Insulating material for prefabricated cable accessories, process for the production thereof and prefabricated cable accessory

Abstract

The application relates to the technical field of insulating materials, and discloses a preformed cable accessory insulating material, a preparation method thereof and a preformed cable accessory. The preformed cable accessory insulating material is composed of the following raw materials in parts by mass: 100 parts of ternary ethylene-propylene rubber, 40-70 parts of reinforcing filler, 20-40 parts of plasticizer, 1.5-3.5 parts of crosslinking agent, 1-3 parts of crosslinking aid, 1-3 parts of antioxidant, and 1-5 parts of processing aid. By introducing the antioxidant with a specific structure, the oxidation resistance and degradation resistance of the material in a complex environment such as high temperature, humidity and electric field are enhanced, the aging process of the insulating material is effectively delayed, and the material can better maintain the original performance in long-term use. Through the synergistic optimization of the formula components and process parameters, the dispersion uniformity of the material in the mixing process is improved, the pre-crosslinking risk is reduced, the vulcanization efficiency and quality stability are improved, so that the production process is more controllable, and the product quality is more consistent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of insulating materials, and particularly relates to an insulating material for prefabricated cable accessories, a preparation method thereof and a prefabricated cable accessory. BACKGROUND

[0002] With the continuous development of power systems, the performance requirements of cable accessories are also increasingly high. As an important component of power equipment, the insulating performance of prefabricated cable accessories is directly related to the safety and reliability of power transmission. However, the existing insulating materials for prefabricated cable accessories have many problems in actual application.

[0003] At present, most of the insulating materials of prefabricated cable accessories are based on rubber, which has certain insulating properties, but is prone to accelerated aging under the influence of environmental factors during long-term operation. For example, in a high-temperature environment, the molecular chain movement of the material is intensified, which can easily cause molecular chain rupture or excessive cross-linking, resulting in brittle and cracking of the material, a significant decrease in mechanical properties, and deterioration of insulating properties. In a humid environment, water can easily penetrate into the material, causing water treeing, damaging the insulating structure of the material, reducing the insulating resistance, and increasing the risk of insulation breakdown. Moreover, under the long-term action of electric field and magnetic field, the internal trap level of the insulating material will change due to electrical aging, the carrier mobility will increase, the electrical conductivity will increase, and finally the insulating performance will be lost.

[0004] At the same time, the comprehensive performance of the existing insulating materials is difficult to meet the high requirements of modern power systems. On the one hand, the mechanical properties need to be improved, for example, during installation and operation, the cable accessory needs to withstand certain mechanical stress, and if the strength of the insulating material is insufficient, deformation or damage can easily occur, affecting the sealing and integrity of the cable accessory; on the other hand, in terms of processing performance, the existing materials are prone to uneven dispersion and incomplete vulcanization during mixing, vulcanization and other processing steps, resulting in unstable product quality and limited production efficiency. In addition, with the increase of voltage level and the complexity of application scenarios of power systems, the requirements for special properties such as corona resistance and partial discharge of insulating materials are also increasing, but the existing materials are not ideal in these aspects.

[0005] Therefore, it is urgent to develop an insulating material for prefabricated cable accessories that can adapt to complex environments, has excellent insulating properties, good mechanical properties and processing performance. SUMMARY

[0006] The present application relates to the technical field of insulating materials, and particularly relates to an insulating material for prefabricated cable accessories, a preparation method thereof and a prefabricated cable accessory.

[0007] To achieve the above object, the technical scheme adopted by the present application is: an insulating material for prefabricated cable accessories, which is composed of the following raw materials in parts by mass: 100 parts of ethylene-propylene-diene rubber, 40-70 parts of reinforcing filler, 20-40 parts of plasticizer, 1.5-3.5 parts of crosslinking agent, 1-3 parts of auxiliary crosslinking agent, 1-3 parts of antioxidant, and 1-5 parts of processing aid.

[0008] The antioxidant is a compound shown in the following formula 1:

[0009] Formula 1;

[0010] The R1 is selected from the group consisting of methyl, ethyl, tert-butyl, and methoxy.

[0011] Further, the reinforcing filler is carbon black.

[0012] Further, the plasticizer is paraffin oil.

[0013] Further, the crosslinking agent is dicumyl peroxide.

[0014] Further, the auxiliary crosslinking agent is triallyl isocyanurate.

[0015] Further, the processing aid is stearic acid.

[0016] Further, the antioxidant is any one of the compounds shown in the following structures:

[0017] ;

[0018] .

[0019] A preparation method of an insulating material for prefabricated cable accessories, which comprises the following steps:

[0020] S1. The ethylene-propylene-diene rubber, reinforcing filler, and plasticizer are added into a mixer and mixed at 70-90 DEG C for 5-8 minutes to obtain material A;

[0021] S2. The antioxidant, processing aid, and auxiliary crosslinking agent are added into the material A and mixed on an open mill at 40-60 DEG C for 10 minutes to obtain material B;

[0022] S3. The material B is cooled to 30-40 DEG C, and the crosslinking agent is added and uniformly mixed, and then the mixture is extruded into a sheet to obtain a rubber compound;

[0023] S4. The rubber compound is placed in a mold and vulcanized at 170-180 DEG C under a pressure of 10-15 MPa for 15-20 minutes, and then cooled to obtain an insulating material for prefabricated cable accessories.

[0024] Further, the S4 is heat treated in an oven at 150 DEG C for 2-4 hours after vulcanization.

[0025] Further, the vulcanizing agent is sulfur.

[0026] Further, the rotor speed of the internal mixer in S1 is 30-50 rpm, and the filling coefficient is 70%-80%.

[0027] Further, the cooling in S4 is air cooling.

[0028] A prefabricated cable accessory, comprising a stress cone, an insulation body and a sealing structure, wherein the stress cone and / or the insulation body is made of the above-mentioned insulation material for prefabricated cable accessories.

[0029] Further, the elongation retention rate of the insulation material is greater than or equal to 85% after 135 DEG C, 168 h air oven aging.

[0030] Further, the Shore A hardness of the stress cone is less than or equal to 68.

[0031] Application of a prefabricated cable accessory to the terminal and / or intermediate connection site of a 10-35 kV cross-linked polyethylene cable.

[0032] The mechanism of the anti-aging agent is mainly reflected in capturing free radicals and inhibiting oxidative chain reactions through the chemical structure, thereby delaying the aging process of the material. The heterocyclic conjugated structure in the molecule provides electronic stability and resonance effect, can effectively absorb and quench free radicals, prevent the oxidative rupture of rubber molecular chains, and enhance the heat resistance and oxidation resistance of the material. The imino group (-NH-) as a nucleophilic group is easy to capture free radicals or participate in hydrogen bond formation, and inhibit the chain propagation of oxidative reactions. The cyano group (-CN) has strong polarity, can enhance the intermolecular interaction force, improve the dispersibility and stability of the anti-aging agent, and reduce the conductivity change of the material under an electric field. In a high temperature or electric field environment, free radicals are easily generated in the insulation material (EPDM), and the heterocyclic conjugated structure and imino group of the anti-aging agent can quickly react with them to form stable intermediates, interrupting the oxidative chain reaction. The strong electronegativity of the cyano group helps to decompose peroxide, preventing it from causing material degradation. This is particularly important during high-temperature vulcanization, which can ensure the uniformity of the cross-linking reaction. The heterocyclic conjugated structure and cyano group form an electron delocalization system, enhancing the electron affinity of the molecule and reducing the material degradation caused by environmental factors such as ultraviolet light or humidity.

[0033] The EPDM (Ethylene Propylene Diene Rubber) based material system described in the present invention improves the environmental aging resistance, mechanical properties and processing performance of the material by adding anti-aging agents, reinforcing fillers, plasticizers, cross-linking agents, co-cross-linking agents, processing aids and other components. The innovative structural design of the anti-aging agent enables it to protect the EPDM chain during high-temperature vulcanization, inhibit water treeing and improve the elongation at break after aging. Carbon black, as a reinforcing filler, enhances the material strength by anchoring molecular chains through surface active sites, and its dispersion is affected by paraffin oil lubrication, thereby optimizing the mixing and filling coefficient. In the cross-linking system, dicumyl peroxide initiates cross-linking, the anti-aging agent quenches excess free radicals, and the co-cross-linking agent forms a three-dimensional network with carbon black. Stearic acid acts as a dispersion medium to prevent pre-cross-linking during low-temperature mixing. The synergistic effect of the components improves the overall performance of the material.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. Significant improvement in environmental aging resistance: By introducing anti-aging agents with specific structures, the material's antioxidant and anti-degradation abilities in complex environments such as high temperature, humidity and electric field are enhanced, effectively slowing down the aging process of the insulation material, allowing it to better maintain its original performance during long-term use.

[0036] 2. Overall optimization of mechanical properties: The material formula and preparation process are optimized, significantly improving the overall mechanical strength and hardness stability of the insulation material, enabling it to better withstand mechanical stress during installation and operation, maintaining structural integrity and sealing.

[0037] 3. Improved processing performance: Through the synergistic optimization of formula components and process parameters, the dispersion uniformity of the material during mixing is improved, the pre-cross-linking risk is reduced, and the vulcanization efficiency and quality stability are improved, making the production process more controllable and the product quality more consistent. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The HNMR chart for the anti-aging agent 1 described in the present invention. 1 HNMR chart.

[0039] Figure 2 The finished product chart for the prefabricated cable accessory described in the present invention. DETAILED DESCRIPTION

[0040] The technical solutions of the present invention will be described in detail below with reference to the drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present invention.

[0041] Synthesis Example One

[0042] Synthesis of Anti-aging Agent 1:

[0043] ;

[0044] First Step: Under nitrogen atmosphere, 20.00 g of raw material 1, 31.90 g of raw material 2, 1.03 g of tri-tert-butyl phosphine, 0.36 g of palladium on carbon, 28.03 g of anhydrous potassium carbonate and 230 g of toluene were added into the reaction system, and the reaction was carried out at 120°C for 12 hours. After the reaction was completed, the temperature was slightly lowered, and diatomite was used for filtration. After the filtrate was cooled to room temperature, it was washed with water three times, and the organic phase was reserved. Then, the water phase was extracted with ethyl acetate, and the combined organic phase was dried with anhydrous magnesium sulfate, filtered and rotary evaporated. Silica gel column chromatography was performed with a mixture of petroleum ether and ethyl acetate as the eluent, and 29.53 g of intermediate 1 was obtained after rotary evaporation.

[0045] Second Step: Under nitrogen atmosphere, 29.53 g of intermediate 1, 29.61 g of raw material 3, 41.56 g of potassium phosphate tribasic, 0.1 g of pyridine-2-carboxylic acid, 0.75 g of CuI and 400 g of DMSO were added into the reaction system, and the reaction was carried out at 85°C for 16 hours. After cooling, the obtained reaction mixture was extracted with ammonia solution and methyl tert-butyl ether, and the organic phase was washed with water five times and saturated NaCl solution twice. Finally, the combined organic phase was dried with anhydrous Na2SO4, rotary evaporated, and purified by silica gel column chromatography with a mixture of petroleum ether and ethyl acetate as the eluent. After rotary evaporation, 38.48 g of anti-aging agent 1 was obtained.

[0046] Structure identification:

[0047] MS (m / z) of intermediate 1: [M+H] + = 379;

[0048] MS (m / z) of anti-aging agent 1: [M+H] + = 614;

[0049] HNMR of anti-aging agent 1 1 HNMR-CDCl3: δ 7.86 (m, 1H), 7.63 (d, 1H), 7.53-7.35 (m, 4H), 7.26-7.04 (m, 5H), 7.01-6.64 (m, 10H), 5.94 (s, 1H), 5.55 (s, 1H), 2.91 (d, 6H), 2.49 (d, 3H), 2.35 (d, 3H).

[0050] Synthesis Examples Two to Four

[0051] Synthetic example two-synthetic example four, the antioxidant 2-antioxidant 4 was synthesized in turn, referring to the synthetic method of synthetic example one, replacing the raw material 1 therein, the rest was the same as synthetic example one. The structure of raw material 1, the structure of antioxidant 2-antioxidant 4, MS (m / z): [M+H] in synthetic example two-synthetic example four was as follows: + Data in Table 1.

[0052] Table 1. The structure of raw material 1, the structure of antioxidant 2-antioxidant 4, MS (m / z): [M+H] involved in synthetic example two-synthetic example four + Data

[0053]

[0054] Example one

[0055] Preparation of a preformed cable accessory insulation material:

[0056] 1. Raw material composition and mass fraction: ternary ethylene-propylene rubber (EPDM) 100 parts (Mooney viscosity ML (1+4) 125℃ 65-75), reinforcing filler (carbon black, carbon black N550) 55 parts, plasticizer (paraffin oil) 30 parts, crosslinking agent (dicumyl peroxide) 2.5 parts, co-crosslinking agent (triallyl isocyanurate) 2 parts, antioxidant (antioxidant 1 synthesized in synthetic example one) 3 parts, processing aid (stearic acid, industrial grade) 3 parts.

[0057] 2. Preparation method:

[0058] S1. Add ternary ethylene-propylene rubber, reinforcing filler and plasticizer into the internal mixer. Set the rotor speed of the internal mixer to 40 rpm and the filling coefficient to 75%. Mix at 80℃ for 6.5 minutes. During the mixing process, the material is uniformly dispersed without caking phenomenon, and material A is obtained.

[0059] S2. Transfer material A to the open mill, add antioxidant, processing aid and co-crosslinking agent. Set the open mill temperature to 50℃ and mix for 10 minutes. After mixing, the material is uniform gel without separation or agglomeration, and material B is obtained.

[0060] S3. Cool material B to 35℃ and add crosslinking agent. After mixing uniformly on the open mill, thin pass out sheet (thin pass frequency 5 times, thickness about 2mm), and get the rubber compound.

[0061] S4. The mixed rubber was placed in a preformed cable accessory mold and cured in a flat vulcanization machine (sulfur as vulcanizing agent). The curing conditions were: temperature 175°C, pressure 12.5 MPa, time 17.5 minutes. After curing, the sample was immediately transferred to an oven for heat treatment at 150°C for 3 hours to eliminate internal stress. Cooling was performed by air cooling at a wind speed of 2 m / s, and the sample was cooled to room temperature (25°C) to obtain an insulation material for a preformed cable accessory.

[0062] Examples Two to Four

[0063] An insulation material for a preformed cable accessory was prepared according to the preparation method of Example One, wherein the antioxidant was replaced by the antioxidants 2 to 4 synthesized in Synthetic Examples Two to Four, respectively, and the rest was the same as in Example One.

[0064] Comparative Example One

[0065] An insulation material for a preformed cable accessory was prepared according to the preparation method of Example One, wherein the antioxidant was not added, and the rest was the same as in Example One.

[0066] Comparative Example Two

[0067] An insulation material for a preformed cable accessory was prepared according to the preparation method of Example One, wherein the antioxidant was replaced by Comparative Compound 1, and the rest was the same as in Example One.

[0068] Comparative Compound 1: .

[0069] Comparative Example Three

[0070] An insulation material for a preformed cable accessory was prepared according to the preparation method of Example One, wherein the amount of plasticizer was changed to 10 parts by mass, and the rest was the same as in Example One.

[0071] Comparative Example Three

[0072] An insulation material for a preformed cable accessory was prepared according to the preparation method of Example One, wherein the amount of reinforcing filler was changed to 85 parts by mass, and the rest was the same as in Example One.

[0073] Performance Test:

[0074] 1. Tear resistance: The tear resistance of the insulation material for a preformed cable accessory prepared in the examples and comparative examples was tested according to GB / T 529 2008, and the data are shown in Table 2.

[0075] 2. Aging performance test: The aging performance of the insulation material prepared in the examples and the comparative examples for a preformed cable accessory was tested according to GB / T 528 2009 (135℃ hot air accelerated aging for 168 hours, test the change rate of elongation at break), the data is shown in Table 2.

[0076] 3. Hardness test: The hardness of the insulation material prepared in the examples and the comparative examples for a preformed cable accessory was tested according to GB / T531.1-2008, the data is shown in Table 2.

[0077] Table 2 Performance test data of the insulation material prepared in the examples and the comparative examples for a preformed cable accessory

[0078]

[0079] The examples using the anti-aging agent of the present application show a significantly improved overall performance trend compared to the comparative examples: the tear resistance is significantly improved, indicating that the material has better mechanical resistance; the change rate of elongation at break is smaller, reflecting that the material can better maintain elasticity after aging, and has better aging resistance; the hardness is also higher, reflecting a more stable material rigidity. In contrast, the comparative examples show a downward trend in tear resistance, performance retention after aging, and hardness due to the absence or adjustment of the anti-aging agent, and have poor overall performance.

[0080] Application example

[0081] A method for preparing a preformed cable accessory (such as shown in Figure 2 ), including the forming of a stress cone, an insulation body, and a sealing structure, the specific steps are as follows:

[0082] 1. Selection of insulation material: the insulation material prepared in Example 1 for a preformed cable accessory is used;

[0083] 2. Stress cone forming: the insulation material is placed in a special stress cone mold and vulcanized and formed in a flat vulcanizing machine, the vulcanization conditions are: temperature 175℃, pressure 12.5MPa, time 17.5 minutes; immediately after vulcanization, it is transferred to a 150℃ oven for heat treatment for 3 hours to eliminate internal stress; air cooling (air speed 2m / s) to room temperature to obtain a stress cone part; the Shore A hardness of the obtained stress cone is 65;

[0084] 3. Insulation body forming: the same insulation material and vulcanization process (step same as 2) are used to form in an insulation body mold, and the insulation body part is obtained after cooling;

[0085] 4. Sealing structure assembly: the vulcanized stress cone and the insulation body are assembled through interference fit, and silicone sealant is applied at the joint to form a complete sealing structure.

[0086] 5. Performance verification: take the insulation material sample, test the elongation retention rate after 135℃, 168h air oven aging according to GB / T 528-2009, the elongation retention rate is 94.8%; the prefabricated cable accessory is suitable for 10-35kV cross-linked polyethylene cable terminal.

[0087] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely divergences and modifications and not limitations of the scope of the application, which is defined by the appended claims and their equivalents.

Claims

1. An insulation material for preformed cable accessories, characterized in that, It is composed of the following raw materials in parts by mass: ternary ethylene-propylene rubber 100 parts, reinforcing filler 40-70 parts, plasticizer 20-40 parts, crosslinking agent 1.5-3.5 parts, auxiliary crosslinking agent 1-3 parts, antioxidant 1-3 parts, processing aid 1-5 parts; The antioxidant is a compound shown in the following structure: Formula 1; The R1 is selected from the group consisting of methyl, ethyl, tert-butyl, methoxy.

2. An insulation material for preformed cable accessories according to claim 1, characterized in that The reinforcing filler is carbon black; The plasticizer is paraffin oil; The crosslinking agent is dicumyl peroxide; The auxiliary crosslinking agent is triallyl isocyanurate; The processing aid is stearic acid.

3. An insulation material for preformed cable accessories according to claim 1, characterized in that The antioxidant is any one of the compounds shown in the following structure: ； 。 4. A process for the production of an insulation material for prefabricated cable accessories according to any one of claims 1 to 3, characterized in that It comprises the following steps: S1. The ternary ethylene-propylene rubber, reinforcing filler and plasticizer are added into an internal mixer and mixed at 70-90℃ for 5-8 minutes to obtain material A; S2. The antioxidant, processing aid and auxiliary crosslinking agent are added into the material A and mixed on an open mill at 40-60℃ for 10 minutes to obtain material B; S3. The material B is cooled to 30-40℃, the crosslinking agent is added, and after uniform mixing, the material is extruded into a sheet to obtain a mixed rubber; S4. The mixed rubber is placed in a mold and vulcanized at 170-180℃ under a pressure of 10-15 MPa for 15-20 minutes, and then cooled to obtain an insulation material for a preformed cable accessory.

5. A method of manufacturing an insulation material for preformed cable accessories according to claim 4, characterized in that, After vulcanization in S4, the material is heat treated in an oven at 150℃ for 2-4 hours; The vulcanizing agent is sulfur.

6. A method of manufacturing an insulation material for preformed cable accessories according to claim 4, characterized in that, In S1, the rotor speed of the internal mixer is 30-50 rpm, and the filling coefficient is 70%-80%.

7. A method of manufacturing an insulation material for preformed cable accessories according to claim 4, characterized in that, In S4, air cooling is used for cooling.

8. A preformed cable accessory comprising a stress cone, an insulating body and a sealing structure, characterized in that, The stress cone and / or the insulation body are made of the insulation material for a preformed cable accessory according to any one of claims 1-3.

9. A preformed cable accessory as claimed in claim 8, characterised in that, The elongation retention rate of the insulation material after air oven aging at 135℃ for 168 hours is ≥85%; The Shore A hardness of the stress cone is ≤68.

10. Use of the preformed cable accessory according to any one of claims 8-9 in the terminal and / or intermediate connection part of a 10-35 kV crosslinked polyethylene cable.

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