Creep resistant epdm insulation, method of manufacture and use in integrated cables

Abstract

This invention belongs to the field of rubber preparation technology, specifically relating to an anti-creep EPDM insulation material, its preparation method, and its application in integrated cables. By optimizing the ratio of EPDM rubber substrate with reinforcing agents, anti-creep agents, compatibilizers, and other components, combined with a specific preparation process, this invention significantly improves the material's anti-creep performance, wide-temperature-range insulation stability, mechanical strength, and compatibility. This material is suitable for ultra-deep vibratory-impact integrated cables and has broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of rubber preparation technology, specifically to an anti-creep EPDM insulation material, its preparation method, and its application in integrated cables. Background Technology

[0002] Currently, cable insulation materials mainly use PVC (polyvinyl chloride), XLPE (cross-linked polyethylene), and ordinary EPDM (ethylene propylene diene monomer rubber). Among them, ordinary EPDM is used in special cables due to its good weather resistance and insulation properties. However, in extreme environments such as ultra-deep vibratory impact operations, existing insulation materials have the following significant defects: (1) Insufficient creep resistance: Ordinary EPDM insulation materials are prone to creep deformation under long-term mechanical tensile force and alternating wide temperature range, resulting in uneven insulation layer thickness, local thinning, and even the risk of insulation breakdown. (2) Poor insulation stability over a wide temperature range: In low temperature (-40℃) environments, the material hardness increases and elasticity decreases, making it prone to cracking; in high temperature (80℃) environments, the insulation resistance decreases significantly and the dielectric properties become unstable. (3) Poor compatibility: The bonding force with the creep-resistant copper conductor is insufficient, and the insulation layer is prone to separation from the conductor during long-term use; the compatibility with TPU (thermoplastic polyurethane) sheath material is poor, and gaps are easily generated between the layers, affecting the overall sealing performance and structural stability of the cable. (4) Insufficient mechanical strength: The tensile strength and tear strength of ordinary EPDM insulation layer are low, and it is easily damaged by mechanical damage during cable assembly and laying, resulting in performance degradation.

[0003] While existing technologies include studies on modifying EPDM materials, such as by adding reinforcing agents or adjusting the vulcanization process to improve performance, these improvements typically target only a single property and fail to systematically address the comprehensive requirements for wide temperature range, creep resistance, compatibility, and mechanical strength. Therefore, those skilled in the art urgently need to develop a novel EPDM insulation material to solve these technical problems. Summary of the Invention

[0004] To address the needs of existing technologies, the purpose of this invention is to provide a creep-resistant EPDM insulation material, its preparation method, and its application in integrated cables. This invention significantly improves the material's creep resistance, wide-temperature-range insulation stability, mechanical strength, and compatibilizer by optimizing the ratio of EPDM rubber substrate to reinforcing agents, creep resistant agents, compatibilizers, and other components, combined with a specific preparation process. This material is suitable for ultra-deep vibratory impact integrated cables and has broad application prospects.

[0005] Specifically, the present invention provides the following technical solution: In a first aspect, the present invention provides a creep-resistant EPDM insulating material, comprising the following components by weight percentage: 60%~65% EPDM rubber, 20%~25% reinforcing agent, 5%~8% plasticizer, 3%~5% creep-resistant agent, 0.8%~1.5% crosslinking agent, 1%~2% compatibilizer, 0.5%~1% anti-aging agent, and 0.5%~1% processing aid.

[0006] Optionally, the creep-resistant EPDM insulation material comprises, by weight percentage, the following components: 62.5% EPDM rubber, 22.5% reinforcing agent, 7% plasticizer, 4% creep-resistant agent, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid.

[0007] Optionally, the Mooney viscosity ML1+4 of the EPDM rubber at 125°C is 50~70.

[0008] Optionally, the reinforcing agent is a compound of carbon black N550 and silica, with a mass ratio of 6~7:3~4.

[0009] Optionally, the plasticizer is selected from paraffin oil, naphthenic oil, and a compound of paraffin oil and naphthenic oil, wherein the mass ratio of the paraffin oil and naphthenic oil in the compound is 1:1.

[0010] Optionally, the anti-creep agent is selected from one or more of organically modified montmorillonite and nano-kaolinite.

[0011] Optionally, the crosslinking agent is selected from one or more of dicumyl peroxide (DCP) and benzoyl peroxide (BPO).

[0012] Optionally, the compatibilizer is selected from one or more of maleic anhydride-grafted ethylene-octene copolymer and maleic anhydride-grafted ethylene-vinyl acetate copolymer (EVA-g-MAH); the grafting rate of the maleic anhydride-grafted ethylene-octene copolymer is 1.0% to 1.5%.

[0013] Optionally, the anti-aging agent is a compound of antioxidant 4010NA (N-isopropyl-N'-phenyl-p-phenylenediamine) and antioxidant RD (2,2,4-trimethyl-1,2-dihydroquinoline polymer), with a compound mass ratio of 0.8~1.2:0.8~1.2, preferably 1:1.

[0014] Optionally, the processing aids include stearic acid and zinc oxide.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned creep-resistant EPDM insulating material, specifically comprising: plasticizing EPDM rubber, then sequentially adding reinforcing agent, plasticizer, creep-resistant agent, compatibilizer, anti-aging agent and processing aid to the plasticized EPDM rubber for mixing treatment to make the components uniformly dispersed, then adding crosslinking agent to the mixed rubber compound for further mixing to obtain a mixed rubber compound, extruding the mixed rubber compound into sheets, and cooling it to obtain the creep-resistant EPDM insulating material.

[0016] Optionally, the plasticizing temperature is 100~110℃, the time is 5~8 min, and the Mooney viscosity of the EPDM rubber is controlled at 30~40.

[0017] Optionally, the mixing process is carried out at a temperature of 110~120℃ for 15~20 min.

[0018] Optionally, the mixed rubber compound needs to be cooled to 80~90℃ before adding the crosslinking agent, and then mixed for another 5~8 minutes to obtain the mixed rubber.

[0019] Optionally, the sheet thickness of the compound is 2-3 mm.

[0020] A third aspect of the present invention provides the application of the creep-resistant EPDM insulation material described in the first aspect in integrated cable materials.

[0021] A fourth aspect of the present invention provides a cable comprising a conductor and an insulating layer covering the conductor, the insulating layer being made of the creep-resistant EPDM insulating material described in the first aspect.

[0022] Optionally, the cable is an integrated cable for ultra-deep vibratory compaction, with the main core insulation layer thickness being 3~4 mm and the control core insulation layer thickness being 1~1.5 mm.

[0023] The fifth aspect of the present invention provides a method for applying the anti-creep EPDM insulation material described in the first aspect in an integrated cable, comprising the following steps: extruding the anti-creep EPDM insulation material described in the first aspect onto an anti-creep copper conductor and performing an extrusion process; cross-linking and curing the extruded core wire; water cooling and winding the vulcanized core wire; and twisting the obtained insulated core wire with a central reinforcing layer and a heterogeneous filler according to a cable-forming structure to obtain the cable.

[0024] Optionally, the cross-sectional area of ​​the creep-resistant copper conductor is 120 mm² for the main wire core. 2 1.5 mm control wire core 2 The number of voltage ratings can be increased or decreased depending on the voltage level used.

[0025] Optionally, the extrusion temperature in the extrusion process is 120~140℃, and the die temperature is 130~150℃.

[0026] Optionally, the vulcanization temperature is 160~170℃, the vulcanization time is 10~15 minutes, and the degree of crosslinking during the crosslinking curing is controlled at 70%~80%.

[0027] Optionally, the water cooling temperature is 20~30℃, the time is 5~10 min, and the winding speed is 10~15 m / min.

[0028] The beneficial effects achieved by one or more of the above technical solutions of the present invention are as follows: (1) By optimizing the compounding ratio of EPDM rubber substrate with reinforcing agent, anti-creep agent, compatibilizer and other components, and combining it with a specific preparation process, the present invention constructs a triple interpenetrating structure of "chemical cross-linking network + physical entanglement network + intercalation anchoring network", thereby systematically solving the comprehensive technical problems of insufficient anti-creep performance, poor wide temperature range stability, poor compatibility and low mechanical strength in the prior art.

[0029] (2) The creep-resistant EPDM insulating material prepared by the present invention has excellent creep resistance. At 25℃ and 5 MPa pressure, the creep rate of the material is ≤0.03% / 1000 h; at 80℃ and 3 MPa pressure, the creep rate is ≤0.06% / 1000 h, which can meet the long-term stress requirements.

[0030] (3) The creep-resistant EPDM insulating material prepared by this invention has wide-temperature-range insulation stability, that is, in a wide temperature range of -40℃ to 80℃: insulation resistance ≥10 12 With a dielectric strength of ≥25 kV / mm and no cracking or softening, this solves the problem of ordinary EPDM being prone to brittleness at low temperatures and a significant decrease in insulation resistance at high temperatures, ensuring the electrical safety of the cable in extreme environments.

[0031] (4) The creep-resistant EPDM insulation material prepared by the present invention has good compatibility: the peel strength with creep-resistant copper conductor is ≥1.2 N / mm, the compatibility with TPU sheath material is excellent, the interlayer bonding is tight and there are no gaps.

[0032] (5) The mechanical strength of the creep-resistant EPDM insulation material prepared by the present invention is significantly improved: the tensile strength of the insulation layer is ≥12MPa, the elongation at break is ≥400%, and the tear strength is ≥25 kN / m, which can ensure that it is not easily damaged during cabling and laying.

[0033] (5) The creep-resistant EPDM insulation material prepared by the present invention has good anti-aging performance: after 24 months of use in a wide temperature range alternating environment, the insulation performance retention rate is ≥90% and the mechanical performance retention rate is ≥85%, and the material has long-term service capability. Detailed Implementation

[0034] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0035] While some modifications to EPDM materials have been studied in the prior art, such as improving performance by adding reinforcing agents or adjusting the vulcanization process, these improvements typically target only a single property (e.g., high temperature resistance or tear resistance) and fail to systematically address the comprehensive requirements of wide temperature range, creep resistance, compatibility, and mechanical strength. Therefore, this invention, by optimizing the synergistic ratio of EPDM substrate and various functional additives, combined with a specific preparation process, solves the comprehensive problems of insufficient creep resistance, poor wide temperature range stability, poor compatibility, and low mechanical strength in the prior art, providing a high-performance insulation material solution for ultra-deep vibratory bonding cables.

[0036] Specifically, the present invention provides a creep-resistant EPDM insulation material, comprising the following components by mass percentage: 60%~65% EPDM rubber, 20%~25% reinforcing agent, 5%~8% plasticizer, 3%~5% creep-resistant agent, 0.8%~1.5% crosslinking agent, 1%~2% compatibilizer, 0.5%~1% anti-aging agent, and 0.5%~1% processing aid.

[0037] In some embodiments of the present invention, the creep-resistant EPDM insulating material comprises, by weight percentage, the following components: 61% EPDM rubber (Mounney viscosity ML1+4 125°C is 55), 25% reinforcing agent, 6% plasticizer, 3% creep-resistant agent, 1.2% crosslinking agent, 2% compatibilizer, 1% anti-aging agent, and 0.8% processing aid.

[0038] In some embodiments of the present invention, the creep-resistant EPDM insulating material comprises, by mass percentage, the following components: 62.5% EPDM rubber (Mounney viscosity ML1+4 125°C is 60), 22.5% reinforcing agent, 7% plasticizer, 4% creep-resistant agent, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid.

[0039] In some embodiments of the present invention, the creep-resistant EPDM insulating material comprises, by weight percentage, the following components: 64.5% EPDM rubber (Mounney viscosity ML1+4 125°C is 68), 20% reinforcing agent, 7.5% plasticizer, 5% creep-resistant agent, 0.8% crosslinking agent, 1% compatibilizer, 0.5% anti-aging agent, and 0.7% processing aid.

[0040] In this invention, the performance improvement of the prepared material is not due to the independent effect of a single component, but rather the result of synergistic enhancement of multiple components and the construction of an interpenetrating stable network. The core interactions are as follows: (1) Synergistic reinforcement effect of substrate and reinforcement system EPDM serves as the continuous phase matrix, providing basic weather resistance, elasticity, and insulation. Carbon black N550 and silica form a particle-graded composite reinforcing system: the high structural density of carbon black N550 embeds itself in the interstices of EPDM molecular chains, constructing a physical entanglement network to enhance tensile and tear resistance; the silanol groups on the surface of silica form hydrogen bonds with the unsaturated bonds of EPDM, while simultaneously adsorbing paraffin oil to form a "slow-release reservoir," preventing the precipitation of plasticizers and increased hardness at low temperatures. The 6:4 to 7:3 ratio of the two compounds balances strength and elasticity over a wide temperature range, solving the problems of low-temperature brittleness and high-temperature creep associated with single reinforcing agents.

[0041] (2) Synergistic effect of intercalation between the anti-creep system and the matrix and reinforcement system Organically modified montmorillonite is a layered nanomaterial. After modification, its oleophilicity is enhanced, allowing it to be uniformly dispersed in an EPDM matrix and form an intercalation anchoring structure with the molecular chains. On one hand, it restricts molecular chain slippage under long-term stress, significantly reducing creep rate; on the other hand, it forms a composite barrier network of "two-dimensional sheets + zero-dimensional particles" with carbon black and silica, synergistically blocking oxygen and moisture penetration and improving anti-aging performance. An addition of 3%~5% can form a complete intercalation network; too low an addition will have no anchoring effect, while too high an addition will easily lead to agglomeration and damage to insulation.

[0042] (3) Bridging and synergistic effect of compatibilizers Maleic anhydride-grafted POE has an amphiphilic structure. The nonpolar POE segments are completely compatible with the EPDM matrix, while the polar maleic anhydride groups achieve dual bridging: first, they form chemical bonds with the oxide layer on the copper conductor surface, improving the peel strength between the insulation layer and the conductor and preventing delamination; second, they form hydrogen bonds with the polar groups of montmorillonite and silica, improving the dispersibility of inorganic fillers and preventing insulation defects caused by agglomeration. Simultaneously, the POE segments exhibit excellent compatibility with the TPU sheath, eliminating interlayer gaps between the insulation layer and the sheath and improving cable sealing.

[0043] (4) Synergistic effect of the cross-linking system and the overall network in solidification The DCP crosslinking agent decomposes at the vulcanization temperature to generate free radicals, which initiate the crosslinking of EPDM double bonds, forming a three-dimensional chemical network. This network, together with the physical entanglement network of the reinforcing system and the intercalation network of the anti-creep agent, forms a triple interpenetrating structure: the chemical network provides permanent structural stability and restricts high-temperature molecular chain slippage; the physical network provides elasticity and tear resistance; and the intercalation network provides creep resistance and barrier properties. These three elements work synergistically to achieve structural stability over a wide temperature range. A crosslinking degree of 70%–80% can balance elasticity and rigidity; too low a degree results in an incomplete network, while too high a degree increases material brittleness.

[0044] (5) Synergistic protective effect of anti-aging system Antioxidant 4010NA (chain-terminating type) and antioxidant RD (peroxide decomposition type) are compounded in a 1:1 ratio to form a full-chain anti-aging system of "free radical capture + peroxide decomposition", which has a protective effect far superior to that of a single antioxidant. At the same time, it works synergistically with the layered barrier network of montmorillonite. Montmorillonite blocks oxygen / moisture penetration and reduces the aging rate, while the anti-aging agent eliminates the aging reaction caused by the already penetrated oxygen, achieving a high performance retention rate after 24 months of aging.

[0045] The specifications of the experimental reagents and materials used in this invention are shown in Table 1.

[0046] Table 1

[0047] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0048] Example 1: This example provides a creep-resistant EPDM insulating material and its preparation method. The creep-resistant EPDM insulating material prepared in this embodiment comprises, by mass percentage, the following raw materials: 61% EPDM rubber (Mounney viscosity ML1+4 125℃ is 55), 25% reinforcing agent, 6% plasticizer, 3% creep-resistant agent, 1.2% crosslinking agent, 2% compatibilizer, 1% anti-aging agent, and 0.8% processing aid; The reinforcing agent is a blend of carbon black N550 and silica in a mass ratio of 7:3; the plasticizer is paraffin oil; the creep inhibitor is organically modified montmorillonite (organically intercalated modified hexadecyltrimethylammonium chloride, a commercially available industrial product); the crosslinking agent is dicumyl peroxide (DCP); the compatibilizer is maleic anhydride-grafted ethylene-octene copolymer (maleic anhydride-grafted POE) with a grafting rate of 1.2%; the anti-aging agent is a blend of antioxidant 4010NA (N-isopropyl-N'-phenyl-p-phenylenediamine) and antioxidant RD (2,2,4-trimethyl-1,2-dihydroquinoline polymer) in a mass ratio of 1:1; and the processing aids are 0.3% stearic acid and 0.5% zinc oxide. The specific preparation method is as follows: (1) Plasticizing: Put EPDM rubber into an internal mixer, the plasticizing temperature is 105℃, the plasticizing time is 6 minutes, and the Mooney viscosity is controlled at 35±2. (2) Mixing: Add reinforcing agent, plasticizer, creep inhibitor, compatibilizer, anti-aging agent and processing aid to the plasticized EPDM rubber in sequence. The mixing temperature is 115℃ and the mixing time is 18 minutes to ensure that each component is evenly dispersed. (3) Add crosslinking agent: Cool the mixed rubber compound to 85°C, add crosslinking agent, and continue mixing for 6 minutes to obtain the mixed rubber; (4) Sheeting and cooling: The compounded rubber is sheeted through a two-roll mill with a sheet thickness of 2.5 mm. It is then allowed to cool naturally to room temperature and is ready for use.

[0049] Example 2: This example provides a creep-resistant EPDM insulating material and its preparation method. The creep-resistant EPDM insulating material prepared in this embodiment comprises, by mass percentage, the following raw materials: 62.5% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 22.5% reinforcing agent, 7% plasticizer, 4% creep-resistant agent, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid; The reinforcing agent is a blend of carbon black N550 and silica in a mass ratio of 6:4; the plasticizer is paraffin oil; the creep inhibitor is modified montmorillonite; the crosslinking agent is dicumyl peroxide (DCP); the compatibilizer is maleic anhydride-grafted ethylene-octene copolymer (maleic anhydride-grafted POE) with a grafting rate of 1.5%; the anti-aging agent is a blend of antioxidant 4010NA (N-isopropyl-N'-phenyl-p-phenylenediamine) and antioxidant RD (2,2,4-trimethyl-1,2-dihydroquinoline polymer) in a mass ratio of 1:1; and the processing aids are 0.3% stearic acid and 0.4% zinc oxide.

[0050] The specific preparation method is as follows: (1) Plasticizing: Put EPDM rubber into a mixer, the plasticizing temperature is 105℃, the plasticizing time is 7 minutes, and the Mooney viscosity is controlled at 35±2. (2) Mixing: Add reinforcing agent, plasticizer, creep inhibitor, compatibilizer, anti-aging agent and processing aid to the plasticized EPDM rubber in sequence. The mixing temperature is 115℃ and the mixing time is 18 minutes to ensure that each component is evenly dispersed. (3) Add crosslinking agent: Cool the mixed rubber compound to 85°C, add crosslinking agent, and continue mixing for 7 minutes to obtain the mixed rubber; (4) Sheeting and cooling: The compounded rubber is sheeted through a two-roll mill with a sheet thickness of 2.5 mm. It is then allowed to cool naturally to room temperature and is ready for use.

[0051] Example 3: This example provides a creep-resistant EPDM insulating material and its preparation method. The creep-resistant EPDM insulating material prepared in this embodiment comprises, by mass percentage, the following raw materials: 64.5% EPDM rubber (Mounney viscosity ML1+4 125℃ is 68), 20% reinforcing agent, 7.5% plasticizer, 5% creep-resistant agent, 0.8% crosslinking agent, 1% compatibilizer, 0.5% anti-aging agent, and 0.7% processing aid; The reinforcing agent is a blend of carbon black N550 and silica in a mass ratio of 7:3; the plasticizer is paraffin oil; the creep inhibitor is modified montmorillonite; the crosslinking agent is dicumyl peroxide (DCP); the compatibilizer is maleic anhydride-grafted ethylene-octene copolymer (maleic anhydride-grafted POE) with a grafting rate of 1.2%; the anti-aging agent is a blend of antioxidant 4010NA (N-isopropyl-N'-phenyl-p-phenylenediamine) and antioxidant RD (2,2,4-trimethyl-1,2-dihydroquinoline polymer) in a mass ratio of 1:1; and the processing aids are 0.1% stearic acid and 0.1% zinc oxide. The specific preparation method is as follows: (1) Plasticizing: Put EPDM rubber into an internal mixer, the plasticizing temperature is 110℃, the plasticizing time is 8 minutes, and the Mooney viscosity is controlled at 35±2. (2) Mixing: Add reinforcing agent, plasticizer, creep inhibitor, compatibilizer, anti-aging agent and processing aid to the plasticized EPDM rubber in sequence. The mixing temperature is 120℃ and the mixing time is 20 minutes to ensure that each component is evenly dispersed. (3) Add crosslinking agent: Cool the mixed rubber compound to 85°C, add crosslinking agent, and continue mixing for 6 minutes to obtain the mixed rubber; (4) Sheeting and cooling: The compounded rubber is sheeted through a two-roll mill with a sheet thickness of 2.5 mm. It is then allowed to cool naturally to room temperature and is ready for use.

[0052] Comparative Example 1: The difference between this comparative example and Example 2 is that it is only a common EPDM formulation, without the addition of anti-creep agents, compatibilizers, and anti-aging agents. By mass percentage, it includes the following raw materials: 62.5% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 22.5% reinforcing agent, 6.5% plasticizer, 1% crosslinking agent, and 0.7% processing aid. Other preparation methods are the same as in Example 1.

[0053] Comparative Example 2: The difference between this comparative example and Example 2 is that no reinforcing agent was added, while the other components, contents, and preparation methods are the same as in Example 2.

[0054] Comparative Example 3: The difference between this comparative example and Example 2 is that the mass ratio of carbon black N550 to silica in the reinforcing agent is 9:1, while the other components, contents and preparation methods are the same as in Example 2.

[0055] Comparative Example 4: The difference between this comparative example and Example 2 is that the mass ratio of carbon black N550 to silica in the reinforcing agent is 4:6, while the other components, contents and preparation methods are the same as in Example 2.

[0056] Comparative Example 5: The difference between this comparative example and Example 2 is that, by mass percentage, it includes the following raw materials: 62.5% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 18% reinforcing agent, 7% plasticizer, 4% anti-creep agent, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid. The other components, contents, and preparation methods are the same as in Example 2.

[0057] Comparative Example 6: The difference between this comparative example and Example 2 is that, by mass percentage, it includes the following raw materials: 62.5% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 28% reinforcing agent, 7% plasticizer, 4% anti-creep agent, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid. The other components, contents, and preparation methods are the same as in Example 2.

[0058] Comparative Example 7: The difference between this comparative example and Example 2 is that no anti-creep agent was added, while the other components, contents, and preparation methods are the same as in Example 2.

[0059] Comparative Example 8: The difference between this comparative example and Example 2 is that, by mass percentage, it includes the following raw materials: 62.5% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 22.5% reinforcing agent, 7% plasticizer, 8% creep inhibitor, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid. The other components, contents, and preparation methods are the same as in Example 2.

[0060] Comparative Example 9: The difference between this comparative example and Example 2 is that, by mass percentage, it includes the following raw materials: 62.5% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 22.5% reinforcing agent, 7% plasticizer, 1% creep inhibitor, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid. Other components, contents, and preparation methods are the same as in Example 2.

[0061] Comparative Example 10: The difference between this comparative example and Example 2 is that no anti-aging agent was added, while the other components, contents, and preparation methods are the same as in Example 2.

[0062] Comparative Example 11: The difference between this comparative example and Example 2 is that, by mass percentage, it includes the following raw materials: 62.5% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 22.5% reinforcing agent, 7% plasticizer, 4% creep inhibitor, 1% crosslinking agent, 1.5% compatibilizer, 1.5% anti-aging agent, and 0.7% processing aid. Other components, contents, and preparation methods are the same as in Example 2.

[0063] Comparative Example 12: The difference between this comparative example and Example 2 is that, by mass percentage, it includes the following raw materials: 62.5% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 22.5% reinforcing agent, 7% plasticizer, 4% anti-creep agent, 1% crosslinking agent, 1.5% compatibilizer, 0.2% anti-aging agent, and 0.7% processing aid. The other components, contents, and preparation methods are the same as in Example 2.

[0064] Comparative Example 13: The difference between this comparative example and Example 2 is that the mass ratio of antioxidant 4010NA to antioxidant RD in the anti-aging agent is 3:1, while the other components, contents and preparation methods are the same as in Example 2.

[0065] Comparative Example 14: The difference between this comparative example and Example 2 is that the mass ratio of antioxidant 4010NA to antioxidant RD in the anti-aging agent is 1:3, while the other components, contents and preparation methods are the same as in Example 2.

[0066] Comparative Example 15: The difference between this comparative example and Example 2 is that: a single antioxidant RD is used as the anti-aging agent, the total amount added is the same as the anti-aging agent in Example 2, and the other components, contents and preparation methods are the same as in Example 2.

[0067] Comparative Example 16: The difference between this comparative example and Example 2 is that: a single antioxidant 4010NA is used as the anti-aging agent, the total amount added is the same as the anti-aging agent in Example 2, and the other components, contents and preparation methods are the same as in Example 2.

[0068] Comparative Example 17: The difference between this comparative example and Example 2 is that: the antioxidant MB (2-mercaptobenzimidazole) is used as the anti-aging agent, the total amount added is the same as the anti-aging agent in Example 2, and the other components, contents and preparation methods are the same as in Example 2.

[0069] Comparative Example 18: The difference between this comparative example and Example 2 is that, by mass percentage, it includes the following raw materials: 55% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 22.5% reinforcing agent, 7% plasticizer, 4% anti-creep agent, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid. Other components, contents, and preparation methods are the same as in Example 2.

[0070] Comparative Example 19: The difference between this comparative example and Example 2 is that, by mass percentage, it includes the following raw materials: 70% EPDM rubber (Mounney viscosity ML1+4 125℃ is 60), 22.5% reinforcing agent, 7% plasticizer, 4% anti-creep agent, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid. The other components, contents, and preparation methods are the same as in Example 2.

[0071] Test Example 1: This test example provides application performance testing of integrated cables using EPDM insulation materials prepared in Examples 1-3 and Comparative Examples 1-19. The manufacturing steps of integrated cables are as follows: (1) Insulation extrusion: The creep-resistant copper conductor (main core 120 mm², control core 1.5 mm²) is fed into the extruder, and the cooled compound rubber (EPDM insulation material prepared in the example or comparative example) is fed into the extruder hopper to extrude the insulation layer; the extrusion temperature is controlled at 120~140℃, the die temperature is 130~150℃, and the insulation layer thickness is controlled according to the cable design requirements (main core insulation thickness 3~4 mm, control core insulation thickness 1~1.5 mm). In Examples 1-2, the extrusion temperature was 130°C, the die temperature was 140°C, the insulation thickness of the main wire core was 3.5 mm, and the insulation thickness of the control wire core was 1.2 mm. For Example 3, the extrusion temperature was 140°C and the die temperature was 150°C, while the other preparation processes were the same as those in Example 1.

[0072] (2) Cross-linking and curing: The extruded core wire is sent into a vulcanizing tube for cross-linking and curing. The vulcanization temperature is 160~170℃, the vulcanization time is 10~15 minutes, and the degree of cross-linking is controlled at 70%~80%. In Examples 1-2, the vulcanization temperature was 165°C, the time was 12 min, and the degree of crosslinking was 75%. For Example 3, the vulcanization temperature was 170°C and the time was 15 min, while other preparation processes were the same as in Example 1.

[0073] (3) Cooling and winding: The cross-linked core wire is cooled by water (water temperature 20~30℃) for 5~10 minutes, and then wound up at a speed of 10~15 m / min to obtain the insulated core wire; Among them, for Examples 1 to 3, the water cooling was carried out at 25°C for 8 minutes and the take-up speed was 12 m / min.

[0074] (4) Cable assembly: The insulated core wires, the central reinforcing layer, and the heterogeneous filler are twisted together according to the cable structure, and then wrapped, braided, and extruded with sheaths are carried out to produce finished cables.

[0075] Specific application performance test data are shown in Table 2: Table 2

[0076] Analysis of the data in Table 1 shows that: Examples 1-3 are all within the scope of protection of the claims of this patent, and all performance indicators meet the standards. All performance indicators of Examples 1-3 meet or exceed those of GB / T 12706.1-2020 "Extruded Insulated Power Cables and Accessories with Rated Voltages of 1kV (Um=1.2 kV) to 35kV (Um=40.5 kV) Part 1: Cables with Rated Voltages of 1kV (Um=1.2kV) and 3kV (Um=3.6 kV)" and GB / T The invention meets the requirements of national standards such as 2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Fibers - Part 11: General Test Methods for Thickness and Dimensional Measurement and Mechanical Properties Tests", among which the creep resistance and wide-temperature-range insulation stability reach the industry-leading level. Example 2 is the optimal ratio, with each component forming the optimal synergy. The creep rate, insulation resistance, peel strength, and anti-aging performance are all optimal, perfectly matching the extreme working conditions of ultra-deep vibratory impact integrated cables. This verifies the wide-window adaptability and performance stability of the formulation system of the embodiments of the present invention. Examples 1 to 3 adjusted the proportion of matrix and filler, respectively, and still met all the core indicators, proving that the formulation of the present invention has good industrial production tolerance within the protection scope.

[0077] Compared with the examples, Comparative Example 1 is a basic EPDM formulation without the core anti-creep agent, compatibilizer, and anti-aging agent of this patent. All core performance indicators are seriously substandard: the creep rate is more than 15 times higher than that of Example 2, which cannot meet the dimensional stability requirements under long-term stress conditions at all; the peel strength with copper conductor is only 0.32 N / mm, which makes it very easy for the insulation layer to delaminate and the interface to break down; the anti-aging performance drops sharply, and the insulation performance retention rate is less than 50% after 24 months of aging, which cannot meet the requirements for long-term service. Compared with the examples, Comparative Example 2, without the addition of reinforcing agent, had a tensile strength of only 5.2 MPa, a decrease of 64% compared to Example 2. The material was completely unable to withstand the mechanical stress of cabling and laying, and experienced severe brittleness at low temperatures, with complete failure of creep performance. Comparative Examples 3-4 had a compounding ratio that deviated from the protection range: an excessively high carbon black ratio (9:1) would cause the insulation resistance to decrease by one order of magnitude, failing to meet insulation requirements; an excessively high silica ratio (4:6) would lead to poor filler dispersion, a significant decrease in tensile and creep resistance, a sharp increase in low-temperature hardness, and easy cracking. Comparative Examples 5-6 had a ratio that deviated from the protection range: when the reinforcing agent was less than 20%, an effective physical entanglement network could not be formed, and the creep resistance and tensile strength were substandard; when the reinforcing agent was more than 25%, excessive filler agglomeration occurred, resulting in deterioration of insulation and low-temperature performance. Therefore, the reinforcing agent compounding ratio and addition range specified in this invention are the core of balancing the insulation, mechanical strength, and wide-temperature stability of the material. Only within this range can the synergistic improvement of "strength-insulation-temperature resistance" be achieved.

[0078] Compared with the examples, Comparative Example 7, without the addition of anti-creep agent, showed a creep rate at both room temperature and high temperature that was more than 10 times higher than that of Example 2, completely failing to meet the dimensional stability requirements under long-term stress, and easily leading to thinning and breakdown of the insulation layer; Comparative Example 9, with an addition of 1% (below the lower limit), could not form a complete intercalation anchoring network, its anti-creep performance was substandard, and it could not limit the long-term slippage of molecular chains; Comparative Example 8, with an addition of 8% (above the upper limit), resulted in excessive agglomeration of nanofillers, which destroyed the continuous phase structure of the matrix, reduced insulation resistance, and reversed the deterioration of anti-creep performance, making it prone to microcracks at low temperatures; Therefore, setting the addition amount of anti-creep agent to 3%~5% is the golden range for forming a complete intercalation network without damaging the insulation performance, forming a synergistic barrier structure of "two-dimensional sheets + zero-dimensional particles" with the reinforcing system, which is one of the core innovations of this invention.

[0079] Compared to the examples, Comparative Example 10, without the addition of anti-aging agents, showed no significant deterioration in performance at room temperature, but its insulation performance retention rate after 24 months of aging was only 38%, which completely failed to meet the long-term service requirements of more than 2 years. Comparative Examples 11-12 had dosages that deviated from the range; below 0.5%, a complete anti-aging protection system could not be formed, and the aging retention rate did not meet the standard; above 1%, antioxidants would become supersaturated and precipitate, affecting the crosslinking system and leading to a decrease in mechanical and creep resistance properties. Comparative Examples 13-14 had a compounding ratio that deviated from 1:1, failing to form a "free radical capture + superoxide dismutase" mixture. The entire chain of protection against "chemical decomposition" significantly reduces the anti-aging effect, and the aging retention rate cannot reach the benchmark requirement of 90%. The protective effects of single-type antioxidants and other types of antioxidants in Comparative Examples 15-17 are far lower than the synergistic protection system compounded in the embodiments of this invention, and the performance deteriorates significantly after aging. Therefore, the 1:1 mass compounding ratio of antioxidant 4010NA and antioxidant RD in the anti-aging agent and the addition range of 0.5% to 1% can form synergistic protection with the lamellar barrier network of the creep inhibitor, which is a necessary condition for achieving long-term weather resistance of materials.

[0080] Compared with the examples, in Comparative Example 18, the EPDM content was 55% (below the lower limit): the matrix continuous phase was insufficient, the filler could not be uniformly dispersed, and the insulation, mechanical, creep resistance and low temperature resistance properties were comprehensively deteriorated, resulting in severe brittleness at low temperature; in Comparative Example 19, the EPDM content was 70% (above the upper limit): the functional filler content was insufficient, and an effective reinforcing and creep-resistant network could not be formed, and the tensile strength and creep resistance properties did not meet the standards; therefore, an EPDM content of 60%~65% is the optimal range for balancing matrix continuity and functional filler modification effect, providing a stable matrix environment for each functional system.

[0081] In summary, only within the component and ratio range defined by this invention can all the core indicators of creep resistance, wide temperature range insulation, interface compatibility, mechanical strength, and aging resistance be simultaneously met, thus solving the four core defects of ordinary EPDM materials in the background technology. The absence of any component or deviation of the ratio from the protected range will result in at least one core performance failing to meet the standard, making it unsuitable for the extreme service conditions of ultra-deep vibratory impact integrated cables, fully verifying the scientific nature, necessity, and inventiveness of the scope of protection of this patent. In addition, the optimal ratio of Embodiment 2 of this invention can achieve maximum synergy of various performances, serving as the basic formula for industrial production recommended by this patent.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A creep-resistant EPDM insulating material, characterized in that, By weight percentage, it includes the following components: 60%~65% EPDM rubber, 20%~25% reinforcing agent, 5%~8% plasticizer, 3%~5% anti-creep agent, 0.8%~1.5% crosslinking agent, 1%~2% compatibilizer, 0.5%~1% anti-aging agent, and 0.5%~1% processing aid.

2. The creep-resistant EPDM insulating material as described in claim 1, characterized in that, The creep-resistant EPDM insulation material comprises, by weight percentage: 62.5% EPDM rubber, 22.5% reinforcing agent, 7% plasticizer, 4% creep-resistant agent, 1% crosslinking agent, 1.5% compatibilizer, 0.8% anti-aging agent, and 0.7% processing aid.

3. The creep-resistant EPDM insulating material as described in claim 1, characterized in that, The Mooney viscosity ML1+4 of the EPDM rubber is 50~70 at 125℃; The reinforcing agent is a compound of carbon black N550 and silica, with a mass ratio of 6~7:3~4. The plasticizer is paraffin oil; The anti-creep agent is selected from one or more of organically modified montmorillonite and nano-kaolinite; The crosslinking agent is selected from one or more of dicumyl peroxide and benzoyl peroxide; The compatibilizer is selected from one or more of maleic anhydride-grafted ethylene-octene copolymer and maleic anhydride-grafted ethylene-vinyl acetate copolymer; the grafting rate of the maleic anhydride-grafted ethylene-octene copolymer is 1.0%~1.5%; The anti-aging agent is a compound of antioxidant 4010NA and antioxidant RD, with a compound mass ratio of 1:

1. The processing aids include stearic acid and zinc oxide.

4. A method for preparing the creep-resistant EPDM insulating material according to any one of claims 1 to 3, characterized in that, Specifically, the process involves: plasticizing EPDM rubber, then sequentially adding reinforcing agents, plasticizers, anti-creep agents, compatibilizers, anti-aging agents, and processing aids to the plasticized EPDM rubber for mixing to ensure uniform dispersion of each component; then adding a crosslinking agent to the mixed rubber compound and continuing mixing to obtain a compounded rubber; finally, extruding the compounded rubber into sheets and cooling it to obtain an anti-creep EPDM insulating material.

5. The preparation method according to claim 4, characterized in that, The plasticizing temperature is 100~110℃, the time is 5~8 min, and the Mooney viscosity of the EPDM rubber is controlled at 30~40. The mixing process is carried out at a temperature of 110~120℃ for 15~20 min. The mixed rubber compound needs to be cooled to 80~90℃ before adding the crosslinking agent, and then continue mixing for 5~8 minutes to obtain the mixed rubber. The sheet thickness of the compounded rubber is 2-3 mm.

6. The application of the creep-resistant EPDM insulation material according to any one of claims 1 to 3 in integrated cable materials.

7. A cable, characterized in that, It includes a conductor and an insulating layer covering the conductor, the insulating layer being made of the creep-resistant EPDM insulating material as described in any one of claims 1 to 3.

8. The cable as claimed in claim 7, characterized in that, The cable is an integrated cable for ultra-deep vibratory impacting, with a main core insulation layer thickness of 3~4 mm and a control core insulation layer thickness of 1~1.5 mm.

9. A method for applying the anti-creep EPDM insulation material according to any one of claims 1 to 3 in integrated cables, characterized in that, Includes the following steps: The anti-creep EPDM insulation material as described in any one of claims 1 to 3 is extruded onto an anti-creep copper conductor and subjected to extrusion treatment. The extruded core wire is cross-linked and cured. The vulcanized core wire is cooled by water and then wound up. The obtained insulated core wire is stranded with the central reinforcing layer and the anisotropic filler according to the cable structure.

10. The application method as described in claim 9, characterized in that, The cross-sectional area of ​​the anti-creep copper conductor is 120 mm² for the main conductor and 1.5 mm² for the control conductor. In the extrusion process, the extrusion temperature is 120~140℃ and the die temperature is 130~150℃; The vulcanization temperature is 160~170℃, the vulcanization time is 10-15 minutes, and the degree of crosslinking during the crosslinking curing is controlled at 70%~80%. The water cooling temperature is 20~30℃, the time is 5~10 min, and the winding speed is 10~15 m / min.

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