Cable insulating material for long-length extrusion, its preparation method, application and cable

Abstract

The present application provides a cable insulating compound for long-length extrusion, a preparation method, an application thereof, and a cable. The cable insulating compound for long-length extrusion comprises polyethylene, an antioxidant, a crosslinking agent, and a crosslinking aid. The cable insulating compound for long-length extrusion provided by the present application performs blend modification on the insulating compound at the formulation stage. By regulating the properties of polyethylene and using specific antioxidant and crosslinking agent in combination, when the prepared insulating compound is subjected to long-length extrusion, the pressure fluctuation is small, the stability is good, and the discharging is smooth, thereby improving the stability of the insulating compound during long-length extrusion. In addition, the cable insulating compound has excellent quality and excellent thermal stability, anti-scorching characteristics, electrical insulation performance, and anti-aging performance, which is of great significance for enhancing the market competitiveness of cable products.

Description

Technical Field

[0001] The present application relates to the technical field of insulating materials, and particularly to a cable insulating compound for long-length extrusion, its preparation method, application, and cable. Background Art

[0002] In the field of power transmission, as the main carrier for electric energy transmission, the performance of cables is directly related to the stable operation of the power system. With the acceleration of urbanization and the improvement of industrialization level, the requirements for the reliability and stability of power supply are increasing day by day, which puts forward higher performance requirements for cable insulating materials. Especially in long-distance power transmission, urban power grid construction, and submarine cable power transmission, long-length cables have gradually become the mainstream market demand due to their advantages such as reducing the number of joints, lowering failure rates, and improving transmission efficiency.

[0003] However, the development of long-length cable insulating compound preparation technology still faces many challenges. For example, how to extend the continuous extrusion time of long lengths and achieve the extrusion of longer cables 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 insulating compound for long-length extrusion, its preparation method, application, and cable to improve the continuity of long-length extrusion of cable insulating compounds.

[0005] The first aspect of the present application provides a cable insulating compound for long-length extrusion, which includes polyethylene, antioxidant, crosslinking agent, and crosslinking aid;

[0006] Among them, the number of small molecules with a weight-average molecular weight less than 4000 Da 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-ethylidene), and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol];

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

[0009] The crosslinking aid includes one or more of poly(α-methylstyrene) dimer, 1,4-bis(tert-butylperoxyisopropyl)benzene, 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 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-ethylidene) 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-ethylidene) 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 crosslinking agent comprises a mixture of 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-bis(tert-butylperoxy)ethane in a mass ratio of (0.5 - 1.5):(0.7 - 2.3).

[0015] In some embodiments, the crosslinking agent comprises a mixture of dicumyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-bis(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 crosslinking aid comprises a mixture of poly(α-methylstyrene) dimer and 1,4-bis(tert-butylperoxyisopropyl)benzene in a mass ratio of (0.1 - 0.5):(0.1 - 0.3).

[0017] In some embodiments, 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).

[0018] In some embodiments, the polyethylene comprises at least one of the following characteristics:

[0019] (1) The density of the polyethylene is 0.915 g / cm 3 - 0.935 g / 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 60,000 Da - 120,000 Da;

[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 the number of branched carbon atoms per thousand carbon atoms is 1.5 - 5.5;

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

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

[0026] 90 parts - 100 parts of polyethylene;

[0027] 0.05 parts - 0.4 parts of antioxidant;

[0028] 0.6 parts - 3.5 parts of crosslinking agent; and

[0029] 0.05 parts - 0.5 parts of crosslinking aid.

[0030] In some embodiments, compared with the conventional insulating materials used in the cable field, the anti-scorch property, electrical insulation property and thermo-mechanical property of the cable insulating material are all improved.

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

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

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

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

[0035] (4) The change rate of the elongation at break of the cable insulating material is 1.9% - 15.3%;

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

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

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

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

[0040] (9) The volume resistivity of the cable insulating 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 insulating material for long - length extrusion, including the following steps:

[0042] Mix polyethylene with an antioxidant and then extrude and pelletize to prepare a semi - finished material;

[0043] Perform dehydration treatment on the semi - finished material;

[0044] While shaking the dehydrated semi - finished material, spray a mixed liquid containing a crosslinking agent and a crosslinking aid onto it;

[0045] After the spraying ends, continue to shake for a preset time, and then perform heat preservation and absorption to prepare the cable insulating material;

[0046] Among them, the number of small molecules with a weight - average molecular weight less than 4000 Da 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 - ethylidene), and 4,4'-thiobis[5 - decyl - 2-(1,1 - dimethylethyl)phenol];

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

[0049] The crosslinking aid includes one or more of poly(α - methylstyrene) dimer, 1,4 - bis(tert - butylperoxy)cumene, tert - butyl hydroperoxide, and methyltriacetoxysilane.

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

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

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

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

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

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

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

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

[0058] For the above-mentioned cable insulating material for long-length extrusion, the insulating material is compounded and modified at the formulation stage. By regulating the properties of polyethylene and using specific antioxidants, cross-linking agents, and cross-linking aids in combination, when the prepared insulating material is extruded in a long length, the pressure fluctuation is small, the stability is good, the discharging is smooth, and the scorch resistance performance is excellent, thereby improving the stability during the extrusion of the insulating material. In addition, the quality of this cable insulating material is good, and it has excellent thermal stability, anti-scorch characteristics, electrical insulation performance, and anti-aging performance, which is of great significance for enhancing the market competitiveness of cable products. Description of the Drawings

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application and more comprehensively understand the present application and its beneficial effects, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0060] Figure 1 For the long-time extrusion test results of Example 1 and Comparative Example 4. Detailed Embodiments

[0061] For the convenience of understanding the present invention, the present application will be described more comprehensively below with reference to related embodiments. The following gives preferred embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present application more thorough and comprehensive.

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

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

[0064] In this application, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0065] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0066] Only some numerical ranges are specifically disclosed herein. However, any lower limit can be combined with any upper limit to form a range not explicitly recorded; and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, each separately disclosed point or single numerical value itself can be used as a lower limit or an upper limit to be combined with any other point or single numerical value or with other lower limits or upper limits to form a range not explicitly recorded.

[0067] The temperature parameters in this application, unless otherwise specified, allow for 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 ranges such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0068] In this text, the "suitable" in "suitable combination method", "suitable method", "any suitable method", etc. is 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 this application, "further", "even further", "especially", etc. are used for descriptive purposes, indicating differences in content, but should not be construed as limiting the protection scope of this application.

[0070] In this application, "optionally", "optional", "option" mean that it can be either present or absent, that is, it refers to any one of the two parallel options of "present" or "absent". If "optional" appears multiple times in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" is independent.

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

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

[0073] If there is no special description, all steps of this application can be carried out in sequence or randomly, and preferably in sequence.

[0074] Due to advantages such as reducing the number of joints, lowering the failure rate, and improving the transmission efficiency, large-length cables have gradually become the mainstream demand in the market. However, the preparation technology of large-length cable insulating materials faces many challenges. Traditional methods for preparing cable insulating materials often have difficulty achieving continuous extrusion of large lengths, resulting in low production efficiency and difficult-to-guarantee quality.

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

[0076] Based on the above problems, in this application, the insulating material is blended and modified at the formulation stage, the properties of polyethylene are regulated, and specific antioxidants and crosslinking agents are used in combination to improve the stability during the long-length extrusion of the insulating material and improve the quality of the cable insulating material.

[0077] One or more embodiments of this application provide a cable insulating material for long-length extrusion, including polyethylene, an antioxidant, a crosslinking agent, and a crosslinking aid;

[0078] Among them, the number of small molecules with a weight-average molecular weight less than 4000 Da 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 dicumyl peroxide (DCP), benzoyl peroxide, 4-allyl-1-(allyloxy)-2-methoxybenzene, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)ethane; the crosslinking aid includes one or more of poly(α-methylstyrene) dimer, 1,4-bis(tert-butylperoxyisopropyl)benzene, tert-butyl hydroperoxide, and methyltriacetoxysilane.

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

[0080] It can be understood that for the cable insulating material for long-length extrusion provided in this application, the insulating material is blended and modified at the formulation stage. By regulating the properties of polyethylene and using specific antioxidants, crosslinking agents, and crosslinking aids in combination, when the prepared insulating material is extruded in a long length, the pressure fluctuation is small, the stability is good, and the discharging is smooth, thus improving the stability during the extrusion of the insulating material. In addition, this cable insulating material has good quality and excellent thermal stability, scorch resistance, electrical insulation performance, and anti-aging performance, which is of great significance for enhancing 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) with 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 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-ethylidene) 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-ethylidene) in the antioxidant can 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 embodiment, the antioxidant comprises a mixture of 4,4'-thiobis(6-tert-butyl-2,3-ethylidene) 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-ethylidene) and 4,4'-thiobis[5-decyl-2-(1,1-dimethylethyl)phenol] in the antioxidant can 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 respectively adopts a mixture of two or more antioxidants with the above mass ratio, it is beneficial to further improve the extrusion stability and aging resistance characteristics of the insulating material, as well as enhance the scorch resistance, electrical insulation performance, and thermomechanical properties of the insulating material.

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

[0089] As an example, the mass ratio of dicumyl peroxide and 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 alternative embodiments, the crosslinking agent includes a mixture of 4-allyl-1-(allyloxy)-2-methoxybenzene and 2,5-dimethyl-2,5-bis(tert-butylperoxy)ethane with 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 to 2,5-dimethyl-2,5-di(tert-butylperoxy)ethane in the crosslinking 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 with 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 crosslinking 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 crosslinking agent uses a mixture of two or more crosslinking agents with the above mass ratios, it is beneficial to further improve the extrusion stability and anti-scorch characteristics of the insulating material, as well as enhance the electrical insulation performance and thermo-mechanical properties of the insulating material.

[0095] In some alternative implementations, the crosslinking aid includes a mixture of poly(α-methylstyrene) dimer and 1,4-bis(tert-butylperoxyisopropyl)benzene with 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 to 1,4-bis(tert-butylperoxyisopropyl) benzene 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 of these embodiments, 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).

[0098] As a non-limiting example, 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 crosslinking aid respectively adopts a mixture of two or more crosslinking aids having the above mass ratio, it is beneficial to further improve the scorch resistance, electrical insulation performance, and thermomechanical properties of the insulating material.

[0100] In some embodiments, the density of the polyethylene is 0.915 g / cm 3 - 0.935 g / cm 3 ; for example, it can be, but is not limited to, 0.915 g / cm 3 , 0.917 g / cm 3 , 0.92 g / cm 3 , 0.923 g / cm 3 , 0.925 g / cm 3 , 0.927 g / cm 3 , 0.93 g / cm 3 , 0.932 g / cm 3 , 0.935 g / cm 3Or a range between any two of the above densities, etc. When the density of polyethylene is within the above range, the molecular chains of the polyethylene base material have an appropriate content of physical entanglement sites, which is conducive to improving the crosslinking degree of the prepared insulating material, reducing the dosage of various additives, and decreasing the crosslinking rate. In addition, it occupies a smaller volume in the storage and transportation media, which is beneficial to improving the space utilization rate of the insulating material production workshop.

[0101] As a possible implementation manner, the melt index of the polyethylene is 1.6 g / 10 min - 2.4 g / 10 min; for example, it can be, 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, 2.0 g / 10 min, 2.1 g / 10 min, 2.2 g / 10 min, 2.3 g / 10 min, 2.4 g / 10 min, or a range between any two of the above melt indexes, etc. When the melt index of the polyethylene is within the above range, it is beneficial to the parameter regulation during the extrusion processing of long-length insulating materials.

[0102] It should be noted that the test conditions for the "melt index" mentioned above are: when the load is 2.16 kg, the test is carried out in accordance with the ASTM D1238 standard.

[0103] In some of the implementation manners, the weight-average molecular weight of the polyethylene is 60,000 Da - 120,000 Da; for example, it can be, but is not limited to, 60,000 Da, 61,000 Da, 62,000 Da, 64,000 Da, 66,000 Da, 68,000 Da, 70,000 Da, 72,000 Da, 74,000 Da, 76,000 Da, 78,000 Da, 80,000 Da, 82,000 Da, 84,000 Da, 86,000 Da, 88,000 Da, 90,000 Da, 92,000 Da, 94,000 Da, 96,000 Da, 98,000 Da, 100,000 Da, 102,000 Da, 104,000 Da, 106,000 Da, 108,000 Da, 110,000 Da, 112,000 Da, 114,000 Da, 116,000 Da, 118,000 Da, 120,000 Da, or a range between any two of the above weight-average molecular weights, etc. When the weight-average molecular weight of the 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 the crosslinking of the material, is conducive to reducing the addition content of additives, improving the purity of the insulating material, and prolonging the extrusion time of the cable insulating material.

[0104] In some exemplary embodiments, the molecular weight distribution of the polyethylene is 4.0 PDI - 9.0 PDI; for example, it can 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 the 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 degree of 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 embodiment, the degree of branching of the polyethylene is such that the number of branched carbon atoms per thousand carbon atoms is 1.5 - 5.5; for example, it can be, but is 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, etc. When the degree of branching of the polyethylene is within the above range, it indicates that the content of branched chain segments in the polyethylene molecule is relatively low, and the low number of branched chain segments is beneficial to improving the degree of crosslinking of the polyethylene, reducing the content of additives, and prolonging the extrusion time of the insulating material.

[0106] In some alternative embodiments, the double bond content of the polyethylene is such that the number of terminal double bond carbon atoms per thousand carbon atoms is 0.1 - 1.5; for example, it can be, but is 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, etc. When the double bond content of the polyethylene is within the above range, the terminal double bonds of the polyethylene can effectively crosslink with the additives to control the crosslinking rate of the insulating material within an appropriate range.

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

[0108] 90 parts - 100 parts of polyethylene;

[0109] 0.05 parts - 0.4 parts of antioxidant;

[0110] 0.6 parts - 3.5 parts of crosslinking agent; and

[0111] 0.05 parts - 0.5 parts of crosslinking aid.

[0112] As a non-limiting example, by weight parts, the weight parts of polyethylene contained in the cable insulating material can be, but are 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 the range between any two of the above weight parts, etc.

[0113] By weight parts, the weight parts of the antioxidant contained in the cable insulating material can be, but are 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, or the range between any two of the above weight parts, etc.

[0114] By weight parts, the weight parts of the crosslinking agent contained in the cable insulating material can be, but are not limited to, 0.6 parts, 0.8 parts, 1 part, 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, etc.

[0115] By weight parts, the weight parts of the crosslinking aid contained in the cable insulating material can be, but are 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 the range between any two of the above weight parts, etc.

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

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

[0118] As a possible embodiment, the elongation at break of the cable insulating material for long-length extrusion is 480% - 550%; it can be optionally 520% - 550%.

[0119] It should be noted that the test temperature of the tensile strength and elongation at break mentioned in the context is 23 °C.

[0120] In some embodiments, the rate of change of the tensile strength of the cable insulating material for long-length extrusion is 5 Mpa - 22.5 Mpa; it can be 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 rate of change of elongation at break of the cable insulating material for long-length extrusion is 1.9% - 15.3%; optionally 1.9% - 5.9%.

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

[0123] In some implementations, the elongation at load of the cable insulating material for long-length extrusion is 50% - 90%; optionally 50% - 65%.

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

[0125] It should be noted that the test methods for the elongation at load and the permanent set rate after cooling mentioned in the context include: placing the insulating material at 200°C and 0.2 MPa for 15 min, and then testing the elongation at load and the permanent set rate after cooling of the insulating material.

[0126] In some implementations, the scorch time of the cable insulating 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 time mentioned in the context is tested by the method of rotorless curing, and the test parameters include: temperature is 160°C, time is 2 h, and vibration frequency is 100 cpm.

[0128] As a possible implementation, the crosslinking rate of the cable insulating 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 crosslinking rate mentioned in the context is tested by a torque rheometer, and the test parameters include: temperature is 140°C and rotation speed is 60 rpm.

[0130] In some implementations, the volume resistivity of the cable insulating material for long-length extrusion is 0.2×10 12 Ω·m - 9.3×10 12 Ω·m; optionally 1.8×10 12 Ω·m - 9.3×10 12 Ω·m.

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

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

[0133] Mix polyethylene with an antioxidant and then extrude and pelletize to prepare a semi-finished material; perform dehydration treatment on the semi-finished material; while shaking the dehydrated semi-finished material, spray a mixture liquid containing a cross-linking agent and a cross-linking aid onto it; continue to shake for a preset time after the spraying ends, and then perform heat preservation and absorption to prepare the cable insulating material;

[0134] Among them, the number of small molecules with a weight-average molecular weight less than 4000 Da 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-bis(tert-butylperoxy)ethane.

[0135] It can be understood that in the preparation method for the cable insulating material for long-length extrusion provided by the present application, the mixture liquid containing the cross-linking agent and the cross-linking aid is applied in a way of spraying while shaking, which is beneficial to the uniform application of the cross-linking agent and the cross-linking aid on the surface of the semi-finished material; subsequent heat preservation post-treatment is beneficial to the penetration of the cross-linking agent and the cross-linking aid into the interior of the semi-finished material, so that the cross-linking agent and the cross-linking aid can be uniformly distributed in the cable insulating material, improving the quality of the cable insulating 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 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 the range between any two of the above temperatures, etc.

[0137] It should be noted that the temperature control during twin-screw extrusion is in 6 segments, and the above-mentioned extrusion temperature refers to the temperature of the highest temperature section during twin-screw extrusion.

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

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

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

[0141] As a non-limiting example, the semi-finished material after dehydration treatment is placed in a shaking tank to shake it, and the temperature of the shaking tank can be 80°C.

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

[0143] In some alternative embodiments, the temperature after heat preservation and absorption is 60°C - 80°C; for example, it can be but is 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 the range between any two of the above temperatures, etc.

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

[0145] It should be noted that the temperature and time after heat preservation and absorption can be combined in any suitable manner, and both can be selected from any of the temperatures and times after heat preservation and absorption described herein respectively.

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

[0147] One or more embodiments of the present application provide a cable, and the raw materials for its preparation include the above-mentioned cable insulating material for long-length extrusion or the cable insulating 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 load-bearing voltage of the cable is 500 kV or less.

[0150] It should be noted that the "load-bearing voltage" mentioned in the context refers to the voltage at which the cable can operate safely and stably.

[0151] The technical solutions of the present invention will be 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 not to limit the scope of the present invention. For the experimental methods without specific conditions in the following embodiments, priority is given to the guidance given in the present invention, and it can also be carried out according to the experimental manuals or conventional conditions in the art, or according to the conditions recommended by the manufacturer, or referring to the experimental methods known in the art.

[0152] In the following specific embodiments, for the measurement parameters of the raw material components, if there is no special description, there may be slight deviations within the weighing accuracy range. For the temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed.

[0153] I. Preparation of Cable Insulating Material

[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 Examples 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 Tables 1-1, 1-2 and 1-3, LDPE represents low-density polyethylene. Among them, the density of the LDPE used in Examples 1-15, Comparative Example 1-2 and Comparative Example 4 is 0.925 g / cm 3 , the melt index is 2.0 g / 10 min, the weight-average molecular weight is 100,000 Da, the molecular weight distribution is 5.5 PDI, 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 less than 4000 Da is 0. The density of the LDPE used in Comparative Example 3 is 0.89 g / cm 3 , the melt index is 3.0 g / 10 min, the weight-average molecular weight is 100,000 Da, the molecular weight distribution is 5.5 PDI, 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 less than 4000 Da is 380.

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

[0164] 2. Preparation process

[0165] Example 1

[0166] Step S1: Thoroughly mix low-density polyethylene and antioxidant in a high-speed mixer for 20 min, and then extrude and pelletize twice through a twin-screw extruder to obtain a semi-finished material; among them, the six-section heating temperatures during 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 150 rpm.

[0167] Step S2: Centrifuge and dehydrate the semi-finished material, then dry it and place it in a shaking tank. Keep the temperature in the shaking tank at 80°C. Heat the mixed cross-linking agent and cross-linking aid to 80°C respectively, then spray them into the shaking tank. At the same time, start the shaking tank to maintain a constant speed and continue to shake for 60 min after spraying; among them, the shaking speed of the shaking tank is 20 rpm.

[0168] Step S3: Transfer the shaken material to an incubator, keep the temperature of the incubator at 80°C, let it stand and post-absorb for 24 h to prepare the cable insulating material.

[0169] Example 2

[0170] Step S1: Thoroughly mix low-density polyethylene and antioxidant in a high-speed mixer for 20 minutes, and then perform extrusion granulation twice through a twin-screw extruder to obtain semi-finished material. Among them, the six-stage heating temperatures during 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 100 rpm.

[0171] Step S2: Centrifugally dehydrate and dry the semi-finished material, and place it in a shaking tank. Keep the temperature in the tank at 80°C. Heat the mixed cross-linking agent and cross-linking assistant to 80°C respectively, and then spray them into the shaking tank. At the same time, start the shaking tank to maintain a constant speed and continue to shake for 60 minutes after spraying. Among them, the shaking speed of the shaking tank is 10 rpm.

[0172] Step S3: Transfer the material after shaking to an incubator, keep the temperature of the incubator at 80°C, let it stand and post-absorb for 24 hours to prepare the cable insulating material.

[0173] Example 3

[0174] Step S1: Thoroughly mix low-density polyethylene and antioxidant in a high-speed mixer for 20 minutes, and then perform extrusion granulation twice through a twin-screw extruder to obtain semi-finished material. Among them, the six-stage heating temperatures during 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 120 rpm.

[0175] Step S2: Centrifugally dehydrate and dry the semi-finished material, and place it in a shaking tank. Keep the temperature in the tank at 80°C. Heat the mixed cross-linking agent and cross-linking assistant to 80°C respectively, and then spray them into the shaking tank. At the same time, start the shaking tank to maintain a constant speed and continue to shake for 60 minutes after spraying. Among them, the shaking speed of the shaking tank is 30 rpm.

[0176] Step S3: Transfer the material after shaking to an incubator, keep the temperature of the incubator at 80°C, let it stand and post-absorb for 24 hours to prepare the cable insulating material.

[0177] The differences between the preparation methods of Examples 4-15 and Comparative Examples 1-3 and the preparation method of Example 1 are as follows: at least one of the mixing time when mixing the materials in Step S1, the six-stage heating temperature settings and screw speed during the twin-screw extrusion process, the time of continuing to shake after spraying in Step S2, the shaking speed of the shaking tank, and the temperature and time of post-absorbing 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: Thoroughly mix low-density polyethylene and 4,4'-thiobis(6-tert-butyl-3-methylphenol) in a high-speed mixer for 10 minutes, and then extrude and pelletize twice through a twin-screw extruder to obtain a semi-finished material. Among them, the six-section heating temperatures during the twin-screw extrusion process are 100°C, 145°C, 150°C, 160°C, 166°C, and 174°C respectively, and the screw rotation speed is 100 rpm.

[0182] Step S2: Centrifuge and dehydrate the semi-finished material, and place it in a shaking tank. Keep the temperature in the shaking tank 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 rotation speed, and continue to shake for 30 minutes after the spraying ends. Among them, the shaking speed of the shaking tank is 20 rpm.

[0183] Step S3: Transfer the material after shaking to an incubator, keep the temperature of the incubator at 65°C, let it stand and post-absorb for 24 hours to prepare the cable insulating material.

[0184] II. Performance Testing

[0185] 1. The test conditions and test results of the thermal mechanical properties and anti-scorch characteristics of the cable insulating materials prepared in the above examples and comparative examples are shown in Table 3 respectively.

[0186] Table 3

[0187]

[0188] It can be seen from the result comparison of Examples 1-15 and Comparative Examples 1-4 in Table 3 that, compared with Comparative Examples 1-4, the tensile strength and elongation at break of the cable insulating materials in Examples 1-15 are greater, the change rate of tensile strength (≤20 MPa) and the change rate of elongation at break are smaller (≤20%), the elongation at load is smaller, the scorch time is longer, the cross-linking rate is lower, and the volume resistivity is greater, indicating that the cable insulating material provided by the present application has more excellent thermal stability, anti-aging performance, and anti-scorch characteristics.

[0189] It can be seen from the result comparison of Example 1, Examples 4-5, and Examples 10-15 that by using 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 characteristics of the cable insulating material.

[0190] Similarly, it can be understood 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 aid 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 aid composition does not adopt a suitable ratio, all will have similar results to those in Examples 10 - 15, that is, they will all affect the quality of the prepared cable insulating material. Therefore, by adjusting the ratios of the antioxidant composition, the crosslinking agent composition, and the crosslinking aid composition in Example 2 within suitable ranges respectively, and by adjusting the ratios of the antioxidant composition, the crosslinking agent composition, and the crosslinking aid composition in Example 3 within suitable ranges respectively, it also helps to further improve the thermal stability, anti-aging performance, and anti-scorch characteristics of the cable insulating material.

[0191] From the comparison of the results of Examples 1 - 15 and Comparative Examples 1 - 2, it can be seen that by using specific types of antioxidants, crosslinking agents, and crosslinking aids in combination, it helps to further improve the quality of the cable insulating material and extend the extrusion processing time.

[0192] From the comparison of the results of Example 1 and Comparative Example 3, it can be seen that using small molecule polyethylene with a weight average molecular weight less than 4000 Da will significantly shorten the scorch time of the insulating material. The introduction of small molecules leads to the rapid occurrence of crosslinking of the insulating material, resulting in a rapid reduction in the extrusion time of the insulating material.

[0193] The cable insulating materials in Example 1 and Comparative Example 4 were subjected to a long-term extrusion test. The test method for long-term extrusion was to use a single-screw extruder with a pressure sensor in front of the screen, conduct long-term extrusion experiments on insulating materials with different formulations, and study the change of extrusion pressure with time; the test results are as Figure 1 shown.

[0194] From Figure 1 it can be seen that compared with the long-term extrusion of the cable insulating material in Comparative Example 4, when the cable insulating material provided in this application is subjected to long-term extrusion, the extrusion pressure fluctuates less and has better stability; the cable insulating material provided in this application has excellent long-term extrusion stability.

[0195] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combinations of these technical features do not conflict, they should all be considered as the scope described in this specification.

[0196] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A cable insulation material for long-length extrusion, characterized in that: including polyethylene, antioxidant, cross-linking agent and cross-linking aid; The number of small molecules with a weight average molecular weight of less than 4000Da contained in the polyethylene is 0; the weight average molecular weight of the polyethylene is 60000Da-120000Da; the molecular weight distribution of the polyethylene is 4.0PDI-9.0PDI; the branching degree of the polyethylene is 1.5-5.5 branched carbon atoms per thousand carbon atoms; The antioxidant is 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); The cross-linking agent is a mixture of dicumyl peroxide and benzoyl peroxide in a mass ratio of (0.8-3.5):(0.5-2.5); The cross-linking auxiliary agent is a mixture of poly(alpha-methylstyrene) dimer and 1,4-di-tert-butylperoxyisopropylbenzene in a mass ratio of (0.1-0.5):(0.1-0.3).

2. 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 double bond content of the polyethylene is 0.1 to 1.5 carbon atoms containing terminal double bonds per thousand carbon atoms.

3. The cable insulation material according to any one of claims 1 to 2, 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.

4. The cable insulation material according to any one of claims 1 to 2, 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 varies from 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.

5. 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; The number of small molecules with a weight average molecular weight of less than 4000Da contained in the polyethylene is 0; the weight average molecular weight of the polyethylene is 60000Da-120000Da; the molecular weight distribution of the polyethylene is 4.0PDI-9.0PDI; the branching degree of the polyethylene is 1.5-5.5 branched carbon atoms per thousand carbon atoms; The antioxidant is 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); The cross-linking agent is a mixture of dicumyl peroxide and benzoyl peroxide in a mass ratio of (0.8-3.5):(0.5-2.5); The cross-linking auxiliary agent is a mixture of poly(alpha-methylstyrene) dimer and 1,4-di-tert-butylperoxyisopropylbenzene in a mass ratio of (0.1-0.5):(0.1-0.3).

6. The preparation method according to claim 5, 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.

7. The preparation method according to claim 5, characterized in that: The semi-finished product is dehydrated by centrifugation.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The shaking speed is 10rpm-30rpm; The preset time is 30min-60min.

9. The preparation method according to any one of claims 5 to 7, characterized in that: The temperature of the absorption after the insulation is 60° C.-80° C., and the time is 16 h-28 h.

10. Use of the cable insulation material for long-length extrusion according to any one of claims 1 to 4 in the preparation of cables.

11. A cable, characterized in that: The raw materials for preparing the cable include the cable insulation material for long-length extrusion as described in any one of claims 1 to 4.

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

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