A cross-linked polyethylene cable material and its preparation method

Abstract

This invention discloses a cross-linked polyethylene cable material and its preparation method. The raw material formulation of the cross-linked polyethylene cable material includes the following components in parts by weight: 80-100 parts polyethylene, 0.5-3 parts cross-linking sensitizer, 0.1-0.5 parts primary antioxidant, 0.1-0.5 parts secondary antioxidant, and 0.5-5 parts antioxidant. The cable material of this invention exhibits excellent heat aging resistance; the elongation at break after aging decreases slightly compared to the elongation at break before aging. Simultaneously, the volume resistivity of the cable material increases significantly during aging, indicating a significant improvement in insulation performance. The excellent heat aging resistance and the continuously improving insulation performance during aging ensure that cables using this material have excellent heat-resistant service life, saving cable replacement costs and showing great application potential.

Description

Technical Field

[0001] This invention belongs to the field of wire and cable material technology, specifically relating to a cross-linked polyethylene cable material whose insulation performance can be improved after aging and its preparation method. Background Technology

[0002] During prolonged use, cross-linked polyethylene (XLPE) insulated cables experience accelerated insulation aging due to factors such as overload heating, insulation moisture absorption, and chemical corrosion, thus affecting the cable's service life. Among these factors, thermo-oxidative aging is a major cause of insulation aging. Under the influence of heat and oxygen, the polymer molecular chains within the cable insulation layer react with oxygen. Through chain initiation, chain transfer, chain growth, and chain termination, the internal structure is damaged, leading to a decrease in the mechanical and insulation properties of the XLPE insulation layer, ultimately resulting in insulation failure.

[0003] Generally, adding antioxidants can effectively improve the heat aging resistance of cross-linked polyethylene (XLPE) cable materials, specifically reflected in the retention of elongation at break after aging being greater than 50% of that before aging. Even if the heat aging resistance meets the above requirements, XLPE generates a large number of polar groups during the aging process, leading to a significant reduction in its insulation performance and making the insulation layer susceptible to breakdown, causing cable failure. Therefore, focusing solely on heat aging resistance during long-term cable use is insufficient; changes in insulation performance during aging should also be considered. Only when the heat aging resistance is excellent and the insulation performance remains stable throughout the aging process can it be stated that the cable possesses excellent heat-resistant service life.

[0004] Therefore, developing a cable material with excellent heat aging resistance and stable or even improved insulation performance after aging is very promising. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a cross-linked polyethylene cable material and its preparation method. This cable material exhibits excellent heat aging resistance, with a slight decrease in elongation at break after aging compared to before aging. Simultaneously, the insulation performance (volume resistivity) of this cable material significantly improves during the aging process compared to before aging.

[0006] The specific technical solution of the present invention is as follows: A cross-linked polyethylene cable material, wherein the mass parts of each component of the cross-linked polyethylene cable material are:

[0007]

[0008] Furthermore, the polyethylene is one of low-density polyethylene, linear low-density polyethylene, or high-density polyethylene; the crosslinking sensitizer is one of triallyl isocyanurate or trimethylolpropane triacrylate.

[0009] Furthermore, the primary antioxidant is one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], diethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0010] Furthermore, the auxiliary antioxidant is one of tris(2,4-di-tert-butyl)phosphite or pentaerythritol tetra(3-lauryl thiopropionate).

[0011] Furthermore, the antioxidant is 2-mercaptobenzimidazole.

[0012] Another object of the present invention is to provide a method for preparing the above-mentioned cross-linked polyethylene cable material, the method specifically comprising the following steps:

[0013] S1) Add polyethylene, crosslinking sensitizer, main antioxidant, auxiliary antioxidant and antioxidant into the internal mixer;

[0014] S2) Start the internal mixer and mix at a certain mixing temperature for a certain time. After mixing, filter and granulate through a twin-screw extruder at a temperature of 170°C to obtain cross-linked polyethylene cable material.

[0015] Furthermore, the mixing temperature in S2) is 110–180°C, and the time is 5–15 min.

[0016] Furthermore, the cross-linked polyethylene cable material achieves a volume resistivity of 10 after aging. 19 The order of magnitude; and after aging at 165℃ / 168h, the elongation at break reaches no less than 71.5% of the elongation before aging.

[0017] A cross-linked polyethylene insulated cable, wherein the cross-linked polyethylene insulated cable is prepared by the above method.

[0018] Studies have shown that cross-linked polyethylene (XLPE) generates free radicals during thermal aging. These free radicals react with oxygen to form polymer-based hydroperoxides, which further decompose into new free radicals that attack the molecular chains. This leads to a gradual expansion of the chain growth reaction, ultimately destroying the cross-linked network structure and resulting in reduced mechanical properties. Under the influence of heat and oxygen, the molecular chains also generate polar groups such as carbonyl groups, increasing the conductivity of XLPE and decreasing its insulation performance. This invention addresses this issue by employing a heat-resistant aging system composed of a primary antioxidant, an auxiliary antioxidant, and an anti-aging agent. The primary antioxidant captures peroxide free radicals, while the auxiliary antioxidant and anti-aging agent react with the hydroperoxides generated during aging, decomposing them into stable substances and terminating the chain reaction. The synergistic effect of these three agents prevents the oxidation of XLPE, inhibits the generation of polar groups such as carbonyl groups, improves insulation performance, and stabilizes mechanical properties. This invention is not only low-cost but also achieves excellent heat aging resistance in cable insulation materials during long-term aging through a simple manufacturing process, while simultaneously ensuring further improvement in insulation performance during the aging process. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating a method for preparing cross-linked polyethylene cable material according to the present invention. Detailed Implementation

[0020] The present invention will be further illustrated by the following examples.

[0021] This invention discloses a cross-linked polyethylene cable material, the composition and mass fraction of which are as follows:

[0022]

[0023] Preferably, the polyethylene is one of low-density polyethylene, linear low-density polyethylene, or high-density polyethylene, and the crosslinking sensitizer is one of triallyl isocyanurate or trimethylolpropane triacrylate.

[0024] By employing the above technology, high-performance cross-linked polyethylene cable materials can be obtained.

[0025] Preferably, the primary antioxidant is one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], diethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], or octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; the selected secondary antioxidant is one of tris(2,4-di-tert-butyl)phosphite or pentaerythritol tetrakis(3-lauryl thiopropionate); and the antioxidant is 2-mercaptobenzimidazole.

[0026] By employing the above technologies, the primary antioxidant can effectively capture free radicals and interrupt the growth of active chains. The auxiliary antioxidants and anti-aging agents can effectively decompose the hydroperoxides generated in the chain reaction and generate stable substances. The synergistic effect of these three agents prevents the thermal oxidation of cross-linked polyethylene, reduces the generation of polar groups, stabilizes the internal three-dimensional network structure, thereby enhancing the heat aging resistance of cross-linked polyethylene and improving its insulation performance after aging.

[0027] The preparation method of the above-mentioned cross-linked polyethylene cable material with improved insulation performance after aging includes the following steps:

[0028] Polyethylene, crosslinking sensitizer, primary antioxidant, secondary antioxidant, and anti-aging agent are added to a Banbury mixer and mixed at a temperature of 110–180°C for 5–15 minutes. After mixing, the mixture is filtered and extruded through a twin-screw extruder at a temperature of 170°C to obtain the crosslinked polyethylene cable material with improved insulation performance after aging. Figure 1 As shown.

[0029] Example 1

[0030] A cross-linked polyethylene cable material with improved insulation performance after aging, the method for preparing the cable material includes the following steps:

[0031] Linear polyethylene, crosslinking sensitizer triallyl isocyanurate, primary antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], auxiliary antioxidant tris(2,4-di-tert-butyl)phosphite, and antioxidant 2-mercaptobenzimidazole were added to an internal mixer in weight ratios of 40.0 parts, 0.4 parts, 0.1 parts, 0.1 parts, and 0.2 parts, respectively, and mixed at a mixing temperature of 110–180°C for 5–15 minutes. After mixing, the mixture was filtered and extruded by a twin-screw extruder at a temperature of 170°C to obtain the crosslinked polyethylene cable material with improved insulation performance after aging.

[0032] Example 2

[0033] A cross-linked polyethylene cable material with improved insulation performance after aging, the method for preparing the cable material includes the following steps:

[0034] Linear polyethylene, crosslinking sensitizer triallyl isocyanurate, primary antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], auxiliary antioxidant tris(2,4-di-tert-butyl)phosphite, and antioxidant 2-mercaptobenzimidazole were added to an internal mixer in weight ratios of 40.0 parts, 0.4 parts, 0.1 parts, 0.1 parts, and 0.4 parts, respectively, and mixed at a mixing temperature of 110–180°C for 5–15 minutes. After mixing, the mixture was filtered and extruded by a twin-screw extruder at a temperature of 170°C to obtain the crosslinked polyethylene cable material with improved insulation performance after aging.

[0035] Example 3

[0036] A cross-linked polyethylene cable material with improved insulation performance after aging, the method for preparing the cable material includes the following steps:

[0037] Linear polyethylene, crosslinking sensitizer triallyl isocyanurate, primary antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], auxiliary antioxidant tris(2,4-di-tert-butyl)phosphite, and antioxidant 2-mercaptobenzimidazole were added to an internal mixer in weight ratios of 40.0 parts, 0.4 parts, 0.1 parts, 0.1 parts, and 0.6 parts, respectively, and mixed at a mixing temperature of 110–180°C for 5–15 minutes. After mixing, the mixture was filtered and extruded by a twin-screw extruder at a temperature of 170°C to obtain the crosslinked polyethylene cable material with improved insulation performance after aging.

[0038] Comparative Example

[0039] Comparative Example 1 is a cross-linked polyethylene cable material with improved insulation performance after aging. The difference between this material and Example 1 is that it does not contain a primary antioxidant, an auxiliary antioxidant, or an anti-aging agent.

[0040] Performance testing

[0041] Cable material samples were prepared according to the methods in each embodiment and comparative example. The cable materials prepared in Examples 1 to 3 and Comparative Example 1 were prepared into samples with the same size. The specific sample preparation process was as follows: the samples were placed on a flat vulcanizing apparatus and preheated at 170°C for 10 min. Then, the samples were prepared at 15 MPa / 170°C / 10 min. The prepared samples were then subjected to irradiation crosslinking with an irradiation dose of 200 kGy.

[0042] The elongation at break was tested according to the mechanical property test method described in GB / T 1040-2006, with a tensile rate of 200 mm / min. The volume resistivity was tested according to the volume resistivity test method described in GB / T 1410-2006, at a test temperature of 20℃. The life test evaluation conditions were applied to the samples at 165℃ for 168 hours, followed by the elongation at break and volume resistivity tests. The test results are shown in Tables 1 and 2.

[0043] Table 1 Comparison of volume resistivity of cross-linked polyethylene with different formulations before and after aging

[0044]

[0045] Table 2. Elongation at break of cross-linked polyethylene with different formulations before and after aging.

[0046]

[0047]

[0048] As can be seen from Table 1, the cross-linked polyethylene cable materials prepared in Examples 1-3 all had a volume resistivity of 10 Ω after aging. 19 The order of magnitude is greater than 10 before aging. 6 ~10 7 The difference is orders of magnitude, far superior to the cable material prepared in Comparative Example 1, indicating that the cross-linked polyethylene cable material prepared in this invention has significantly improved insulation performance during the aging process.

[0049] As can be seen from Table 2, the cross-linked polyethylene cable materials prepared in Examples 1-3, after aging at 165℃ / 168h, had elongation at break of 96.7%, 84.1%, and 71.5% respectively, compared to before aging. This is significantly higher than the requirement in standard JG / T 442-2014 that the elongation at break should not be less than 50% of the original value after aging at 165℃ / 168h, and is also much higher than the value in Comparative Example 1. This indicates that the cross-linked polyethylene cable material prepared by this invention has strong heat aging resistance.

[0050] In summary, based on the results in Tables 1 and 2, the cross-linked polyethylene cable material prepared by this invention not only exhibits excellent heat aging resistance during the aging process, but also shows a significant improvement in insulation performance during aging.

[0051] The foregoing has provided a detailed description of a cross-linked polyethylene cable material and its preparation method according to the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this application; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0052] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0053] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0054] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0055] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A cross-linked polyethylene cable material, characterized in that, The mass fractions of each component of the cross-linked polyethylene cable material are as follows: Polyethylene 80.0~100.0 parts, Crosslinking sensitizer 0.5~3.0 parts, 0.1-0.5 parts of the main antioxidant. Add 0.1-0.5 parts of auxiliary antioxidant. Anti-aging agent 0.5~5.0 parts; The polyethylene is one of low-density polyethylene, linear low-density polyethylene, or high-density polyethylene; The crosslinking sensitizer is one of triallyl isocyanurate and trimethylolpropane triacrylate; The main antioxidant is one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], diethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; The auxiliary antioxidant is one of tris(2,4-di-tert-butyl)phosphite and pentaerythritol tetra(3-lauryl thiopropionate); The antioxidant is 2-mercaptobenzimidazole.

2. A method for preparing the cross-linked polyethylene cable material as described in claim 1, characterized in that, The method specifically includes the following steps: S1) Add polyethylene, crosslinking sensitizer, main antioxidant, auxiliary antioxidant and antioxidant into the internal mixer; S2) Start the internal mixer and mix at a certain mixing temperature for a certain time. After mixing, filter and granulate through a twin-screw extruder at a temperature of 170 ℃ to obtain cross-linked polyethylene cable material.

3. The method according to claim 2, characterized in that, The mixing temperature in S2) is 110~180℃ and the time is 5~15 min.

4. The method according to claim 2, characterized in that, The cross-linked polyethylene cable material, after aging at 165℃ for 168 hours, achieves a volume resistivity of 10 Ω·cm at 20℃. 19 The order of magnitude; and after aging at 165 ℃ / 168 h, the elongation at break reaches no less than 71.5% of the elongation before aging.

5. A cross-linked polyethylene insulated cable, characterized in that, The cross-linked polyethylene insulated cable is prepared by the method described in any one of claims 2-4 to obtain the cross-linked polyethylene cable material.

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