Cable insulation material for large-length extrusion, preparation method and application thereof, and cable

Abstract

The invention provides a cable insulation material for large-length extrusion, a preparation method and application of the cable insulation material and a cable. The cable insulation material for large-length extrusion comprises polyethylene, an antioxidant, a cross-linking agent and a cross-linking aid. According to the cable insulation material for large-length extrusion provided by the invention, the insulation material is subjected to blending modification from a formula stage, and the prepared insulation material is small in pressure fluctuation, good in stability and smooth in discharging when being subjected to large-length extrusion by regulating the property of polyethylene and adopting the specific antioxidant and the cross-linking agent for cooperative use; therefore, the stability of the insulating material during large-length extrusion is improved. In addition, the cable insulation material is excellent in quality, has excellent thermal stability, scorching resistance, electrical insulation performance and aging resistance, and is of great significance in improving the market competitiveness of cable products.

Description

Technical Field

[0001] The present application relates to the technical field of insulating materials, and in particular to a cable insulating material for long-length extrusion, a preparation method thereof, an application thereof, and a cable. Background Art

[0002] In the field of power transmission, cables are the main carrier of power transmission, and their performance is directly related to the stable operation of the power system. With the acceleration of urbanization and the improvement of industrialization, the reliability and stability of power supply are increasingly required, which puts higher performance requirements on cable insulation materials. Especially in long-distance power transmission, urban power grid construction and submarine cable power transmission, long-length cables have gradually become the mainstream demand of the market because of their advantages of reducing the number of joints, reducing failure rates and improving transmission efficiency.

[0003] However, the development of long-length cable insulation material preparation technology still faces many challenges. For example, how to extend the continuous extrusion time of long lengths and achieve longer cable extrusion is one of the key technical problems that need to be solved urgently. Summary of the invention

[0004] Based on this, the present application provides a cable insulation material for long-length extrusion and a preparation method, application and cable thereof, so as to improve the continuity of long-length extrusion of the cable insulation material.

[0005] The first aspect of the present application provides a cable insulation material for long-length extrusion, comprising polyethylene, an antioxidant, a cross-linking agent and a cross-linking aid;

[0006] Wherein, the number of small molecules with a weight average molecular weight less than 4000Da contained in the polyethylene is 0;

[0007] The antioxidant includes one or more of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol), 4,4'-thiobis(6-tert-butyl-2,3-ethylene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol];

[0008] The cross-linking agent includes one or more of dicumyl peroxide, benzoyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane;

[0009] The cross-linking auxiliary agent includes one or more of poly(α-methylstyrene) dimer, 1,4-di-tert-butylperoxyisopropylbenzene, tert-butyl hydroperoxide and methyltriacetoxysilane.

[0010] In some embodiments, the antioxidant comprises a mixture of 4,4'-thiobis(6-tert-butyl-m-cresol) and 4,4'-thiobis(5-tert-butyl-m-cresol) in a mass ratio of (1.2-2.1):(0.8-1.0).

[0011] In some embodiments, the antioxidant includes a mixture of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol) and 4,4'-thiobis(6-tert-butyl-2,3-ethylene) in a mass ratio of (0.8-1.2):(0.5-1.0):(0.2-0.5).

[0012] In some embodiments, the antioxidant comprises a mixture of 4,4'-thiobis(6-tert-butyl-2,3-ethylene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol] in a mass ratio of (0.8-1.5):(1.0-2.0).

[0013] In some embodiments, the crosslinking agent comprises a mixture of dicumyl peroxide and benzoyl peroxide in a mass ratio of (0.8-3.5):(0.5-2.5).

[0014] In some embodiments, the cross-linking agent includes a mixture of 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane in a mass ratio of (0.5-1.5):(0.7-2.3).

[0015] In some embodiments, the crosslinking agent includes a mixture of dicumyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane in a mass ratio of (1.0-2.0):(0.5-1.5):(0.2-0.6).

[0016] In some embodiments, the cross-linking aid comprises a mixture of poly(α-methylstyrene) dimer and 1,4-di-tert-butylperoxyisopropylbenzene in a mass ratio of (0.1-0.5):(0.1-0.3).

[0017] In some embodiments, the crosslinking aid includes a mixture of tert-butyl hydroperoxide and methyltriacetoxysilane in a mass ratio of (0.2-1.0):(0.5-2.0).

[0018] In some embodiments, the polyethylene includes at least one of the following features:

[0019] (1) The density of the polyethylene is 0.915 g / cm 3 -0.935g / cm 3 ;

[0020] (2) The melt index of the polyethylene is 1.6 g / 10 min-2.4 g / 10 min;

[0021] (3) The weight average molecular weight of the polyethylene is 60000Da-120000Da;

[0022] (4) The molecular weight distribution of the polyethylene is 4.0 PDI-9.0 PDI;

[0023] (5) The degree of branching of the polyethylene is 1.5 to 5.5 branched carbon atoms per thousand carbon atoms;

[0024] (6) The double bond content of the polyethylene is 0.1 to 1.5 carbon atoms containing terminal double bonds per thousand carbon atoms.

[0025] In some embodiments, the cable insulation material comprises, by weight:

[0026] Polyethylene 90-100 parts;

[0027] Antioxidant 0.05-0.4 parts;

[0028] 0.6 to 3.5 parts of a cross-linking agent; and

[0029] Cross-linking aid: 0.05-0.5 parts.

[0030] In some embodiments, compared with conventional insulation materials used in the cable field, the cable insulation material has improved anti-scorch properties, electrical insulation properties, and thermomechanical properties.

[0031] In some embodiments, the cable insulation material has at least one of the following features (1)-(9):

[0032] (1) The tensile strength of the cable insulation material is 17.5MPa-25MPa;

[0033] (2) The elongation at break of the cable insulation material is 480%-550%;

[0034] (3) The tensile strength variation rate of the cable insulation material is 5Mpa-22.5Mpa;

[0035] (4) The elongation at break of the cable insulation material has a variation rate of 1.9% to 15.3%;

[0036] (5) The elongation under load of the cable insulation material is 50%-90%;

[0037] (6) The permanent deformation rate of the cable insulation material after cooling is 0-2%;

[0038] (7) The scorch time of the cable insulation material is 3.5min-9.7min;

[0039] (8) The cross-linking rate of the cable insulation material is 2.6 N·m / min -5.9 N·m / min;

[0040] (9) The volume resistivity of the cable insulation material is 0.2×10 12 Ω·m -9.3×10 12 Ω·m.

[0041] The second aspect of the present application provides a method for preparing a cable insulation material for long-length extrusion, comprising the following steps:

[0042] The polyethylene and the antioxidant are mixed, extruded, and granulated to prepare a semi-finished product;

[0043] Dehydrating the semi-finished product;

[0044] Spraying a mixed liquid containing a cross-linking agent and a cross-linking aid into the semi-finished product after shaking the dehydrated product;

[0045] After the spraying is finished, the shaking is continued for a preset time, and then the insulation is performed and then absorbed to prepare the cable insulation material;

[0046] Wherein, the number of small molecules with a weight average molecular weight less than 4000Da contained in the polyethylene is 0;

[0047] The antioxidant includes one or more of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol), 4,4'-thiobis(6-tert-butyl-2,3-ethylene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol];

[0048] The cross-linking agent includes one or more of dicumyl peroxide, benzoyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane;

[0049] The cross-linking auxiliary agent includes one or more of poly(α-methylstyrene) dimer, 1,4-di-tert-butylperoxyisopropylbenzene, tert-butyl hydroperoxide and methyltriacetoxysilane.

[0050] In some embodiments, a twin-screw extruder is used for the extrusion, the extrusion temperature is 160° C.-185° C., and the screw speed is 100 rpm-175 rpm.

[0051] In some embodiments, the semi-finished product is dehydrated by centrifugation.

[0052] In some embodiments, the shaking speed is 10 rpm-30 rpm.

[0053] In some embodiments, the preset time is 30 min-60 min.

[0054] In some embodiments, the temperature of the absorption after insulation is 60°C-80°C, and the time is 16h-28h.

[0055] The third aspect of the present application provides a use of the cable insulation material for long-length extrusion of the first aspect of the present application or the cable insulation material for long-length extrusion prepared by the preparation method of the second aspect of the present application in preparing cables.

[0056] The third aspect of the present application provides a cable, wherein the raw materials for preparing the cable include the cable insulation material for long-length extrusion of the first aspect of the present application or the cable insulation material for long-length extrusion prepared by the preparation method of the second aspect of the present application.

[0057] In some embodiments, the cable is a submarine cable.

[0058] The cable insulation material for long-length extrusion provided above is blended and modified from the formulation stage, and the prepared insulation material has small pressure fluctuation, good stability, smooth material discharge, and excellent scorch resistance when it is extruded for a long length by regulating the properties of polyethylene and using specific antioxidants, crosslinking agents and crosslinking aids, thereby improving the stability of the insulation material during extrusion. In addition, the cable insulation material is of good quality, has excellent thermal stability, scorch resistance, electrical insulation performance and anti-aging performance, which is of great significance for improving the market competitiveness of cable products. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0060] Figure 1 The long-term extrusion test results of Example 1 and Comparative Example 4 are shown. DETAILED DESCRIPTION

[0061] For ease of understanding of the present invention, the application will be described more fully below with reference to relevant embodiments. The following provides preferred embodiments of the application. However, the application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the application more thorough and comprehensive.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0063] The terms "and / or", "or / and", and "and / or" used herein include any one of two or more related listed items, and also include any and all combinations of the related listed items, wherein the any and all combinations include any combination of two related listed items, any more related listed items, or all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in the present application, the technical solution undoubtedly includes technical solutions connected by "logical and", and also undoubtedly includes technical solutions connected by "logical or".

[0064] 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.

[0065] 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.

[0066] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range. In addition, each separately disclosed point or single value can itself be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an unspecified range.

[0067] The temperature parameters in this application, unless otherwise specified, allow both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0068] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc., shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0069] In the present application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of the present application.

[0070] 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.

[0071] In the description of the application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0072] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0073] If there is no special explanation, all the steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0074] Long-length cables have gradually become the mainstream demand of the market due to their advantages of reducing the number of joints, reducing failure rates and improving transmission efficiency. However, the preparation technology of long-length cable insulation materials faces many challenges. Traditional cable insulation material preparation methods often make it difficult to achieve long-length continuous extrusion, resulting in low production efficiency and difficulty in ensuring product quality.

[0075] In addition, due to long-term operation under high temperature and high voltage conditions, the insulation materials of long-length cables must have excellent thermal stability, scorch resistance, electrical insulation performance and anti-aging performance, and the improvement of these properties often requires complex material modifications.

[0076] Based on the above problems, the present application blends and modifies the insulating material from the formulation stage, regulates the properties of polyethylene, and uses specific antioxidants and cross-linking agents in combination to improve the stability of the insulating material during long-length extrusion and improve the quality of the cable insulating material.

[0077] One or more embodiments of the present application provide a cable insulation material for long-length extrusion, comprising polyethylene, an antioxidant, a cross-linking agent, and a cross-linking aid;

[0078] Among them, the number of small molecules with a weight average molecular weight less than 4000Da contained in the polyethylene is 0; the antioxidant includes one or more of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol), 4,4'-thiobis(6-tert-butyl-2,3-ethylene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol]; the crosslinking agent includes one or more of diisopropylbenzene peroxide (DCP), benzoyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane; the crosslinking aid includes one or more of poly(α-methylstyrene) dimer, 1,4-di-tert-butylperoxyisopropylbenzene, tert-butyl hydroperoxide and methyltriacetoxysilane.

[0079] By regulating the number of small molecules with a weight average molecular weight less than 4000Da contained in polyethylene to 0, it is helpful to reduce or even avoid the adverse effects of low molecular weight segments in polyethylene molecules on cross-linking and improve the cross-linking efficiency.

[0080] Understandably, the cable insulation material for long-length extrusion provided by the present application is blended and modified from the formulation stage, and the prepared insulation material has small pressure fluctuation, good stability, and smooth discharge when it is extruded over a long length by regulating the properties of polyethylene and using specific antioxidants, crosslinking agents, and crosslinking aids, thereby improving the stability of the insulation material during extrusion. In addition, the cable insulation material is of good quality, with excellent thermal stability, anti-scorch properties, electrical insulation performance, and anti-aging performance, which is of great significance for improving the market competitiveness of cable products.

[0081] In some optional embodiments, the antioxidant includes a mixture of 4,4'-thiobis(6-tert-butyl-m-cresol) and 4,4'-thiobis(5-tert-butyl-m-cresol) in a mass ratio of (1.2-2.1):(0.8-1.0).

[0082] As a non-limiting example, the mass ratio of 4,4'-thiobis(6-tert-butyl-m-cresol) to 4,4'-thiobis(5-tert-butyl-m-cresol) in the antioxidant can be, but is not limited to, (1.25-2.05):(0.8-0.99), (1.3-2.0):(0.8-0.98), (1.35-1.95):(0.8-0.97), (1.4-1.9):(0.8-0.96), (1.3-1.85):(0.8-0.95), (1.3-1.8):(0.81-0.95), (1.3-1.75):(0.82-0.95) or (1.3-1.7):(0.85-0.95), etc.

[0083] In some exemplary embodiments, the antioxidant includes a mixture of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol) and 4,4'-thiobis(6-tert-butyl-2,3-ethylene) in a mass ratio of (0.8-1.2):(0.5-1.0):(0.2-0.5).

[0084] As a non-limiting example, the mass ratio of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol) and 4,4'-thiobis(6-tert-butyl-2,3-ethylene) in the antioxidant may be, but is not limited to, (0.8-1.15):(0.55-1.0):(0.2-0.45), (0.8-1.1):(0.6-1.0):(0.2-0.4), (0.8-1.05):(0.65-1.0):(0.2-0.38), (0.8-1. 0):(0.7-1.0):(0.2-0.35), (0.8-0.95):(0.75-1.0):(0.2-0.32), (0.8-0.9):(0.8-1.0):(0.2-0.3), (0.8-0.87):(0.85-1.0):(0.2-0.28), (0.8-0.85):(0.85-0.98):(0.2-0.25) or (0.8-0.82):(0.85-0.95):(0.2-0.22), etc.

[0085] As a possible implementation, the antioxidant includes a mixture of 4,4'-thiobis(6-tert-butyl-2,3-ethylene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol] in a mass ratio of (0.8-1.5):(1.0-2.0).

[0086] As a non-limiting example, the mass ratio of 4,4'-thiobis(6-tert-butyl-2,3-ethylene) to 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol] in the antioxidant may be, but is not limited to, (0.8-1.48):(1.1-2.0), (0.8-1.45):(1.2-2.0), (0.8-1.43):(1.3-2.0). , (0.8-1.4):(1.4-2.0), (0.8-1.35):(1.5-2.0), (0.8-1.3):(1.6-2.0), (0.8-1.25):(1.7-2.0), (0.8-1.2):(1.8-2.0), (0.8-1.15):(1.9-2.0), (0.8-1.1):(1.85-2.0), (0.8-1.05):(1.75-2.0) or (0.8-1.0):(1.65-2.0), etc.

[0087] When the antioxidant is a mixture of two or more antioxidants having the above mass ratio, it is beneficial to further improve the extrusion stability and aging resistance of the insulating material, as well as enhance the anti-scorch properties, electrical insulation performance and thermomechanical properties of the insulating material.

[0088] In some embodiments, the cross-linking agent includes a mixture of dicumyl peroxide and benzoyl peroxide in a mass ratio of (0.8-3.5):(0.5-2.5).

[0089] As an example, the mass ratio of dicumyl peroxide to benzoyl peroxide in the crosslinking agent can be, but is not limited to, (1-3.5):(0.6-2.5), (1.2-3.5):(0.7-2.5), (1.4-3.5):(0.8-2.5), (1.6-3.5):(0.9-2.5), (1.8-3.5):(1-2.5), (2-3.5):(1- 2.4), (2-3.4):(1-2.3), (2-3.3):(1-2.2), (2-3.2):(1-2.1), (2-3.1):(1-2), (2-3):(1-1.9), (2.1-2.9):(1.1-1.9), (2.2-2.8):(1.2-1.8) or (2.3-2.7):(1.2-1.7), etc.

[0090] In some optional embodiments, the cross-linking agent includes a mixture of 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane in a mass ratio of (0.5-1.5):(0.7-2.3).

[0091] As a non-limiting example, the mass ratio of 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane in the cross-linking agent can be, but is not limited to, (0.6-1.5):(0.8-2.3), (0.7-1.5):(0.9-2.2), (0.8-1.5):(1-2.1), (0.9-1.5):(1.1-2), (1.0-1.5):(1.2-1.9), (1.1-1.5):(1.2-1.8) or (1.2-1.5):(1.2-1.7), etc.

[0092] As a possible implementation, the crosslinking agent includes a mixture of dicumyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane in a mass ratio of (1.0-2.0):(0.5-1.5):(0.2-0.6).

[0093] As a non-limiting example, the mass ratio of dicumyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane in the cross-linking agent can be, but is not limited to, (1.05-1.95):(0.55-1.45):(0.2-0.6), (1.1-1.9):(0.6-1.4):(0.2-0.55), (1.15-1.85):(0.65-1.35):(0.2 -0.5), (1.2-1.8):(0.7-1.3):(0.2-0.45), (1.25-1.75):(0.75-1.25):(0.2-0.4), (1.3-1.7):(0.8-1.2):(0.2-0.35), (1.35-1.65):(0.85-1.15):(0.23-0.35) or (1.4-1.6):(0.9-1.1):(0.25-0.35), etc.

[0094] When the cross-linking agent is a mixture of two or more cross-linking agents having the above-mentioned mass ratio, it is beneficial to further improve the extrusion stability and anti-scorch properties of the insulating material, as well as enhance the electrical insulation performance and thermomechanical properties of the insulating material.

[0095] In some optional embodiments, the cross-linking aid includes a mixture of poly(α-methylstyrene) dimer and 1,4-di-tert-butylperoxyisopropylbenzene in a mass ratio of (0.1-0.5):(0.1-0.3).

[0096] As a non-limiting example, the mass ratio of poly(α-methylstyrene) dimer and 1,4-di-tert-butylperoxyisopropylbenzene in the crosslinking aid can be, but is not limited to, (0.1-0.45):(0.1-0.28), (0.1-0.4):(0.1-0.25), (0.1-0.35):(0.1-0.23), (0.1-0.3):(0.1-0.2), (0.1-0.25):(0.1-0.18) or (0.15-0.25):(0.1-0.15), etc.

[0097] In some embodiments, the crosslinking aid includes a mixture of tert-butyl hydroperoxide and methyltriacetoxysilane in a mass ratio of (0.2-1.0):(0.5-2.0).

[0098] As non-limiting examples, the mass ratio of tert-butyl hydroperoxide to methyltriacetoxysilane in the crosslinking aid can be, but is not limited to, (0.2-0.95):(0.55-1.95), (0.2-0.9):(0.6-1.9), (0.2-0.85):(0.65-1.85), (0.2-0.8):(0.7-1.8), (0.2-0.75):(0.75-1.75 ), (0.2-0.7):(0.8-1.7), (0.2-0.65):(0.95-1.65), (0.2-0.6):(1-1.6), (0.2-0.55):(1.05-1.55), (0.2-0.5):(1.1-1.5), (0.2-0.45):(1.15-1.45) or (0.2-0.4):(1.2-1.4), etc.

[0099] When the cross-linking aid is a mixture of two or more cross-linking aids having the above mass ratio, it is beneficial to further improve the anti-scorching characteristics, electrical insulation performance and thermomechanical properties of the insulating material.

[0100] In some embodiments, the density of polyethylene is 0.915 g / cm 3 -0.935g / cm 3 ; For example, it can be but not limited to 0.915g / cm 3 , 0.917g / cm 3 , 0.92g / cm 3 , 0.923g / cm 3 , 0.925g / cm 3 , 0.927g / cm 3 、0.93g / cm 3 , 0.932g / cm 3 , 0.935g / cm 3Or the range between any two of the above densities. When the density of polyethylene is within the above range, the molecular chain of the polyethylene base material has a suitable amount of physical entanglement sites, which is beneficial to improve the cross-linking degree of the insulating material, reduce the amount of various additives, and reduce the cross-linking rate. In addition, it occupies a smaller volume in the storage and transportation medium, which is beneficial to improve the space utilization rate of the insulating material production workshop.

[0101] As a possible implementation, the melt index of polyethylene is 1.6 g / 10min-2.4 g / 10min; for example, it may be, but not limited to, 1.6 g / 10min, 1.7 g / 10min, 1.8 g / 10min, 1.9 g / 10min, 2.0 g / 10min, 2.1 g / 10min, 2.2 g / 10min, 2.3 g / 10min, 2.4 g / 10min, or a range between any two of the above melt indexes, etc. When the melt index of polyethylene is within the above range, it is beneficial to parameter control during the extrusion process of long-length insulation materials.

[0102] It should be noted that the test conditions of the above-mentioned "melt index" are: testing according to ASTM D1238 standard when the load is 2.16 kg.

[0103] In some embodiments, the weight average molecular weight of the polyethylene is 60000Da-120000Da; for example, it can be but not limited to 60000Da, 61000Da, 62000Da, 64000Da, 66000Da, 68000Da, 70000Da, 72000Da, 74000Da, 76000Da, 78000Da, 80000Da, 82000Da, 84000Da, 86000Da a, 88000Da, 90000Da, 92000Da, 94000Da, 96000Da, 98000Da, 100000Da, 102000Da, 104000Da, 106000Da, 108000Da, 110000Da, 112000Da, 114000Da, 116000Da, 118000Da, 120000Da or the range between any two of the above weight average molecular weights, etc. When the weight average molecular weight of polyethylene is within the above range, the proportion of long molecular chains in the polyethylene molecules is relatively high, which can provide more physical entanglement crosslinking points for material crosslinking, which is conducive to reducing the added content of additives, improving the purity of insulating materials, and extending the extrusion time of cable insulating materials.

[0104] In some exemplary embodiments, the molecular weight distribution of the polyethylene is 4.0 PDI-9.0 PDI; for example, it may be, but is not limited to, 4.0 PDI, 4.3 PDI, 4.5 PDI, 4.8 PDI, 5.0 PDI, 5.2 PDI, 5.5 PDI, 5.8 PDI, 6.0 PDI, 6.3 PDI, 6.5 PDI, 6.8 PDI, 7.0 PDI, 7.3 PDI, 7.5 PDI, 7.7 PDI, 8.0 PDI, 8.3 PDI, 8.5 PDI, 8.8 PDI, 9.0 PDI or a range between any two of the above values, etc. When the molecular weight distribution of the polyethylene is within the above range, it indicates that the uniformity of the molecular weight in the polyethylene is within a similar range and the molecular weight is relatively concentrated, and the processing characteristics are relatively uniform.

[0105] As a possible implementation, the degree of branching of polyethylene is 1.5-5.5 branched carbon atoms per thousand carbon atoms; for example, it can be but not limited to 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5 or the range between any two of the above values. When the degree of branching of polyethylene is within the above range, it indicates that the content of branched segments in the polyethylene molecule is low, and its low number of branched segments is conducive to improving the crosslinking degree of polyethylene, reducing the content of additives, and extending the extrusion time of the insulating material.

[0106] In some optional embodiments, the double bond content of polyethylene is 0.1-1.5 carbon atoms containing terminal double bonds per thousand carbon atoms; for example, it can be but not limited to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 or the range between any two of the above values. When the double bond content of polyethylene is within the above range, the terminal double bonds of polyethylene can effectively undergo cross-linking reaction with the additive, and the cross-linking rate of the insulating material is controlled within an appropriate range.

[0107] In some embodiments, the cable insulation material comprises, by weight:

[0108] Polyethylene 90-100 parts;

[0109] Antioxidant 0.05-0.4 parts;

[0110] 0.6 to 3.5 parts of a cross-linking agent; and

[0111] Cross-linking aid: 0.05-0.5 parts.

[0112] As a non-limiting example, the weight percentage of polyethylene contained in the cable insulation material can be, but is not limited to, 90 parts, 91 parts, 92 parts, 93 parts, 94 parts, 95 parts, 96 parts, 97 parts, 98 parts, 99 parts, 100 parts, or a range between any two of the above weight percentages, etc.

[0113] In terms of weight percentage, the weight percentage of the antioxidant contained in the cable insulation material can be but is not limited to 0.05 part, 0.1 part, 0.15 part, 0.2 part, 0.25 part, 0.3 part, 0.35 part, 0.4 part or a range between any two of the above weight percentages.

[0114] In terms of weight parts, the weight parts of the cross-linking agent contained in the cable insulation material can be but not limited to 0.6 parts, 0.8 parts, 1 parts, 1.3 parts, 1.5 parts, 1.8 parts, 2 parts, 2.3 parts, 2.5 parts, 2.8 parts, 3 parts, 3.3 parts, 3.5 parts or the range between any two of the above weight parts.

[0115] In parts by weight, the weight amount of the crosslinking aid contained in the cable insulation material can be but is not limited to 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, 0.5 parts or a range between any two of the above weight amounts.

[0116] In this article, compared with conventional insulation materials used in the cable field, the anti-scorch properties of the cable insulation material used for long-length extrusion are improved, and its electrical insulation properties and thermomechanical properties are also improved.

[0117] In some embodiments, the tensile strength of the cable insulation material for long-length extrusion is 17.5 MPa-25 MPa; optionally 17.5 MPa-24.6 MPa; further optionally 21 MPa-24.6 MPa.

[0118] As a possible implementation, the elongation at break of the cable insulation material used for long-length extrusion is 480%-550%; optionally 520%-550%.

[0119] It should be noted that the test temperature for the tensile strength and break growth rate mentioned above and below is 23°C.

[0120] In some embodiments, the tensile strength variation rate of the cable insulation material for long-length extrusion is 5 MPa-22.5 MPa; optionally 5.2 MPa-22.5 MPa; further optionally 5.2 MPa-16 MPa; further optionally 5.2 MPa-15.7 MPa.

[0121] As a possible implementation, the elongation at break variation rate of the cable insulation material used for long-length extrusion is 1.9%-15.3%; optionally 1.9%-5.9%.

[0122] It should be noted that the test method for the change rate of tensile strength and the change rate of elongation at break mentioned in the context includes: after placing the insulating material at 135°C for 168 hours, testing the change rate of tensile strength and the change rate of elongation at break of the insulating material.

[0123] In some embodiments, the elongation under load of the cable insulation for long length extrusion is 50%-90%; optionally 50%-65%.

[0124] As a possible implementation, the permanent deformation rate of the cable insulation material used for long-length extrusion after cooling is 0-2%; optionally 0%.

[0125] It should be noted that the test method for the elongation under load and the permanent deformation after cooling mentioned above includes: placing the insulating material under the conditions of 200°C and 0.2MPa for 15 minutes, and then testing the elongation under load and the permanent deformation after cooling of the insulating material.

[0126] In some embodiments, the scorch time of the cable insulation material for long-length extrusion is 3.5 min-9.7 min; optionally 6 min-9.7 min.

[0127] It should be noted that the scorch mentioned in the context was tested using a rotorless vulcanization method, and the test parameters included: temperature of 160°C, time of 2h, and vibration frequency of 100cpm.

[0128] As a possible implementation, the crosslinking rate of the cable insulation material for long-length extrusion is 2.6 N·m / min-5.9 N·m / min; optionally 2.6 N·m / min-4.1 N·m / min; further optionally 2.6 N·m / min-4.05 N·m / min.

[0129] It should be noted that the cross-linking rate mentioned above and below is tested using a torque rheometer, and the test parameters include: temperature of 140° C. and rotation speed of 60 rpm.

[0130] In some embodiments, the volume resistivity of the cable insulation for long-length extrusion is 0.2×10 12 Ω·m -9.3×10 12 Ω·m; optional: 1.8×10 12 Ω·m -9.3×10 12 Ω·m.

[0131] It should be noted that the test parameters of volume resistivity mentioned in the context include: sample thickness of 0.2 mm, temperature of 70° C., and electric field strength of 20 kV / mm.

[0132] One or more embodiments of the present application provide a method for preparing a cable insulation material for long-length extrusion, which can be used to prepare the cable insulation material mentioned above. The preparation method comprises the following steps:

[0133] The polyethylene and the antioxidant are mixed, extruded, and granulated to prepare a semi-finished product; the semi-finished product is dehydrated; a mixed liquid containing a cross-linking agent and a cross-linking aid is sprayed into the semi-finished product after shaking the dehydrated semi-finished product; after the spraying is completed, the semi-finished product is shaken for a preset time, and then the semi-finished product is heated and absorbed to prepare a cable insulation material;

[0134] Among them, the number of small molecules with a weight average molecular weight less than 4000Da contained in the polyethylene is 0; the antioxidant includes one or more of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol), 4,4'-thiobis(6-tert-butyl-2,3-ethylene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol]; the crosslinking agent includes one or more of diisopropyl peroxide, benzoyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane.

[0135] It can be understood that the preparation method of cable insulation material for long-length extrusion provided in the present application adopts a shaking and spraying method to apply a mixed liquid containing a cross-linking agent and a cross-linking aid, which is conducive to the uniform application of the cross-linking agent and the cross-linking aid on the surface of the semi-finished material; the subsequent heat preservation post-treatment is conducive to the cross-linking agent and the cross-linking aid to penetrate into the interior of the semi-finished material, so that the cross-linking agent and the cross-linking aid can be evenly distributed in the cable insulation material, thereby improving the quality of the cable insulation material.

[0136] In some embodiments, a twin-screw extruder is used for extrusion, and the extrusion temperature is 160°C-185°C; for example, it can be but is not limited to 160°C, 162°C, 164°C, 166°C, 168°C, 170°C, 172°C, 174°C, 176°C, 178°C, 180°C, 182°C, 184°C, 185°C or a range between any two of the above temperatures.

[0137] It should be noted that the temperature control during twin-screw extrusion is divided into 6 stages, and the extrusion temperature mentioned above refers to the temperature of the highest temperature stage during twin-screw extrusion.

[0138] As a possible implementation mode, a twin-screw extruder is used for extrusion, and the screw speed is 100rpm-175rpm; for example, it can be but not limited to 100rpm, 105rpm, 110rpm, 115rpm, 120rpm, 125rpm, 130rpm, 135rpm, 140rpm, 145rpm, 150rpm, 155rpm, 160rpm, 165rpm, 170rpm, 175rpm or a range between any two of the above speeds.

[0139] In some embodiments, the semi-finished product is dehydrated by centrifugation.

[0140] In some optional embodiments, the shaking speed is 10rpm-30rpm; for example, it can be but not limited to 10rpm, 12rpm, 14rpm, 16rpm, 20rpm, 22rpm, 24rpm, 26rpm, 28rpm, 30rpm or a range between any two of the above speeds.

[0141] As a non-limiting example, the semi-finished product after the dehydration process is placed in a shaking tank to be shaken, and the temperature of the shaking tank may be 80°C.

[0142] As a possible implementation, the preset time is 30min-60min; for example, it may be but not limited to 30min, 32min, 34min, 36min, 38min, 40min, 42min, 44min, 46min, 48min, 50min, 52min, 54min, 56min, 58min, 60min or a range between any two of the above times.

[0143] In some optional embodiments, the absorption temperature after insulation is 60°C-80°C; for example, it can be but not limited to 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C or a range between any two of the above temperatures.

[0144] As a possible implementation manner, the absorption time after insulation is 16h-28h; for example, it can be but not limited to 16h, 18h, 20h, 22h, 24h, 26h, 28h or a range between any two of the above times.

[0145] It should be noted that the temperature and time of absorption after insulation can be combined in any appropriate manner, and both can be selected from any temperature and time of absorption after insulation described in this article.

[0146] One or more embodiments of the present application provide a use of the above-mentioned cable insulation material for long-length extrusion or the cable insulation material for long-length extrusion prepared by the above-mentioned preparation method in preparing cables.

[0147] One or more embodiments of the present application provide a cable, the raw materials for preparing the cable include the above-mentioned cable insulation material for long-length extrusion or the cable insulation material for long-length extrusion prepared by the above-mentioned preparation method.

[0148] In some exemplary embodiments, the cable is a submarine cable.

[0149] As a non-limiting example, the cable has a carrying voltage of 500 kV and below.

[0150] It should be noted that the “carrying voltage” mentioned in this context refers to the voltage at which the cable can operate safely and stably.

[0151] The technical scheme of the present invention is described in detail below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods for which specific conditions are not specified in the following embodiments are preferably referred to the guidance given in the present invention, and can also be carried out according to the experimental manual or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0152] In the following specific embodiments, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed.

[0153] 1. Preparation of cable insulation materials

[0154] 1. Prescription composition

[0155] The prescription compositions of Examples 1-7 are shown in Table 1-1, the prescription compositions of Examples 8-14 are shown in Table 1-2, and the prescription compositions of Example 15 and Comparative Examples 1-4 are shown in Table 1-3.

[0156] Table 1-1

[0157]

[0158] Table 1-2

[0159]

[0160] Table 1-3

[0161]

[0162] In Table 1-1, Table 1-2 and Table 1-3, LDPE represents low-density polyethylene, wherein the density of LDPE used in Examples 1-15, Comparative Examples 1-2 and Comparative Example 4 is 0.925 g / cm 3 , melt index is 2.0g / 10min, weight average molecular weight is 100000Da, molecular weight distribution is 5.5PDI, branching degree is 3.5 per thousand carbon atoms, double bond content is 1.0 per thousand carbon atoms, and the number of small molecules with a weight average molecular weight less than 4000Da is 0. The density of LDPE used in Comparative Example 3 is 0.89g / cm 3 The melt index is 3.0g / 10min, the weight average molecular weight is 100000Da, the molecular weight distribution is 5.5PDI, the degree of branching is 3.5 branched carbon atoms per thousand carbon atoms, the double bond content is 1.0 double bond carbon atoms per thousand carbon atoms, and the number of small molecules with a weight average molecular weight of less than 4000Da is 380.

[0163] DCP stands for dicumyl peroxide, AMSD stands for poly(α-methylstyrene) dimer, BIPB stands for 1,4-bis-tert-butylperoxyisopropylbenzene, and TBHP stands for tert-butyl hydroperoxide.

[0164] 2. Preparation process

[0165] Example 1

[0166] Step S1, the low-density polyethylene and the antioxidant are fully mixed in a high-speed mixer for 20 minutes, and then extruded and granulated twice through a twin-screw extruder to obtain a semi-finished product; wherein, the six-stage heating temperatures in the twin-screw extrusion process are 120°C, 145°C, 155°C, 160°C, 165°C and 170°C, respectively, and the screw speed is 150rpm.

[0167] Step S2, centrifugally dehydrate and dry the semi-finished product, and place it in a shaking tank, maintain the temperature in the shaking tank at 80°C, heat the mixed cross-linking agent and the cross-linking auxiliary agent to 80°C respectively, and then spray them into the shaking tank, while starting the shaking tank to maintain a constant speed and continue shaking for 60 minutes after the spraying is completed; wherein the shaking speed of the shaking tank is 20rpm.

[0168] Step S3, transferring the material after shaking to a thermostatic box, maintaining the temperature of the thermostatic box at 80°C, standing and absorbing for 24 hours, and preparing a cable insulation material.

[0169] Example 2

[0170] Step S1, the low-density polyethylene and the antioxidant are fully mixed in a high-speed mixer for 20 minutes, and then extruded and granulated twice by a twin-screw extruder to obtain a semi-finished product; wherein, the six-stage heating temperatures in the twin-screw extrusion process are 130°C, 150°C, 160°C, 165°C, 170°C and 175°C, respectively, and the screw speed is 100rpm.

[0171] Step S2, centrifugally dehydrate and dry the semi-finished product, and place it in a shaking tank, keep the temperature inside the tube at 80°C, heat the mixed cross-linking agent and the cross-linking auxiliary agent to 80°C respectively, and then spray them into the shaking tank, start the shaking tank at a constant speed and continue shaking for 60 minutes after the spraying is completed; wherein the shaking speed of the shaking tank is 10rpm.

[0172] Step S3, transferring the material after shaking to a thermostatic box, maintaining the temperature of the thermostatic box at 80°C, standing and absorbing for 24 hours, and preparing a cable insulation material.

[0173] Example 3

[0174] Step S1, fully mixing the low-density polyethylene and the antioxidant in a high-speed mixer for 20 minutes, and then extruding and granulating them twice through a twin-screw extruder to obtain a semi-finished product; wherein the six-stage heating temperatures in the twin-screw extrusion process are 120°C, 155°C, 165°C, 170°C, 175°C and 185°C, respectively, and the screw speed is 120rpm.

[0175] Step S2, centrifugally dehydrate and dry the semi-finished product, and place it in a shaking tank, keep the temperature inside the tube at 80°C, heat the mixed cross-linking agent and the cross-linking auxiliary agent to 80°C respectively, and then spray them into the shaking tank, start the shaking tank at a constant speed and continue shaking for 60 minutes after the spraying is completed; wherein the shaking speed of the shaking tank is 30rpm.

[0176] Step S3, transferring the material after shaking to a thermostatic box, maintaining the temperature of the thermostatic box at 80°C, standing and absorbing for 24 hours, and preparing a cable insulation material.

[0177] The difference between the preparation methods of Examples 4-15 and Comparative Examples 1-3 and the preparation method of Example 1 is that at least one of the mixing time when mixing the materials in step S1, the six-stage heating temperature settings during the twin-screw extrusion process, the screw speed, the time for continuing to shake after the spraying in step S2, the shaking speed of the shaking can, and the temperature and time of post-absorption in step S3 is different. See Table 2 for details.

[0178] Table 2

[0179]

[0180] The preparation process of Comparative Example 4 is as follows:

[0181] Step S1, fully mixing low-density polyethylene and 4,4'-thiobis(6-tert-butyl-3-methylphenol) in a high-speed mixer for 10 minutes, and then extruding and granulating the mixture twice in a twin-screw extruder to obtain a semi-finished product; wherein the six heating temperatures in the twin-screw extrusion process are 100°C, 145°C, 150°C, 160°C, 166°C and 174°C, respectively, and the screw speed is 100rpm.

[0182] Step S2, centrifugally dehydrate and dry the semi-finished product, and place it in a shaking tank, maintain the temperature at 80°C, heat the cross-linking agent to 72°C, and then spray it into the shaking tank. At the same time, start the shaking tank to maintain a constant speed and continue shaking for 30 minutes after the spraying is completed; wherein the shaking speed of the shaking tank is 20rpm.

[0183] Step S3, transferring the material after shaking to a thermostatic box, maintaining the temperature of the thermostatic box at 65°C, standing and absorbing for 24 hours, and preparing a cable insulation material.

[0184] 2. Performance Test

[0185] 1. The test conditions and test results of the thermomechanical properties and scorch resistance of the cable insulation materials prepared in the above embodiments and comparative examples are shown in Table 3.

[0186] Table 3

[0187]

[0188] From the comparison of the results of Examples 1-15 and Comparative Examples 1-4 in Table 3, it can be seen that compared with Comparative Examples 1-4, the tensile strength and elongation at break of the cable insulation materials in Examples 1-15 are greater, the change rate of tensile strength (≤20MPa) and the change rate of elongation at break are both smaller (≤20%), the elongation under load is smaller, the scorch time is longer, the cross-linking rate is lower, and the volume resistivity is greater, indicating that the cable insulation material provided in the present application has better thermal stability, anti-aging performance and anti-scorch properties.

[0189] By comparing the results of Example 1, Examples 4-5 and Examples 10-15, it can be seen that by adopting an antioxidant composition with a suitable ratio, a cross-linking agent composition with a suitable ratio and a cross-linking aid composition with a suitable ratio, it helps to further improve the thermal stability, anti-aging performance and anti-scorch properties of the cable insulation material.

[0190] It is also understandable that if the antioxidant composition in Example 2 does not adopt a suitable ratio, the crosslinking agent composition does not adopt a suitable ratio, or the crosslinking auxiliary composition does not adopt a suitable ratio, and if the antioxidant composition in Example 3 does not adopt a suitable ratio, the crosslinking agent composition does not adopt a suitable ratio, or the crosslinking auxiliary composition does not adopt a suitable ratio, the results will be similar to those in Examples 10-15, that is, the quality of the prepared cable insulation material will be affected. Therefore, by adjusting the ratio of the antioxidant composition, the ratio of the crosslinking agent composition, and the ratio of the crosslinking auxiliary composition in Example 2 to be within a suitable range, and by adjusting the ratio of the antioxidant composition, the ratio of the crosslinking agent composition, and the ratio of the crosslinking auxiliary composition in Example 3 to be within a suitable range, it is also helpful to further improve the thermal stability, anti-aging performance, and anti-scorch properties of the cable insulation material.

[0191] From the comparison of the results of Examples 1-15 and Comparative Examples 1-2, it can be seen that the use of specific types of antioxidants, crosslinking agents and crosslinking aids in combination can help further improve the quality of cable insulation materials and extend the extrusion processing time.

[0192] Comparison of the results in Example 1 and Comparative Example 3 shows that the use of small molecule polyethylene with a weight average molecular weight of less than 4000 Da can significantly shorten the scorch time of the insulating material. The introduction of small molecules leads to rapid cross-linking of the insulating material, resulting in a rapid reduction in the extrusion time of the insulating material.

[0193] The cable insulation materials in Example 1 and Comparative Example 4 were subjected to a long-term extrusion test. The long-term extrusion test method was to use a single-screw extruder with a pre-net pressure sensor to carry out a long-term extrusion experiment on insulation materials of different formulations, and to study the change of extrusion pressure over time; the test results are shown in FIG. Figure 1 shown.

[0194] Depend on Figure 1 It can be seen that compared with the long-term extrusion of the cable insulation material in Comparative Example 4, the cable insulation material provided in the present application has small extrusion pressure fluctuation and good stability when it is extruded for a long time; the cable insulation material provided in the present application has excellent long-term extrusion stability.

[0195] 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.

[0196] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A cable insulation material for long-length extrusion, characterized in that: including polyethylene, antioxidant, cross-linking agent and cross-linking aid; Wherein, the number of small molecules with a weight average molecular weight less than 4000Da contained in the polyethylene is 0; The antioxidant includes one or more of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol), 4,4'-thiobis(6-tert-butyl-2,3-ethylene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol]; The cross-linking agent includes one or more of dicumyl peroxide, benzoyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane; The cross-linking auxiliary agent includes one or more of poly(α-methylstyrene) dimer, 1,4-di-tert-butylperoxyisopropylbenzene, tert-butyl hydroperoxide and methyltriacetoxysilane.

2. The cable insulation material according to claim 1, characterized in that: The antioxidant has one of the following characteristics (1)-(3): (1) The antioxidant comprises a mixture of 4,4'-thiobis(6-tert-butyl-m-cresol) and 4,4'-thiobis(5-tert-butyl-m-cresol) in a mass ratio of (1.2-2.1):(0.8-1.0); (2) The antioxidant comprises a mixture of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol) and 4,4'-thiobis(6-tert-butyl-2,3-ethylene) in a mass ratio of (0.8-1.2):(0.5-1.0):(0.2-0.5); (3) The antioxidant comprises a mixture of 4,4'-thiobis(6-tert-butyl-2,3-ethylene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol] in a mass ratio of (0.8-1.5):(1.0-2.0).

3. The cable insulation material according to claim 1, characterized in that: The crosslinking agent has one of the following characteristics (1)-(3): (1) The crosslinking agent comprises a mixture of dicumyl peroxide and benzoyl peroxide in a mass ratio of (0.8-3.5):(0.5-2.5); (2) The crosslinking agent comprises a mixture of 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane in a mass ratio of (0.5-1.5):(0.7-2.3); (3) The crosslinking agent comprises a mixture of diisopropylbenzene peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane in a mass ratio of (1.0-2.0):(0.5-1.5):(0.2-0.6).

4. The cable insulation material according to claim 1, characterized in that: The crosslinking aid has one of the following characteristics (1)-(2): (1) The crosslinking aid comprises a mixture of poly(α-methylstyrene) dimer and 1,4-di-tert-butylperoxyisopropylbenzene in a mass ratio of (0.1-0.5):(0.1-0.3); (2) The crosslinking aid comprises a mixture of tert-butyl hydroperoxide and methyltriacetoxysilane in a mass ratio of (0.2-1.0):(0.5-2.0).

5. The cable insulation material according to claim 1, characterized in that: The polyethylene comprises at least one of the following features: (1) The density of the polyethylene is 0.915 g / cm 3 -0.935g / cm 3 ; (2) The melt index of the polyethylene is 1.6 g / 10 min-2.4 g / 10 min; (3) The weight average molecular weight of the polyethylene is 60000Da-120000Da; (4) The molecular weight distribution of the polyethylene is 4.0 PDI-9.0 PDI; (5) The degree of branching of the polyethylene is 1.5 to 5.5 branched carbon atoms per thousand carbon atoms; (6) The double bond content of the polyethylene is 0.1 to 1.5 carbon atoms containing terminal double bonds per thousand carbon atoms.

6. The cable insulation material according to any one of claims 1 to 5, characterized in that: In parts by weight, the cable insulation material comprises: Polyethylene 90-100 parts; Antioxidant 0.05-0.4 parts; 0.6 to 3.5 parts of a cross-linking agent; and Cross-linking aid: 0.05-0.5 parts.

7. The cable insulation material according to any one of claims 1 to 5, characterized in that: The cable insulation material has at least one of the following characteristics (1)-(9): (1) The tensile strength of the cable insulation material is 17.5MPa-25MPa; (2) The elongation at break of the cable insulation material is 480%-550%; (3) The tensile strength variation rate of the cable insulation material is 5Mpa-22.5Mpa; (4) The elongation at break of the cable insulation material has a variation rate of 1.9% to 15.3%; (5) The elongation under load of the cable insulation material is 50%-90%; (6) The permanent deformation rate of the cable insulation material after cooling is 0-2%; (7) The scorch time of the cable insulation material is 3.5min-9.7min; (8) The cross-linking rate of the cable insulation material is 2.6 N·m / min -5.9 N·m / min; (9) The volume resistivity of the cable insulation material is 0.2×10 12 Ω·m -9.3×10 12 Ω·m.

8. A method for preparing a cable insulation material for long-length extrusion, characterized in that: The steps include: The polyethylene and the antioxidant are mixed, extruded, and granulated to prepare a semi-finished product; Dehydrating the semi-finished product; Spraying a mixed liquid containing a cross-linking agent and a cross-linking aid into the semi-finished product after shaking the dehydrated product; After the spraying is finished, the shaking is continued for a preset time, and then the insulation is performed and then absorbed to prepare the cable insulation material; Wherein, the number of small molecules with a weight average molecular weight less than 4000Da contained in the polyethylene is 0; The antioxidant includes one or more of 4,4'-thiobis(6-tert-butyl-m-cresol), 4,4'-thiobis(5-tert-butyl-m-cresol), 4,4'-thiobis(6-tert-butyl-2,3-ethylene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol]; The cross-linking agent includes one or more of dicumyl peroxide, benzoyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane; The cross-linking auxiliary agent includes one or more of poly(α-methylstyrene) dimer, 1,4-di-tert-butylperoxyisopropylbenzene, tert-butyl hydroperoxide and methyltriacetoxysilane.

9. The preparation method according to claim 8, characterized in that: The extrusion is performed using a twin-screw extruder, the extrusion temperature is 160° C.-185° C., and the screw speed is 100 rpm-175 rpm.

10. The preparation method according to claim 8, characterized in that: The semi-finished product is dehydrated by centrifugation.

11. The preparation method according to any one of claims 8 to 10, characterized in that: The shaking speed is 10rpm-30rpm; The preset time is 30min-60min.

12. The preparation method according to any one of claims 8 to 10, characterized in that: The temperature of the absorption after the insulation is 60° C.-80° C., and the time is 16 h-28 h.

13. Use of the cable insulation material for long-length extrusion according to any one of claims 1 to 7 in the preparation of cables.

14. A cable, characterized in that: The raw materials for preparing the cable include the cable insulation material for long-length extrusion according to any one of claims 1 to 7.

15. The cable according to claim 14, characterized in that The cable is a submarine cable.

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