Polyvinyl insulation and process for its preparation, high voltage direct current crosslinked cable

Abstract

The application relates to the technical field of cables, in particular to a polyethylene-based insulating material, a preparation method thereof and a high-voltage direct-current crosslinked cable. The polyethylene-based insulating material comprises the following preparation raw materials in parts by weight: 90-99.4 parts of polyethylene, 0.3-3 parts of a crosslinking agent, 0.1-3 parts of an auxiliary crosslinking agent, 0.1-1 part of an antioxidant and 0.1-3 parts of a voltage stabilizer; wherein the voltage stabilizer comprises one or more of compounds with structures shown in the following formula (I) and formula (II). The polyethylene-based insulating material disclosed by the application has excellent compatibility of each component, can effectively inhibit the problem that the voltage stabilizer is prone to migration, and can effectively ensure the electrical tree resistance of the insulating material and reduce the electrical conductivity and space charge injection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cables, in particular to a polyethylene-based insulation material, a preparation method thereof and a high-voltage direct-current crosslinked cable. BACKGROUND

[0002] Cable power transmission has been widely applied in power transmission and distribution projects due to its advantages of no need to occupy surface corridors, small influence of climate and environment, high operation reliability, less maintenance workload, flexible laying, etc. At present, the widely used power cables can be divided into oil-filled cables, oil-paper insulation cables, impregnated paper insulation cables and plastic insulation cables according to different insulation media. Plastic insulation cables are widely used in cables of various voltage grades due to their high working temperature, good insulation performance, simple operation and maintenance, light weight, no risk of oil leakage, etc.

[0003] At present, plastic insulation cables mainly use crosslinked polyethylene (XLPE) as insulation material. When the traditional polyethylene-based insulation material is applied to cables, it can induce electrical trees, which can cause the cable to break down in a short time, greatly affecting the service life of the cable. In order to improve the performance and service life of the polyethylene-based insulation material, the main modification methods at present include improving the purity of the material, nano-doping modification and voltage stabilizer modification. Among them, the addition of voltage stabilizer modification can improve the electrical tree resistance of the polyethylene-based insulation material. However, the voltage stabilizer is generally an organic small molecule, and its compatibility with polyethylene material is poor, which can easily migrate out of the material during long-term operation, affecting the long-term operation reliability of the cable. In addition, most voltage stabilizers have strong polarity, which can increase the dielectric loss of the cable and affect its application in the alternating current field. SUMMARY

[0004] Therefore, the present application provides a polyethylene-based insulation material, a preparation method thereof and a high-voltage direct-current crosslinked cable. The compatibility of each component of the polyethylene-based insulation material of the present application is excellent, which can effectively inhibit the easy migration of the voltage stabilizer, and can effectively ensure the electrical tree resistance of the insulation material and reduce the electrical conductivity, and inhibit the injection of space charge.

[0005] In a first aspect, the present application provides a polyethylene-based insulation material, which comprises the following preparation raw materials in parts by weight: polyethylene 90-99.4 parts, crosslinking agent 0.3-3 parts, auxiliary crosslinking agent 0.1-3 parts, antioxidant 0.1-1 part, and voltage stabilizer 0.1-3 parts.

[0006] The voltage stabilizer comprises one or more of the compounds having the structures of the following formula (I) to formula (II):

[0007] , ;

[0008] L is independently at each occurrence , , , , or , q is independently at each occurrence an integer from 1 to 20;

[0009] m is independently at each occurrence an integer from 1 to 4;

[0010] R is independently at each occurrence H, halogen or C1-C4 alkyl; n1 is an integer from 1 to 2, and n2 is an integer from 1 to 3. 20

[0011] In one embodiment, the voltage stabilizer comprises one or more of and . q is independently at each occurrence an integer from 1 to 10.

[0012] In one embodiment, the polyethylene has one or more of the following characteristics:

[0013] (1) the polyethylene has a density of 0.9 g / cm 3 ~0.95 g / cm 3 ;

[0014] (2) the polyethylene has a molecular weight distribution index of 5.5~5.9;

[0015] (3) the polyethylene has a melt index of 1.9 g / min~2.1 g / min.

[0016] In one embodiment, the crosslinking agent comprises one or more of dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide isopropyl benzene and 2,5-dimethyl-2,5-bis(t-butylperoxy) hexane.

[0017] In one embodiment, the co-crosslinking agent comprises one or more of 2,4-diphenyl-4-methyl-1-pentene, triallyl cyanurate and triallyl isocyanurate.

[0018] In one embodiment, the antioxidant comprises one or more of phenolic antioxidant, phosphite antioxidant and thioester antioxidant.

[0019] In a second aspect, the present application provides a method for preparing a polyethylene-based insulation material, comprising the following steps:

[0020] melting and mixing the polyethylene, the antioxidant and the voltage stabilizer, and then extruding to prepare an intermediate material;

[0021] ​coating a cross-linking agent and a cross-linking aid on the surface of the intermediate material, and allowing the cross-linking agent and the cross-linking aid to be absorbed, to prepare the polyvinyl insulation material;

[0022] wherein the voltage stabilizer comprises one or more of compounds having structures shown in the following formula (I)~(II):

[0023] 、 ;

[0024] L is independently at each occurrence one of 、 、 、 、 or q is independently at each occurrence an integer from 1 to 20;

[0025] m is independently at each occurrence an integer from 1 to 4;

[0026] R is independently at each occurrence H, halogen or C1-C 20 alkyl; n1 is an integer from 1 to 2, and n2 is an integer from 1 to 3.

[0027] In one embodiment, the step of preparing the polyvinyl insulation material by coating a cross-linking agent and a cross-linking aid on the surface of the intermediate material, and allowing the cross-linking agent and the cross-linking aid to be absorbed, comprises:

[0028] melting and blending the cross-linking agent and the cross-linking aid to prepare a molten material;

[0029] spraying the atomized liquid formed by atomizing the molten material on the surface of the intermediate material, and allowing the cross-linking agent and the cross-linking aid to be absorbed at 60°C~90°C, to prepare the polyvinyl insulation material.

[0030] In one embodiment, the step of preparing the intermediate material comprises:

[0031] melting and blending the polyethylene, the antioxidant and the voltage stabilizer in sequence at a temperature of 115°C~125°C, at a temperature of 125°C~135°C, at a temperature of 145°C~155°C, and at a temperature of 158°C~165°C, and extruding at a temperature of 175°C~185°C and a rotation speed of 100r / min~250r / min, to prepare the intermediate material.

[0032] In a third aspect of the present application, a high-voltage direct-current crosslinked cable is provided, comprising the polyethylene-based insulating material according to any one of the first aspect of the present application or the high-voltage direct-current crosslinked cable prepared by the preparation method according to any one of the second aspect of the present application.

[0033] The polyethylene-based insulating material provided by the present application has at least the following beneficial effects:

[0034] The voltage stabilizer with the specific structure provided by the present application has a ketone-alkali intramolecular isomerization of the aromatic ketone group, which can consume the energy of high-energy electrons to inhibit the damage of high-energy electrons to the insulating material, thereby improving the breakdown strength and the electrical tree resistance of the insulating material. At the same time, the unsaturated end hydrocarbon group contained in the voltage stabilizer with the specific structure can undergo grafting reaction with polyethylene, and the chain entanglement of the long alkyl chain connected with the unsaturated end hydrocarbon group can effectively inhibit the migration of the voltage stabilizer during long-term storage and use, thereby improving the operation reliability of the cable. In addition, the end group unsaturated bond can also improve the crosslinking degree of the crosslinked polyethylene, and further ensure the compatibility between the components in the insulating material in a specific weight ratio. Further, the aromatic ring structure contained in the voltage stabilizer with the specific structure has a high electron affinity energy, which can capture the injected space charge as a charge trap, inhibit the migration of the carrier and the injection of the space charge, and reduce the electrical conductivity of the insulating material.

[0035] In summary, the polyethylene-based insulating material provided by the present application has excellent compatibility between the components, can effectively inhibit the easy migration of the voltage stabilizer, and can effectively ensure the electrical tree resistance of the insulating material and reduce the electrical conductivity to inhibit the injection of the space charge. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The process flow chart of the preparation method of the polyethylene-based insulating material provided by an example of the present application is shown. DETAILED DESCRIPTION

[0037] The polyethylene-based insulating material and the preparation method thereof, and the high-voltage direct-current crosslinked cable of the present application will be further described in detail below in combination with specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0038] "Electrical tree" refers to the tree-like local damage formed by the fine cracking in the insulating material due to partial discharge under the action of high electric field intensity.

[0039] In the present application, "*" represents a connection site or a fused site. In the present application, when the connection site is not specified in a group, it means that any optional connection site in the group is used as the connection site; in the present application, when the fused site is not specified in a group, it means that any optional fused site in the group is used as the fused site, and preferably two or more sites in the ortho position of the group are used as the fused site.

[0040] In the present application, when the connection site is not specified in a group, it means that any optional connection site in the group is used as the connection site.

[0041] In the present application, a single bond connecting a substituent group runs through the corresponding ring, indicating that the substituent group can be connected to any optional position of the ring, for example R is connected to any optional position of the benzene ring.

[0042] The voltage stabilizer used in the prior art is acetophenone However, acetophenone is an organic small molecule, which is prone to diffusion and migration under long-term operation of the insulating material, thereby affecting the operation stability of the insulating material.

[0043] Therefore, the present application provides a voltage stabilizer resistant to migration and an insulating material comprising the same. The polyethylene-based insulating material of the present application has excellent compatibility of components, can effectively inhibit the problem of easy migration of the voltage stabilizer, and can effectively ensure the electrical tree resistance of the insulating material and reduce the dielectric loss.

[0044] In a first aspect of the present application, a polyethylene-based insulating material is provided, comprising the following raw materials in parts by weight: 90-99.4 parts of polyethylene, 0.3-3 parts of a crosslinking agent, 0.1-3 parts of a co-crosslinking agent, 0.1-1 part of an antioxidant, and 0.1-3 parts of a voltage stabilizer.

[0045] The weight fraction of each raw material plays an important role in ensuring the synergistic effect of each component and the compatibility and use stability of each component of the polyethylene-based insulating material. Polyethylene is the base material of the insulating material, and its weight fraction plays an important role in ensuring the electrical insulation performance and mechanical performance of the insulating material. For example, the weight fraction of polyethylene includes but is not limited to 90 parts, 92 parts, 94 parts, 95 parts, 96 parts, 97 parts, 97.5 parts, 97.8 parts, 97.9 parts, 98 parts, 98.1 parts, 98.2 parts, 98.5 parts, 99 parts, or 99.4 parts, or a range formed by any two of the above values as end points.

[0046] The cross-linking agent and the co-cross-linking agent can be used in combination to cross-link the polyethylene molecules to form a three-dimensional network structure, thereby improving the stability of the insulating material. For example, the weight fraction of the cross-linking agent includes but is not limited to 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, or 3 parts, or a range formed by any two of the above point values as end point values.

[0047] The antioxidant plays an important role in inhibiting the oxidation reaction of the insulating material and prolonging the service life of the insulating material. The weight fraction of the antioxidant includes but is not limited to 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, or 1 part, or a range formed by any two of the above point values as end point values.

[0048] The weight fraction of the voltage stabilizer plays an important role in improving the electrical tree resistance of the insulating material, reducing the electrical conductivity and space charge injection, and ensuring the operation reliability of the cable. For example, the weight fraction of the voltage stabilizer includes but is not limited to 0.1 parts, 0.11 parts, 0.12 parts, 0.15 parts, 0.18 parts, 0.19 parts, 0.2 parts, 0.21 parts, 0.22 parts, 0.25 parts, 0.28 parts, 0.29 parts, 0.3 parts, 0.5 parts, 0.7 parts, 0.9 parts, 1 part, 1.1 parts, 1.3 parts, 1.5 parts, 1.7 parts, 1.9 parts, 2 parts, 2.1 parts, 2.3 parts, 2.5 parts, 2.7 parts, 2.9 parts, or 3 parts, or a range formed by any two of the above point values as end point values.

[0049] The voltage stabilizer includes one or more of the compounds having the structures shown in the following formula (I) to formula (II):

[0050] , .

[0051] L is independently at each occurrence a C1-C20 linear, branched, or cyclic alkyl group, a C6-C20 aryl group, or a C6-C20 aralkyl group. , , , , or . q is independently at each occurrence an integer from 1 to 20. For example, q is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20.

[0052] m, at each occurrence, is independently an integer from 1 to 4. It is understood that m is the number of L groups on the aromatic group. By way of example, m includes, but is not limited to, 1, 2, 3, or 4.

[0053] R, at each occurrence, is independently H, halogen, or C1-C6alkyl. 20 alkyl.

[0054] As used herein, "halogen" or "halo" means -F, -CI, -Br, or -I.

[0055] As used herein, "alkyl" means a saturated hydrocarbon radical of a primary (normal), or secondary, or tertiary, or quaternary carbon, or a combination thereof, which loses one hydrogen atom to form a monovalent radical. Phrases encompassed by this term, for example, "C1-C6alkyl" means a straight or branched chain alkyl radical containing from 1 to 6 carbon atoms, which can be independently C1alkyl, C4alkyl, C6alkyl, C8alkyl, C10alkyl, C12alkyl, or C14alkyl at each occurrence. 20 alkyl" means a straight or branched chain alkyl radical containing from 1 to 20 carbon atoms, which can be independently C1alkyl, C4alkyl, C6alkyl, C8alkyl, C10alkyl, C12alkyl, or C14alkyl at each occurrence. 10 alkyl, C 12 alkyl, C 14 alkyl, C 16 alkyl, C 18 alkyl, C 20Alkyl. Suitable examples include, but are not limited to, methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-l-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(CH3)CH2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-l-butyl (-CH2CH2CH(CH3)2), 2-methyl-l-butyl (-CH2CH(CH3)CH2CH3), 1-hexyl (-CH2CH2CH2CH2CH2CH3), 2-hexyl (-CH(CH3)CH2CH2CH2CH3), 3-hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl (-CH(CH3)CH(CH3)CH2CH3), 4-methyl-2-pentyl (-CH(CH3)CH2CH(CH3)2), 3-methyl-3-pentyl (-C(CH3)(CH2CH3)2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3, and octyl (-(CH2)7CH3).

[0056] The voltage stabilizer of the structure represented by the above formula (I) to formula (II) includes a ketone group connected to an aromatic group, which undergoes intramolecular keto-enol tautomerism upon impact of high-energy electron energy, and consumes the energy of the high-energy electron through the above tautomerism to inhibit the destruction of the insulating material by the high-energy electron, thereby improving the breakdown strength and the electrical tree resistance of the insulating material.

[0057] Meanwhile, the unsaturated end group hydrocarbon group contained in the voltage stabilizer can react with the polyethylene by grafting, and the chain entanglement of the long alkyl chain connected to the unsaturated end group hydrocarbon group can effectively inhibit the migration of the voltage stabilizer during long-term storage and use, thereby improving the operation reliability of the cable. In addition, the end group double bond can also improve the crosslinking degree of the crosslinked polyethylene, and further ensure the compatibility between the components in the insulating material with a specific weight fraction, both of which synergistically inhibit the migration of the voltage stabilizer.

[0058] Further, the voltage stabilizer with the specific structure includes an aromatic ring structure with a high electron affinity, which can capture the injected space charge as a charge trap, inhibit the migration of the charge carriers and the injection of the space charge, reduce the conductivity of the insulating material, and thus effectively reduce the dielectric loss of the insulating material.

[0059] n1 is any integer from 1 to 2. For example, n1 is 1 or 2.

[0060] n2 is any integer from 1 to 3. For example, n2 is 1, 2, or 3.

[0061] In one example, the voltage stabilizer includes one or more of and . q is independently at each occurrence an integer from 1 to 10. q is independently at each occurrence 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0062] Further, the voltage stabilizer includes one or more of and .

[0063] In one example, the polyethylene has a density of 0.9 g / cm 3 ~0.95 g / cm 3 . For example, the density of the polyethylene includes but is not limited to 0.9 g / cm 3 , 0.91 g / cm 3 , 0.92 g / cm 3 , 0.93 g / cm 3 , 0.94 g / cm 3 , or 0.95 g / cm 3 , or a range formed by any two of the above values as end points. Further, the density of the polyethylene is 0.91 g / cm 3 ~0.93 g / cm 3 .

[0064] The present application finds that, when low-density polyethylene is used as a base material, its good molecular weight flexibility and spatial structure can cross-link with a voltage stabilizer to form a more compact network structure, thereby further reducing the free space of the voltage stabilizer and reducing the migration of the voltage stabilizer.

[0065] In one example, the polyethylene has a molecular weight distribution index of 5.5-5.9. For example, the polyethylene has a molecular weight distribution index of 5.5, 5.6, 5.7, 5.8, or 5.9, or a range defined by any two of the above values as end points.

[0066] In the present application, the "molecular weight distribution index" refers to the ratio of the weight average molecular weight to the number average molecular weight. It can reflect the dispersion degree of the molecular weight distribution of the polyethylene. A suitable molecular weight distribution allows the polyethylene to have a higher crystallinity while ensuring the processing performance, and the compact crystal structure reduces the probability of migration of the voltage stabilizer to the surface.

[0067] In one example, the polyethylene has a melt index of 1.9 g / min-2.1 g / min. The melt index of the polyethylene includes, but is not limited to, 1.9 g / min, 1.95 g / min, 2 g / min, 2.05 g / min, 2.08 g / min, or 2.1 g / min, or a range defined by any two of the above values as end points.

[0068] In one example, the cross-linking agent includes one or more of dicumyl peroxide , benzoyl peroxide , di-t-butyl peroxide isopropylbenzene , and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane . Further, the cross-linking agent includes dicumyl peroxide.

[0069] In one example, the co-cross-linking agent includes one or more of 2,4-diphenyl-4-methyl-1-pentene, triallyl cyanurate, and triallyl isocyanurate.

[0070] When the above-mentioned cross-linking agent and co-cross-linking agent are used in combination, the cross-linking reaction speed can be accelerated, the cross-linking efficiency can be improved, and the cross-linking network can be more uniform and perfect.

[0071] In one example, the antioxidant includes one or more of a phenolic antioxidant, a phosphite antioxidant, and a thioester antioxidant.

[0072] Exemplarily, the kinds of phenolic antioxidants include, but are not limited to, 4,4'-thiobis(6-tert-butyl-m-cresol), tetra-β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid) pentaerythritol ester, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester or N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hydrazine. The corresponding model of 4,4'-thiobis(6-tert-butyl-m-cresol) is antioxidant 300. The corresponding model of tetra-β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid) pentaerythritol ester is antioxidant 1010. The corresponding model of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester is antioxidant 1076. The corresponding model of N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hydrazine is antioxidant 1024.

[0073] The kinds of phosphite antioxidants include, but are not limited to, tris(2,4-di-tert-butylphenyl) phosphite. The corresponding model of tris(2,4-di-tert-butylphenyl) phosphite is antioxidant 168.

[0074] The kinds of thioester antioxidants include, but are not limited to, dioctadecyl thiodipropionate. The corresponding model of dioctadecyl thiodipropionate is antioxidant DSTP.

[0075] In a second aspect of the present application, a preparation method of a polyethylene-based insulation material is provided, comprising the following steps:

[0076] S10: After melt mixing and extruding the polyethylene, the antioxidant and the voltage stabilizer, an intermediate material is prepared.

[0077] S20: The surface of the intermediate material is coated with a crosslinking agent and a crosslinking aid, so that the crosslinking agent and the crosslinking aid are absorbed, and the polyethylene-based insulation material is prepared.

[0078] In one of the examples, the voltage stabilizer comprises one or more of the compounds having the structures shown in the following formula (I) to formula (II):

[0079] 、 .

[0080] L is independently at each occurrence one of 、 、 、 、 or . q is independently at each occurrence any integer from 1 to 20.

[0081] m is independently at each occurrence any integer from 1 to 4.

[0082] R, at each occurrence, is independently H, halogen, or C1-C6alkyl. n1 is any integer from 1 to 2. n2 is any integer from 1 to 3. 20 alkyl. n1 is any integer from 1 to 2. n2 is any integer from 1 to 3.

[0083] It is appreciated that the voltage stabilizer of the second aspect of the present application is the same as the first aspect of the present application, and thus is not repeated here.

[0084] In one example, the step S10, the step of preparing the intermediate material, comprises:

[0085] The polyethylene, the antioxidant and the voltage stabilizer are sequentially subjected to a first melt mixing process at a temperature of 115°C to 125°C, a second melt mixing process at a temperature of 125°C to 135°C, a third melt mixing process at a temperature of 145°C to 155°C, and a fourth melt mixing process at a temperature of 158°C to 165°C, and then extruded at a temperature of 175°C to 185°C and a rotation speed of 100r / min to 250r / min to prepare the intermediate material.

[0086] For example, the step of preparing the intermediate material can be performed in a twin-screw extruder. In this case, the first melt mixing process corresponds to the first zone of the extruder, the second melt mixing process corresponds to the second zone of the extruder, the third melt mixing process corresponds to the third zone of the extruder, and the fourth melt mixing process corresponds to the fourth zone of the extruder. The material temperature and the rotation speed correspond to the process parameters of the extrusion. In the present application, unless otherwise specified, the screw diameter of the twin-screw extruder is 20mm, and the screw length-diameter ratio is 40:1.

[0087] For example, the temperature for the first melt mixing process includes, but is not limited to, 115℃, 116℃, 117℃, 118℃, 119℃ or 120℃, or a range formed by any two of the above values as end points. The temperature for the second melt mixing process includes, but is not limited to, 125℃, 126℃, 127℃, 128℃, 129℃, 130℃, 131℃, 132℃, 133℃, 134℃ or 135℃, or a range formed by any two of the above values as end points. The temperature for the third melt mixing process includes, but is not limited to, 145℃, 146℃, 147℃, 148℃, 149℃, 150℃, 151℃, 152℃, 153℃, 154℃ or 155℃. The temperature for the fourth melt mixing process includes, but is not limited to, 158℃, 159℃, 160℃, 161℃, 162℃, 163℃, 164℃ or 165℃. The extrusion temperature includes, but is not limited to, 175℃, 176℃, 177℃, 178℃, 179℃, 180℃, 181℃, 182℃, 183℃, 184℃ or 185℃. The extrusion speed includes, but is not limited to, 100 r / min, 120 r / min, 140 r / min, 160 r / min, 180 r / min, 200 r / min, 220 r / min, 240 r / min or 250 r / min.

[0088] The step of melt mixing the polyethylene, the antioxidant and the voltage stabilizer according to the weight fraction includes:

[0089] After the antioxidant and the voltage stabilizer are premixed according to the weight fraction, the polyethylene is added according to the weight fraction for melt mixing.

[0090] In one of the examples, the process parameters for the premixing include a temperature of 25℃ to 35℃ and a speed of 140 r / min to 160 r / min.

[0091] In one of the examples, the step S20 of coating the crosslinking agent and the crosslinking aid on the surface of the intermediate material and allowing the crosslinking agent and the crosslinking aid to be absorbed to prepare the polyethylene-based insulation material includes:

[0092] The crosslinking agent and the crosslinking aid are melt blended to prepare a melt material;

[0093] The atomized liquid formed by atomizing the melt material is sprayed on the surface of the intermediate material, and after allowing the crosslinking agent and the crosslinking aid to be absorbed at 60℃ to 90℃, the polyethylene-based insulation material is prepared.

[0094] In one example, the process parameters for melt blending the crosslinking agent and the co-crosslinking agent include a temperature of 60°C to 90°C. For example, the temperature for melt blending includes, but is not limited to, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C, or a range defined by any two of the foregoing as endpoints.

[0095] In a third aspect of the present application, a high voltage direct current crosslinked cable is provided, which comprises the polyethylene-based insulation material of any one of the first aspect of the present application or the high voltage direct current crosslinked cable prepared by the method of any one of the second aspect of the present application.

[0096] In one example, the high voltage direct current crosslinked cable has a voltage of 110 kV to 640 kV.

[0097] The following further specific examples are provided to further illustrate the present application. It is also to be understood that the following examples are only for further illustrating the present application and should not be construed to limit the scope of the present application. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present application are within the scope of the present application. The specific process parameters in the following examples are only one example in the appropriate range, i.e., those skilled in the art can make appropriate selection within the range through the description herein, and are not necessarily limited to the specific values in the following examples.

[0098] Preparation Example 1

[0099] Preparation Example 1 provides a synthesis method of the voltage stabilizer .

[0100] Raw material: 2,7-dibromo-phenanthrene (purity 98%, CAS: 62325-30-8) ; 5-hexenenitrile (purity 95%, CAS: 5048-19-1) .

[0101] Experimental procedure: (1) Into a dry round bottom flask was added magnesium turnings (0.855 g, 35.2 mmol, 4.0 equiv) and diethyl ether (25 mL). The flask was purged with argon and cooled to 0 °C in an ice bath. (2) A solution of 2,7-dibromo- phenanthrene (3.0 mol / L in diethyl ether, 5.9 mL, 17.6 mmol, 2.0 equiv) was added slowly to the round bottom flask using a syringe. The mixture was stirred for 45 minutes. (3) After the Grignard reagent was fully formed, 5-hexenenitrile (1 mL, 8.8 mmol, 1 equiv) was added to the reaction mixture. (4) The reaction mixture was allowed to warm to room temperature and stirred for 6 hours. (5) The reaction mixture was cooled to 0 °C and quenched with the slow addition of 30 mL of water. (6) The aqueous layer was extracted with ethyl acetate. (7) The organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated. (8) The crude product was purified by gradient elution silica gel column chromatography to yield the product.

[0102] Product NMR results: 1 H NMR (CDC13): δ 1.66 (4H, m), 1.99 (4H, m), 2.62 (4H, t), 4.80 (4H, dd), 5.62 (2H, m), 7.90 (2H, m), 8.03 (2H, m), 8.07 (2H, dd), 8.38 (2H, s).

[0103] Preparation Example 2

[0104] Preparation Example 2 provides a method of synthesizing a voltage stabilizer .

[0105] Starting materials: 7-methoxy-1-tetralone (purity 98%, CAS: 6836-19-7) ; 5-hexen-1-ol (purity 98%, CAS: 821-41-0) ; phenylboronic acid pinacol ester (purity 98%, CAS: 24388-23-6) .

[0106] Experimental steps: (1) Add potassium tert-butoxide (KOtBu) as base (2.5 mmol, 5.0 equivalent), 7-methoxy-1-naphthone as substrate (7-methoxy-1-naphthone, 0.5 mmol, 1.0 equivalent), pinacol phenylboronic acid as promoter (2.0 mmol, 4.0 equivalent), and 2.0 mL of 5-hexen-1-ol / xylene (v:v) = 3:2 to a dry round-bottom flask, and replace the air in the flask with argon. (2) Heat the reaction mixture to 80 °C in an argon atmosphere and stir for 12 hours. (3) After cooling the reaction mixture to room temperature, dilute the reaction solution with dichloromethane. (4) Extract with dichloromethane. (5) Combine the organic phases, wash with saturated brine, dry with anhydrous sodium sulfate, and concentrate under reduced pressure. (6) Purify the crude product by gradient elution silica gel column chromatography to obtain the product.

[0107] Product NMR results: 1 H NMR(CDCl3): δ 1.53 (2H, m), 1.82 (2H, m), 1.96 (2H, m), 1.97 (2H, m), 2.55 (2H, m), 2.70 (2H, m), 4.05 (2H, t), 4.80 (2H, dd), 5.61(1H, ddt), 7.06 (1H, dd), 7.12 (1H, dd), 7.49 (1H, dd).

[0108] Example 1

[0109] (1) Antioxidant (0.006 kg, antioxidant 300) and voltage stabilizer (0.006 kg, selected from Preparation Example 1) were premixed at a temperature of 30°C and a rotation speed of 150 r / min, and then low-density polyethylene (2.94 kg, density 0.92 g / cm³) was added. 3 The intermediate material was prepared by sequentially performing a first melt mixing treatment at 120°C, a second melt mixing treatment at 130°C, a third melt mixing treatment at 150°C, and a fourth melt mixing treatment at 160°C, followed by extrusion at 180°C and a rotation speed of 200 r / min.

[0110] (2) The crosslinking agent (0.042 kg, dicumyl peroxide (DCP)) and the co-crosslinking agent (0.006 kg, 2,4-diphenyl-4-methyl-1-pentene AMSD) were melt-blended at a temperature of 80 °C to prepare a melt material;

[0111] (3) Spraying the atomized liquid formed by atomizing the molten material on the surface of the intermediate material, and preparing the polyvinyl insulation material after the cross-linking agent and the co-cross-linking agent are absorbed at 80°C.

[0112] Example 2

[0113] (1) After pre-mixing the antioxidant (0.2 kg, antioxidant 300) and the voltage stabilizer (0.2 kg, selected from Preparation Example 1) at a temperature of 30°C and a rotation speed of 150 r / min, adding low-density polyethylene (98 kg, density 0.92 g / cm 3 , molecular weight distribution index 5.6, melt index 2.1 g / min), sequentially performing first melt mixing treatment at a temperature of 120°C, second melt mixing treatment at a temperature of 130°C, third melt mixing treatment at a temperature of 150°C, and fourth melt mixing treatment at a temperature of 160°C, and extruding at a temperature of 180°C and a rotation speed of 200 r / min, the intermediate material is prepared.

[0114] (2) After melt blending the cross-linking agent (1.4 kg, dicumyl peroxide (DCP)) and the co-cross-linking agent (0.2 kg, 2,4-diphenyl-4-methyl-1-pentene AMSD) at a temperature of 80°C, the molten material is prepared.

[0115] (3) Spraying the atomized liquid formed by atomizing the molten material on the surface of the intermediate material, and preparing the polyvinyl insulation material after the cross-linking agent and the co-cross-linking agent are absorbed at 80°C.

[0116] Example 3

[0117] (1) After pre-mixing the antioxidant (0.2 kg, antioxidant 300) and the voltage stabilizer (0.3 kg, selected from Preparation Example 1) at a temperature of 30°C and a rotation speed of 150 r / min, adding low-density polyethylene (98 kg, density 0.92 g / cm 3 , molecular weight distribution index 5.6, melt index 2.1 g / min), sequentially performing first melt mixing treatment at a temperature of 120°C, second melt mixing treatment at a temperature of 130°C, third melt mixing treatment at a temperature of 150°C, and fourth melt mixing treatment at a temperature of 160°C, and extruding at a temperature of 180°C and a rotation speed of 200 r / min, the intermediate material is prepared.

[0118] (2) After melt blending the cross-linking agent (1.4 kg, dicumyl peroxide (DCP)) and the co-cross-linking agent (0.2 kg, 2,4-diphenyl-4-methyl-1-pentene AMSD) at a temperature of 80°C, the molten material is prepared.

[0119] (3) Spray the atomized liquid formed by atomizing the molten material onto the surface of the intermediate material, and then allow the crosslinking agent and co-crosslinking agent to absorb it at 80°C to prepare the polyethylene-based insulation material.

[0120] Example 4

[0121] (1) Antioxidant (0.2 kg, antioxidant 300) and voltage stabilizer (0.1 kg, selected from Preparation Example 1) were premixed at a temperature of 30°C and a rotation speed of 150 r / min, and then low-density polyethylene (98.1 kg, density 0.92 g / cm³) was added. 3 The intermediate material was prepared by sequentially performing a first melt mixing treatment at 120°C, a second melt mixing treatment at 130°C, a third melt mixing treatment at 150°C, and a fourth melt mixing treatment at 160°C, followed by extrusion at 180°C and a rotation speed of 200 r / min.

[0122] (2) The crosslinking agent (1.4 kg, dicumyl peroxide (DCP)) and the co-crosslinking agent (0.2 kg, 2,4-diphenyl-4-methyl-1-pentene AMSD) were melt-blended at a temperature of 80 °C to prepare a melt material;

[0123] (3) Spray the atomized liquid formed by atomizing the molten material onto the surface of the intermediate material, and then allow the crosslinking agent and co-crosslinking agent to absorb it at 80°C to prepare the polyethylene-based insulation material.

[0124] Comparative Example 1

[0125] Comparative Example 1 is basically the same as Example 1, the main difference being that Comparative Example 1 does not include a voltage stabilizer. The preparation steps of Comparative Example 1 include:

[0126] (1) Add antioxidant (0.2 kg, antioxidant 300) and low-density polyethylene (98.2 kg, density 0.92 g / cm³) 3 The intermediate material was prepared by sequentially performing a first melt mixing treatment at 120°C, a second melt mixing treatment at 130°C, a third melt mixing treatment at 150°C, and a fourth melt mixing treatment at 160°C, followed by extrusion at 180°C and a rotation speed of 200 r / min.

[0127] (2) The crosslinking agent (1.4 kg, dicumyl peroxide (DCP)) and the co-crosslinking agent (0.2 kg, 2,4-diphenyl-4-methyl-1-pentene AMSD) were melt-blended at a temperature of 80 °C to prepare a melt material;

[0128] (3) Spraying the atomized liquid formed after atomizing the molten material on the surface of the intermediate material, and absorbing the cross-linking agent and the co-cross-linking agent at 80°C to prepare the polyethylene-based insulating material.

[0129] Comparative Example 2

[0130] Comparative Example 2 and Example 1 are basically the same, the main difference is that the voltage stabilizer selected in Comparative Example 2 is phenylethanone.

[0131] The component content of the polyethylene-based insulating material and the type of voltage stabilizer in the above examples and comparative examples are shown in Table 1.

[0132] Table 1

[0133]

[0134] The above examples and comparative examples were tested for performance.

[0135] Sample preparation: The sample was prepared into a sheet-shaped sample of different thicknesses using a flat plate vulcanizing machine, first melted and plasticized at 120°C, then cross-linked at 180°C and a pressure of 15 MPa for 15 min, and then water-cooled to room temperature. Then the sheet-shaped sample was vacuum degassed in a vacuum oven at 70°C for 24 h to remove the cross-linking by-products.

[0136] Cross-linking density test: The cross-linking density of the sample was tested using a low-field nuclear magnetic resonance instrument, the test temperature was 140°C, and the constant temperature time was 8 min.

[0137] Additive migration ability test: 20g of sheet-shaped sample was cut and weighed, soaked in ethanol for 24h, then dried in an oven, and the remaining mass and migration rate of the sample were weighed, and each sample was measured three times to obtain the average value.

[0138] Treeing inception voltage: The needle-plate electrode structure was used for testing, and a uniform voltage rise was used during the experiment, with a voltage of 50Hz applied at a rate of 50V / s. Meanwhile, the results of 10 experiments for each sample were statistically analyzed using a two-parameter Weibull distribution to obtain the final treeing inception voltage.

[0139] Breakdown strength: The DC breakdown experiment used a column electrode (diameter 25mm), and the test temperature was room temperature. The breakdown test was tested at a voltage rise rate of 5kV / mm, and the test results were processed using a two-parameter Weibull distribution to obtain the characteristic breakdown field strength of the sample.

[0140] Volume resistivity: The volume resistivity of the sample was measured by a three-electrode method. The test temperature was room temperature, the polarization field strength was 30 kV / mm, and the polarization time was 60 min. The average current value in the last 20 s was taken as the steady-state conductive current under the electric field, and the volume resistivity was calculated.

[0141] Space charge: The space charge was tested by a PEA method, the polarization field strength was 30 kV / mm, the test temperature was room temperature, and the polarization time was 30 min. The corresponding test results are shown in Table 2.

[0142] Table 2

[0143]

[0144] Each of the technical features of the above-described embodiments can be combined arbitrarily. In order to make the description simple, each of the technical features in the above-described embodiments is not described in all possible combinations, however, as long as the combination of the technical features does not exist, it should be considered as the scope of the present disclosure.

[0145] The above-described embodiments only express several implementation manners of the present application, facilitate the understanding of the technical solutions of the present application, but should not be understood as a limitation on the scope of patent protection. It should be pointed out that, for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. It should be understood that, for ordinary skilled in the art, on the basis of the technical solutions provided by the present application, through logical analysis, reasoning or limited experiments, the technical solutions obtained are all within the protection scope of the appended claims of the present application. Therefore, the protection scope of the present patent should be based on the contents of the appended claims, and the description can be used to explain the contents of the claims.

Claims

1. A polyethylene-based insulation material, characterized by, The preparation raw materials include, in parts by weight, 90-99.4 parts of polyethylene, 0.3-3 parts of crosslinking agent, 0.1-3 parts of auxiliary crosslinking agent, 0.1-1 part of antioxidant, and 0.1-3 parts of voltage stabilizer; wherein the voltage stabilizer comprises and one or more of q is independently at each occurrence an integer of 2-6.

2. The polyethylene insulation of claim 1, wherein, The voltage stabilizer includes and one or more of.

3. The polyethylene insulation of claim 2, wherein, The preparation steps of the compound of formula (I) include: adding 0.855 g, 35.2 mmol of magnesium powder and 25 mL of diethyl ether into a dry round-bottom flask, cooling to 0 DEG C in an ice bath after replacing the air in the flask with argon; slowly adding 5.9 mL of a 2,7-dibromophenanthrene solution into the round-bottom flask by using a syringe, wherein the solvent of the 2,7-dibromophenanthrene solution is diethyl ether, and the molar concentration is 3.0 mol / L, to obtain a mixture; stirring the mixture for 45 minutes; after the Grignard reagent is completely formed, adding 1 mL of 5-hexenenitrile, and the molar amount of 5-hexenenitrile is 8.8 mmol, to obtain a reaction mixture; allowing the reaction mixture to rise to room temperature and stirring for 6 hours; cooling the reaction mixture to 0 DEG C, and slowly adding 30 mL of water to quench the reaction; extracting the aqueous phase layer with ethyl acetate; combining the organic phases, washing with saturated brine, drying over anhydrous sodium sulfate, and concentrating; purifying the crude product by gradient elution silica gel column chromatography to obtain the product; The preparation steps of the compound of formula (I) include: adding 2.5 mmol of potassium tert-butoxide, 0.5 mmol of 7-methoxy-1-tetralone as a substrate, 2.0 mmol of phenylboronic acid pinacol ester and 2.0 mL of 5-hexen-1-ol / xylene mixture into a dry round-bottom flask in sequence, and replacing the air in the flask with argon to prepare a reaction mixture, wherein the volume ratio of 5-hexen-1-ol to xylene in the 5-hexen-1-ol / xylene mixture is 3:2; heating the reaction mixture to 80°C in an argon atmosphere and stirring for 12 hours; cooling the reaction mixture to room temperature, diluting the reaction solution with dichloromethane, extracting with dichloromethane, combining the organic phases, washing with saturated brine, drying over anhydrous sodium sulfate and concentrating under reduced pressure; and purifying the crude product by gradient elution silica gel column chromatography to obtain the product.

4. The polyethylene insulation of claim 1, wherein, The polyethylene has one or more of the following characteristics: (1) the polyethylene has a density of 0.9 g / cm 3 0.95 g / cm 3 ; (2) The polyethylene has a molecular weight distribution index of 5.5-5.

9.

5. The polyethylene insulation of any of claims 1-4, wherein, The crosslinking agent includes one or more of dicumyl peroxide, benzoyl peroxide, di-t-butyl peroxide isopropyl benzene, and 2,5-dimethyl-2,5-bis(t-butylperoxy) hexane.

6. The polyethylene insulation of any of claims 1-4, wherein, The auxiliary crosslinking agent includes one or more of 2,4-diphenyl-4-methyl-1-pentene, triallyl cyanurate, and triallyl isocyanurate.

7. The polyethylene insulation of any of claims 1-4, wherein, The antioxidant includes one or more of phenolic antioxidant, phosphite antioxidant, and thioester antioxidant.

8. A process for the preparation of the polyethylene-based insulation material according to any one of claims 1 to 7, characterized in that, The method includes the following steps: After melt mixing and extruding the polyethylene, antioxidant, and voltage stabilizer, an intermediate material is prepared; The crosslinking agent and the auxiliary crosslinking agent are absorbed on the surface of the intermediate material to prepare the polyethylene-based insulation material; wherein the voltage stabilizer comprises and one or more of q is independently at each occurrence an integer of 2-6.

9. The method for preparing polyethylene-based insulating material according to claim 8, characterized in that, The step of coating the crosslinking agent and the auxiliary crosslinking agent on the surface of the intermediate material to prepare the polyethylene-based insulation material includes: The crosslinking agent and the auxiliary crosslinking agent are melt blended to prepare a melt material; The polyethylene-based insulation material is prepared by spraying the atomized liquid formed after atomizing the melt material on the surface of the intermediate material and absorbing the crosslinking agent and the auxiliary crosslinking agent at 60-90°C.

10. The process for the preparation of polyethylene-based insulation according to claim 8 or 9, characterized in that, The step of preparing the intermediate material includes: The polyethylene, the antioxidant, and the voltage stabilizer are sequentially subjected to first melt mixing treatment at a temperature of 115-125°C, second melt mixing treatment at a temperature of 125-135°C, third melt mixing treatment at a temperature of 145-155°C, and fourth melt mixing treatment at a temperature of 158-165°C, and then extruded at a temperature of 175-185°C and a rotation speed of 100-250 r / min to prepare the intermediate material.

11. A high voltage DC crosslinked cable, characterized in that The polyethylene-based insulation material of any one of claims 1-7 or prepared by the preparation method of any one of claims 8-10.

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