阅读说明：本技术 一种半导电屏蔽料及其制备方法和应用 (Semiconductive shielding material and preparation method and application thereof ) 是由 俞杰 陈胜立 杨强 李秀娟 堵志祥 陈卓 赵淑群 于 2020-12-29 设计创作，主要内容包括：本发明提供一种半导电屏蔽料及其制备方法和应用。半导电屏蔽料包括以下组分：乙烯-丙烯酸丁酯共聚物,高密度聚乙烯,导电炭黑,PE蜡,硬脂酸锌,分散剂以及抗氧剂；其中,乙烯-丙烯酸丁酯共聚物、高密度聚乙烯的质量比为1:(0.05～0.2),优选1:(0.07～0.1)。本发明的半导电屏蔽料以乙烯-丙烯酸丁酯共聚物作为基体,加入高密度聚乙烯,从而使得材料挤出后具备骨架支撑效果,防止绝缘层与屏蔽层分离,预防硫化过程中出现应力开裂现象。(The invention provides a semiconductive shielding material and a preparation method and application thereof. The semiconductive shielding material comprises the following components: ethylene-butyl acrylate copolymer, high-density polyethylene, conductive carbon black, PE wax, zinc stearate, a dispersing agent and an antioxidant; wherein the mass ratio of the ethylene-butyl acrylate copolymer to the high-density polyethylene is 1 (0.05-0.2), preferably 1 (0.07-0.1). The semiconductive shielding material disclosed by the invention takes the ethylene-butyl acrylate copolymer as a matrix, and the high-density polyethylene is added, so that the material has a skeleton supporting effect after being extruded, an insulating layer and a shielding layer are prevented from being separated, and the stress cracking phenomenon in the vulcanization process is prevented.)

1. A semiconductive shielding material, which is characterized by comprising the following components: ethylene-butyl acrylate copolymer, high-density polyethylene, conductive carbon black, PE wax, zinc stearate, dispersant and antioxidant;

wherein the mass ratio of the ethylene-butyl acrylate copolymer to the high-density polyethylene is 1 (0.05-0.2), preferably 1 (0.07-0.1).

2. The semiconductive shielding material according to claim 1, wherein the semiconductive shielding material contains, by weight, 45 to 50 parts of the ethylene-butyl acrylate copolymer, 2 to 10 parts of the high-density polyethylene, 37 to 40 parts of the conductive carbon black, 0.5 to 2 parts of the PE wax, 1 to 4 parts of the zinc stearate, 0.05 to 1 part of the dispersant, and 0.05 to 1 part of the antioxidant;

preferably, in the ultra-smooth semi-conductive shield, by weight, the content of the ethylene-butyl acrylate copolymer is 45-50 parts, the content of the high-density polyethylene is 4-6 parts, the content of the conductive carbon black is 39-40 parts, the content of the PE wax is 1-1.2 parts, the content of the zinc stearate is 1.5-2.5 parts, the content of the dispersing agent is 0.1-0.4 part, and the content of the antioxidant is 0.1-0.4 part.

3. The semiconductive shield material according to claim 1 or 2, wherein the high density polyethylene has a melt index of 14 to 19g/10min at 190 ℃ and 2.16 kg.

4. The semiconductive shield material according to claim 1 or 2, wherein the ethylene-butyl acrylate copolymer has a melt index of 5 to 7g/10min at 190 ℃ under 2.16 kg;

in the ethylene-butyl acrylate copolymer, the content of butyl acrylate is 25-30%.

5. The semiconductive shield material according to claim 1 or 2, wherein the PE wax has a number average molecular weight of 3000 to 5000.

6. Semiconducting shield according to claim 1 or 2, characterized in that the dispersant is a wetting dispersant, preferably a multifunctional wetting dispersant.

7. The semiconducting shield according to claim 1 or 2, wherein the antioxidant comprises one or two of 4, 4' -thiobis (6-tert-butyl-m-cresol), pentaerythrityl tetrakis [ β - (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ].

8. A method for preparing a semiconducting shield according to any of claims 1-7, comprising the steps of:

premixing PE wax, a dispersing agent, an antioxidant and zinc stearate to obtain a premix;

mixing ethylene-butyl acrylate copolymer, high-density polyethylene and conductive carbon black for the first time, and then adding the premix for mixing again to obtain a cured rubber;

and extruding, bracing and granulating the cooked adhesive to obtain the semiconductive shielding material.

9. Use of a semiconducting shield according to any of claims 1-7 and/or prepared according to the preparation method of claim 8 for the preparation of a high voltage cable.

10. A high voltage cable, characterized in that it comprises a semiconducting shield according to any of claims 1-7 and/or prepared according to the preparation method of claim 8.

Technical Field

The invention relates to a semiconductive shielding material, a preparation method and application thereof, in particular to a low-thermal-shrinkage ultra-smooth semiconductive shielding material for a 110kV large-square cable and a preparation method thereof, and belongs to the technical field of production of materials for high-voltage cables.

Background

A cable generally consists of a conductor, an inner shield layer, an insulating layer, an outer shield layer and a sheath. ICE specifies that cables of voltage class 6kV and above should be provided with an inner and an outer shield. The conductor is formed by twisting a plurality of wires, the surface of the conductor is not smooth, a gap is easily formed between the conductor and the insulating layer to cause electric field concentration, the surface of the conductor is provided with an inner shielding layer made of a semi-conductive material, the inner shielding layer is equipotential to the shielded conductor and is in good contact with the insulating layer, and therefore partial discharge between the conductor and the insulating layer is avoided; similarly, there may be a gap between the insulating layer and the sheath, which is easy to cause partial discharge, so that an outer shielding layer of a semi-conductive material is disposed on the surface of the insulating layer to achieve good contact with the shielded insulating layer and equipotential with the sheath, thereby preventing partial discharge from occurring between the insulating layer and the sheath.

With the development of high-voltage cable technology, many cable manufacturers in China have the capacity of producing high-voltage cables at present, but due to the fact that the purity of nitrogen in a vulcanizing tube of the cable factory is not enough, the phenomenon that an outer shielding layer cracks occasionally occurs when 110kV large-square cables are produced; meanwhile, when the cable is connected, the insulating layer and the shielding layer are easily separated due to thermal contraction of materials, so that the quality of the high-voltage cable is affected.

Disclosure of Invention

The invention is to solveProblem(s)

In view of the technical problems in the prior art, the purity of nitrogen in a vulcanization pipe in a cable plant is insufficient, so that the outer screen is occasionally cracked when a 110kV large square cable is produced; meanwhile, the insulating layer and the shielding layer are easily separated and the like due to the thermal shrinkage of the material during jointing; the invention firstly provides a semiconductive shielding material which can solve the problem of separation of an insulating layer and a shielding layer and can prevent stress cracking of a large-square high-voltage cable during production.

Furthermore, the invention also provides a preparation method of the semiconductive shielding material, which has the advantages of easily obtained raw materials and simple and feasible preparation steps.

Means for solving the problems

The invention provides a semiconductive shielding material, which comprises the following components: ethylene-butyl acrylate copolymer, high-density polyethylene, conductive carbon black, PE wax, zinc stearate, dispersant and antioxidant;

wherein the mass ratio of the ethylene-butyl acrylate copolymer to the high-density polyethylene is 1 (0.05-0.2), preferably 1 (0.07-0.1).

The semiconductive shielding material comprises, by weight, 45-50 parts of an ethylene-butyl acrylate copolymer, 2-10 parts of high-density polyethylene, 37-40 parts of conductive carbon black, 0.5-2 parts of PE wax, 1-4 parts of zinc stearate, 0.05-1 part of a dispersing agent and 0.05-1 part of an antioxidant;

the semi-conductive shielding material comprises, by weight, 45-50 parts of ethylene-butyl acrylate copolymer, 4-6 parts of high-density polyethylene, 39-40 parts of conductive carbon black, 1-1.2 parts of PE wax, 1.5-2.5 parts of zinc stearate, 0.1-0.4 part of dispersing agent and 0.1-0.4 part of antioxidant in the ultra-smooth semi-conductive shielding.

The semiconductive shielding material provided by the invention is characterized in that the melt index of the high-density polyethylene at 190 ℃ and 2.16kg is 14-19 g/10 min.

The semiconductive shielding material provided by the invention is characterized in that the melt index of the ethylene-butyl acrylate copolymer at 190 ℃ under 2.16kg is 5-7 g/10 min;

in the ethylene-butyl acrylate copolymer, the content of butyl acrylate is 25-30%.

The semiconductive shielding material is characterized in that the PE wax has a number average molecular weight of 3000-5000.

The semiconductive shield according to the present invention, wherein the dispersant is a wetting dispersant, preferably a multifunctional wetting dispersant.

The semiconductive shielding material according to the present invention, wherein the antioxidant comprises one or two of 4, 4' -thiobis (6-tert-butyl-m-cresol), and pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ].

The invention also provides a preparation method of the semiconductive shielding material, which comprises the following steps:

premixing PE wax, a dispersing agent, an antioxidant and zinc stearate to obtain a premix;

mixing ethylene-butyl acrylate copolymer, high-density polyethylene and conductive carbon black for the first time, and then adding the premix for mixing again to obtain a cured rubber;

and extruding, bracing and granulating the cooked adhesive to obtain the semiconductive shielding material.

The invention also provides an application of the semiconductive shielding material and/or the semiconductive shielding material prepared by the preparation method in preparation of a high-voltage cable.

The invention also provides a high-voltage cable which comprises the semiconductive shielding material and/or the semiconductive shielding material prepared by the preparation method.

ADVANTAGEOUS EFFECTS OF INVENTION

The semiconductive shielding material disclosed by the invention takes the ethylene-butyl acrylate copolymer as a matrix, and the high-density polyethylene is added, so that the material has a skeleton supporting effect after being extruded, an insulating layer and a shielding layer are prevented from being separated, and the stress cracking phenomenon in the vulcanization process is prevented.

Further, when the semiconductive shielding material is used, the thermal shrinkage phenomenon of a 110kV large-square cable can be reduced on the premise of not changing the existing processing technology of the 110kV high-voltage cable.

Furthermore, the raw materials of the preparation method of the semiconductive shielding material are easy to obtain, the preparation steps are simple and feasible, and the preparation method is suitable for mass production.

Detailed Description

The present invention will be described in detail below. The technical features described below are explained based on typical embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

in the present specification, the numerical range represented by "numerical value a to numerical value B" means a range including the end point numerical value A, B.

In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

In this specification, "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

In the present specification, reference to "some particular/preferred embodiments," "other particular/preferred embodiments," "embodiments," and the like, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.

The invention firstly provides a semiconductive shielding material, which comprises the following components: ethylene-butyl acrylate copolymer, high-density polyethylene, conductive carbon black, PE wax, zinc stearate, dispersant and antioxidant; wherein the mass ratio of the ethylene-butyl acrylate copolymer to the high-density polyethylene is 1 (0.05-0.2), preferably 1 (0.07-0.1).

The ethylene-butyl acrylate copolymer is a good thermoplastic elastomer and has good elasticity and flexibility.

The high-density polyethylene of the invention is a thermoplastic high polymer material with better performance, compared with low-density polyethylene, the high-density polyethylene has the advantages of high crystallinity, high softening point, high modulus, high strength and the like, has particularly outstanding low-temperature performance, and can still keep the flexibility in a cold environment of 60 ℃ below zero, thereby leading the environmental stress cracking resistance of the high-density polyethylene to be better. The high-density polyethylene has small permeability to water vapor and air, low water absorption, good chemical stability, and resistance to corrosion of acid, alkali and various salts.

The inventor finds that when the semiconductive shielding material is produced, the ethylene-butyl acrylate copolymer is used as a matrix, and the high-density polyethylene is added, so that the extruded material has a skeleton supporting effect, and the insulating layer and the shielding layer can be prevented from being separated; meanwhile, the environmental stress cracking resistance of the high-density polyethylene can be fully exerted, and the stress cracking phenomenon in the vulcanization process can be prevented.

Specifically, in the ethylene-butyl acrylate copolymer, the melt index of the ethylene-butyl acrylate copolymer at 190 ℃ under 2.16kg is 5-7 g/10min, the content of butyl acrylate is 25-30%, and the ethylene-butyl acrylate copolymer with the melt index has better fluidity and compatibility in a system.

Specifically, among the high-density polyethylenes of the present invention, it is preferable to use a high-density polyethylene having a melt index of 14 to 19g/10min at 190 ℃ under 2.16kg, for example: ME9180, and the like.

The mass ratio of the ethylene-butyl acrylate copolymer to the high-density polyethylene is 1 (0.05-0.2), preferably 1 (0.07-0.1). When the mass ratio of the ethylene-butyl acrylate copolymer to the high-density polyethylene is 1 (0.05-0.2), the prepared semiconductive shielding material has good mechanical properties, and the tensile strength of the semiconductive shielding material can reach more than 20 MPa. Specifically, the mass ratio of the ethylene-butyl acrylate copolymer of the present invention to the high-density polyethylene may be 1:0.08, 1:0.09, 1:0.11, 1:0.12, 1:0.15, 1:0.16, 1:0.18, or the like.

In some specific embodiments, the content of the ethylene-butyl acrylate copolymer in the semiconductive shielding material is 45 to 50 parts by weight, for example: 46 parts, 47.5 parts, 48 parts, 49.5 parts, 50 parts and the like; the content of the high-density polyethylene is 2-10 parts, preferably 4-6 parts, for example: 3 parts, 3.5 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 8 parts and the like. When the content of the ethylene-butyl acrylate copolymer is 48-50 parts and the content of the high-density polyethylene is 2-10 parts, the prepared semiconductive shielding material has excellent heat shrinkage performance, and the heat shrinkage of the product can be controlled within 0.2% as verified by extrusion in a cable plant.

In order to obtain proper conductivity, conductive carbon black is also added when the semiconductive shielding material is produced. In the semiconductive shielding material, the content of the conductive carbon black is 37 to 40 parts by weight, preferably 39 to 40 parts by weight, for example: 37 parts, 37.5 parts, 38 parts, 38.5 parts, 39 parts, 39.5 parts and the like. When the content of the conductive carbon black is 37-40 parts, the effect of balancing an electric field can be better achieved.

Specifically, in the present invention, the conductive carbon black may be Unico LK-2107, Yongdont 260, Yongdont YD-280C, Columbia 7090, Carbote carbon black VXC200, Carbote carbon black VXC68, and the like.

Further, since high temperature extrusion is required in the preparation method, the present invention protects the ethylene-butyl acrylate copolymer from decomposition by using PE wax. In the invention, the content of the PE wax in the semiconductive shielding material is 0.5-2 parts by weight, preferably 1-1.2 parts by weight, such as: 0.7 part, 0.9 part, 1.1 part, 1.3 parts, 1.4 parts, 1.6 parts, 1.8 parts and the like. When the content of the PE wax is 0.5-2 parts, the material can be extruded for a long time during processing.

In some specific embodiments, the number average molecular weight of the PE wax is 3000-5000, and when the number average molecular weight of the PE wax is 3000-5000, the PE wax is beneficial to the dispersion of the conductive carbon black in the system, and the PE wax has excellent compatibility with other components of the semiconductive shielding material and is not easy to precipitate.

In addition, the semiconductive shielding material of the present invention further contains zinc stearate, and zinc stearate is used as a lubricating aid. In the semiconductive shielding material, the content of zinc stearate is 1-4 parts by weight, preferably 1.5-2.5 parts by weight, for example: 1.2 parts, 1.8 parts, 2 parts, 2.2 parts, 2.8 parts, 3 parts, 3.2 parts, 3.5 parts, 3.8 parts and the like. When the content of the zinc stearate is 1-4 parts, the zinc stearate has an excellent lubricating effect and a good stripping effect compared with other lubricating additives, so that the self-cleaning performance of the material is more excellent.

In order to achieve better dispersion of the conductive carbon black and to facilitate smoother and smoother extrusion surfaces, the present invention, in some particular embodiments, achieves this by adding a dispersant. Specifically, the content of the dispersant in the semiconductive shielding material is 0.05 to 1 part by weight, preferably 0.1 to 0.4 part by weight, for example: 0.2 part, 0.3 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part and the like. When the content of the dispersing agent is 0.05-1 part, the conductive carbon black is favorably and better dispersed, and the extrusion surface is favorably smooth and flat. OCS extrusion verifies that the number of surface protrusions of the semiconductive shielding material is 0, wherein the surface protrusions are larger than 75 micrometers, and the surface protrusions are formed by adding the dispersing agent.

In some specific embodiments, the dispersant of the present invention is a wetting dispersant, preferably a multifunctional dispersant. Specifically, the dispersant may be TEGO Dispers 760W (an aqueous solution of a multifunctional surfactant with pigment affinity groups).

Further, the semiconductive shielding material of the present invention further comprises an antioxidant, specifically, in parts by weight, the content of the antioxidant in the semiconductive shielding material is 0.05 to 1 part, preferably 0.1 to 0.4 part, for example: 0.2 part, 0.3 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part and the like. Preferably, in the present invention, the antioxidant is one or two of 4, 4' -thiobis (6-t-butyl-m-cresol) and pentaerythritol tetrakis [ β - (3, 5-di-t-butyl-4-hydroxyphenyl) propionate ].

The invention also provides a preparation method of the semiconductive shielding material, which comprises the step of mixing the components of the semiconductive shielding material.

Specifically, the preparation method comprises the following steps:

premixing PE wax, a dispersing agent, an antioxidant and zinc stearate to obtain a premix;

mixing ethylene-butyl acrylate copolymer, high-density polyethylene and conductive carbon black for the first time, and then adding the premix for mixing again to obtain a cured rubber;

and extruding, bracing and granulating the cooked adhesive to obtain the semiconductive shielding material.

Further, the preparation method may include the steps of:

(1) adding the PE wax, the dispersing agent, the antioxidant and the zinc stearate into a stirrer for premixing to obtain a premix;

(2) adding ethylene-butyl acrylate copolymer, high-density polyethylene and conductive carbon black into an internal mixer for primary closed mixing for 40-80 seconds, then adding the premix obtained in the step (1), performing closed mixing for 200-400 seconds again, and mixing to obtain a cured rubber, wherein cooling water is required to be started in the process to ensure that the material temperature is lower than 180 ℃;

(3) and feeding the mixed cooked rubber into a double screw for extrusion, bracing and granulation, screening out irregular particles from the obtained particles through a vibrating screen, absorbing the corresponding cross-linking agent by using a post-absorption method, and then air-drying, cooling and packaging to obtain a final product, namely the semi-conductive shielding material.

In addition, the invention also provides an application of the semiconductive shielding material and/or the semiconductive shielding material prepared by the preparation method in preparation of a high-voltage cable, which can solve the problems of cracking of an outer shielding layer and separation of an insulating layer and the shielding layer.

In addition, the invention also provides a high-voltage cable which comprises the semiconductive shielding material and/or the semiconductive shielding material prepared by the preparation method.

Examples

Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

Raw materials

Ethylene-butyl acrylate copolymer: arcoma, france; wherein the melt index of the ethylene-butyl acrylate copolymer at 190 ℃ under 2.16kg is 7g/10min, and the content of butyl acrylate is 27%;

high density polyethylene: LG chemistry; wherein the melt index of the high-density polyethylene at 190 ℃ under 2.16kg is 18g/10 min;

PE wax: yanshan petrochemical Co;

zinc stearate: polymer materials group ltd, wan ma, zhejiang.

The contents of the components in the examples are in parts by weight.

Example 1

The method comprises the following steps: taking 1.2 parts of PE wax with the number average molecular weight of 3000-5000, 0.3 part of polyfunctional group type dispersant TEGO dispers 760W, 0.4 part of antioxidant 4, 4' -thiobis (6-tert-butyl-m-cresol) and 2.1 parts of zinc stearate, and adding a stirrer for premixing to obtain a premix.

Step two: 50 parts of ethylene-butyl acrylate copolymer, 6 parts of high-density polyethylene and 50040 parts of cabot carbon black VXC are put into an internal mixer for primary closed mixing for 60 seconds, then the pre-mixture pretreated in the step one is added, closed mixing is carried out for 300 seconds again, the mature rubber is mixed, and cooling water is started to ensure that the material temperature is lower than 180 ℃ in the process;

step three: and feeding the mixed cooked rubber into a double screw for extrusion, bracing and granulation, screening out irregular particles from the obtained particles through a vibrating screen, absorbing a corresponding cross-linking agent by using a post-absorption method, air-drying, cooling and packaging to obtain a final product, namely the semi-conductive shielding material.

Example 2

The difference between this example and example 1 is that 49.5 parts of ethylene-butyl acrylate copolymer, 6 parts of high density polyethylene and 6 parts of cabot carbon black VXC 50039.5 parts are used, and the composition is the same as that of example 1. And the preparation process of the embodiment 2 is the same as that of the embodiment 1, and the semiconductive shielding material is prepared.

Example 3

This example differs from example 1 only in 49 parts of ethylene-butyl acrylate copolymer, 7 parts of high density polyethylene, 50039 parts of cabot carbon black VXC, and the rest of the composition is the same as example 1. And the preparation process of the embodiment 3 is the same as that of the embodiment 1, and the semiconductive shielding material is prepared.

Example 4

This example differs from example 1 in 48.5 parts of ethylene-butyl acrylate copolymer, 8 parts of high density polyethylene and 50039.5 parts of cabot carbon black VXC. The rest of the composition is the same as that of example 1. And the preparation process of the embodiment 4 is the same as that of the embodiment 1, and the semiconductive shielding material is prepared.

Example 5

This example differs from example 1 in 49 parts of ethylene-butyl acrylate copolymer, 9 parts of high density polyethylene, 50037 parts of cabot carbon black VXC, and the rest of the composition is the same as example 1. And the preparation process of the embodiment 5 is the same as that of the embodiment 1, and the semiconductive shielding material is prepared.

Example 6

The difference between the example and the example 1 is 48 parts of ethylene-butyl acrylate copolymer, 7 parts of high-density polyethylene and 50040 parts of cabot carbon black VXC. The rest of the composition is the same as that of example 1. And the preparation process of the embodiment 6 is the same as that of the embodiment 1, and the semiconductive shielding material is prepared.

Comparative example 1

The semiconductive shielding material was prepared by replacing the ethylene-butyl acrylate copolymer of example 6 with high density polyethylene, i.e., 0 part of ethylene-butyl acrylate copolymer and 55 parts of high density polyethylene, the remainder being the same as in example 6, and the preparation process of comparative example 1 being the same as in example 6.

Comparative example 2

The high density polyethylene in example 6 was replaced with an ethylene-butyl acrylate copolymer, and the balance was the same as in example 6, i.e., 0 part of high density polyethylene and 55 parts of ethylene-butyl acrylate copolymer, and the balance was the same as in example 6. And the preparation process of comparative example 2 was the same as that of example 6, to prepare a semiconductive shield material.

Comparative example 3

The PE wax of example 1 was replaced with an ethylene-butyl acrylate copolymer, i.e., 51.2 parts of ethylene-butyl acrylate copolymer and 0 part of PE wax, and the composition was the same as in example 1. And the preparation process of comparative example 3 is the same as that of example 1, and the semiconductive shield material was prepared.

Comparative example 4

The zinc stearate in example 1 was replaced with an ethylene-butyl acrylate copolymer, i.e., 52.1 parts of ethylene-butyl acrylate copolymer and 0 part of zinc stearate, and the composition was the same as in example 1. And the preparation process of comparative example 4 was the same as that of example 1, to prepare a semiconductive shield material.

Comparative example 5

The multi-functional dispersant TEGO dispers 760W in example 1 was replaced with high density polyethylene, i.e., 6.3 parts high density polyethylene and 0 part multi-functional dispersant TEGO dispers 760W, all having the same composition as in example 1. And the preparation process of comparative example 5 was the same as that of example 1, to prepare a semiconductive shield material.

Comparative example 6

The multi-functional dispersant TEGO dispers 760W in example 1 was replaced with ethylene-butyl acrylate copolymer, i.e., 50.3 parts ethylene-butyl acrylate copolymer and 0 part multi-functional dispersant TEGO dispers 760W, and the composition was the same as in example 1. And the preparation process of comparative example 5 was the same as that of example 1, to prepare a semiconductive shield material.

Performance testing

The semiconductive shield materials of examples 1-6 and comparative examples 1-6 were subjected to the relevant performance tests according to the test standards and requirements of table 1 below, and the results are shown in tables 2 and 3:

TABLE 1

The surface bump verification method comprises the following steps: the test is carried out under the optical scanning equipment with a high-resolution camera, and the scanning speed is 0.025-0.05 m²Min, the lowest height scanned by the device is 25 μm, the surface of the sample belt is scanned by a high-resolution camera, the test is carried out in a standard state with the temperature of 23 +/-2 ℃ and the relative humidity of 50 +/-5%, and the time for adjusting the device in the standard state is not less than 6 h. And adjusting the temperature of each temperature zone of the extruder to ensure that the extruded material reaches a good plasticizing state for testing, and adjusting the thickness of the sample belt to the optimal measurement thickness, wherein the detection sensitivity of the device is not lower than 85%. After the extruded sample has stabilized thickness, the test can be started, and the total surface area of the test sample is about 1m²。

TABLE 2

TABLE 3

After the shielding layer is prepared from the semiconductive shielding materials of embodiments 1-6, the materials have a skeleton supporting effect, so that the insulating layer and the shielding layer can be prevented from being separated due to thermal shrinkage of the materials, and the stress cracking phenomenon in the vulcanization process can be prevented.

By comparing example 6 with comparative example 1, when the ethylene-butyl acrylate copolymer is not used in comparative example 1, the elongation at break is greatly reduced (only 50%, which is far lower than the minimum requirement (200%) of the industry), and the elongation at break (210%) of the semiconductive shielding material prepared in example 6 can meet the requirement of the industry. This shows that the addition of high density polyethylene can increase the elongation at break of the semiconductive shielding material and prevent the cracking of the shielding layer.

By comparing example 6 with comparative example 2, the tensile strength of comparative example 2 was reduced (only 10% below the industry minimum requirement (12%)), and the tensile strength of the semiconductive shield of example 6 (17%) was higher than the industry requirement, when no high density polyethylene was used in comparative example 2. This shows that the addition of high density polyethylene can increase the tensile strength of the semiconductive shielding material and prevent cracking of the shielding layer.

By comparing example 1 with comparative example 3, when the PE wax is not used in comparative example 3, the tensile strength is slightly reduced, the elongation at break is greatly reduced (only 160%, which is lower than the minimum requirement (200%) of the industry), and the elongation at break (210%) of the semiconductive shielding material prepared in example 1 can meet the requirement of the industry. The result shows that the PE wax can prevent the ethylene-butyl acrylate copolymer from decomposing, so that the ethylene-butyl acrylate copolymer plays a role, the tensile strength and the elongation at break of the semiconductive shielding material are improved, and the cracking phenomenon of the shielding layer is further prevented.

By comparing example 1 with comparative example 4, when zinc stearate is not used in comparative example 4, the tensile strength is slightly reduced, the elongation at break is greatly reduced (only 150%, which is lower than the minimum requirement (200%) of the industry), and the elongation at break (210%) of the semiconductive shielding material prepared in example 1 can meet the industry standard.

By comparing example 1 with comparative example 5, when the high density polyethylene is used in place of the dispersant in comparative example 5, the number of surface protrusions of more than 75 μm is excessive (15), resulting in poor surface smoothness of the high voltage cable. The addition of the dispersing agent can reduce the surface protrusions of the semiconductive shielding material and ensure the smooth surface of the high-voltage cable.

By comparing example 1 with comparative example 6, when the ethylene-butyl acrylate copolymer was used in place of the dispersant in comparative example 6, the number of surface protrusions of more than 75 μm was too large (13), resulting in poor surface smoothness of the high voltage cable. The addition of the dispersing agent can reduce the surface protrusions of the semiconductive shielding material and ensure the smooth surface of the high-voltage cable.

It should be noted that, although the technical solutions of the present invention are described by specific examples, those skilled in the art can understand that the present invention should not be limited thereto.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.