CN114031837A - Crosslinkable polyethylene insulating material for high-voltage cable, preparation method and application thereof - Google Patents
Crosslinkable polyethylene insulating material for high-voltage cable, preparation method and application thereof Download PDFInfo
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- CN114031837A CN114031837A CN202111566202.9A CN202111566202A CN114031837A CN 114031837 A CN114031837 A CN 114031837A CN 202111566202 A CN202111566202 A CN 202111566202A CN 114031837 A CN114031837 A CN 114031837A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/06—Polyethene
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
- H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
- H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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- C08L2203/00—Applications
- C08L2203/20—Applications use in electrical or conductive gadgets
- C08L2203/202—Applications use in electrical or conductive gadgets use in electrical wires or wirecoating
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
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- C08L2312/00—Crosslinking
Abstract
The invention relates to a crosslinkable polyethylene insulating material for a high-voltage cable, a preparation method and application thereof. The insulating material comprises the following components in percentage by mass: 97.5-99.3% of polyethylene base material, 0.5-2% of cross-linking agent, 0.1-0.5% of auxiliary cross-linking agent and 0.1-0.5% of antioxidant. The traditional insulating material is modified by introducing the polyethylene with high branching degree, so that polar crosslinking decomposition byproducts causing nonlinear change of conductivity in the insulating material are reduced, the generation and migration of charges in a direct-current electric field are effectively inhibited, and further the nonlinear effect of conductivity in the high-voltage cable is inhibited. Meanwhile, the preparation method of the insulating material is simple and feasible, and the industrial applicability is strong. The polyethylene insulating material can be applied to high-voltage direct-current cables.
Description
Technical Field
The invention relates to the field of insulating materials, in particular to a crosslinkable polyethylene insulating material for a high-voltage cable, a preparation method and application thereof.
Background
With the rapid development of electric power construction, the insulating material cable is widely applied to the aspects of production, transportation, installation, recovery and the like due to the advantages of small volume, light weight, high working temperature, low maintenance cost and environmental protection.
Because the nonlinear change effect of the electric conductivity of the insulating material along with the temperature and the field intensity is overlarge, the existing polyethylene cable insulating material can only be used for transmitting direct current electric energy in a low-voltage distribution system and cannot be directly applied to a high-voltage direct current system. In addition, the local electric field intensity is far higher than the running intensity of the cable, so that the cable material can be directly punctured, and the additives and crosslinking byproducts in the insulating material are ionized and polarized under the direct-current electric field, so that the nonlinear change phenomenon of the conductivity in the polyethylene insulating cable is intensified. Therefore, it is an urgent technical problem to inhibit the accumulation of the nonlinear excessive increase effect of the conductivity in the high-voltage direct-current cable.
Disclosure of Invention
The invention aims to provide a crosslinkable polyethylene insulating material for a high-voltage cable, a preparation method and application thereof, wherein the material can inhibit the aggregation of the nonlinear excessive increase effect of the conductivity in the high-voltage direct-current cable.
In order to solve the technical problems, the invention adopts the following technical scheme:
the crosslinkable polyethylene insulating material for the high-voltage cable comprises the following components in percentage by mass:
(a) 97.5 to 99.3 percent of polyethylene base material;
(b) 0.5 to 2 percent of cross-linking agent;
(c) 0.1 to 0.5 percent of auxiliary crosslinking agent; and
(c) 0.1 to 0.5 percent of antioxidant;
the polyethylene base material comprises high-branching-degree polyethylene, the high-branching-degree polyethylene accounts for 30-70% of the mass of the polyethylene base material, and the branching degree of the high-branching-degree polyethylene is 1.5-4.5.
According to the invention, the high-branching polyethylene is introduced to modify the traditional polyethylene insulating material, so that the content of polar crosslinking decomposition byproducts causing nonlinear change of conductivity in the insulating material is reduced, the generation and migration of charges under a direct-current electric field are effectively inhibited, and the nonlinear effect of conductivity in a high-voltage cable is inhibited. The polyethylene insulating material can be applied to high-voltage direct-current cables.
The polyethylene base material comprises high-branching-degree polyethylene, wherein the high-branching-degree polyethylene accounts for 30-70% of the mass of the polyethylene base material, namely, the polyethylene base material comprises other non-high-branching-degree polyethylene besides the high-branching-degree polyethylene, and the mass sum of the high-branching-degree polyethylene and the non-high-branching-degree polyethylene is 100%. The branching degree of the high-branching-degree polyethylene is 1.5-4.5. In addition to the highly branched polyethylene, the polyethylene base may also include non-highly branched polyethylene, typically but not limited to, for example, linear polyethylene and branched polyethylene having a degree of branching of less than 1.5.
In a preferred embodiment of the present invention, the crosslinkable polyethylene insulation material for high voltage cables is prepared from the following components by mass percent:
(a) 97.5 to 99.3 percent of polyethylene base material;
(b) 0.5 to 2 percent of cross-linking agent;
(c) 0.1 to 0.5 percent of crosslinking assistant; and
(d) 0.1 to 0.5 percent of antioxidant;
the polyethylene base material comprises high-branching-degree polyethylene, the high-branching-degree polyethylene accounts for 30-70% of the mass of the polyethylene base material, and the branching degree of the high-branching-degree polyethylene is 1.5-4.5.
Preferably, the high-branching-degree polyethylene accounts for 40-60% of the mass of the polyethylene base material.
In the present invention, the content of the polyethylene base material is 97.5 to 99.3%, for example, 97.8%, 98.1%, 98.5%, 98.7%, 99.0% or 99.3%, preferably 97.5 to 98.5%.
In the present invention, the content of the crosslinking agent is 0.5 to 2%, for example, 0.5%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, 1.9%, or 2%. If the content of the crosslinking agent is less than 0.5%, the heat-resistant temperature of the insulating material is low, and if the content of the crosslinking agent is more than 2%, the mechanical properties of the insulating material are deteriorated. From the viewpoint of temperature resistance and mechanical properties of the insulating material, the content of the cross-linking agent is preferably 1.5-2%.
In the present invention, the content of the co-crosslinking agent is 0.1 to 0.5%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, preferably 0.2 to 0.4%.
In the present invention, the antioxidant is contained in an amount of 0.1 to 0.5%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%. If the content of the antioxidant is less than 0.1%, the requirement of the anti-aging property cannot be satisfied, and if the content of the antioxidant is more than 0.5%, the generation of the free radical of the crosslinking agent is suppressed. The antioxidant is preferably contained in an amount of 0.1 to 0.2% from the viewpoint of aging and crosslinking characteristics of the insulating material.
In a preferred embodiment of the invention, the polyethylene base is a mixture of a low-density polyethylene and a highly branched polyethylene, the mixture having a melt flow rate of from 0.15 to 0.25g/min and a density of 910-915g/m3The high-branching-degree polyethylene accounts for 30-70% of the mass of the polyethylene base material, the low-density polyethylene accounts for 70-30% of the mass of the polyethylene base material, and the mass of the polyethylene base material is the mass of the mixture of the low-density polyethylene and the high-branching-degree polyethylene.
The low-density polyethylene accounts for 70-30% of the total mass of the mixture of the low-density polyethylene and the high-branching-degree polyethylene, and if the mass fraction of the low-density polyethylene is less than 30%, the crystallization characteristic of the insulating material is affected. If the mass fraction of the low density polyethylene is more than 70%, the content of the crosslinking agent in the insulating material increases and the crosslinking by-products increase.
The melt flow rate of the mixture is 0.15-0.25g/min, the density is 910-3. If the melt flow rate is less than 0.15g/min, the extrusion characteristics of the insulation material are affected, and if the melt flow rate is greater than 0.25g/min, the eccentricity of the insulation layer during extrusion of the cable is affected. If the density is less than 910g/m3The crystalline properties of the insulation material are affected if the density is greater than 915g/m3The processing of the insulating material is not facilitated.
The melt flow rate test method comprises the following steps: GB/T3682.1-2018, and the density test method is (GB/T1033.1-2008).
In a preferred embodiment of the invention, the low density polyethylene is ultra-clean low density polyethylene, the molecular weight distribution of the ultra-clean low density polyethylene is 4.7-6.3, and the ash content is less than or equal to 100 ppm.
If the molecular weight distribution is less than 4.7, the melt fluidity of the insulation material is significantly reduced, and if the molecular weight distribution is more than 6.3, the melt strength of the insulation material is reduced and the scorch resistance is reduced.
The method for measuring the molecular weight distribution is as follows: the test was carried out by Gel Permeation Chromatography (GPC).
In a preferred embodiment of the invention, the highly branched polyethylene is DFDA-7042 polyethylene produced by Yulin energy chemical Co., Ltd. of Zhongsha Shaanxi and/or LL6201RQ polyethylene produced by Exxon Mobil.
In a preferred embodiment of the invention, the ultra-clean low density polyethylene is DJ210 polyethylene produced by the medium petrochemical shanghai company (shanghai petrochemical).
In a preferred embodiment of the present invention, the crosslinking agent is a peroxide-based compound, preferably a peroxide-based compound having a purity of 99.5% or more. The peroxide type crosslinking agent with the purity of more than 99.5 percent is adopted, so that the impurities in the crosslinking agent can be controlled, the purity of the crosslinkable polyethylene insulating material is improved, and the polar impurities causing nonlinear change of the electric conductivity in the insulating material are reduced. Typical but non-limiting crosslinking agents are, for example, tert-butyl peroxide or triethylenetriamine, preferably dicumyl peroxide. The crosslinking agent is commercially available.
In a preferred embodiment of the present invention, the antioxidant is a hindered phenol type antioxidant, more preferably a hindered phenol type antioxidant having a purity of 99.5% or more, and still more preferably a thiobisphenol type compound. By adopting the antioxidant with the purity, impurities in the antioxidant can be controlled, the purity of the crosslinkable polyethylene insulating material is improved, and polar impurities causing nonlinear change of electric conduction in the insulating material are reduced. Typical but non-limiting antioxidants are for example hindered phenols or thiobisphenols, preferably bisthioethers. The antioxidants are commercially available.
In a preferred embodiment of the present invention, the co-crosslinking agent comprises at least one of trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate (TMPTAMA), or Ethylene Glycol Diacrylate (EGDA).
The invention also provides a preparation method of the crosslinkable polyethylene insulating material for the high-voltage cable, which comprises the following steps:
and mixing the polyethylene base material, the cross-linking agent, the auxiliary cross-linking agent and the antioxidant to obtain the cross-linkable polyethylene insulating material for the high-voltage cable.
In a preferred embodiment of the present invention, the method comprises: melting and mixing the mixture of the polyethylene base material, the auxiliary crosslinking agent and the antioxidant, cooling the melted and mixed mixture to 60-90 ℃, and then adding the crosslinking agent into the mixture by a spray absorption method to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
In a preferred embodiment of the present invention, the melt-mixing is performed at 120 to 125 ℃.
In a preferred embodiment of the present invention, the method further comprises the steps of drying and cooling after adding the crosslinking agent to the mixture.
Drying can be carried out by drying means known to the person skilled in the art, said cooling being for example possible to room temperature.
In a preferred embodiment of the present invention, the method comprises:
melting and mixing: melting and mixing a mixture of the polyethylene base material, the auxiliary crosslinking agent and the antioxidant at 120-125 ℃;
absorption: cooling the melted and mixed mixture to 80 ℃, and adding the cross-linking agent into the mixture by a spray absorption method;
and (3) drying: and drying the product obtained by absorption, and cooling to room temperature to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
In the preferred scheme, the insulation material is prepared by melting, mixing, absorbing and drying, the method is simple and feasible, and the industrial applicability is strong.
The invention also provides an application of the crosslinkable polyethylene insulating material for the high-voltage cable in the high-voltage direct-current cable. The polyethylene insulating material can inhibit the accumulation of the nonlinear excessive increase effect of the conductivity in the high-voltage direct-current cable, and can be used in the high-voltage direct-current cable.
Has the advantages that:
according to the invention, the high-branching polyethylene is introduced to modify the traditional polyethylene insulating material, so that the content of polar cross-linking decomposition byproducts causing nonlinear change of conductivity in the insulating material is reduced, the generation and migration of charges under a direct-current electric field are effectively inhibited, the nonlinear change of the conductivity of the insulating material under the conditions of 30 ℃, 10kV/mm, 70 ℃ and 50kV/mm is reduced to 200-500 times from 1000-2000 times of that of the conventional common polyethylene insulating material, and the nonlinear effect of the conductivity in a high-voltage cable is inhibited. The polyethylene insulating material can be applied to high-voltage direct-current cables.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a process flow diagram of a method for preparing a crosslinkable polyethylene insulation material for a high voltage cable according to an embodiment of the present invention;
fig. 2 is a measured value and a fitted curve of the conductivity of the crosslinkable polyethylene insulation for high voltage cables according to one embodiment of the present invention as a function of temperature and field strength;
fig. 3 shows measured values and fitted curves of the conductivity of a commercially available (northern european chemical LS428) high-voltage cable crosslinkable polyethylene as a function of temperature and field strength.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
Example 1
The crosslinkable polyethylene insulating material for the high-voltage cable is prepared from the following components in percentage by mass:
97.5% of polyethylene base material, 1.9% of cross-linking agent (Achimarox dicumyl peroxide) and 0.5% of antioxidant (antioxidant 300#, 4,4' -thiobis (6-tert-butyl-3-methylphenol)); 0.1 percent of auxiliary crosslinking agent (trimethylolpropane triacrylate).
The polyethylene base stock comprises: DJ210 polyethylene produced by China petrochemical Shanghai and high-branching-degree polyethylene (LL 6201RQ polyethylene produced by Exxon Mobil), wherein the mass ratio of the DJ210 polyethylene to the high-branching-degree polyethylene is 60: 40. The polyethylene base material has MFR of 0.21g/10min and density of 913g/m3。
The preparation method of the crosslinkable polyethylene insulating material for the high-voltage cable comprises the following steps:
1) melting and mixing: mixing polyethylene base material, auxiliary cross-linking agent and antioxidant at 120 deg.c;
2) absorption: cooling the mixture of step 1) to 80 ℃ and incorporating the cross-linking agent into the mixture by a spray absorption method;
3) and (3) drying: drying the product obtained in the step 2), and then cooling to room temperature to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
Example 2
The crosslinkable polyethylene insulating material for the high-voltage cable is prepared from the following components in percentage by mass:
98.0 percent of polyethylene base stock, 1.7 percent of cross-linking agent (Achimarox dicumyl peroxide), 0.1 percent of antioxidant (300#, 4,4' -thiobis (6-tert-butyl-3-methylphenol)), and 0.2 percent of auxiliary cross-linking agent (trimethylolpropane triacrylate).
The polyethylene base stock comprises: DJ210 polyethylene produced by the Shanghai medium petrochemical industry and high branching degree polyethylene (LL 6201RQ polyethylene produced by exxonmobil), wherein the mass ratio of the DJ210 polyethylene to the high branching degree polyethylene is 60:40, and the MFR of the polyethylene base stock is 0.21g ═ 0.21 g-10min, density 913g/m3。
The preparation method of the crosslinkable polyethylene insulating material for the high-voltage cable comprises the following steps:
1) melting and mixing: the polyethylene base stock, the auxiliary crosslinking agent and the antioxidant are mixed at 122 ℃;
2) absorption: cooling the mixture of step 1) to 80 ℃ and incorporating the cross-linking agent into the mixture by a spray absorption method;
3) and (3) drying: drying the product obtained in the step 2), and then cooling to room temperature to obtain the crosslinked polyethylene insulating material.
Example 3
The crosslinkable polyethylene insulating material for the high-voltage cable is prepared from the following components in percentage by mass:
97.9 percent of polyethylene base stock, 1.5 percent of cross-linking agent (Achimarox dicumyl peroxide), 0.3 percent of antioxidant (300#, 4,4' -thiobis (6-tert-butyl-3-methylphenol)) and 0.3 percent of auxiliary cross-linking agent (trimethylolpropane triacrylate).
The polyethylene base stock comprises: DJ210 polyethylene produced by China petrochemical Shanghai and high-branching-degree polyethylene (LL 6201RQ polyethylene produced by Exxon Mobil), wherein the mass ratio of the DJ210 polyethylene to the high-branching-degree polyethylene is 60:40, the MFR of the polyethylene base stock is 0.21g/10min, and the density is 913g/m3。
The preparation method of the crosslinkable polyethylene insulating material for the high-voltage cable comprises the following steps:
1) melting and mixing: blending the polyethylene base material with an antioxidant at 123 ℃;
2) absorption: cooling the mixture of step 1) to 80 ℃ and incorporating the cross-linking agent into the mixture by a spray absorption method;
3) and (3) drying: drying the product obtained in the step 2), and then cooling to room temperature to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
Example 4
The crosslinkable polyethylene insulating material for the high-voltage cable is prepared from the following components in percentage by mass:
98.8% of polyethylene base stock, 0.5% of crosslinking agent (Achimarox dicumyl peroxide), 0.2% of antioxidant (300#, 4,4' -thiobis (6-tert-butyl-3-methylphenol)) and 0.5% of auxiliary crosslinking agent (trimethylolpropane triacrylate).
The polyethylene base stock comprises: DJ210 polyethylene produced by China petrochemical Shanghai and high-branching-degree polyethylene (LL 6201RQ polyethylene produced by Exxon Mobil), wherein the mass ratio of the DJ210 polyethylene to the high-branching-degree polyethylene is 60:40, the MFR of the polyethylene base stock is 0.21g/10min, and the density is 913g/m3。
The preparation method of the crosslinkable polyethylene insulating material for the high-voltage cable comprises the following steps:
1) melting and mixing: mixing polyethylene base material, auxiliary cross-linking agent and antioxidant at 124 deg.c;
2) absorption: cooling the mixture of step 1) to 80 ℃ and incorporating the cross-linking agent into the mixture by a spray absorption method;
3) and (3) drying: drying the product obtained in the step 2), and then cooling to room temperature to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
Example 5
The crosslinkable polyethylene insulating material for the high-voltage cable is prepared from the following components in percentage by mass:
99.3 percent of polyethylene base stock, 0.5 percent of cross-linking agent (Achimarox dicumyl peroxide), 0.1 percent of antioxidant (300#, 4,4' -thiobis (6-tert-butyl-3-methylphenol)) and 0.1 percent of auxiliary cross-linking agent (trimethylolpropane triacrylate).
The polyethylene base stock comprises: DJ210 polyethylene produced by China petrochemical Shanghai and high-branching-degree polyethylene (LL 6201RQ polyethylene produced by Exxon Mobil), wherein the mass ratio of the DJ210 polyethylene to the high-branching-degree polyethylene is 60:40, the MFR of the polyethylene base stock is 0.21g/10min, and the density is 913g/m3。
The crosslinkable polyethylene insulating material for the high-voltage cable comprises the following steps:
1) melting and mixing: mixing polyethylene base material, auxiliary cross-linking agent and antioxidant at 125 deg.c;
2) absorption: cooling the mixture of step 1) to 80 ℃ and incorporating the cross-linking agent into the mixture by a spray absorption method;
3) and (3) drying: drying the product obtained in the step 2), and then cooling to room temperature to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
Example 6
The crosslinkable polyethylene insulating material for the high-voltage cable is prepared from the following components in percentage by mass:
97.5 percent of polyethylene base stock, 1.8 percent of cross-linking agent (Achimarox dicumyl peroxide), 0.5 percent of antioxidant (300#, 4,4' -thiobis (6-tert-butyl-3-methylphenol)) and 0.2 percent of auxiliary cross-linking agent (trimethylolpropane triacrylate).
The polyethylene base stock comprises: DJ210 polyethylene produced by China petrochemical Shanghai and high-branching-degree polyethylene (LL 6201RQ polyethylene produced by Exxon Mobil), wherein the mass ratio of the DJ210 polyethylene to the high-branching-degree polyethylene is 60:40, the MFR of the polyethylene base stock is 0.21g/10min, and the density is 913g/m3。
The preparation method of the crosslinkable polyethylene insulating material for the high-voltage cable comprises the following steps:
1) melting and mixing: mixing polyethylene base material, auxiliary cross-linking agent and antioxidant at 120 deg.c;
2) absorption: cooling the mixture of step 1) to 80 ℃ and incorporating the cross-linking agent into the mixture by a spray absorption method;
3) and (3) drying: drying the product obtained in the step 2), and then cooling to room temperature to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
Example 7
The crosslinkable polyethylene insulating material for the high-voltage cable is prepared from the following components in percentage by mass:
97.5 percent of polyethylene base stock, 1.7 percent of cross-linking agent (Achimarox dicumyl peroxide), 0.5 percent of antioxidant (300#, 4,4' -thiobis (6-tert-butyl-3-methylphenol)) and 0.3 percent of auxiliary cross-linking agent (trimethylolpropane triacrylate).
The polyethylene base stock comprises: DJ210 polyethylene produced by China petrochemical Shanghai and high-branching-degree polyethylene (LL 6201RQ polyethylene produced by Exxon Mobil), wherein the mass ratio of the DJ210 polyethylene to the high-branching-degree polyethylene is 60:40, the MFR of the polyethylene base stock is 0.21g/10min, and the density is 913g/m3。
The preparation method of the crosslinkable polyethylene insulating material for the high-voltage cable comprises the following steps:
1) melting and mixing: mixing polyethylene base material, auxiliary cross-linking agent and antioxidant at 120 deg.c;
2) absorption: cooling the mixture of step 1) to 80 ℃ and incorporating the cross-linking agent into the mixture by a spray absorption method;
3) and (3) drying: drying the product obtained in the step 2), and then cooling to room temperature to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
Example 8
The crosslinkable polyethylene insulating material for the high-voltage cable is prepared from the following components in percentage by mass:
97.5 percent of polyethylene base stock, 1.8 percent of cross-linking agent (Achimarox dicumyl peroxide), 0.5 percent of antioxidant (300#, 4,4' -thiobis (6-tert-butyl-3-methylphenol)) and 0.2 percent of auxiliary cross-linking agent (trimethylolpropane triacrylate).
The polyethylene base stock comprises: DJ210 polyethylene produced by China petrochemical Shanghai and high-branching-degree polyethylene (LL 6201RQ polyethylene produced by Exxon Mobil), wherein the mass ratio of the DJ210 polyethylene to the high-branching-degree polyethylene is 60:40, the MFR of the polyethylene base stock is 0.21g/10min, and the density is 913g/m3。
The preparation method of the crosslinkable polyethylene insulating material for the high-voltage cable comprises the following steps:
1) melting and mixing: mixing polyethylene base material, auxiliary cross-linking agent and antioxidant at 120 deg.c;
2) absorption: cooling the mixture of step 1) to 80 ℃ and incorporating the cross-linking agent into the mixture by a spray absorption method;
3) and (3) drying: drying the product obtained in the step 2), and then cooling to room temperature to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
Example 9
The other was the same as in example 1 except that the mass ratio of the DJ210 polyethylene to the highly branched polyethylene was replaced by 70: 30.
Example 10
The other was the same as in example 1 except that the mass ratio of the DJ210 polyethylene to the highly branched polyethylene was replaced by 30: 70.
The crosslinkable polyethylene insulation for high-voltage cables obtained in examples 1 to 10 and the commercially available samples a (nordic chemical LS4258) and B (dow chemical 4201) were subjected to the following tests:
the crosslinkable polyethylene insulating material for the high-voltage cable obtained in the embodiment 1 to the embodiment 10 and the commercially available samples A and B are subjected to heat preservation at 120 ℃ for 5min, the crosslinkable polyethylene insulating material and the commercially available samples A and B are melted and pre-pressed into a film sample under the pressure of 5 to 10MPa by a hot sulfur machine, then the temperature is increased to 180 ℃ for crosslinking reaction, and the pressure is maintained at 180 ℃ under the pressure of 5 to 10MPa for 10 min. After the crosslinking reaction is completed, the sample is gradually cooled to room temperature, and degassing is carried out in a high-temperature environment of 70 ℃ to remove crosslinking byproducts as much as possible. Then, the volume resistivity of the insulating material is tested according to GB/T1410-:
TABLE 1 volume resistivity Change for examples of the invention
TABLE 2
As can be seen from tables 1 and 2, the nonlinear change of the conductivity of the crosslinkable polyethylene insulating material for the high-voltage cable is reduced to 200-500 times from 1000-2000 times of the existing commercially available sample under the conditions of 30 ℃ and 10 kV/mm-70 ℃ and 50kV/mm, and the fact that the nonlinearity of the conductivity is reduced shows that the technical scheme provided by the invention effectively inhibits the nonlinear effect of the conductivity in the high-voltage cable.
Fig. 2 and 3 show the change of the conductivity of the material with the field strength and the temperature, and the comparison of the two graphs shows that the conductivity of the material increases with the increase of the field strength and the temperature, but the change rate of the material in fig. 2 is smaller than that in fig. 3, which shows that the crosslinking by-products in the polyethylene insulating material can be reduced by the method, and the change of the conductivity is reduced.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (10)
1. The crosslinkable polyethylene insulating material for the high-voltage cable is characterized by comprising the following components in percentage by mass:
(a) 97.5 to 99.3 percent of polyethylene base material;
(b) 0.5 to 2 percent of cross-linking agent;
(c) 0.1 to 0.5 percent of auxiliary crosslinking agent; and
(d) 0.1 to 0.5 percent of antioxidant;
the polyethylene base material comprises high-branching-degree polyethylene, the high-branching-degree polyethylene accounts for 30-70% of the mass of the polyethylene base material, and the branching degree of the high-branching-degree polyethylene is 1.5-4.5.
2. The insulation material according to claim 1, wherein the insulation material is prepared from the following components in percentage by mass:
(a) 97.5 to 99.3 percent of polyethylene base material;
(b) 0.5 to 2 percent of cross-linking agent;
(c) 0.1 to 0.5 percent of auxiliary crosslinking agent; and
(d) 0.1 to 0.5 percent of antioxidant;
the polyethylene base material comprises high-branching-degree polyethylene, the high-branching-degree polyethylene accounts for 30-70% of the mass of the polyethylene base material, and the branching degree of the high-branching-degree polyethylene is 1.5-4.5;
preferably, the high-branching-degree polyethylene accounts for 40-60% of the mass of the polyethylene base material.
3. The insulation material of claim 1 or 2, wherein the polyethylene base is present in an amount of 97.5 to 98.5%;
preferably, the content of the cross-linking agent is 1.5-2%;
preferably, the content of the auxiliary crosslinking agent is 0.2-0.4%;
preferably, the content of the antioxidant is 0.1-0.2%.
4. The insulation of claim 1 or 2, wherein the polyethylene base is a mixture of low density polyethylene and highly branched polyethylene, the mixture having a melt flow rate of 0.15 to 0.25g/min and a density of 910-915g/m3The high-branching-degree polyethylene accounts for 30-70% of the mass of the polyethylene base material, and the low-density polyethylene accounts for 70-30% of the mass of the polyethylene base material.
5. The insulation material according to claim 4, wherein the low density polyethylene is ultra-clean low density polyethylene having a molecular weight distribution of 4.7 to 6.3 and an ash content of 100ppm or less.
6. The insulating material according to claim 4 or 5, wherein the highly branched polyethylene is DFDA-7042 polyethylene produced by Ulmus Shaanxi elmin energy and chemical industries, Inc. of Zhongsha and/or LL6201RQ polyethylene produced by Exxon Mobil;
preferably, the ultra-clean low density polyethylene is DJ210 polyethylene produced by Shanghai stone production;
preferably, the crosslinking agent is a peroxide compound, preferably a peroxide compound with a purity of 99.5% or more, and more preferably dicumyl peroxide;
preferably, the co-crosslinking agent comprises at least one of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate or ethylene glycol diacrylate;
preferably, the antioxidant is a hindered phenol antioxidant or a thiobisphenol antioxidant, preferably a hindered phenol antioxidant or a thiobisphenol antioxidant having a purity of 99.5% or more, more preferably a thiobisphenol compound, and still more preferably a bisthioether.
7. A process for the preparation of a crosslinkable polyethylene insulation for high voltage cables according to any of claims 1-6, characterized in that it comprises the following steps:
and mixing the polyethylene base material, the cross-linking agent, the auxiliary cross-linking agent and the antioxidant to obtain the cross-linkable polyethylene insulating material for the high-voltage cable.
8. The method of claim 7, wherein the method comprises: melting and mixing a mixture of the polyethylene base material, the auxiliary crosslinking agent and the antioxidant, cooling the melted and mixed mixture to 80 ℃, and then adding the crosslinking agent into the mixture by a spray absorption method to obtain the crosslinkable polyethylene insulating material for the high-voltage cable;
preferably, melting and mixing are carried out at 120-125 ℃;
preferably, the method further comprises the steps of drying and cooling after the addition of the cross-linking agent to the mixture.
9. The method of claim 7 or 8, wherein the method comprises:
melting and mixing: melting and mixing a mixture of the polyethylene base material, the auxiliary crosslinking agent and the antioxidant at 120-125 ℃;
absorption: cooling the melted and mixed mixture to 80 ℃, and adding the cross-linking agent into the mixture by a spray absorption method;
and (3) drying: and drying the product obtained by absorption, and cooling to room temperature to obtain the crosslinkable polyethylene insulating material for the high-voltage cable.
10. Use of a crosslinkable polyethylene insulation for high voltage cables according to any of claims 1-6 in high voltage direct current cables.
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| CN116199963A (en) * | 2023-03-10 | 2023-06-02 | 南京中超新材料股份有限公司 | Peroxide crosslinked polyethylene material and preparation method thereof |
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