CN114015148A - Method for preparing high-voltage cable semiconductive shielding material by using low-impurity conductive carbon black - Google Patents
Method for preparing high-voltage cable semiconductive shielding material by using low-impurity conductive carbon black Download PDFInfo
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- CN114015148A CN114015148A CN202111367060.3A CN202111367060A CN114015148A CN 114015148 A CN114015148 A CN 114015148A CN 202111367060 A CN202111367060 A CN 202111367060A CN 114015148 A CN114015148 A CN 114015148A
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- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
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Abstract
The invention discloses a method for preparing a high-voltage cable semiconductive shielding material by using low-impurity conductive carbon black, which comprises the following raw material components in parts by weight: 55-65 parts of polar polyolefin copolymer, 26-35 parts of conductive carbon black, 1-3 parts of dispersant, 0.5-2 parts of cross-linking agent, 1-2 parts of lubricant and 0.5-1 part of antioxidant. The conductive carbon black is obtained by reducing the screen residue content through classification treatment in the post-treatment stage of the carbon black, so that the conductive carbon black with the 325-mesh screen residue content of less than 7ppm is obtained. The preparation method comprises the following steps: uniformly mixing conductive carbon black, a dispersant, a lubricant, an antioxidant and a polar polyolefin copolymer; the mixture is melted and extruded in a double-screw extruder, and then is subjected to underwater bracing, grain cutting and drying to obtain granular materials; heating the granules to 65 ℃, uniformly mixing the granules with a cross-linking agent, and placing the mixture in a 65 ℃ oven for 8 hours to obtain the semiconductive shielding material. The semiconductive shielding material prepared by the invention has excellent mechanical property and electrical property, the extruded surface has extremely high smoothness, and the use requirement of a high-voltage cable can be met.
Description
Technical Field
The invention relates to the field of crosslinked polyethylene power cable materials, in particular to a high-voltage cable semiconductive shielding material based on conductive carbon black with low impurity content and a preparation method thereof.
Background
The semi-conductive shielding layer is an important component of a medium-high voltage power cable structure, can enable a lead to be in close contact with an insulating layer, reduces air gaps, and accordingly protects the insulating layer from being damaged. When a fault occurs in a cable core wire, the semi-conductive inner shielding layer can guide leaked current into the ground grid, and the main insulation is protected from being damaged. The semi-conductive inner shielding layer has a homogenized electric field, so that the electric field stress of the insulating layer can be reduced, the main insulation can be prevented from being damaged by partial discharge, the electric tree phenomenon of the insulating layer can be inhibited, and the electric field shielding layer has great significance for maintaining the operation safety of the cable and prolonging the service life of the cable. The semiconductive shielding material is a composite material using polymer as matrix, and is made up by adding conductive filler (such as carbon black) into high-molecular matrix, using cross-linking agent to make matrix cross-link and simultaneously adding antioxidant, processing adjuvant and proper quantity of other additives.
The conductive carbon black is used as a core material of the semiconductive shielding material of the high-voltage cable, and the quality of the conductive carbon black determines the performance of the semiconductive shielding material product. The carbon black not only determines the conductivity of the semiconductive shielding material, but also can control the change of physical properties of the product, the excellent functionality of the product, and even the market value of the product. However, the conductive carbon black produced by the prior art has the problems of large filling amount, poor mechanical property and processability of the material, unsmooth surface of the semiconductive shielding material and more convex points when being applied to the semiconductive shielding material of the high-voltage cable due to large impurity content and poor conductivity, and can not meet the actual use requirements of the semiconductive shielding material of the high-voltage cable. Therefore, the conductive carbon black with low impurity content is produced and applied to the high-voltage cable semiconductive shielding material, and the preparation of the ultra-smooth and ultra-clean high-voltage cable semiconductive shielding material is hopeful to be realized, so that the conductive carbon black has important practical value for the development of high-voltage cables.
Disclosure of Invention
The invention aims to provide a method for preparing a high-voltage cable semiconductive shielding material based on conductive carbon black with low impurity content, aiming at the problems that the conductive carbon black produced in the prior art is large in impurity content and poor in conductivity, the filling amount in a cable semiconductive shielding material is large, the surface of the semiconductive shielding material is not smooth, a plurality of convex points are formed, and the like.
The invention provides a method for preparing a semiconductive shielding material of a high-voltage cable by using low-impurity conductive carbon black, which comprises the following steps:
(1) weighing the raw material components according to the following weight parts:
55-65 parts of polar polyolefin copolymer, 26-35 parts of conductive carbon black, 1-3 parts of dispersant, 0.5-2 parts of cross-linking agent, 1-2 parts of lubricant and 0.5-1 part of antioxidant; the conductive carbon black is conductive carbon black with low impurity content and 325-mesh screen residue content of less than 7 ppm;
(2) removing water from the conductive carbon black, and uniformly mixing the conductive carbon black and a dispersing agent through a mechanical mixer;
(3) continuously and uniformly mixing the mixture obtained in the step (2) with a lubricant and an antioxidant under mechanical mixing, then adding a polar polyolefin copolymer, and continuously and uniformly mixing;
(4) melting and extruding the mixture obtained in the step (3) in a double-screw extruder, and then carrying out underwater bracing, granulating and drying to obtain granular materials;
(5) and (3) putting the granules obtained in the step (4) into a container, putting the container into a 65 ℃ oven, heating the granules to 65 ℃, uniformly mixing the granules and the cross-linking agent, and then putting the mixture into the 65 ℃ oven for 8 hours to enable the granules to fully absorb the cross-linking agent, thus obtaining the high-voltage cable semiconductive shielding material.
The conductive carbon black is prepared by reducing the content of screen residue through classification treatment in the post-treatment stage of the carbon black, and the preparation of the conductive carbon black with low impurity content is realized, wherein the impurity content of the conductive carbon black can be divided into the following components according to the difference of the content of 325-mesh screen residue: low impurity content (325 mesh screen residue < 7ppm), medium impurity content (7-10ppm), high impurity content (> 10 ppm). In the invention, the conductive carbon black is low-impurity-content conductive carbon black, wherein the content of 325-mesh screen residue is less than 7 ppm.
The polar polyolefin copolymer is ethylene butyl acrylate resin (EBA resin), the melt index of the polar polyolefin copolymer is 8-10g/min at 190 ℃ and 2.16kg, and the elongation at break is more than or equal to 700%. EBA resin is used as a base material, and the thermal decomposition temperature of EBA is 330 ℃ which is far higher than 240 ℃ of EVA. The high-voltage cable can pass through a vulcanization pipe at 270 ℃ in the manufacturing process, and the matrix resin with high thermal decomposition temperature is selected, so that the thermal decomposition of the base material can be reduced to the maximum extent, and the service life of the high-voltage cable is prolonged. The melt index range is 8-10g/min, the basic flow property of the system is ensured, and the processability can be met only by adding a small amount of lubricant.
The antioxidant is 1010 or 300 or a mixture of the two.
The lubricant is zinc stearate.
The cross-linking agent is dicumyl peroxide (DCP) or di-tert-butylperoxy diisopropylbenzene (BIPB) or a mixture of the dicumyl peroxide and the BIPB. BIPB molecular weight 338, melting point range 46-52 deg.C, purity > 96%, DCP molecular weight 270, melting point range 39-41 deg.C, purity > 96%.
The dispersing agent is one or more of ethylene bis stearamide and oleamide.
Compared with the prior art, the invention has the advantages that:
the invention adopts the conductive carbon black with low impurity content, the residue content of the 325-mesh sieve is less than 7ppm, the impurity content is low, the conductivity is good, and the conductive carbon black is applied to the high-voltage semi-conductive shielding material, thereby overcoming the problems that the filling amount of the common conductive carbon black filled in the high-voltage semi-conductive shielding material is too large, the mechanical property and the processing property of the material are deteriorated, the surface of the semi-conductive shielding material is not smooth, the convex points are more, and the like.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
Fig. 1 is a surface micro-topography of the semiconductive shield of the high voltage cable of example 1.
Fig. 2 is a surface micro-topography of the semiconductive shield of the cable of comparative example 1.
Fig. 3 is a surface micro-topography of the semiconductive shield of the cable of comparative example 2.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
Example 1
A semiconductive shielding material for a high-voltage cable comprises the following components in parts by weight:
60.5 parts of EBA resin, 35 parts of low-impurity-content conductive carbon black, 2 parts of a dispersing agent, 1 part of a crosslinking agent BIPB, 1 part of zinc stearate and 0.5 part of an antioxidant.
The EBA resin has a melt index of 9g/min and an elongation at break of 800% at 190 ℃ and 2.16 kg.
The conductive carbon black is conductive carbon black with low impurity content, and the content of 325-mesh screen residue is 5 ppm.
The antioxidant is a mixture of an antioxidant 1010 and an antioxidant 300, and the weight ratio is 2: 1.
The dispersant is oleamide.
The preparation method of the cable semiconductive shielding material comprises the following steps:
(1) removing water from the conductive carbon black according to the weight ratio, and uniformly mixing the conductive carbon black and the dispersant according to the weight ratio through a high-speed mixer.
(2) And (2) continuously and uniformly mixing the mixture obtained in the step (1), the lubricant and the antioxidant under a high-speed mixer, and then adding the EBA resin for continuously and uniformly mixing.
(3) And (3) carrying out melt extrusion on the mixture obtained in the step (2) in a double-screw extruder, and then carrying out underwater bracing, granulating and drying to obtain the granular material.
(4) And (4) putting the dried granules obtained in the step (3) into a container, putting the container into a 65 ℃ oven, heating the granules to 65 ℃, uniformly mixing the granules with a cross-linking agent, and then putting the mixture into the 65 ℃ oven for 8 hours to enable the granules to fully absorb the cross-linking agent, thus obtaining the high-voltage semi-conductive shielding material.
Example 2
A semiconductive shielding material for a high-voltage cable comprises the following components in parts by weight: 63 parts of EBA resin, 32 parts of low-impurity-content conductive carbon black, 1.5 parts of cross-linking agent BIPB, 2 parts of zinc stearate, 1 part of dispersing agent and 0.5 part of antioxidant.
The EBA resin has a melt index of 9g/min and an elongation at break of 800% at 190 ℃ and 2.16 kg.
The conductive carbon black is conductive carbon black with low impurity content, and the content of 325-mesh screen residue is 5 ppm.
The antioxidant is a mixture of an antioxidant 1010 and an antioxidant 300, and the weight ratio is 2: 1.
A compound of the dispersant oleamide.
The preparation method is the same as example 1.
Example 3
A semiconductive shielding material for a high-voltage cable comprises the following components in parts by weight: 65 parts of EBA resin, 30 parts of low-impurity-content conductive carbon black, 1 part of cross-linking agent BIPB, 2 parts of zinc stearate, 1 part of dispersing agent and 0.5 part of antioxidant.
The EBA resin has a melt index of 9g/min and an elongation at break of 800% at 190 ℃ and 2.16 kg.
The conductive carbon black is conductive carbon black with low impurity content, and the content of 325-mesh screen residue is 5 ppm.
The antioxidant is a mixture of an antioxidant 1010 and an antioxidant 300, and the weight ratio is 2: 1.
The dispersant is oleamide.
The preparation method is the same as example 1.
Comparative example 1
The semiconductive shielding material for the high-voltage cable comprises the following components in proportion as in example 1, and the only difference is that: the conductive carbon black is conductive carbon black with medium impurity content, and the content of 325-mesh screen residue is 8 ppm.
Comparative example 2
The semiconductive shielding material for the high-voltage cable comprises the following components in proportion as in example 1, and the only difference is that: the conductive carbon black is conductive carbon black with high impurity content, and the content of 325-mesh screen residue is 12 ppm.
Comparative example 3
The semiconductive shielding material for the high-voltage cable comprises the following components in proportion as in example 1, and the only difference is that: DCP was used as the crosslinking agent.
Comparative example 4
The semiconductive shielding material for the high-voltage cable comprises the following components in proportion as in example 1, and the only difference is that: the amount of the cross-linking agent is 2 parts.
Performance testing
(1) The physical and mechanical properties, electrical properties and surface smoothness of the semiconductive shields for high voltage cables of comparative examples 1-3 and comparative examples 1-4 are shown in table 1.
TABLE 1 physical mechanical and electrical properties of semiconductive shield for high-voltage cables
As can be seen from Table 1, the semiconductive shielding material prepared by using the conductive carbon black with low impurity content has various physical and mechanical properties and electrical properties obviously superior to those of the semiconductive shielding material prepared by using the conductive carbon black with medium impurity content and high impurity content.
(2) Fig. 1 to 3 are surface smoothness and micro-topography images of the cable semiconductive shields prepared in example 1, comparative example 1 and comparative example 2, respectively. The circled position numbers in the figures are the diameter of the projections. As can be seen by comparing the three figures, the surface burrs or protrusions of the semi-conductive shielding material of the high-voltage cable are not only fewer in number, but also smaller in diameter, namely, the surface of the semi-conductive shielding material of the high-voltage cable is smoother.
In conclusion, in the high-voltage cable semiconductive shielding material, the conductive carbon black with low impurity content is selected, the 325-mesh screen residue content is low, the dispersion is easy, the conductive performance is higher, the conductive performance requirement can be met under the condition of low content of filling amount, the mechanical performance and the processing flowability are better, the extrusion surface is smoother, and burrs or protrusions are fewer.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (7)
1. A method for preparing a high-voltage cable semiconductive shielding material by using low-impurity conductive carbon black is characterized by comprising the following steps of:
(1) weighing the raw material components according to the following weight parts:
55-65 parts of polar polyolefin copolymer, 26-35 parts of conductive carbon black, 1-3 parts of dispersant, 0.5-2 parts of cross-linking agent, 1-2 parts of lubricant and 0.5-1 part of antioxidant; the conductive carbon black is conductive carbon black with low impurity content and 325-mesh screen residue content of less than 7 ppm;
(2) removing water from the conductive carbon black, and uniformly mixing the conductive carbon black and a dispersing agent through a mechanical mixer;
(3) continuously and uniformly mixing the mixture obtained in the step (2) with a lubricant and an antioxidant under mechanical mixing, then adding a polar polyolefin copolymer, and continuously and uniformly mixing;
(4) melting and extruding the mixture obtained in the step (3) in a double-screw extruder, and then carrying out underwater bracing, granulating and drying to obtain granular materials;
(5) and (3) putting the granules obtained in the step (4) into a container, putting the container into a 65 ℃ oven, heating the granules to 65 ℃, uniformly mixing the granules and the cross-linking agent, and then putting the mixture into the 65 ℃ oven for 8 hours to enable the granules to fully absorb the cross-linking agent, thus obtaining the high-voltage cable semiconductive shielding material.
2. The method of claim 1, wherein the conductive carbon black is obtained by reducing the amount of rejects by a fractional milling treatment during a carbon black post-treatment stage.
3. The method for preparing the semiconductive shielding material of the high-voltage cable by using the low-impurity conductive carbon black as claimed in claim 1, wherein the polar polyolefin copolymer is ethylene butyl acrylate resin, the melt index of the ethylene butyl acrylate resin is 8-10g/min at 190 ℃ and 2.16kg, and the elongation at break of the ethylene butyl acrylate resin is more than or equal to 700%.
4. The method of claim 1, wherein the antioxidant is antioxidant 1010 or antioxidant 300 or a mixture of both.
5. The method of making a high voltage cable semiconductive shield using a low impurity conductive carbon black of claim 1, wherein the lubricant is zinc stearate.
6. The method of claim 1, wherein the crosslinking agent is dicumyl peroxide or di-t-butylperoxy diisopropylbenzene or a mixture thereof.
7. The method of claim 1, wherein the dispersant is one or more of ethylene bis stearamide, oleamide.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114685883A (en) * | 2022-04-22 | 2022-07-01 | 南方电网科学研究院有限责任公司 | Ultra-smooth high-voltage cable semi-conductive inner shielding material and preparation method thereof |
| CN114940784A (en) * | 2022-03-16 | 2022-08-26 | 重庆大学 | Water-blocking cable semiconductive shielding layer material and preparation method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110079004A (en) * | 2019-04-01 | 2019-08-02 | 江阴市海江高分子材料有限公司 | A kind of ultra-clean ultra-smooth semiconductive shieldin material of voltage rating 220kv and preparation method thereof |
| CN112457567A (en) * | 2020-11-27 | 2021-03-09 | 南方电网科学研究院有限责任公司 | High-voltage cable semi-conductive shielding material and preparation method thereof |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110079004A (en) * | 2019-04-01 | 2019-08-02 | 江阴市海江高分子材料有限公司 | A kind of ultra-clean ultra-smooth semiconductive shieldin material of voltage rating 220kv and preparation method thereof |
| CN112457567A (en) * | 2020-11-27 | 2021-03-09 | 南方电网科学研究院有限责任公司 | High-voltage cable semi-conductive shielding material and preparation method thereof |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114940784A (en) * | 2022-03-16 | 2022-08-26 | 重庆大学 | Water-blocking cable semiconductive shielding layer material and preparation method thereof |
| CN114685883A (en) * | 2022-04-22 | 2022-07-01 | 南方电网科学研究院有限责任公司 | Ultra-smooth high-voltage cable semi-conductive inner shielding material and preparation method thereof |
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