Polyolefin insulating material, method for producing the same, and use thereof

Abstract

The application discloses a kind of polyolefin insulating material and its preparation method and application, belong to polymer material field.The polyolefin insulating material includes 25-45 parts of high-density polyethylene, 20-40 parts of linear low-density polyethylene and 20-35 parts of electric tracking resistance additives.The polyolefin insulating material has excellent flame retardancy, electric tracking resistance and high-temperature oxidation resistance, is used to prepare the spacer for distribution network transmission line, can improve the high-temperature aging, short circuit and other problems of distribution network transmission line, reduce the occurrence of fire, and the material can be recycled, is environment-friendly.

Description

Technical Field

[0001] This application relates to the field of insulating materials, and more particularly to a polyolefin insulating material, its preparation method, and its application. Background Technology

[0002] With the rapid development of my country's power industry, high-voltage transmission has become one of the main methods for long-distance power transmission. When transmission networks are laid in old urban areas, the narrow streets and dense buildings limit the space for building distribution lines. To meet residential electricity demand, multiple circuits often run in parallel. Similarly, industrial parks require multiple distribution lines to meet their electricity needs, also resulting in parallel circuits. In these scenarios, the spacing between distribution lines decreases, and the air gaps between lines cannot withstand the electric field strength of high-voltage lines, making short circuits highly likely. Furthermore, in areas with frequent strong winds, distribution transmission lines are also affected by wind, causing wires to sway, come into contact, or rub against each other, leading to short circuits and tripping. When distribution transmission lines need to cross rivers, lakes, or other bodies of water, the insulation stability of the conductors faces challenges due to the large span.

[0003] To stabilize the distance between conductors in distribution network lines, avoid frictional short circuits, and improve the stability of conductors in distribution network lines, spacers are generally used as auxiliary structures. However, existing polymer spacers have problems with poor flame retardancy and electrical tracking resistance, and cannot achieve good stability in use. During long-term use, this can lead to short circuits and fires in distribution network lines.

[0004] Therefore, there is an urgent need to develop an insulating spacer with excellent flame retardancy and electrical tracking resistance to improve the short circuit problem of power distribution transmission lines. Summary of the Invention

[0005] This invention provides a polyolefin insulating material, its preparation method, and its application. The polyolefin insulating material has excellent flame retardant properties and resistance to electrical tracking. When used to prepare spacers, it can improve the short-circuit problem in power distribution transmission lines.

[0006] In a first aspect, the present invention provides a polyolefin insulating material comprising, by weight, the following raw materials: 25-45 parts of high-density polyethylene, 20-40 parts of linear low-density polyethylene, and 20-35 parts of an anti-tracking agent.

[0007] In one possible implementation, the high-density polyethylene has a molecular weight of 40,000-300,000 g / mol;

[0008] And / or, the density of the high-density polyethylene is 0.946-0.956 g / cm³. 3 .

[0009] In one possible implementation, the linear low-density polyethylene has a density of 0.915-0.935 g / cm³. 3 ;

[0010] The linear low-density polyethylene includes metallocene linear low-density polyethylene.

[0011] In one possible implementation, the tracking-resistant agent includes at least one of magnesium hydroxide, aluminum hydroxide, and nano-calcium carbonate.

[0012] In one possible implementation, the raw materials of the polyolefin insulating material further include at least one of a compatibilizer, a lubricant, a colorant, an antioxidant, a light stabilizer, or a hydrophobic agent.

[0013] In one possible implementation, the raw materials of the polyolefin insulating material further include, by weight, 2-4 parts compatibilizer, 0.3-0.6 parts lubricant, 0.1-2.5 parts colorant, 0.3-0.6 parts antioxidant, 0.1-0.6 parts light stabilizer, and 0.1-0.4 parts hydrophobic additive.

[0014] In one possible implementation, the compatibilizer comprises maleic anhydride-grafted polyethylene and / or maleic anhydride-grafted polyolefin elastomer.

[0015] And / or, the lubricating agent includes at least one of silicone oil, polyethylene wax, stearic acid, and polyphthalamide fluorinated additives;

[0016] And / or, the color additives include at least one of color masterbatch and color powder;

[0017] And / or, the antioxidant includes at least one of antioxidant 1010, antioxidant 168, and antioxidant DLTDP;

[0018] And / or, the light stabilizer includes at least one of UV-944, UV-622, and UV-531;

[0019] And / or, the hydrophobic additive includes at least one of polysiloxane, fluorocarbon surfactant, calcium stearate, zinc stearate, and magnesium stearate.

[0020] In one possible implementation, the coloring agent comprises carbon black, the mass of which does not exceed 2.5% of the total mass of the raw materials of the polyolefin insulation material.

[0021] Secondly, the present invention provides a method for preparing the polyolefin insulating material, comprising: sequentially subjecting a mixture of raw materials including high-density polyethylene, linear low-density polyethylene and an anti-tracking agent to a melting and curing process to obtain the polyolefin insulating material.

[0022] Thirdly, the present invention provides a spacer rod comprising the above-described polyolefin insulating material or a polyolefin insulating material prepared by the above-described preparation method.

[0023] This invention provides a polyolefin insulating material, its preparation method, and its application. The polyolefin insulating material is prepared using 25-45 parts of high-density polyethylene, 20-40 parts of linear low-density polyethylene, and 20-35 parts of anti-tracking additive as raw materials. The polyolefin insulating material has excellent flame retardancy and anti-tracking properties. It can be used to prepare spacers, which can improve the short-circuit problem of power distribution transmission lines. The spacers can also be recycled and reused. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the spacer provided in an embodiment of this application.

[0025] Explanation of reference numerals in the attached figures:

[0026] 100-spacer bar;

[0027] 110 - Locking bolt;

[0028] 120-Rubber clamping block;

[0029] 130-Hinge;

[0030] 140-clamp. Detailed Implementation

[0031] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0032] First, let me explain the terms used in this application:

[0033] Spacer bar: In the field of power transmission, it is a key component installed on overhead lines using split conductors to fix the spacing between multiple sub-conductors in the same phase, prevent sub-conductors from colliding with each other, suppress harmful vibrations, and ensure the safe and stable operation of the line.

[0034] Water trees: Microchannels that develop in polymer insulating materials in the presence of moisture, electrical stress, and certain inducing factors such as impurities, protrusions, space charges, or ions.

[0035] Electrical treeing: refers to dendritic defects that can be observed under a microscope, such as air gaps, impurities, or moisture in the insulation layer of cross-linked polyethylene cables, as well as surface unevenness between the shielding layer and the insulation layer.

[0036] Existing spacers have technical problems such as poor flame retardancy and poor resistance to electrical tracking.

[0037] The polyolefin insulation material provided in this application embodiment uses high-density polyethylene and linear low-density polyethylene in combination and adjusts their dosage, while adding anti-tracking additives, which improves the mechanical properties, flame retardancy and anti-tracking properties of the insulation material. When used to prepare spacers, it solves the technical problems of poor anti-tracking properties and lack of flame retardancy of spacers, and also improves their service life and allows for recycling.

[0038] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0039] Unless otherwise specified, all raw materials used in this application are commercially available.

[0040] This application provides a polyolefin insulation board material, which, by weight, comprises: 25-45 parts of high-density polyethylene, 20-40 parts of linear low-density polyethylene, and 20-35 parts of anti-tracking additive.

[0041] High-density polyethylene (HDPE) typically has a high crystallinity of over 70%, with tightly packed and regularly arranged molecular chains that form large, well-developed spherulites. These spherulites themselves are rigid, but the amorphous regions connected by ligands between them absorb energy and prevent crack propagation upon impact, contributing to their toughness. Linear low-density polyethylene (LLDPE) has a short-branched structure and lower crystallinity, typically 40-60%, resulting in smaller, less well-developed spherulites or microcrystals. The presence of numerous amorphous regions and molecular chain entanglements due to short branches within the LLDPE molecule effectively dissipates impact energy, contributing to its toughness. When HDPE and LLDPE are blended, with a relatively high HDPE content, it forms a continuous or co-continuous phase, with its larger, relatively well-developed spherulite structure providing skeletal support. LLDPE then acts as a dispersed phase or fills the amorphous regions between / inside the HDPE spherulites. The presence of LLDPE can plasticize the crystalline regions of HDPE, hindering the excessive growth of HDPE spherulites, making the spherulites smaller and less perfect, while providing more entanglement points. This refined morphology is beneficial to improving the toughness of polyolefin insulation materials.

[0042] The inventors discovered that excessively high HDPE content increases the rigidity of polyolefin insulation materials, i.e., weakens their toughness. This is due to the presence of rigid spherulites in HDPE, and the relatively low amount of linear low-density polyethylene cannot disperse the rigid stress caused by these spherulites.

[0043] When the amount of HDPE decreases relatively while the amount of LLDPE increases relatively, the supporting effect of HDPE weakens, and it no longer forms an effective continuous skeleton or large spherulite network. In this case, LLDPE becomes the dominant continuous phase. In LLDPE-dominated polyolefin material systems, the crystalline regions are smaller, more numerous, and less complete, with numerous small crystalline region interfaces becoming potential stress concentration points. Furthermore, the number and strength of the tying molecules connecting the crystalline regions may not be as effective as the tying molecular network connecting large spherulites in HDPE-dominated systems. The branched structure of LLDPE also limits the extension and entanglement density of the molecular chains, thus weakening the toughness of the polyolefin insulation material.

[0044] In order to obtain a polyolefin insulation material with excellent mechanical properties and practical application, the polyolefin insulation material provided in this application contains 25-45 parts by weight of high-density polyethylene and 20-40 parts by weight of linear low-density polyethylene.

[0045] Meanwhile, by adding anti-tracking additives, the resulting polyolefin insulating material exhibits excellent tracking resistance and flame retardancy.

[0046] Increasing the amount of tracking-resistant additives to achieve higher tracking resistance can cause excessive rigid particles to induce stress concentration within the material, leading to a deterioration in the mechanical properties of polyolefin insulation materials, which in turn affects their anti-aging properties and stability in use.

[0047] High-density polyethylene has a molecular weight of 40,000-300,000 g / mol and a density of 0.945-0.956 g / cm³.

[0048] To enhance the insulation properties of polyolefin insulation materials, high-density polyethylene (HDPE) can be used, including Borealis Borstar® 3364, Borealis 7000F, Dow UNIGARD™ 6098, Shanghai Petrochemical 5000S, and ExxonMobil LE0592. These HDPEs possess exceptionally high electrical insulation performance and long-term stability. Their extremely low dielectric loss factor results in minimal heat generation under high voltage, preventing overheating and aging of the insulation layer.

[0049] The density of linear low-density polyethylene is 0.915-0.935 g / cm³; including metallocene-catalyzed linear low-density polyethylene.

[0050] To enhance the long-term anti-aging properties and low-temperature toughness of the polyolefin insulation material presented in this application, enabling its application in harsh environments, the linear low-density polyethylene (LDPE) specifically includes ExxonMobil 218W, Dow 3518, Sinopec 7042, and Borealis FB2230, among others. Metallocene catalysts can precisely control the molecular structure of LLDPE, resulting in denser molecular chain windings, improved resistance to external damage, and maintained toughness even at low temperatures. The aforementioned LLDPEs are all prepared using metallocene catalysis, possessing numerous long branches that allow for better molecular-level bonding with high-density polyethylene, thereby enhancing mechanical properties such as crack resistance.

[0051] The anti-tracking additives include at least one of magnesium hydroxide, aluminum hydroxide, and nano-calcium carbonate.

[0052] Magnesium hydroxide and aluminum hydroxide, upon thermal decomposition, release water vapor to dilute oxygen and form a ceramic barrier, thereby blocking combustion and isolating heat. Furthermore, as alkaline compounds, magnesium hydroxide and aluminum hydroxide can neutralize acidic substances, preventing acid-catalyzed carbonization reactions and reducing the degree of carbonization in polyolefin insulation materials. Nano-calcium carbonate can fill the micro-gaps in polyolefin insulation materials, blocking the expansion of carbonization channels, and also improving the material's hardness and wear resistance, resisting arc erosion. This application preferably uses at least one of the above three compounds as a tracking-resistant additive to obtain polyolefin insulation materials with excellent tracking resistance and flame retardancy.

[0053] To achieve better processing performance and application results, the polyolefin insulation material of this application also includes at least one of the following: compatibilizer, lubricant, colorant, antioxidant, light stabilizer, or hydrophobic agent.

[0054] Since the aforementioned tracking-resistant additives are inorganic particles with hydrophilic surfaces, while high-density polyethylene and linear low-density polyethylene are organic materials with hydrophobic surfaces, their interfacial bonding is poor, leading to easy agglomeration during mixing and processing, resulting in deteriorated processing flowability. Therefore, in the preparation of polyolefin insulating materials, this application may also add compatibilizers to improve the mixing compatibility and processability of the raw materials. Based on the fact that this application uses polyethylene as the main component to prepare polyolefin insulating materials, specifically, the compatibilizers include maleic anhydride-grafted polyethylene and / or maleic anhydride-grafted polyolefin elastomers, which have good compatibility with high-density polyethylene and linear low-density polyethylene. It should be noted that the compatibilizers used in this application are not limited to the above-mentioned types; other compatibilizers that can achieve similar effects are also applicable.

[0055] Because low molecular weight lubricants may migrate and precipitate over time, affecting not only the surface resistivity of the material but also accelerating insulation aging, this application selects lubricants with high compatibility with the high-density polyethylene and linear low-density polyethylene used. Specifically, lubricants may include silicone oil, polyethylene wax, stearic acid, fluorinated polyphthalamide, etc.

[0056] Adding internal lubricants such as stearic acid and fluorinated polyphthalamide can weaken interchain forces, resulting in better melt flow during extrusion or injection molding when preparing polyolefin insulation materials, thereby reducing processing energy consumption. Adding external lubricants such as silicone oil and polyethylene wax can reduce melt adhesion to equipment during processing, improve material release properties, and enhance the surface finish of polyolefin insulation materials.

[0057] Based on the fact that the polyolefin insulating material in this application can be used as a spacer bar, color additives can be added during preparation to provide color identification and distinguish phase wires, ground wires, etc. Specifically, color additives can include at least one of color masterbatch and color powder. Color masterbatch can include PE color masterbatch, PP color masterbatch, ABS color masterbatch, PVC color masterbatch, EVA color masterbatch, etc., and the pigments it contains can include phthalocyanine red, phthalocyanine blue, phthalocyanine green, fast red, macromolecular red, macromolecular yellow, permanent yellow, permanent violet, azo red, etc. Color powder can include carbon black, titanium dioxide, iron oxide pigment, cobalt blue, bismuth yellow, titanium nickel yellow, cerium red, etc. It should be noted that the color additives used in this application are not limited to the above types; other color additives that can achieve similar effects are also applicable.

[0058] When the color additives include carbon black, the mass of carbon black shall not exceed 2.5% of the total mass of the raw materials.

[0059] Because carbon black has a certain degree of conductivity, when its addition exceeds 2.5%, carbon black particles will form a continuous conductive network in polyolefin insulation materials, making the insulation material a semiconductor or even a conductor. Moreover, high carbon black content will destroy the crystallinity of polyolefins, increasing the crystallinity of the material, allowing water molecules to penetrate along the carbon black-polyolefin interface and accelerating material aging.

[0060] This application may also add antioxidants to break the thermo-oxidative degradation chain in the material, improve the oxidation resistance of the polyolefin insulation material, and thus prevent the material surface from becoming brittle and cracking. Specifically, to obtain better oxidation resistance, the antioxidants in this application may include antioxidant 1010, antioxidant 168, antioxidant DLTDP, etc. It should be noted that the antioxidants used in this application are not limited to the above types; other antioxidants capable of achieving similar effects are also applicable.

[0061] To achieve better resistance to photoaging, this application may also add light stabilizers. Specifically, light stabilizers may include UV-944, UV-622, UV-531, etc. It should be noted that, to avoid acid-base interactions, when the light stabilizer includes hindered amine light stabilizers, the light stabilizer must be used in conjunction with an antioxidant. It should also be noted that the light stabilizers used in this application are not limited to the types mentioned above; other light stabilizers capable of achieving similar effects are also applicable.

[0062] In atmospheric environments, moisture intrusion into materials is inevitable. Moisture intrusion is a major factor contributing to water treeing and aging of insulating materials. To enhance the hydrophobicity of polyolefin insulating materials and reduce the risk of tracking, this application may also add hydrophobic additives to inhibit surface wetting of the polyolefin insulating materials. Specifically, hydrophobic additives may include polysiloxanes, fluorocarbon surfactants, stearates, etc.

[0063] Because perfluorooctanoic acid and perfluorosulfonic acid have persistent environmental pollution, when selecting fluorocarbon surfactants as hydrophobic additives, at least one of perfluoroalkyl quaternary ammonium salts, perfluorobetaines, and perfluoropolyether alcohols is preferred.

[0064] Considering that some stearates have problems such as heavy metal pollution and ionic conductivity, in this application, the stearates are preferably at least one of calcium stearate, zinc stearate, and magnesium stearate.

[0065] It should be noted that the hydrophobic additives used in this application are not limited to the types mentioned above; other hydrophobic additives that can achieve similar effects are also applicable.

[0066] It is understandable that, in order to use polyolefin insulation materials with superior performance, the amount of each of the above-mentioned additives has been adjusted in this application.

[0067] Furthermore, by weight, the polyolefin insulating material also includes 2-4 parts compatibilizer, 0.3-0.6 parts lubricant, 0.1-2.5 parts colorant, 0.3-0.6 parts antioxidant, 0.1-0.6 parts light stabilizer and 0.1-0.4 parts hydrophobic additive.

[0068] In this application, when the amount of compatibilizer added is too small, the interfacial compatibility between the inorganic components in the raw materials and other organic components is poor, and the materials are not evenly dispersed, which will lead to a deterioration in the mechanical properties of the resulting polyolefin insulating material, and a reduction in its resistance to high-temperature oxidation and electrical tracking.

[0069] Excessive lubricants can disrupt interchain forces, leading to a decrease in the tensile strength and elongation at break of polyolefin insulation materials. Furthermore, excessive lubricants can precipitate and migrate to the surface of the insulation layer, forming weak interfaces and reducing the material's impact toughness and resistance to environmental stress cracking.

[0070] Excessive antioxidants can decompose during high-temperature processing, producing polar small molecules that migrate to the material surface and form thermally conductive channels. This leads to a decrease in the material's volume resistivity and a weakening of its insulation properties. Simultaneously, antioxidant molecules can occupy the gaps between polymer molecular chains, disrupting crystal integrity and consequently affecting the mechanical properties of polyolefin insulating materials.

[0071] Excessive light stabilizers can also migrate to the material surface, reducing the material's volume resistivity. Moreover, UV absorber-type light stabilizers can photodegrade under ultraviolet light to form colored quinone structures, leading to an increased yellowing rate in polyolefin insulation materials and shortening the material's lifespan.

[0072] When the total amount of antioxidants and light stabilizers is too high, the resulting polyolefin insulation material is prone to polarization under an electric field, resulting in local field strength distortion and an increased probability of electrical treeing.

[0073] The method for preparing polyolefin insulating material provided in this application involves sequentially processing a mixture of raw materials, including high-density polyethylene, linear low-density polyethylene, and an anti-tracking agent, including melting and curing, to ultimately obtain the polyolefin insulating material.

[0074] Specifically, the preparation method of polyolefin insulating material includes the following steps:

[0075] Step 1: Weigh the raw materials including high-density polyethylene, linear low-density polyethylene and anti-tracking additives and put them into a high-speed mixer. Stir at room temperature for 1 to 3 minutes at a speed of 200 to 500 rpm to perform preliminary mixing and obtain the mixture.

[0076] Step 2: The mixture is fed into the hopper of a twin-screw extruder, where it undergoes melting, mixing, extrusion, cooling, and granulation processes. The heating temperature for each process is controlled between 180 and 260°C. After drying, the polyolefin insulation material is obtained.

[0077] Since the melting or pyrolysis temperatures of the components in the raw material differ, in order to achieve better mixing of the components during processing, the temperature at which the mixture melts in the twin-screw extruder in this application is 180~260℃.

[0078] This application also provides a spacer bar, which includes the aforementioned polyolefin insulating material. Using this spacer bar in power distribution transmission lines offers a long service life, effectively improves line short-circuit problems, reduces the incidence of fires, and the material can be recycled and reused.

[0079] Figure 1 A schematic diagram of the spacer provided in this application is shown below. Figure 1 As shown, the spacer 100 provided in this embodiment includes:

[0080] Locking bolt 110 is used to firmly press rubber clamp 120 onto the conductor. By applying and maintaining sufficient bolt preload, it ensures that the clamp generates sufficient friction against the conductor, preventing the conductor from sliding or rotating within the clamp 140. It also provides mechanical connection when components such as connecting arms, hinges 130, and clamps 140 need to be joined. Locking bolt 110 typically employs anti-loosening nuts, cotter pins, and locking washers to prevent bolt loosening and failure under long-term vibration.

[0081] Rubber clamp 120 is used to protect the conductor and provide friction damping. It is typically made of highly elastic, wear-resistant, and aging-resistant rubber (such as silicone rubber or EPDM), and wraps around the conductor surface to prevent direct contact and damage to the conductor from the metal clamp (such as flattening or scratching the aluminum strands). Furthermore, the elastic properties of rubber can absorb and dissipate the energy of conductor vibrations (micro-wind vibrations, secondary span oscillations), reducing fatigue damage to the conductor, the clamp 140 itself, and the spacer bar 100 connection structure.

[0082] Hinges 130 provide flexibility for the installation of spacer 100, allowing each "arm" of the spacer to bend with the natural curvature of the conductor, avoiding excessive bending stress on the spacer itself or the conductor at the low point or corner of the conductor (rigid connections can lead to stress concentration).

[0083] The clamp 140 is used to directly grip and fix the conductor, and can transfer the force on the conductor (wind load, ice load, dynamic load generated by vibration) and the friction force generated by the clamp to the connecting arm of the spacer and the frame structure.

[0084] This application also provides a method for preparing a spacer, including the following steps:

[0085] Step 1: Put the above-mentioned polyolefin insulation material into a plastic dryer and dry it at 80°C for 2 hours;

[0086] Step 2: The dried material is introduced into the prepared injection molding machine hopper, injected into the mold, cooled and demolded to obtain spacer bars; the heating temperature of each section of the injection molding machine is controlled at 180~260℃.

[0087] To improve the product qualification rate, this application also uses X-ray inspection equipment to detect pores in the produced spacers, ensuring that each product is free of pores.

[0088] The present invention will be described in more detail below through specific embodiments.

[0089] Example 1

[0090] Step 1: Weigh 40 parts of high-density polyethylene (Dow HDPE 3364), 25 parts of linear low-density polyethylene (Wanhua Chemical DFDA 7042), 25 parts of anti-tracking agent aluminum hydroxide, 2 parts of compatibilizer maleic anhydride grafted polyethylene, 0.4 parts of lubricating agent polyethylene wax, 0.8 parts of coloring agent PE masterbatch, 0.6 parts of antioxidant 1010, 0.1 parts of light stabilizer 944, and 0.4 parts of hydrophobic agent silane coupling agent A-172 according to the weight proportions and put them into a high-speed mixer. Stir at room temperature for 3 minutes at a speed of 350 rpm to perform preliminary mixing and obtain the mixture.

[0091] Step 2: The mixture is fed into the hopper of a twin-screw extruder, where it undergoes melting, mixing, extrusion, cooling, and granulation. The heating temperature during melting is 210℃, and the temperature during mixing and extrusion is 180℃. The mixture is then dried to obtain a polyolefin insulation material.

[0092] Example 2

[0093] Similar to Example 1, the difference lies in the following parts by weight of the raw materials used: 45 parts of high-density polyethylene (Dow HDPE 3364), 20 parts of linear low-density polyethylene (Wanhua Chemical DFDA 7042), 25 parts of tracking-resistant agent aluminum hydroxide, 2 parts of compatibilizer maleic anhydride grafted polyethylene, 0.5 parts of lubricant polyethylene wax, 2 parts of color-related agent PE masterbatch, 0.45 parts of antioxidant 1010, 0.3 parts of light stabilizer 944, and 0.3 parts of hydrophobic agent silane coupling agent A-172.

[0094] Example 3

[0095] Similar to Example 2, except that the mass fraction of the compatibilizer used is 1.5 parts.

[0096] Example 4

[0097] Similar to Example 1, the difference lies in the following parts by weight of the raw materials used: 35 parts of high-density polyethylene (Dow HDPE 3364), 33 parts of linear low-density polyethylene (Wanhua Chemical DFDA 7042), 35 parts of tracking-resistant agent aluminum hydroxide, 4 parts of compatibilizer maleic anhydride grafted polyethylene, 0.6 parts of lubricating agent polyethylene wax, 2.5 parts of color-related agent PE masterbatch, 0.3 parts of antioxidant 1010, 0.6 parts of light stabilizer 944, and 0.2 parts of hydrophobic agent silane coupling agent A-172.

[0098] Example 5

[0099] Similar to Example 1, the difference lies in the following parts by weight of the raw materials used: 25 parts of high-density polyethylene (Dow HDPE 3364), 40 parts of linear low-density polyethylene (Wanhua Chemical DFDA 7042), 30 parts of tracking-resistant agent aluminum hydroxide, 3 parts of compatibilizer maleic anhydride grafted polyethylene, 0.3 parts of lubricating agent polyethylene wax, 0.1 parts of color-related agent PE masterbatch, 0.4 parts of antioxidant 1010, 0.5 parts of light stabilizer 944, and 0.1 parts of hydrophobic agent silane coupling agent A-172.

[0100] Example 6

[0101] Similar to Example 1, except that no hydrophobic additives are added.

[0102] Comparative Example 1

[0103] Similar to Example 1, except that the mass fraction of the tracking-resistant additive used is 15 parts.

[0104] Comparative Example 2

[0105] Similar to Example 1, except that the mass fraction of the tracking-resistant additive used is 40 parts.

[0106] Comparative Example 3

[0107] Similar to Example 2, except that the mass fraction of high-density polyethylene Dow HDPE 3364 used was 50 parts.

[0108] Comparative Example 4

[0109] Similar to Example 2, except that the mass fraction of linear low-density polyethylene Wanhua Chemical DFDA 7042 used was 15 parts.

[0110] Comparative Example 5

[0111] Similar to Example 5, except that the mass fraction of linear low-density polyethylene Wanhua Chemical DFDA 7042 used was 50 parts.

[0112] The following performance tests were conducted on the polyolefin insulating materials obtained in Examples 1-6 and Comparative Examples 1-5:

[0113] Tensile strength: Tested in accordance with GB / T 2951.11-2008;

[0114] Nominal strain at fracture: Tested in accordance with GB / T 2951.11-2008;

[0115] Environmental stress cracking resistance: Tested according to GB / T 2951.41-2008 under F0 and 500h conditions;

[0116] Oxidation induction period at 200℃: Tested using differential scanning calorimetry according to ASTM-D3895-07;

[0117] Resistance to electrical tracking and corrosion: Tested according to GB / T 6553-2024;

[0118] Water repellency rating: Tested in accordance with GB / T 24622-2022;

[0119] Flame retardancy: Tested according to UL-94 standard for the flammability of plastic materials;

[0120] The test results are detailed in Table 1:

[0121] Table 1

[0122]

[0123] As can be seen from the data in Table 1, the polyolefin insulating material provided in this application has excellent mechanical properties, aging resistance and electrical tracking resistance.

[0124] Compared to Example 3, the polyolefin insulation material obtained in Example 2 has a longer oxidation induction period at 200°C. This shows that the use of a compatibilizer helps to improve the compatibility between raw materials, thereby helping to improve the oxidation resistance of the polyolefin insulation material.

[0125] Compared to Example 6, the polyolefin insulation material obtained in Example 5 has a longer oxidation induction period at 200°C and better hydrophobicity. It can be seen that the presence of hydrophobic additives not only gives the polyolefin insulation material good hydrophobicity, but more importantly, it can improve the high-temperature oxidation resistance of the polyolefin insulation material.

[0126] Compared to Comparative Example 1, the polyolefin insulation material obtained in Example 1 exhibits better toughness, high-temperature oxidation resistance, tracking resistance, and flame retardancy. This demonstrates that the use of tracking resistant additives helps improve the toughness, high-temperature oxidation resistance, and tracking resistance of polyolefin insulation materials. However, using too little tracking resistant additive can degrade the toughness, high-temperature oxidation resistance, tracking resistance, and flame retardancy of polyolefin insulation materials.

[0127] Compared to Comparative Example 2, the polyolefin insulation material obtained in Example 1 has better toughness, high-temperature oxidation resistance, and water repellency. It can be seen that the use of tracking-resistant additives helps to improve the toughness, high-temperature oxidation resistance, and water repellency of polyolefin insulation materials. However, excessive use of tracking-resistant additives can also degrade the toughness, high-temperature oxidation resistance, and water repellency of polyolefin insulation materials.

[0128] Compared to Comparative Example 3, the polyolefin insulation material obtained in Example 1 has slightly lower tensile strength, but better toughness and resistance to environmental stress cracking. It can be seen that increasing the mass fraction of high-density polyethylene used helps to improve the tensile strength of the polyolefin insulation material, but it will deteriorate the nominal strain performance at break and the resistance to environmental stress cracking of the polyolefin insulation material.

[0129] Compared to Comparative Examples 4 and 5, the polyolefin insulation material obtained in Example 1 exhibits better tensile strength and high-temperature oxidation resistance. This demonstrates that controlling the addition of linear low-density polyethylene (LLDPE) to 20-40 parts by mass helps to simultaneously improve the mechanical properties and high-temperature oxidation resistance of the polyolefin insulation material. Excessive use of LLDPE will degrade the mechanical properties and high-temperature oxidation resistance of the polyolefin insulation material.

[0130] In summary, the polyolefin insulation material provided in this application has excellent high-temperature oxidation resistance, electrical tracking resistance, and flame retardancy. When used to prepare spacer bars, it can improve problems such as high-temperature aging and short circuits in circuits, reduce the incidence of fires, and the material can also be recycled and reused.

[0131] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A spacer bar, characterized in that, It includes polyolefin insulating materials; by weight, the polyolefin insulating materials include the following raw materials: 25-45 parts of high-density polyethylene, 20-40 parts of linear low-density polyethylene, 20-35 parts of anti-tracking agent and 0.1-0.4 parts of hydrophobic agent.

2. The spacer according to claim 1, characterized in that, The molecular weight of the high-density polyethylene is 40,000-300,000 g / mol; And / or, the density of the high-density polyethylene is 0.946-0.956 g / cm³.

3. The spacer according to claim 1 or 2, characterized in that, The linear low-density polyethylene has a density of 0.915-0.935 g / cm³; The linear low-density polyethylene includes metallocene-catalyzed linear low-density polyethylene.

4. The spacer according to claim 1, characterized in that, The tracking-resistant additive includes at least one of magnesium hydroxide, aluminum hydroxide, and nano-calcium carbonate.

5. The spacer according to claim 1, characterized in that, The raw materials for the polyolefin insulating material also include at least one of the following: compatibilizer, lubricant, colorant, antioxidant, and light stabilizer.

6. The spacer according to claim 5, characterized in that, The raw materials of the polyolefin insulating material, by weight, also include 2-4 parts compatibilizer, 0.3-0.6 parts lubricant, 0.1-2.5 parts colorant, 0.3-0.6 parts antioxidant, and 0.1-0.6 parts light stabilizer.

7. The spacer according to claim 6, characterized in that, The compatibilizer includes maleic anhydride-grafted polyethylene and / or maleic anhydride-grafted polyolefin elastomer. And / or, the lubricating agent includes at least one of silicone oil, polyethylene wax, stearic acid, and polyphthalamide fluorinated additives; And / or, the color additives include at least one of color masterbatch and color powder; And / or, the antioxidant includes at least one of antioxidant 1010, antioxidant 168, and antioxidant DLTDP; And / or, the light stabilizer includes at least one of UV-944, UV-622, and UV-531; And / or, the hydrophobic additive includes at least one of polysiloxane, fluorocarbon surfactant, and stearate.

8. The spacer according to claim 5, characterized in that, The color additive includes carbon black, and the mass of the carbon black does not exceed 2.5% of the total mass of the raw materials of the polyolefin insulation material.

9. The spacer according to claim 1, characterized in that, The method for preparing the polyolefin insulating material includes the following steps: The polyolefin insulating material is obtained by sequentially subjecting a mixture of raw materials, including high-density polyethylene, linear low-density polyethylene, and an anti-tracking agent, to a process including melting and curing.

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