert an excellent toughening effect, so that the obtained material has good toughness. DETAILED DESCRIPTION

[0046] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] Preparation of modified vinyl silane:

[0049] A1. After 0.1 mol 2,2-dimethylolpropionic acid, 0.1 mol acrylic acid and 100 mL toluene are uniformly mixed, 0.5 g p-toluenesulfonic acid is added under stirring, and the mixture is heated to 70° C. and stirred for 8 h. The mixture is then concentrated by rotary evaporation, water is added, and the mixture is extracted with ethyl acetate, washed, and dried to obtain a 2,2-dimethylolpropionic acid derivative;

[0050] A2, 0.1 mol epoxy silane coupling agent (KH560), 0.1 mol 2,2-dimethylol propionic acid derivative obtained in step A1 and 120 mL DMF were mixed evenly, heated to 50 ° C, and the pH of the reaction solution was adjusted to 9-10, and the mixture was stirred and reacted for 4 hours. The mixture was heated to 70 ° C, and 50 mL of 0.16 mol DCC and 0.03 mol DMAP were added under stirring, and the mixture was activated by stirring for 1.5 hours. Subsequently, 40 mL of DMF containing 0.1 mol 1,4-butanediamine was added, and the mixture was stirred and reacted for 6 hours. Subsequently, the reaction solution was concentrated, and water was added and then extracted with ethyl acetate, and then washed and dried to obtain modified vinyl silane.

[0051] Example 2

[0052] Preparation of modified vinyl silane:

[0053] A1. After 0.1 mol 2,2-dimethylolpropionic acid, 0.12 mol acrylic acid and 100 mL toluene are uniformly mixed, 0.5 g p-toluenesulfonic acid is added under stirring, and the mixture is heated to 95° C. and stirred for 3 h. The solvent is then removed by rotary evaporation, and the mixture is washed and dried to obtain a 2,2-dimethylolpropionic acid derivative.

[0054] A2, 0.1 mol epoxy silane coupling agent (KH560), 0.13 mol 2,2-dihydroxymethylpropionic acid derivative obtained in step A1 and 120 mL DMF were mixed evenly, heated to 70 ° C, and the pH of the reaction solution was adjusted to 9-10 with sodium hydroxide, and the reaction was stirred for 2 hours. The temperature was raised to 95 ° C, and 50 mL of 0.16 mol DCC and 0.03 mol DMAP were added under stirring, and the mixture was activated by stirring for 1 hour. Subsequently, 40 mL of DMF containing 0.1-0.15 mol 1,4-butanediamine was added, and the reaction was stirred for 3 hours. Subsequently, the reaction solution was concentrated, and water was added and extracted with ethyl acetate, and then washed and dried to obtain modified vinyl silane.

[0055] Example 3

[0056] Preparation of epoxy flame retardant:

[0057] B1. After uniformly mixing 0.1 mol hexachlorocyclotrimer phosphazene, 0.7 mol 1,12-dodecanediol, excess potassium carbonate powder (0.5 mol) and 200 mL acetone, the mixture was stirred and reacted for 6 h under nitrogen protection at 0-10°C, and then filtered and the filtrate was collected. Water was added to the filtrate, and the formed precipitate was filtered and the filter cake was washed and dried to obtain a terminal hydroxyl dendrimer compound.

[0058] B2. Evenly mix the terminal hydroxyl dendrimer obtained in step B1, 1.4 mol epichlorohydrin and 300 mL tetrahydrofuran, adjust the pH of the reaction solution to 10.5-11 with sodium hydroxide, heat to 50° C., react for 10 h, remove the solvent by rotary evaporation, wash, and dry to obtain an epoxy flame retardant.

[0059] Example 4

[0060] Preparation of epoxy flame retardant:

[0061] B1. After uniformly mixing 0.1 mol hexachlorocyclotripolyphosphazene, 1 mol 1,12-dodecanediol, excess potassium carbonate powder (0.5 mol) and 200 mL acetone, the mixture was stirred and reacted for 1 h at 10° C. under nitrogen protection, and the mixture was filtered and the filtrate was collected. Water was added to the filtrate, and the formed precipitate was filtered and the filter cake was washed and dried to obtain a terminal hydroxyl dendrimer compound.

[0062] B2. Evenly mix the terminal hydroxyl dendrimer obtained in step B1, 3 mol epichlorohydrin and 300 mL tetrahydrofuran, adjust the pH of the reaction solution to 10.5-11 with sodium hydroxide, heat to 70° C., react for 5 h, remove the solvent by rotary evaporation, wash, and dry to obtain an epoxy flame retardant.

[0063] Example 5

[0064] Preparation of self-crosslinking flame retardant insulating materials:

[0065] The first step includes the following raw materials in parts by weight: 100 parts of low-density polyethylene, 5 parts of modified vinyl silane prepared in Example 1, 20 parts of epoxy flame retardant prepared in Example 2, 0.05 parts of water generating agent (zinc acetate), 0.1 parts of catalyst (dibutyltin dilaurate), and 0.1 parts of initiator (tert-butyl benzoyl peroxide);

[0066] The second step is to mix the low-density polyethylene, modified vinyl silane and initiator, melt-blend them through a twin-screw extruder, and granulate them to obtain the first material, wherein the extrusion temperature is 170-190°C; the first material, epoxy flame retardant, water-generating agent and catalyst are mixed, melt-blended, extruded and molded (radiated) through a twin-screw extruder to obtain a cross-linked flame-retardant insulating material, wherein the extrusion temperature is 180-200°C.

[0067] Example 6

[0068] Preparation of self-crosslinking flame retardant insulating materials:

[0069] The first step includes the following raw materials in parts by weight: 100 parts of low-density polyethylene, 7 parts of modified vinyl silane prepared in Example 1, 28 parts of epoxy flame retardant prepared in Example 2, 0.1 parts of water generating agent (zinc acetate), 0.5 parts of catalyst (dibutyltin dilaurate), and 0.3 parts of initiator (tert-butyl benzoyl peroxide);

[0070] The second step is to mix the low-density polyethylene, modified vinyl silane and initiator, melt-blend them through a twin-screw extruder, and granulate them to obtain the first material, wherein the extrusion temperature is 170-190°C; the first material, epoxy flame retardant, water-generating agent and catalyst are mixed, melt-blended, extruded and molded (radiated) through a twin-screw extruder to obtain a cross-linked flame-retardant insulating material, wherein the extrusion temperature is 180-200°C.

[0071] Example 7

[0072] Preparation of self-crosslinking flame retardant insulating materials:

[0073] The first step includes the following raw materials in parts by weight: 100 parts of low-density polyethylene, 12 parts of modified vinyl silane prepared in Example 1, 35 parts of epoxy flame retardant prepared in Example 2, 0.4 parts of water generating agent (zinc acetate), 1 part of catalyst (dibutyltin dilaurate), and 0.5 parts of initiator (tert-butyl benzoyl peroxide);

[0074] The second step is to mix the low-density polyethylene, modified vinyl silane and initiator, melt-blend them through a twin-screw extruder, and granulate them to obtain the first material, wherein the extrusion temperature is 170-190°C; the first material, epoxy flame retardant, water-generating agent and catalyst are mixed, melt-blended, extruded and molded (radiated) through a twin-screw extruder to obtain a cross-linked flame-retardant insulating material, wherein the extrusion temperature is 180-200°C.

[0075] Example 8

[0076] Preparation of self-crosslinking flame retardant insulating materials:

[0077] The first step includes the following raw materials in parts by weight: 100 parts of low-density polyethylene, 5 parts of modified vinyl silane prepared in Example 1, 20 parts of epoxy flame retardant prepared in Example 2, 0.05 parts of water generating agent (zinc acetate), 0.1 parts of catalyst (dibutyltin dilaurate), 0.1 parts of initiator (tert-butyl benzoyl peroxide), 0.5 parts of lubricant (polyethylene wax), and 10101.2 parts of antioxidant;

[0078] The second step is to mix the low-density polyethylene, modified vinyl silane and initiator, melt-blended and granulated through a twin-screw extruder to obtain the first material, wherein the extrusion temperature is 170-190°C; the first material, epoxy flame retardant, water producing agent, lubricant, antioxidant 1010 and catalyst are mixed, melt-blended, extruded and molded (radiated) through a twin-screw extruder to obtain a cross-linked flame-retardant insulating material, wherein the extrusion temperature is 180-200°C.

[0079] Comparative Example 1

[0080] Preparation of self-crosslinking insulating materials:

[0081] Compared with Example 5, an equal amount of the epoxy flame retardant in the raw material is replaced by an organic phosphorus flame retardant DMMP, and the rest is the same.

[0082] Comparative Example 2

[0083] Preparation of self-crosslinking insulating materials:

[0084] Compared with Example 5, an equal amount of modified vinyl silane in the raw material was replaced with vinyl trimethoxyethoxy silane, and the rest was the same.

[0085] Comparative Example 3

[0086] Preparation of self-crosslinking insulating materials:

[0087] Compared with Example 5, an equal amount of modified vinyl silane in the raw material is replaced with vinyl trimethoxyethoxy silane, and the epoxy flame retardant is deleted, and the rest is the same.

[0088] The physical properties of the insulating materials obtained in Examples 5-8 and Comparative Examples 1-3 were tested, and the test results are shown in Table 1.

[0089] Table 1

[0090] Tensile Strength Tensile elongation at break Notched impact strength Flame retardant grade GB / T 1040.2 GB / T 1040.2 GB / T 1043.1 UL-94 unit Mpa ％ <![CDATA[KJ / m 2 ]]> \ Example 5 26.6 259 10.0 V-0 Example 6 27.1 276 10.5 V-0 Example 7 28.2 285 11.1 V-0 Example 8 26.9 263 10.3 V-0 Comparative Example 1 19.2 202 4.2 V-0 Comparative Example 2 23.7 232 7.4 V-0 Comparative Example 3 23.3 238 6.7 V-2

[0091] It can be seen from the data in Table 1 that the insulating materials obtained in Examples 5 to 8 of the present invention have good flame retardancy, tensile strength and notched impact strength.

[0092] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0093] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A self-crosslinking flame retardant insulating material, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of polyethylene, 5-12 parts of modified vinyl silane, 20-35 parts of epoxy flame retardant, 0.05-0.4 parts of water generating agent, 0.1-1 parts of catalyst, and 0.1-0.5 parts of initiator; The modified vinyl silane is prepared by a condensation reaction between a ring-opening reaction product and a diamine compound; the ring-opening reaction product is prepared by a reaction between an epoxy silane coupling agent and a 2,2-dimethylol propionic acid derivative; the 2,2-dimethylol propionic acid derivative is prepared by an esterification reaction between 2,2-dimethylol propionic acid and acrylic acid; The epoxy flame retardant is prepared by epoxidation reaction of a terminal hydroxyl dendrimer and an epoxidant; and the terminal hydroxyl dendrimer is prepared by substitution reaction of hexachlorocyclotripolyphosphazene and alkyl diol.

2. A self-crosslinking flame retardant insulating material according to claim 1, characterized in that: The condensation reaction conditions are: reacting in the presence of a first organic solvent and a condensing agent, the reaction temperature is 70-95° C., and the reaction time is 4-8 hours.

3. The self-crosslinking flame-retardant insulating material according to claim 1, characterized in that: The reaction conditions of the ring-opening reaction are: reacting in a second organic solvent, the reaction pH is 9-10, the reaction temperature is 50-70° C., and the reaction time is 2-4 hours.

4. The self-crosslinking flame-retardant insulating material according to claim 1, characterized in that: The reaction conditions of the esterification reaction are: reacting in the presence of a third organic solvent and an esterification reaction catalyst, the reaction temperature is 70-95° C., and the reaction time is 3-8 hours.

5. The self-crosslinking flame-retardant insulating material according to claim 1, characterized in that: The molar ratio of the epoxy silane coupling agent, the 2,2-dimethylol propionic acid derivative and the diamine compound is 1:1-1.3:1-1.3; the molar ratio of the 2,2-dimethylol propionic acid and acrylic acid is 1:1-1.

2.

6. The self-crosslinking flame-retardant insulating material according to claim 1, characterized in that: The diamine compound is one of 1,4-butanediamine and 1,6-hexanediamine.

7. The self-crosslinking flame-retardant insulating material according to claim 1, characterized in that: The conditions of the epoxidation reaction are as follows: in the fourth organic solvent, the reaction pH is 10.5-11, the reaction temperature is 50-70° C., and the reaction time is 6-10 h.

8. The self-crosslinking flame-retardant insulating material according to claim 1, characterized in that: The substitution reaction conditions are: reacting in a fifth organic solvent, an acid absorber and under nitrogen protection, the reaction temperature is 0-10° C., and the reaction time is 1-6 hours.

9. The self-crosslinking flame-retardant insulating material according to claim 1, characterized in that: The molar ratio of the hexachlorocyclotripolyphosphazene to the alkyl diol is 1:6-10; the number of carbon atoms of the alkyl group in the alkyl diol is greater than or equal to 4; the molar ratio of the alkyl diol to the epoxidant is 1:2-3, and the epoxidant is epichlorohydrin.

10. The method for preparing a self-crosslinking flame-retardant insulating material according to claim 1, characterized in that: include: The polyethylene, modified vinyl silane and initiator are mixed, melt-blended and granulated in a twin-screw extruder to obtain a first material; The first material, epoxy flame retardant, water generating agent and catalyst are mixed, melt-blended, extruded and formed by a twin-screw extruder to obtain a cross-linked flame retardant insulating material.

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