Insulating material, preparation method thereof and cable

Abstract

The present application relates to an insulating material, a preparation method thereof and a cable. The insulating material comprises polyethylene, a first crosslinking agent, a second crosslinking agent and an antioxidant; the first crosslinking agent comprises one or more of the compounds shown by the following structural formula R1‑O‑O‑R2; wherein, at least one of R1 and R2 is selected from any one of the groups shown by formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o. In each formula, m1, m2, m4, m5, m9, m10, m11 and m12 are each independently an integer from 1 to 10, and * represents the bonding position. The second crosslinking agent at least comprises 2,4‑diphenyl‑4‑methyl‑1‑pentene. The insulating material of the present application can effectively reduce the types and amounts of by‑products during the crosslinking process, and at the same time improve the insulation performance and mechanical properties of the cable.

Description

Technical Field

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

[0002] High-voltage cables are widely used in power transmission systems, and cross-linked polyethylene is widely used due to its excellent electrical properties and mechanical strength. However, cross-linked polyethylene generates a variety of by-products during its preparation, which have an adverse effect on cable performance, especially after long-term use, resulting in a decrease in the insulation performance and mechanical performance of the cable. Summary of the invention

[0003] The present application provides an insulating material, a preparation method thereof, and a cable, aiming to reduce the types and quantities of by-products produced during the cross-linking process of the insulating material, while improving the insulation and mechanical properties of the cable.

[0004] In a first aspect of the present application, there is provided an insulating material, comprising polyethylene, a first cross-linking agent, a second cross-linking agent and an antioxidant;

[0005] The first cross-linking agent includes one or more compounds represented by the following structural formula R1-OO-R2;

[0006] Wherein, at least one of R1 and R2 is selected from the group shown in any one of formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o, and the second cross-linking agent includes at least 2,4-diphenyl-4-methyl-1-pentene;

[0007] Formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o are as follows:

[0008] ; ; ; ; ; ; ; ; ; In each formula, m1, m2, m4, m5, m9, m10, m11 and m12 are each independently an integer of 1 to 10, and * represents a bonding position.

[0009] In some embodiments, R1 and R2 each independently contain at least one of the following groups: formula a, formula d, formula g, formula h, formula i, formula n, formula p;

[0010] Among them, formula a, formula d, formula g, formula h, formula i, formula n, and formula p are as follows:

[0011] ; ; ; ; ; ; ; m3 is an integer of 1 to 10, and m6, m7, and m8 are each independently an integer of 2 to 10;

[0012] The second crosslinking agent further comprises one or more of triethylenetetramine and trimethylolpropane triacrylate.

[0013] In some embodiments, the first cross-linking agent includes at least one or more compounds represented by the following formula I to formula III:

[0014] ; ; .

[0015] In some embodiments, the insulating material includes the following components, measured in mass percentage: 95% to 99.3% polyethylene, 0.3% to 1.5% first cross-linking agent, 0.2% to 3% second cross-linking agent, and 0.2% to 0.5% antioxidant.

[0016] In some embodiments, the density of the polyethylene is 0.91 mol / cm 3 ~0.93mol / cm 3 .

[0017] In some embodiments, the antioxidant includes one or more of pentaerythritol (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris[2,4-di-tert-butylphenyl]phosphite, and 4,4′-thiobis(6-tert-butyl-3-methylphenol).

[0018] A second aspect of the present application provides a method for preparing an insulating material, comprising the following steps:

[0019] Mixing polyethylene and an antioxidant to obtain a mixed material;

[0020] Extruding and granulating the mixed material to obtain an intermediate material;

[0021] The intermediate material, the first cross-linking agent and the second cross-linking agent are mixed and then subjected to post-absorption treatment to obtain the insulating material;

[0022] The first cross-linking agent includes one or more compounds represented by the following structural formula R1-OO-R2;

[0023] Wherein, at least one of R1 and R2 is selected from the group shown in any one of formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o, and the second cross-linking agent includes at least 2,4-diphenyl-4-methyl-1-pentene;

[0024] Formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o are as follows:

[0025] ; ; ; ; ; ; ; ; ; In each formula, m1, m2, m4, m5, m9, m10, m11 and m12 are each independently an integer of 1 to 10, and * represents a bonding position.

[0026] In some embodiments, the extrusion temperature is 90°C to 130°C.

[0027] In some embodiments, the post-absorption treatment is performed at a temperature of 65°C to 85°C and for a time of 12 h to 36 h.

[0028] The third aspect of the present application provides a cable, comprising at least one of the insulating material described in the first aspect of the present application and the insulating material prepared by the preparation method described in the second aspect of the present application.

[0029] In some embodiments, the cable is a submarine cable.

[0030] In some embodiments, the cable has a carrying voltage of 330 kV to 800 kV.

[0031] Compared with traditional technologies, the above-mentioned insulating materials have at least the following advantages:

[0032] The above-mentioned insulating material reduces the types and quantities of by-products in the cross-linking process, especially the generation of non-removable by-products, by optimizing the structural design of the first cross-linking agent and the second cross-linking agent. This not only effectively improves the insulation and mechanical properties of the cable, but also reduces the degassing time and reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a GCMS graph of the types of gas byproducts after degassing the insulating material prepared in Example 1 of the present application for 24 hours.

[0034] Figure 2 This is a GCMS chart of the types of gas byproducts of the insulating material prepared in Comparative Example 1 of the present application after degassing for 24 hours. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0036] In this application, "first aspect", "second aspect", "third aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application. The terms used in this application and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this application includes any and all combinations of one or more related listed items. The term "multiple" in this application means at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0041] An embodiment of the present application provides an insulating material, including polyethylene, a first cross-linking agent, a second cross-linking agent and an antioxidant;

[0042] The first cross-linking agent includes one or more compounds represented by the following structural formula R1-OO-R2;

[0043] Wherein, at least one of R1 and R2 is selected from the group shown in any one of formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o, and the second cross-linking agent includes at least 2,4-diphenyl-4-methyl-1-pentene;

[0044] Formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o are as follows:

[0045] ; ; ; ; ; ; ; ; .

[0046] Traditional technology mainly controls the amount of cable by-products generated by changing the content of the cross-linking agent. However, this method has limited effect in reducing by-products and still cannot fundamentally solve the adverse effects of by-products on cable performance. The insulating material of the above embodiment of the present application reduces the types and quantities of by-products in the cross-linking process by optimizing the structural design of the first cross-linking agent and the second cross-linking agent, especially the generation of non-removable by-products, which not only effectively improves the insulation performance and mechanical properties of the cable, but also reduces the degassing time and reduces the production cost. In addition, the thermal stability and antioxidant properties of the insulating material are also improved, and the service life of the cable is extended. The first cross-linking agent in the insulating material of the above embodiment contains at least one of the groups such as carbon-carbon double bonds and carbon-carbon triple bonds. The first cross-linking agent with a specific structure and the second cross-linking agent of a specific type are matched with each other to promote the rearrangement of the molecular structure of the by-products in the cross-linking reaction, generate more by-products that are easy to remove, such as methane, ethylene, etc., reduce non-removable by-products, and the second cross-linking agent can also further improve the cross-linking efficiency of the first cross-linking agent through the electron-donating effect, and further reduce the generation of by-products.

[0047] Further, the present application found that the unsaturated bonds such as carbon-carbon double bonds and / or carbon-carbon triple bonds in the first crosslinking agent are all located at the ends, and the first crosslinking agent and the second crosslinking agent including 2,4-diphenyl-4-methyl-1-pentene are used in combination, so that the unsaturated bonds in the first crosslinking agent are The structure and the above-mentioned unsaturated bonds can both participate in electron-donating reactions, which can further reduce the generation of by-products and further improve the insulation and mechanical properties of the cable.

[0048] In each formula, m1, m2, m4, m5, m9, m10, m11 and m12 are each independently an integer of 1 to 10, and * represents a bonding position.

[0049] As non-limiting examples, m1, m2, m4, m5, m9, m10, m11 and m12 each independently include, but are not limited to: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0050] m3 independently includes but is not limited to: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0051] m6, m7, and m8 each independently include, but are not limited to: 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0052] In some examples, R1 and R2 also independently contain at least one of the following groups: formula a, formula d, formula g, formula h, formula i, formula n, formula p;

[0053] Among them, formula a, formula d, formula g, formula h, formula i, formula n, and formula p are as follows:

[0054] ; ; ;

[0055] ; ; ; ; m3 is an integer of 1 to 10, and m6, m7, and m8 are each independently an integer of 2 to 10.

[0056] The second crosslinking agent further comprises one or more of triethylenetetramine and trimethylolpropane triacrylate.

[0057] In some embodiments, m8 is 3 to 5. Such a design is more conducive to reducing the generation of by-products and is more conducive to improving the insulation performance and mechanical properties of the cable.

[0058] In some embodiments, the first cross-linking agent includes at least one or more compounds represented by the following formula I to formula III:

[0059] ; ; .

[0060] In some embodiments, the first cross-linking agent further comprises , and One or more of .

[0061] In some embodiments, the insulating material includes the following components by mass percentage: 95% to 99.3% polyethylene, 0.3% to 1.5% first cross-linking agent, 0.2% to 3% second cross-linking agent, and 0.2% to 0.5% antioxidant. The reasonable proportion of polyethylene, the first cross-linking agent, the second cross-linking agent, and the antioxidant in the insulating material is conducive to further improving the insulation performance and mechanical properties of the cable.

[0062] As a non-limiting example, the mass fraction (mass percentage) of polyethylene includes but is not limited to: 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.3% or a range between any two of the foregoing, the mass fraction of the first cross-linking agent includes but is not limited to: 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5% or a range between any two of the foregoing, the mass fraction of the second cross-linking agent includes but is not limited to: 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3% or a range between any two of the foregoing, and the mass fraction of the antioxidant includes but is not limited to: 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5% or a range between any two of the foregoing.

[0063] In some embodiments, the density of polyethylene is 0.91 mol / cm 3 ~0.93 mol / cm 3 The density of polyethylene is within the above range, which is conducive to ensuring a sufficient amount of branched structure inside, so that the polyethylene is fully cross-linked to improve the comprehensive performance of the insulation material. As a non-limiting example, the density of polyethylene includes but is not limited to: 0.91 mol / cm 3 , 0.92mol / cm 3 , 0.93mol / cm 3 Or a range between any two of the foregoing.

[0064] In some embodiments, the antioxidant includes one or more of (3,5-di-tert-butyl-4-hydroxyphenyl) propionate pentaerythritol ester (antioxidant 1010), tris[2,4-di-tert-butylphenyl]phosphite (antioxidant 168) and 4,4'-thiobis(6-tert-butyl-3-methylphenol) (antioxidant 300). The above antioxidants have long-term and short-term effects. By using these antioxidants in combination with polyethylene, the first crosslinking agent, and the second crosslinking agent, the amount of by-products can be further reduced and the stability of the insulating material can be improved.

[0065] Another embodiment of the present application provides a method for preparing an insulating material, comprising the following steps:

[0066] Mixing polyethylene and an antioxidant to obtain a mixed material;

[0067] Extruding and granulating the mixed material to obtain an intermediate material;

[0068] The intermediate material, the first cross-linking agent and the second cross-linking agent are mixed and then subjected to post-absorption treatment to obtain an insulating material.

[0069] Wherein, at least one of R1 and R2 is selected from the group shown in any one of formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o, and the second cross-linking agent includes at least 2,4-diphenyl-4-methyl-1-pentene;

[0070] Formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o are as follows:

[0071] ; ; ; ; ; ; ; ; ; In each formula, m1, m2, m4, m5, m9, m10, m11 and m12 are each independently an integer of 1 to 10, and * represents a bonding position.

[0072] The insulating material prepared by the above preparation method reduces the types and quantities of by-products in the cross-linking process, especially the generation of non-removable by-products, by optimizing the structural design of the first cross-linking agent and the second cross-linking agent, which not only effectively improves the insulation performance and mechanical properties of the cable, but also reduces the degassing time and reduces the production cost. In addition, the thermal stability and antioxidant performance of the insulating material are improved, and the service life of the cable is extended. The above preparation method is simple in process and low in cost, which is conducive to the industrial production of insulating materials.

[0073] Further, at least one of R1 and R2 is a group represented by any one of formula b, formula c, formula e, formula f, formula j, formula k, formula l, formula m and formula o, and the second crosslinking agent at least includes 2,4-diphenyl-4-methyl-1-pentene. The structure and the above-mentioned unsaturated bonds can both participate in electron-donating reactions, which can further reduce the generation of by-products and further improve the insulation and mechanical properties of the cable.

[0074] In some embodiments, the extrusion temperature is 90°C to 130°C. This is conducive to further mixing the components in the mixed material and avoiding damage to the base material structure. As a non-limiting example, the extrusion temperature includes but is not limited to: 90°C, 100°C, 110°C, 120°C, 130°C or a range between any two of the foregoing.

[0075] In some embodiments, the temperature of the post-absorption treatment is 65°C to 85°C, and the time is 12 h to 36 h. As a non-limiting example, the temperature of the post-absorption treatment includes, but is not limited to, 65°C, 70°C, 75°C, 80°C, 85°C, or a range between any two of the foregoing, and the time of the post-absorption treatment includes, but is not limited to, 12 h, 15 h, 18 h, 20 h, 22 h, 25 h, 28 h, 30 h, 32 h, 34 h, 36 h, or a range between any two of the foregoing.

[0076] In some embodiments, the first cross-linking agent includes at least one or more compounds represented by the following formula I to formula III:

[0077] ; ; In some embodiments, the first cross-linking agent further comprises , and One or more of .

[0078] In some embodiments, the insulating material includes the following components by mass percentage: 95% to 99.3% polyethylene, 0.3% to 1.5% first cross-linking agent, 0.2% to 3% second cross-linking agent, and 0.2% to 0.5% antioxidant. The reasonable proportion of polyethylene, the first cross-linking agent, the second cross-linking agent, and the antioxidant in the insulating material is conducive to further improving the insulation performance and mechanical properties of the cable.

[0079] In some embodiments, the density of polyethylene is 0.91 mol / cm 3 ~0.93mol / cm 3 .

[0080] In some embodiments, the antioxidant includes one or more of (3,5-di-tert-butyl-4-hydroxyphenyl) propionate pentaerythritol ester (antioxidant 1010), tris[2,4-di-tert-butylphenyl]phosphite (antioxidant 168) and 4,4'-thiobis(6-tert-butyl-3-methylphenol) (antioxidant 300). The above antioxidants have long-term and short-term effects. By using these antioxidants in combination with polyethylene, the first crosslinking agent, and the second crosslinking agent, the amount of by-products can be further reduced and the stability of the insulating material can be improved.

[0081] By adjusting the process conditions of the above-mentioned preparation method, the insulating material in one embodiment of the present application can be obtained.

[0082] Still another embodiment of the present application provides a cable, comprising at least one of the above-mentioned insulating material and the insulating material prepared by the above-mentioned preparation method.

[0083] In some embodiments, the cable is a submarine cable.

[0084] In some embodiments, the cable has a carrying voltage of 330 kV to 800 kV.

[0085] In this application, "carrying voltage" refers to the voltage at which the cable can operate safely and stably.

[0086] In order to further illustrate the present application, the technical scheme of the present application is described in detail below in conjunction with specific examples. If no specific technology or conditions are specified in the examples, the technology or conditions described in the literature in the field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0087] Example 1

[0088] Prepare the insulating material as follows:

[0089] (1) The density is 0.92 mol / cm 3 polyethylene (LDPE) and (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester (antioxidant 1010) are mixed to obtain a mixed material;

[0090] (2) extruding and granulating the mixed material through a single screw extruder to obtain an intermediate material; the temperature control intervals of the single screw extruder are: 92° C., 105° C., 115° C., 120° C., 120° C., and 120° C.;

[0091] (3) After the intermediate material, the first crosslinking agent and the second crosslinking agent are mixed, a post-absorption treatment is performed. Specifically, the intermediate material is placed in a glass shaker and heated to 70°C, and then the first crosslinking agent preheated to 70°C and the second crosslinking agent preheated to 70°C are added to the intermediate material, and the mixture is mixed evenly by machine vibration, and the mixture is kept warm for 18 hours for post-absorption treatment to obtain an insulating material. The amounts of raw materials used in the preparation of the insulating material in Example 1 are shown in Table 1.

[0092] In terms of mass percentage, the insulating material includes the following components: 98.65% of LDPE, 0.8% of a first cross-linking agent, 0.35% of a second cross-linking agent, and 0.2% of an antioxidant. The first cross-linking agent is allyl peroxycumyl alcohol (CAS: 61808-93-3), and its structural formula is shown in the following formula I. The second cross-linking agent is 2,4-diphenyl-4-methyl-1-pentene (AMSD);

[0093] .

[0094] Example 2

[0095] The preparation method of the insulating material is basically the same as that of Example 1, except that the type of the first cross-linking agent is changed, as described in Table 1;

[0096] The first cross-linking agent in Example 2 is cross-linking agent A (CAS: 64847-06-9), and its structural formula is shown in Formula II below:

[0097] .

[0098] Example 3

[0099] The preparation method of the insulating material is basically the same as that of Example 1, except that the type of the first cross-linking agent is changed, as described in Table 1; the first cross-linking agent of Example 3 adopts cross-linking agent B (CAS: 6729-82-4), and its structural formula is shown in Formula IV below:

[0100] .

[0101] Example 4

[0102] The preparation method of the insulating material is basically the same as that of Example 1, except that the amount of the first cross-linking agent is changed, as described in Table 1.

[0103] Example 5

[0104] The preparation method of the insulating material is basically the same as that of Example 1, except that the amount of the first cross-linking agent is changed, as described in Table 1.

[0105] Comparative Example 1

[0106] The preparation method of the insulating material is basically the same as that of Example 1, except that the type of the first cross-linking agent is changed to diisopropylbenzene peroxide (DCP), and the second cross-linking agent is not added in step (3), as described in Table 1.

[0107] Comparative Example 2

[0108] The preparation method of the insulating material is basically the same as that of Example 1, except that the type of the first crosslinking agent is changed to diisopropylbenzene peroxide (DCP), and the type of the second crosslinking agent is changed to trimethylolpropane triacrylate (TMPTA), as described in Table 1.

[0109] Comparative Example 3

[0110] The preparation method of the insulating material is basically the same as that of Example 1, except that no second cross-linking agent is added in step (3), as described in Table 1.

[0111] Comparative Example 4

[0112] The preparation method of the insulating material is basically the same as that of Example 1, except that the first cross-linking agent is not added in step (3), as described in Table 1.

[0113] Comparative Example 5

[0114] The preparation method of the insulating material is basically the same as that of Example 1, except that the type of the first cross-linking agent is changed to 2,5-di(tert-butylperoxy)-2,5-dimethyl-3-hexyne (CAS: 1068-27-5), as described in Table 1;

[0115] Wherein, the structural formula of the first cross-linking agent is shown in the following formula VII:

[0116] .

[0117] Comparative Example 6

[0118] The preparation method of the insulating material is basically the same as that of Example 1, except that the type of the first cross-linking agent is changed, as described in Table 1;

[0119] The first crosslinking agent of Comparative Example 6 is dibenzoyl peroxide (CAS: 94-36-0), and its structural formula is shown in the following formula III:

[0120] .

[0121] Comparative Example 7

[0122] The preparation method of the insulating material is basically the same as that of Example 1, except that the type of the first cross-linking agent is changed, as described in Table 1; the first cross-linking agent of Comparative Example 7 is di-n-pentyl peroxide (CAS: 3903-88-6), and its structural formula is shown in Formula V below:

[0123] .

[0124] Comparative Example 8

[0125] The preparation method of the insulating material is basically the same as that of Example 1, except that the type of the second cross-linking agent is changed, as described in Table 1.

[0126] Comparative Example 9

[0127] The preparation method of the insulating material is basically the same as that of Example 1, except that the type of the second cross-linking agent is changed, as described in Table 1.

[0128] Comparative Example 10

[0129] The preparation method of the insulating material is basically the same as that of Example 1, except that the types of the first cross-linking agent and the second cross-linking agent are changed, as described in Table 1;

[0130] The first crosslinking agent of Comparative Example 10 is dicumyl peroxide (DCP) (CAS: 80-43-3), the structural formula of which is shown in Formula VI below, and the second crosslinking agent is triethylenetetramine (TETA);

[0131] .

[0132] Comparative Example 11

[0133] The preparation method of the insulating material is basically the same as that of Example 1, except that the types of the first cross-linking agent and the second cross-linking agent are changed, as described in Table 1;

[0134] The first crosslinking agent of Comparative Example 11 is di-n-pentyl peroxide (CAS: 3903-88-6), whose structural formula is shown in Formula V below, and the second crosslinking agent is triethylenetetramine (TETA);

[0135] .

[0136] Table 1

[0137]

[0138] Test Case

[0139] (1) Tensile performance test

[0140] The tensile test was carried out using Shimadzu's universal material testing machine. The sample preparation standard was GB / T 528-2009, and the specimen tensile speed was 100 mm / min.

[0141] (2) Thermal extension test

[0142] The thermal elongation test was carried out using a constant temperature blast oven produced by Binder. The experiment was carried out in accordance with GB / T 2951.21-2008, and the sample test temperature was 200°C.

[0143] (3) DC breakdown performance

[0144] The DC breakdown test was carried out on the samples using a high voltage complete test device (the rated voltage of the high voltage DC generator was 200kV). A ball-to-ball electrode made of brass was selected with an electrode diameter of 10mm. 10 data points were measured for each sample using a continuous voltage boost method. To prevent surface discharge, the sample and the electrode were completely immersed in silicone oil. The test temperature was 90°C, simulating the breakdown field strength under the operating limit of the cable. The statistical data of the sample breakdown strength was analyzed using Weibull distribution.

[0145] (4) AC breakdown performance

[0146] The cross-linking breakdown test is carried out according to GB / T1408.7. The experimental temperature is 90°C, simulating the breakdown field strength under the extreme operating conditions of the cable. The sample thickness is 0.20±0.02mm.

[0147] (5) Resistivity

[0148] The variable temperature resistivity tester produced by Mettler Toledo was used, the test temperature was 70°C, and two voltage tests were performed, the test voltages were 20kV or 30kV respectively.

[0149] (6) Gas chromatography-mass spectrometry (GCMS) testing

[0150] After 10 mL of nitrogen was added to the gas sample, the degassing byproducts of the cable insulation were analyzed using a Bruker Compact gas chromatography-mass spectrometry test system. The separation of methane was achieved by using a 30 m*0.25 mm, 0.25 μm HP-5MS capillary column with a maximum operating temperature of 350 °C. Nitrogen was used as the carrier gas and the column flow rate was set to 2 mL / min (constant flow). The inlet was equipped with a split liner (Agilent Technologies) and operated in a 20:1 split mode at 250 °C with a split ratio of 20:1. The initial column head pressure was 20.9 psi and the gas saving mode was always closed. The GC system was programmed from 60 °C (13 minutes) to 300 °C (30 °C / min). The detector temperature was 250 °C, the hydrogen flow rate was 40 mL / min, the air flow rate was 450 mL / min, and the nitrogen flow rate was 30 mL / min. For comparison testing with the headspace autosampler, a 20 mL vial was used with a vial equilibration time of 30 minutes at 150°C. The sample loop and transfer line temperatures were set at 170°C and 180°C, respectively. The headspace vial pressurization time was 0.5 minutes, and the vial pressure was 15 psig. A cycle fill time of 0.2 minutes and a cycle equilibration time of 0.1 minutes were used, and the injection time was 0.5 minutes.

[0151] The test results are detailed in Table 2 and Table 3.

[0152] Table 2

[0153]

[0154] Table 2

[0155]

[0156] Table 3

[0157]

[0158] Figure 1 This is a GCMS chart of the types of gas byproducts after degassing the insulating material prepared in Example 1 for 24 hours. Figure 2 This is a GCMS chart of the types of gas byproducts after degassing the insulating material prepared in Comparative Example 1 for 24 hours. Figure 1~2 It can be seen from the data in Table 2 that, under the same degassing time, the insulating materials of Comparative Examples 1 to 5 have a variety of complex gas by-product components, while the types of gas by-products of Examples 1 to 5 are relatively small, indicating that Examples 1 to 5 can effectively reduce the types of by-products by regulating the structure of the first cross-linking agent, the structure of the second cross-linking agent, and by reasonably matching the first cross-linking agent and the second cross-linking agent.

[0159] It can be seen from the data in Table 3 that, compared with the comparative example, the insulating materials of Examples 1 to 5 have better insulating properties and mechanical properties.

[0160] The unsaturated acetylenic group of the first crosslinking agent in the insulating material of Comparative Example 5 is in the chain and has relatively low activity. The types and contents of by-products produced after crosslinking are greater, and effective crosslinking cannot be achieved. Therefore, the mechanical properties and insulating properties are poor.

[0161] By comparing Example 1, Example 2, Example 4 and Comparative Examples 6, 7 to 11, it can be seen that the combination of the first cross-linking agent and the second cross-linking agent in the insulating material of Example 1, Example 2 and Example 4 is more conducive to improving the insulating performance and mechanical properties of the insulating material.

[0162] 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.

[0163] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims, and the description may be used to interpret the content of the claims.

Claims

1. An insulating material, characterized in that: In terms of mass percentage, the insulating material comprises the following components: 95% to 99.3% polyethylene, 0.3% to 1.5% first cross-linking agent, 0.2% to 3% second cross-linking agent and 0.2% to 0.5% antioxidant; The first cross-linking agent includes at least one or more compounds represented by the following formula I to formula III; 、 、 ； The second cross-linking agent includes at least 2,4-diphenyl-4-methyl-1-pentene.

2. The insulating material according to claim 1, characterized in that: The first cross-linking agent also includes , and One or more of; The second crosslinking agent further comprises one or more of triethylenetetramine and trimethylolpropane triacrylate.

3. The insulating material according to claim 1, characterized in that: The density of the polyethylene is 0.91 g / cm 3 ~0.93g / cm 3 .

4. The insulating material according to claim 1 or 2, characterized in that: The antioxidant includes one or more of pentaerythritol (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris[2,4-di-tert-butylphenyl]phosphite and 4,4'-thiobis(6-tert-butyl-3-methylphenol).

5. A method for preparing an insulating material, characterized in that: The steps include: Mixing polyethylene and an antioxidant to obtain a mixed material; Extruding and granulating the mixed material to obtain an intermediate material; The intermediate material, the first cross-linking agent and the second cross-linking agent are mixed and then subjected to post-absorption treatment to obtain the insulating material; Wherein, the insulating material comprises the following components, in terms of mass percentage: 95% to 99.3% polyethylene, 0.3% to 1.5% first cross-linking agent, 0.2% to 3% second cross-linking agent and 0.2% to 0.5% antioxidant; The first cross-linking agent includes at least one or more compounds represented by the following formula I to formula III; 、 、 ； The second cross-linking agent includes at least 2,4-diphenyl-4-methyl-1-pentene.

6. The preparation method according to claim 5, characterized in that: The extrusion temperature is 90°C to 130°C.

7. The preparation method according to claim 5, characterized in that: The temperature of the post-absorption treatment is 65°C to 85°C, and the time is 12 h to 36 h.

8. A cable, characterized in that: The invention comprises at least one of the insulating material described in any one of claims 1 to 4 and the insulating material prepared by the preparation method described in any one of claims 5 to 7.

9. The cable according to claim 8, characterized in that The cable is a submarine cable.

10. The cable according to claim 8 or 9, characterized in that: The cable has a carrying voltage of 330 kV to 800 kV.

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