Crosslinked polyethylene insulating material as well as preparation method and application thereof

Abstract

The invention relates to a cross-linked polyethylene insulation material and a preparation method and application thereof, and the cross-linked polyethylene insulation material comprises the following raw materials: low density polyethylene, an antioxidant, a cross-linking agent, a first scorch retarder and a second scorch retarder, the first anti-scorching agent comprises one or more of an olefin anti-scorching agent, an allyl substituted phenol anti-scorching agent and a thiocarbonate anti-scorching agent, the second anti-scorching agent comprises a free radical terminator, low-density polyethylene, an antioxidant and a cross-linking agent, and the first anti-scorching agent and the second anti-scorching agent are matched for use. The scorching phenomenon of the cross-linked polyethylene insulation material in the processing process and the using process can be reduced, the scorching resistance of the cross-linked polyethylene insulation material is improved, and the service life of the cable is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of insulating materials, and in particular to a cross-linked polyethylene insulating material and a preparation method and application thereof. Background Art

[0002] Cables, as the "blood vessels" of modern society, bear the heavy responsibility of information transmission and energy supply. However, the rapid development of science and technology has put forward higher and higher requirements on the performance of cable insulation materials. Among many insulating materials, polyethylene has become the first choice of insulating materials due to its excellent electrical properties, stable mechanical properties and excellent processing properties. Traditional cross-linked polyethylene insulation materials often need to be cross-linked with peroxide to improve mechanical properties, but premature cross-linking under high temperature environment will lead to scorching. Scorching will cause gel-like particles in the insulation material during processing, which will not only affect the processing performance of the insulation material, but also cause a sharp drop in the insulation performance of the cable, seriously shortening the service life of the cable. Therefore, how to improve the scorch performance of polyethylene insulation materials has become one of the important issues that need to be solved in the cable field. Summary of the invention

[0003] The present application provides a cross-linked polyethylene insulation material and a preparation method and application thereof, aiming to reduce the scorching phenomenon of the cross-linked polyethylene insulation material during processing and use, improve the scorching resistance of the cross-linked polyethylene insulation material, and extend the service life of the cable.

[0004] In the first aspect of the present application, a cross-linked polyethylene insulation material is provided, comprising low-density polyethylene, an antioxidant, a cross-linking agent, a first anti-scorch agent and a second anti-scorch agent, wherein the first anti-scorch agent comprises one or more of an olefin anti-scorch agent, an allyl-substituted phenol anti-scorch agent and a thiocarbonate anti-scorch agent, and the second anti-scorch agent comprises a free radical terminator.

[0005] In some embodiments, the cross-linked polyethylene insulation material includes 100 parts of the low-density polyethylene, 0.2 to 0.5 parts of the antioxidant, 0.8 to 1.6 parts of the cross-linking agent, 0.1 to 0.5 parts of the first anti-scorch agent, and 0.05 to 0.2 parts of the second anti-scorch agent.

[0006] In some embodiments, the first anti-scorch agent includes an allyl-substituted phenol anti-scorch agent, and the mass ratio of the first anti-scorch agent to the second anti-scorch agent is 5:1 to 2:1.

[0007] In some embodiments, the free radical terminator includes one or more of 1,1-diphenyl-2-trinitrophenylhydrazine, N,N-diethylhydroxylamine, and 2,3,5-triphenyltetrazolyl.

[0008] In some embodiments, the olefin-based scorch retarder includes one or more of trans-6-phenyl-2-hexene and 2,4-diphenyl-4-methyl-1-pentene.

[0009] In some embodiments, the allyl-substituted phenolic scorch retarder includes one or more of 4-allylphenol, o-allylphenol, and 2-allyl-6-methylphenol.

[0010] In some embodiments, the thiocarbonate scorch retarder includes one or more of S-dodecyl-S'-(α,α"-methyl-α"-acetic acid) trithiocarbonate and dodecyl-S"-isopropionic acid trithiocarbonate.

[0011] In some embodiments, the antioxidant comprises a hindered phenolic antioxidant.

[0012] In some embodiments, the cross-linking agent includes a peroxide-based cross-linking agent.

[0013] In some embodiments, the hindered phenol antioxidant includes one or more of 2,6-di-tert-butyl-4-methylphenol, 4,6-bis(octylthiomethyl)-o-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide), 2,2'-thioethylene glycol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,5-di-tert-butyl-4-hydroxyphenylpropionate and 4,4'-thiobis(6-tert-butyl-3-methylphenol).

[0014] In some embodiments, the peroxide-based crosslinking agent includes one or more of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dicumyl peroxide, and di-tert-butyl peroxide.

[0015] In some embodiments, the density of the low-density polyethylene is 0.9 mol / cm 3 ~0.98mol / cm 3 .

[0016] In some embodiments, the melt index of the low-density polyethylene is 1.6 g / 10 min to 2.5 g / 10 min.

[0017] A second aspect of the present application provides a method for preparing a cross-linked polyethylene insulating material, comprising the following steps:

[0018] Mixing low-density polyethylene, an antioxidant, a first anti-scorch agent and a second anti-scorch agent to obtain a mixed material; the first anti-scorch agent includes one or more of an olefin anti-scorch agent, an allyl-substituted phenol anti-scorch agent and a thiocarbonate anti-scorch agent, and the second anti-scorch agent includes a free radical terminator;

[0019] The mixed material is subjected to melt extrusion treatment and granulation treatment in sequence to obtain an intermediate material;

[0020] The intermediate material is mixed with a cross-linking agent and subjected to a post-absorption treatment to prepare the cross-linked polyethylene insulating material.

[0021] In some embodiments, the temperature for mixing the low-density polyethylene, the antioxidant, the first scorch retarder and the second scorch retarder is 30° C. to 50° C.

[0022] In some embodiments, the process conditions of the melt extrusion treatment include: the melt extrusion temperature is 120°C to 180°C.

[0023] In some embodiments, the process conditions of the post-absorption treatment include: a post-absorption temperature of 60° C. to 80° C., and a post-absorption time of 12 h to 20 h.

[0024] The third aspect of the present application provides the use of at least one of the cross-linked polyethylene insulation material described in the first aspect of the present application and the cross-linked polyethylene insulation material prepared by the preparation method described in the second aspect of the present application in cables or wires.

[0025] The fourth aspect of the present application includes at least one of the cross-linked polyethylene insulation material described in the first aspect of the present application and the cross-linked polyethylene insulation material prepared by the preparation method described in the second aspect of the present application.

[0026] In some embodiments, the cable is a submarine cable.

[0027] In some embodiments, the cable has a withstand voltage of 500 kV or less.

[0028] Compared with traditional technologies, the above cross-linked polyethylene insulation material has at least the following advantages:

[0029] Among the raw materials of the above-mentioned cross-linked polyethylene insulation material, low-density polyethylene is used as the base material of the cross-linked polyethylene insulation material, the antioxidant can effectively improve the antioxidant performance and thermal stability of the cross-linked polyethylene insulation material, the cross-linking agent can improve the mechanical properties and heat resistance of the cross-linked polyethylene insulation material, the first anti-scorch agent has the effect of slowing down the cross-linking speed, and the second anti-scorch agent can consume excess active free radicals. The first anti-scorch agent slows down the cross-linking rate by prolonging the transfer process of free radicals, and the second anti-scorch agent can further reduce the reaction concentration of active free radicals, thereby reducing the scorching phenomenon of the cross-linked polyethylene insulation material during the processing and use process, improving the scorch resistance of the cross-linked polyethylene insulation material, and extending the service life of the cable. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0031] In this application, "first aspect", "second aspect", "third aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0032] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0033] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0034] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0035] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application. The terms used in this application and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more related listed items. The term "multiple" in this application means at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0036] One embodiment of the present application provides a cross-linked polyethylene insulation material, including low-density polyethylene, an antioxidant, a cross-linking agent, a first anti-scorch agent and a second anti-scorch agent, the first anti-scorch agent includes one or more of an olefin anti-scorch agent, an allyl-substituted phenol anti-scorch agent and a thiocarbonate anti-scorch agent, and the second anti-scorch agent includes a free radical terminator.

[0037] In the above embodiment, low-density polyethylene is used as the base material of the cross-linked polyethylene insulation material, the antioxidant can effectively improve the antioxidant performance and thermal stability of the cross-linked polyethylene insulation material, the cross-linking agent can improve the mechanical properties and heat resistance of the cross-linked polyethylene insulation material, the first anti-scorch agent has the effect of slowing down the cross-linking speed, and the second anti-scorch agent can consume excess active free radicals. The first anti-scorch agent slows down the cross-linking rate by prolonging the transfer process of free radicals, and the second anti-scorch agent can further reduce the reaction concentration of active free radicals, thereby reducing the scorch phenomenon of the cross-linked polyethylene insulation material during the processing and use process, improving the scorch resistance of the cross-linked polyethylene insulation material, and extending the service life of the cable.

[0038] In some embodiments, the cross-linked polyethylene insulation material includes 100 parts of low-density polyethylene, 0.2 to 0.5 parts of antioxidant, 0.8 to 1.6 parts of cross-linking agent, 0.1 to 0.5 parts of first anti-scorch agent, and 0.05 to 0.2 parts of second anti-scorch agent. By adjusting the raw materials of the cross-linked polyethylene insulation material to the above composition, the scorch phenomenon of the cross-linked polyethylene insulation material can be reduced, thereby further improving the scorch resistance of the cross-linked polyethylene insulation material. Specifically, the number of antioxidants includes but is not limited to: 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts or a range between any two of the foregoing, the number of cross-linking agents includes but is not limited to: 0.8 parts, 0.9 parts, 1 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts or a range between any two of the foregoing, the first anti-scorching agent includes but is not limited to: 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts or a range between any two of the foregoing, and the number of second anti-scorching agents includes but is not limited to: 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts or a range between any two of the foregoing.

[0039] In some embodiments, the first anti-scorch agent includes an allyl-substituted phenol anti-scorch agent, and the mass ratio of the first anti-scorch agent to the second anti-scorch agent is 5: 1 to 2: 1. The above-mentioned first anti-scorch agent and the second anti-scorch agent are used together to further improve the scorch resistance of the cross-linked polyethylene insulation material, and at the same time, the amount of the second anti-scorch agent can be reduced, thereby reducing the cost of the cross-linked polyethylene insulation material.

[0040] In some embodiments, the free radical terminator includes one or more of 1,1-diphenyl-2-trinitrophenylhydrazine, N,N-diethylhydroxylamine and 2,3,5-triphenyltetrazolyl. The free radical terminators of the above types can make the cross-linked polyethylene insulation material have excellent scorch resistance.

[0041] In some embodiments, the olefin-based scorch retarder includes one or more of trans-6-phenyl-2-hexene and 2,4-diphenyl-4-methyl-1-pentene.

[0042] In some embodiments, the allyl-substituted phenolic scorch retarder includes one or more of 4-allylphenol, o-allylphenol, and 2-allyl-6-methylphenol.

[0043] In some embodiments, the thiocarbonate scorch retarder includes one or more of S-dodecyl-S'-(α,α"-methyl-α"-acetic acid) trithiocarbonate and dodecyl-S"-isopropionic acid trithiocarbonate.

[0044] In some embodiments, the antioxidant comprises a hindered phenolic antioxidant.

[0045] In some embodiments, the cross-linking agent comprises a peroxide-based cross-linking agent.

[0046] In some embodiments, the hindered phenol antioxidant includes one or more of 2,6-di-tert-butyl-4-methylphenol, 4,6-bis(octylthiomethyl)-o-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide), 2,2'-thioethylene glycol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,5-di-tert-butyl-4-hydroxyphenylpropionate and 4,4'-thiobis(6-tert-butyl-3-methylphenol).

[0047] In some embodiments, the peroxide-based crosslinking agent includes one or more of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dicumyl peroxide, and di-tert-butyl peroxide.

[0048] In some embodiments, the density of the low-density polyethylene is 0.9 mol / cm3 ~0.98mol / cm 3 Specifically, the density of low-density polyethylene includes but is not limited to: 0.9 mol / cm 3 、0.91mol / cm 3 , 0.92mol / cm 3 , 0.93mol / cm 3 , 0.94mol / cm 3 , 0.95mol / cm 3 , 0.96mol / cm 3 , 0.97mol / cm 3 、0.98mol / cm 3 Or a range between any two of the foregoing.

[0049] In some embodiments, the melt index of the low-density polyethylene is 1.6 g / 10 min to 2.5 g / 10 min. Specifically, the melt index of the low-density polyethylene includes but is not limited to: 1.6 g / 10 min, 1.7 g / 10 min, 1.8 g / 10 min, 1.9 g / 10 min, 2 g / 10 min, 2.1 g / 10 min, 2.2 g / 10 min, 2.3 g / 10 min, 2.4 g / 10 min, 2.5 g / 10 min.

[0050] Another embodiment of the present application provides a method for preparing a cross-linked polyethylene insulation material, comprising the following steps:

[0051] The low-density polyethylene, an antioxidant, a first anti-scorch agent and a second anti-scorch agent are mixed to obtain a mixed material; the first anti-scorch agent includes one or more of an olefin anti-scorch agent, an allyl-substituted phenol anti-scorch agent and a thiocarbonate anti-scorch agent, and the second anti-scorch agent includes a free radical terminator;

[0052] The mixed material is subjected to melt extrusion treatment and granulation treatment in sequence to obtain an intermediate material;

[0053] The intermediate material is mixed with a cross-linking agent and subjected to a post-absorption treatment to prepare a cross-linked polyethylene insulating material.

[0054] The above preparation method is easy to operate, easy to realize industrial production, reduces production costs, and improves production efficiency. In the above preparation method, the antioxidant can effectively improve the antioxidant performance and thermal stability of the cross-linked polyethylene insulation material, the cross-linking agent can improve the mechanical properties and heat resistance of the cross-linked polyethylene insulation material, the first anti-scorch agent has the effect of slowing down the cross-linking speed, and the second anti-scorch agent can consume excess active free radicals. The first anti-scorch agent slows down the cross-linking rate by prolonging the transfer process of free radicals, and the second anti-scorch agent can further reduce the reaction concentration of active free radicals, thereby reducing the scorching phenomenon of the cross-linked polyethylene insulation material during the processing and use process, improving the scorch resistance of the cross-linked polyethylene insulation material, and extending the service life of the cable.

[0055] In some embodiments, the temperature for mixing the low density polyethylene, the antioxidant, the first scorch retarder and the second scorch retarder is 30°C to 50°C.

[0056] In some embodiments, the process conditions of the melt extrusion process include: the melt extrusion temperature is 120° C. to 180° C. Specifically, the melt extrusion temperature includes but is not limited to: 120° C., 130° C., 140° C., 150° C., 160° C., 170° C., 180° C. or a range between any two of the foregoing.

[0057] In some embodiments, the process conditions of the post-absorption treatment include: the post-absorption temperature is 60°C to 80°C, and the post-absorption time is 12h to 20h. Controlling the process conditions of the post-absorption treatment to the above range is conducive to the rapid absorption of the cross-linking agent and more uniform dispersion in the matrix resin. Specifically, the post-absorption temperature includes but is not limited to: 60°C, 63°C, 65°C, 68°C, 70°C, 73°C, 75°C, 78°C, 80°C or a range between any two of the foregoing, and the post-absorption time includes but is not limited to: 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h or a range between any two of the foregoing.

[0058] In some embodiments, the mixing time of the low-density polyethylene, the antioxidant, the first anti-scorch agent and the second anti-scorch agent is 15 minutes to 30 minutes. Such a design is conducive to uniform mixing of the low-density polyethylene, the antioxidant, the first anti-scorch agent and the second anti-scorch agent. Specifically, the mixing time includes but is not limited to: 15 minutes, 18 minutes, 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes or a range between any two of the foregoing.

[0059] In some embodiments, after the steps of sequentially performing melt extrusion treatment and granulation treatment on the mixed material, the method further comprises: performing a drying treatment on the material obtained by the granulation treatment.

[0060] In some embodiments, the melt extrusion process is carried out in a twin-screw extruder, and the screw speed of the twin-screw extruder is 100 r / min to 200 r / min. The above screw speed includes but is not limited to: 100 r / min, 120 r / min, 140 r / min, 160 r / min, 180 r / min, 200 r / min or a range between any two of the foregoing.

[0061] Another embodiment of the present application provides the use of at least one of the cross-linked polyethylene insulation material mentioned above and the cross-linked polyethylene insulation material prepared by the preparation method mentioned above in cables or wires.

[0062] Another embodiment of the present application further provides a cable, comprising at least one of the cross-linked polyethylene insulation material mentioned above in the present application and the cross-linked polyethylene insulation material prepared by the preparation method mentioned above in the present application.

[0063] In some embodiments, the cable is a submarine cable.

[0064] In some embodiments, the cable has a withstand voltage of 500 kV and below.

[0065] In this application, "withstand voltage" refers to the voltage at which the cable can operate safely and stably.

[0066] In order to further illustrate the present application, the technical scheme of the present application is described in detail below in conjunction with specific examples. If no specific technology or conditions are specified in the examples, the technology or conditions described in the literature in the field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0067] Example 1

[0068] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0069] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.2 parts of 2,4-diphenyl-4-methyl-1-pentene and 0.1 parts of 1,1-diphenyl-2-trinitrophenylhydrazine are placed in a high-speed mixer, and stirred at 40° C. for 20 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0070] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 125° C., 135° C., 145° C., 155° C., 160° C., 155° C., and 150° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0071] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0072] The above cross-linked polyethylene insulation material comprises:

[0073] 100 parts of low density polyethylene;

[0074] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0075] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0076] 2,4-diphenyl-4-methyl-1-pentene (first anti-scorch agent) 0.2 parts;

[0077] 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent) 0.1 part;

[0078] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 2:1.

[0079] Example 2

[0080] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0081] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.2 parts of trans-6-phenyl-2-hexene and 0.1 parts of 1,1-diphenyl-2-trinitrophenylhydrazine are placed in a high-speed mixer, stirred at 40° C. for 25 minutes to mix uniformly, and a mixed material is obtained; wherein the density of the low-density polyethylene is 0.94 mol / cm 3 , melt index is 2.08g / 10min;

[0082] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 130° C., 135° C., 140° C., 150° C., 160° C., 155° C., and 150° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0083] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0084] The above cross-linked polyethylene insulation material comprises:

[0085] 100 parts of low density polyethylene;

[0086] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0087] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0088] 0.2 parts of trans-6-phenyl-2-hexene (first anti-scorch agent);

[0089] 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent) 0.1 part;

[0090] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 2:1.

[0091] Example 3

[0092] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0093] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.25 parts of 4-allylphenol and 0.05 parts of 1,1-diphenyl-2-trinitrophenylhydrazine were placed in a high-speed mixer, and stirred at 40° C. for 25 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0094] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 125° C., 130° C., 145° C., 155° C., 165° C., 160° C., and 155° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0095] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0096] The above cross-linked polyethylene insulation material comprises:

[0097] 100 parts of low density polyethylene;

[0098] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0099] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0100] 4-allylphenol (first anti-scorch agent) 0.25 parts;

[0101] 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent) 0.05 parts;

[0102] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 5:1.

[0103] Example 4

[0104] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0105] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.24 parts of 4-allylphenol and 0.06 parts of 1,1-diphenyl-2-trinitrophenylhydrazine were placed in a high-speed mixer, and stirred at 40° C. for 25 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0106] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 125° C., 130° C., 145° C., 155° C., 165° C., 160° C., and 155° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0107] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0108] The above cross-linked polyethylene insulation material comprises:

[0109] 100 parts of low density polyethylene;

[0110] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0111] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0112] 4-allylphenol (first anti-scorch agent) 0.24 parts;

[0113] 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent) 0.06 parts;

[0114] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 4:1.

[0115] Example 5

[0116] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0117] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.2 parts of 4-allylphenol and 0.1 parts of 1,1-diphenyl-2-trinitrophenylhydrazine were placed in a high-speed mixer, and stirred at 40° C. for 25 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0118] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 125° C., 130° C., 145° C., 155° C., 165° C., 160° C., and 155° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0119] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0120] The above cross-linked polyethylene insulation material comprises:

[0121] 100 parts of low density polyethylene;

[0122] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0123] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0124] 4-allylphenol (first anti-scorch agent) 0.2 parts;

[0125] 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent) 0.1 part;

[0126] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 2:1.

[0127] Example 6

[0128] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0129] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.15 parts of 4-allylphenol and 0.15 parts of 1,1-diphenyl-2-trinitrophenylhydrazine were placed in a high-speed mixer, and stirred at 40° C. for 30 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0130] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 125° C., 130° C., 145° C., 155° C., 165° C., 160° C., and 155° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0131] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0132] The above cross-linked polyethylene insulation material comprises:

[0133] 100 parts of low density polyethylene;

[0134] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0135] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0136] 4-allylphenol (first anti-scorch agent) 0.15 parts;

[0137] 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent) 0.15 parts;

[0138] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 1:1.

[0139] Example 7

[0140] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0141] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.26 parts of 4-allylphenol and 0.04 parts of 1,1-diphenyl-2-trinitrophenylhydrazine were placed in a high-speed mixer, and stirred at 40° C. for 30 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0142] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 125° C., 130° C., 145° C., 155° C., 165° C., 160° C., and 155° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0143] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0144] The above cross-linked polyethylene insulation material comprises:

[0145] 100 parts of low density polyethylene;

[0146] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0147] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0148] 4-allylphenol (first anti-scorch agent) 0.26 parts;

[0149] 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent) 0.04 parts;

[0150] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 6.5:1.

[0151] Example 8

[0152] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0153] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.24 parts of o-allyl phenol and 0.06 parts of 1,1-diphenyl-2-trinitrophenylhydrazine were placed in a high-speed mixer, and stirred at 40° C. for 25 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3, melt index is 1.98g / 10min;

[0154] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 130° C., 135° C., 150° C., 155° C., 160° C., 155° C., and 150° C., respectively, followed by granulation and drying to obtain an intermediate material;

[0155] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0156] The above cross-linked polyethylene insulation material comprises:

[0157] 100 parts of low density polyethylene;

[0158] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0159] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0160] o-allylphenol (first anti-scorch agent) 0.24 parts;

[0161] 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent) 0.06 parts;

[0162] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 4:1.

[0163] Example 9

[0164] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0165] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 0.2 parts of S-dodecyl-S'-(α,α"-methyl-α"-acetic acid) trithiocarbonate and 0.1 parts of 1,1-diphenyl-2-trinitrophenylhydrazine are placed in a high-speed mixer, stirred at 40°C for 25 minutes to mix uniformly, and a mixed material is obtained; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0166] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 125° C., 135° C., 140° C., 150° C., 155° C., 165° C., 155° C., and 150° C., respectively, followed by granulation and drying to obtain an intermediate material;

[0167] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0168] The above cross-linked polyethylene insulation material comprises:

[0169] 100 parts of low density polyethylene;

[0170] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0171] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0172] 0.2 parts of S-dodecyl-S'-(α,α"-methyl-α"-acetic acid) trithiocarbonate (first anti-scorch agent);

[0173] 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent) 0.1 part;

[0174] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 2:1.

[0175] Example 10

[0176] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0177] (1) 100 parts of low-density polyethylene, 0.2 parts of 4,4'-thiobis(6-tert-butyl-3-methylphenol), 0.4 parts of 4-allylphenol and 0.2 parts of N,N-diethylhydroxylamine were placed in a high-speed mixer and stirred at 40°C for 30 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0178] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 125° C., 130° C., 140° C., 150° C., 160° C., 170° C., 160° C., and 150° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0179] (3) 1.5 parts of di-tert-butyl peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 20 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0180] The above cross-linked polyethylene insulation material comprises:

[0181] 100 parts of low density polyethylene;

[0182] 4,4'-Thiobis(6-tert-butyl-3-methylphenol) (antioxidant) 0.2 parts;

[0183] 1.5 parts of di-tert-butyl peroxide (cross-linking agent);

[0184] 4-allylphenol (first anti-scorch agent) 0.4 parts;

[0185] 0.2 parts of N,N-diethylhydroxylamine (second anti-scorch agent);

[0186] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 2:1.

[0187] Embodiment 11

[0188] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0189] (1) 100 parts of low-density polyethylene, 0.2 parts of 2,2'-thioethylene glycol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 0.5 parts of 2-allyl-6-methylphenol and 0.2 parts of 2,3,5-triphenyltetrazolyl are placed in a high-speed mixer, and stirred at 40°C for 30 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0190] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 125° C., 130° C., 140° C., 150° C., 160° C., 155° C., and 150° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0191] (3) 1.5 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane were added to the intermediate material and subjected to post-absorption treatment at 70° C. After post-absorption for 15 hours, a cross-linked polyethylene insulating material was obtained.

[0192] The above cross-linked polyethylene insulation material comprises:

[0193] 100 parts of low density polyethylene;

[0194] 2,2'-Mercaptoethylene glycol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (antioxidant) 0.2 parts;

[0195] 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (cross-linking agent) 1.5 parts;

[0196] 2-allyl-6-methylphenol (first anti-scorch agent) 0.5 parts;

[0197] 2,3,5-triphenyltetrazolium (second anti-scorch agent) 0.2 parts;

[0198] The mass ratio of the first anti-scorching agent to the second anti-scorching agent is 2.5:1.

[0199] Comparative Example 1

[0200] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0201] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 0.3 parts of 2,4-diphenyl-4-methyl-1-pentene are placed in a high-speed mixer, and stirred at 40° C. for 25 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0202] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 125° C., 130° C., 140° C., 150° C., 160° C., 150° C., and 150° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0203] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0204] The above cross-linked polyethylene insulation material comprises:

[0205] 100 parts of low density polyethylene;

[0206] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0207] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0208] 2,4-diphenyl-4-methyl-1-pentene (first anti-scorch agent) 0.3 parts.

[0209] Comparative Example 2

[0210] A method for preparing a cross-linked polyethylene insulating material comprises the following steps:

[0211] (1) 100 parts of low-density polyethylene, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and 0.3 parts of 1,1-diphenyl-2-trinitrophenylhydrazine are placed in a high-speed mixer, and stirred at 40° C. for 25 minutes to obtain a mixed material; wherein the density of the low-density polyethylene is 0.92 mol / cm 3 , melt index is 1.98g / 10min;

[0212] (2) adding the mixed material into a twin-screw extruder through a vector weighing feeding system for melt extrusion, with a screw speed of 190 r / min, and the temperatures of the various zones of the twin-screw body being set to 120° C., 125° C., 130° C., 140° C., 155° C., 160° C., 155° C., and 150° C. in sequence, followed by granulation and drying to obtain an intermediate material;

[0213] (3) 1.5 parts of diisopropylbenzene peroxide were added to the intermediate material, and a post-absorption treatment was performed at 65° C. After 18 hours of post-absorption, a cross-linked polyethylene insulating material was obtained.

[0214] The above cross-linked polyethylene insulation material comprises:

[0215] 100 parts of low density polyethylene;

[0216] 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant);

[0217] 1.5 parts of dicumyl peroxide (cross-linking agent);

[0218] 0.3 parts of 1,1-diphenyl-2-trinitrophenylhydrazine (second anti-scorch agent).

[0219] Test Case

[0220] The cross-linked polyethylene insulation materials prepared in each embodiment or each comparative example were tested for mechanical properties, scorch resistance and electrical properties. The test results are shown in Table 1.

[0221] (1) Mechanical properties

[0222] The tensile properties are tested according to GB / T 1040.2-2022, and the thermal elongation is tested according to GB / T 2951.21-2008.

[0223] (2) Scorch resistance

[0224] The scorch time and balance torque are tested using a rotorless vulcanizer in accordance with GB / T 16584-1996.

[0225] (3) Electrical performance

[0226] The breakdown strength is tested using a ball-to-ball electrode in accordance with GB / T 1408.1-2016, and the dielectric constant and dielectric loss are tested in accordance with GB / T 1409-2006.

[0227] Table 1

[0228]

[0229] It can be seen from the data in Table 1 that the cross-linked polyethylene insulation materials of Examples 1 to 11 have suitable mechanical properties, and compared with Comparative Examples 1 to 2, the scorch time of the cross-linked polyethylene insulation materials of Examples 1 to 11 is relatively long, and the balance torque is relatively small, indicating that the cross-linked polyethylene insulation materials of Examples 1 to 11 have better scorch resistance, the breakdown strength of the cross-linked polyethylene insulation materials of Examples 1 to 11 is relatively high, and the dielectric constant and dielectric loss are relatively low, indicating that the cross-linked polyethylene insulation materials of Examples 1 to 11 have better electrical properties and longer service life.

[0230] By comparing Example 1, Examples 3 to 5, and Examples 6 to 9, it can be seen that the first anti-scorch agent in the cross-linked polyethylene insulation material in Examples 3 to 5 includes an allyl-substituted phenol anti-scorch agent, and the mass ratio of the first anti-scorch agent to the second anti-scorch agent is 5:1 to 2:1, which can further improve the scorch resistance and service life of the cross-linked polyethylene insulation material.

[0231] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0232] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims, and the description may be used to interpret the content of the claims.

Claims

1. A cross-linked polyethylene insulating material, characterized in that: The invention comprises low-density polyethylene, an antioxidant, a cross-linking agent, a first anti-scorch agent and a second anti-scorch agent, wherein the first anti-scorch agent comprises one or more of an olefin anti-scorch agent, an allyl-substituted phenol anti-scorch agent and a thiocarbonate anti-scorch agent, and the second anti-scorch agent comprises a free radical terminator.

2. The cross-linked polyethylene insulation material according to claim 1, characterized in that: The cross-linked polyethylene insulation material includes 100 parts of the low-density polyethylene, 0.2 to 0.5 parts of the antioxidant, 0.8 to 1.6 parts of the cross-linking agent, 0.1 to 0.5 parts of the first anti-scorch agent, and 0.05 to 0.2 parts of the second anti-scorch agent.

3. The cross-linked polyethylene insulation material according to claim 1, characterized in that: The first anti-scorch agent includes an allyl-substituted phenol anti-scorch agent, and the mass ratio of the first anti-scorch agent to the second anti-scorch agent is 5:1 to 2:

1.

4. The cross-linked polyethylene insulation material according to any one of claims 1 to 3, characterized in that: The cross-linked polyethylene insulation material has at least one of the following characteristics (1) to (6): (1) The free radical terminator includes one or more of 1,1-diphenyl-2-trinitrophenylhydrazine, N,N-diethylhydroxylamine and 2,3,5-triphenyltetrazolyl; (2) The olefin scorch retarder includes one or more of trans-6-phenyl-2-hexene and 2,4-diphenyl-4-methyl-1-pentene; (3) the allyl-substituted phenolic scorch retarder comprises one or more of 4-allylphenol, o-allylphenol and 2-allyl-6-methylphenol; (4) The thiocarbonate scorch retarder includes one or more of S-dodecyl-S'-(α,α"-methyl-α"-acetic acid) trithiocarbonate and dodecyl-S"-isopropionic acid trithiocarbonate; (5) The antioxidant includes a hindered phenol antioxidant; (6) The cross-linking agent includes a peroxide cross-linking agent.

5. The cross-linked polyethylene insulation material according to claim 4, characterized in that: The hindered phenol antioxidant includes one or more of 2,6-di-tert-butyl-4-methylphenol, 4,6-bis(octylthiomethyl)-o-cresol, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide), 2,2'-thioethylene glycol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,5-di-tert-butyl-4-hydroxyphenylpropionate and 4,4'-thiobis(6-tert-butyl-3-methylphenol).

6. The cross-linked polyethylene insulation material according to claim 4, characterized in that: The peroxide crosslinking agent includes one or more of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, diisopropylbenzene peroxide and di-tert-butyl peroxide.

7. The cross-linked polyethylene insulation material according to any one of claims 1 to 3, characterized in that: The cross-linked polyethylene insulation material has at least one of the following characteristics (1) to (2): (1) The density of the low-density polyethylene is 0.9 mol / cm 3 ~0.98mol / cm 3 ; (2) The melt index of the low-density polyethylene is 1.6 g / 10 min to 2.5 g / 10 min.

8. A method for preparing a cross-linked polyethylene insulating material, characterized in that: The following steps are involved: Mixing low-density polyethylene, an antioxidant, a first anti-scorch agent and a second anti-scorch agent to obtain a mixed material; the first anti-scorch agent includes one or more of an olefin anti-scorch agent, an allyl-substituted phenol anti-scorch agent and a thiocarbonate anti-scorch agent, and the second anti-scorch agent includes a free radical terminator; The mixed material is subjected to melt extrusion treatment and granulation treatment in sequence to obtain an intermediate material; The intermediate material is mixed with a cross-linking agent and subjected to a post-absorption treatment to prepare the cross-linked polyethylene insulating material.

9. The preparation method according to claim 8, characterized in that: The preparation method satisfies at least one of the following conditions: (1) The temperature at which the low-density polyethylene, the antioxidant, the first anti-scorch agent and the second anti-scorch agent are mixed is 30° C. to 50° C.; (2) The process conditions of the melt extrusion treatment include: the melt extrusion temperature is 120°C to 180°C; (3) The process conditions of the post-absorption treatment include: the post-absorption temperature is 60°C to 80°C, and the post-absorption time is 12h to 20h.

10. Use of at least one of the cross-linked polyethylene insulation material according to any one of claims 1 to 7 and the cross-linked polyethylene insulation material prepared by the preparation method according to any one of claims 8 to 9 in cables or wires.

11. A cable, characterized in that: The invention comprises at least one of the cross-linked polyethylene insulating material according to any one of claims 1 to 7 and the cross-linked polyethylene insulating material prepared by the preparation method according to any one of claims 8 to 9.

12. The cable according to claim 11, characterized in that The cable is a submarine cable.

13. The cable according to claim 11 or 12, characterized in that: The cable has a withstand voltage of 500 kV or less.

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