Process for the preparation of diene-containing bisphenol a diglycidyl ether and dcp dual crosslinking cable material

Abstract

This invention discloses a method for preparing double-crosslinked cable materials containing diallyl bisphenol A diglycidyl ether and DCP, belonging to the field of high-voltage DC cable technology. The method for preparing EAA and LDPE cable materials containing diallyl bisphenol A diglycidyl ether and DCP as double crosslinking agents involves using ethylene-acrylic acid copolymer (EAA) and low-density polyethylene (LDPE) as the matrix, employing a small molecule epoxy compound and DCP as crosslinking agents, and heating and pressurizing on a flat vulcanizing machine to obtain double-crosslinked high-voltage DC cable materials. The preparation method of the double-crosslinked high-voltage DC cable materials prepared by this invention is simple and significantly improves the thermal elongation and breakdown performance of high-voltage cable materials.

Description

Technical Field

[0001] This invention belongs to the field of high voltage DC cable technology, and relates to a method for preparing cable materials containing diallyl bisphenol A diglycidyl ether and DCP double crosslinking. Background Technology

[0002] Currently, domestic and international technological approaches are gradually shifting from the traditional reliance on DCP crosslinking to achieving performance breakthroughs through intrinsic material design and molecular structure regulation. Due to the poor mechanical properties of low-density polyethylene (LDPE), the traditional method to enhance its mechanical properties is to add the crosslinking agent DCP to induce a crosslinking reaction, forming crosslinked polyethylene (XLPE). However, the addition of DCP and other additives such as voltage stabilizers and co-crosslinking agents can cause defects within the material, leading to a decline in cable performance. To ensure the purity of the cable material, it is necessary to introduce newly designed crosslinking agent molecules while maintaining excellent polyethylene performance, thereby reducing the use of other additives.

[0003] This invention uses LDPE and EAA as matrix resins and DCP and 2,2'-diallylbisphenol A diglycidyl ether as dual crosslinking agents. This allows LDPE and EAA to undergo both free radical crosslinking and nucleophilic addition crosslinking simultaneously. While the dual crosslinking system is formed, voltage-stabilizing fragments and electron deep traps are introduced in situ, avoiding the need for the addition of other small molecule additives. At the same time, the diallylbisphenol A diglycidyl ether introduced in this invention, due to the presence of two terminal double bonds, can act as a co-crosslinking agent, reducing the amount of DCP used in the entire composite material and significantly improving the mechanical and electrical properties of the cable composite material. Summary of the Invention

[0004] To overcome the problems mentioned in the background, the present invention provides the following technical solution: Firstly, this invention provides a method for preparing a double-crosslinked cable material containing diallyl bisphenol A diglycidyl ether and DCP, the specific steps of which are as follows: S1: Dicumyl peroxide (DCP), ethylene-acrylic acid copolymer (EAA), low-density polyethylene (LDPE) and diallyl bisphenol A diglycidyl ether were melt-blended in a torque rheometer to obtain a mixed material. S2: The mixed material is placed in a flat vulcanizing machine for pressing and molding, and then subjected to heating and cross-linking, followed by vacuum drying and cooling; S3: After vacuum drying and cooling, a high-voltage DC cable material with significantly improved breakdown strength and tensile strength is obtained.

[0005] Preferably, the dual crosslinking system is composed of dicumyl peroxide (DCP) and diallyl bisphenol A diglycidyl ether as crosslinking agents.

[0006] Preferably, EAA accounts for 3%-9% of the total mass of the composite material.

[0007] Preferably, LDPE accounts for 87%-95% of the total mass of the composite material.

[0008] Preferably, the DCP content is 0.7% of the total mass of the composite material.

[0009] Preferably, 2,2'-diallyl bisphenol A diglycidyl ether accounts for 0.7%-2.1% of the total mass of the composite material.

[0010] Preferably, in step S1, LDPE is added to a torque rheometer, melted at 115°C, and mixed at a speed of 60 r / min for 5 min. Then, EAA and epoxy compound 2,2'-diallylbisphenol A diglycidyl ether (P) are added and mixed for another 10 min. Finally, DCP is added and mixed for 3 min to obtain the blended composite material. In step S2, the pressing temperature is 115℃ and the pressure is 15MPa; the heating crosslinking temperature is 175℃ and the pressure is 15MPa; the vacuum drying temperature is 80℃ and the time is 24h. In step S2, the temperature is cooled to below 25°C.

[0011] On the other hand, the present invention provides a cable material containing diallyl bisphenol A diglycidyl ether and DCP double crosslinked EAA and LDPE, which can achieve a DC breakdown strength of 469.4 KV / mm and a thermal elongation of only 23%.

[0012] Finally, this invention provides an application of cable materials containing diallyl bisphenol A diglycidyl ether and DCP double crosslinked EAA and LDPE, mainly used in high voltage DC cable materials.

[0013] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention designs a bisphenol A type epoxy compound that can crosslink with polymers containing carboxyl groups at the same time, and can also crosslink with LDPE and fuse with each other to form a double crosslinking system, which significantly improves the mechanical properties of the material.

[0014] (2) The present invention introduces the benzene ring structure that can effectively “capture” electrons into the cable material in a cross-linking manner, and introduces electron deep traps in situ at the same time as cross-linking, which significantly enhances the DC breakdown performance of the high voltage DC cable material.

[0015] (3) The LEPD composite insulation material prepared by this invention has a simple preparation process, low cost, and readily available materials, and has the prospect of industrial production. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope.

[0017] Figure 1 Infrared spectral test images of LEPD high-voltage DC cable materials provided in different embodiments; Figure 2 Thermal elongation diagrams of LEPD high-voltage DC cable materials provided in different embodiments; Figure 3 Weibull distribution diagram of DC breakdown field strength of LEPD high voltage DC cable material provided in different embodiments (I); Figure 4 Weibull distribution diagram of DC breakdown field strength of LEPD high voltage DC cable material provided in different embodiments (II). Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0020] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on this embodiment, the positional relationship of each component in the preparation method of a double cross-linked cable material containing diallyl bisphenol A diglycidyl ether and DCP is described in detail.

[0022] The process for preparing the DCP / P / LDPE / EAA modified composite material in this example is as follows: Example 1:

[0023] (1) Melt blending: 38.24g LDPE was added to a torque rheometer and melted at 115℃ with a rotation speed of 60r / min. After blending for 5min, 1.2g EAA and 0.28g epoxy compound 2,2'-diallyl bisphenol A diglycidyl ether were added and blended for another 10min. Finally, 0.28g DCP was added and blended for 3min to obtain a blended composite material with an EAA content of 3%.

[0024] (2) Processing and molding: The blended composite material was pressed in a flat vulcanizing machine at a temperature of 115℃ and a pressure of 15MPa, and then pressed for 30 minutes at a temperature of 175℃ and a pressure of 15MPa to complete the crosslinking, thus obtaining LE3PD. 0.7 High-voltage DC cable materials. Example 2:

[0025] (1) Melt blending: 37.25g LDPE was added to a torque rheometer and melted at 115℃ with a rotation speed of 60r / min. After blending for 5min, 2g EAA and 0.47g epoxy compound 2,2'-diallyl bisphenol A diglycidyl ether were added and blended for another 10min. Finally, 0.28g DCP was added and blended for 3min to obtain a blended composite material with an EAA content of 5%.

[0026] (2) Processing and molding: The blended composite material was pressed in a flat vulcanizing machine at a temperature of 115℃ and a pressure of 15MPa, and then pressed for 30 minutes at a temperature of 175℃ and a pressure of 15MPa to complete the crosslinking, thus obtaining LE5PD. 0.7 High-voltage DC cable materials. Example 3

[0027] (1) Melt blending: 36.27g LDPE was added to a torque rheometer and melted at 115℃ with a rotation speed of 60r / min. After blending for 5min, 3.6g EAA and 0.65g epoxy compound 2,2'-diallyl bisphenol A diglycidyl ether were added and blended for another 10min. Finally, 0.28g DCP was added and blended for 3min to obtain a blended composite material with an EAA content of 7%.

[0028] (2) Processing and molding: The blended composite material was pressed in a flat vulcanizing machine at a temperature of 115℃ and a pressure of 15MPa, and then pressed for 30 minutes at a temperature of 175℃ and a pressure of 15MPa to complete the crosslinking, thus obtaining LE7PD. 0.7 High-voltage DC cable materials. Example 4:

[0029] (1) Melt blending: 35.12g LDPE was added to a torque rheometer and melted at 115℃ with a rotation speed of 60r / min. After blending for 5min, 3.6g EAA and 0.84g epoxy compound 2,2'-diallylbisphenol A diglycidyl ether were added and blended for 10min. Finally, 0.28g DCP was added and blended for 3min to obtain a blended composite material with an EAA content of 9%.

[0030] (2) Processing and molding: The blended composite material was pressed in a flat vulcanizing machine at a temperature of 115℃ and a pressure of 15MPa, and then pressed for 30 minutes at a temperature of 175℃ and a pressure of 15MPa to complete the crosslinking, thus obtaining LE9PD. 0.7 High-voltage DC cable materials. Example 5:

[0031] (1) Melt blending: 38g of LDPE was added to a torque rheometer and melted at 115℃ with a rotation speed of 60r / min. After blending for 5min, 2g of EAA was added and blending was continued for 10min to obtain a blended composite material. The content of EAA was 5%.

[0032] (2) Processing and molding: The blended composite material is pressed in a flat vulcanizing machine at a temperature of 115℃ and a pressure of 15MPa, and then pressed for 30 minutes at a temperature of 110℃ and a pressure of 15MPa to complete the crosslinking, thus obtaining LE5 high voltage DC cable material. Example 6:

[0033] (1) Melt blending: 37.44g of LDPE was added to a torque rheometer and melted at 115℃ with a rotation speed of 60r / min. After blending for 5min, 2g of EAA and 0.56g of epoxy compound 2,2'-diallylbisphenol A diglycidyl ether were added and blended for another 10min to obtain a blended composite material. The content of EAA was 5%.

[0034] (2) Processing and molding: The blended composite material is pressed in a flat vulcanizing machine at a temperature of 115℃ and a pressure of 15MPa, and then pressed for 30 minutes at a temperature of 110℃ and a pressure of 15MPa to complete the crosslinking, thus obtaining LE5P high voltage DC cable material. Example 7:

[0035] (1) Melt blending: 37.72g LDPE was added to a torque rheometer and melted at 115℃ with a rotation speed of 60r / min. After 5min of blending, 2g EAA was added and blended for another 10min. Finally, 0.28g DCP was added and blended for 3min to obtain a blended composite material with an EAA content of 5%.

[0036] (2) Processing and molding: The blended composite material was pressed in a flat vulcanizing machine at a temperature of 115℃ and a pressure of 15MPa, and then pressed for 30 minutes at a temperature of 175℃ and a pressure of 15MPa to complete the crosslinking, thus obtaining LE5D. 0.7 High-voltage DC cable materials.

[0037] The performance of high-voltage DC cable materials with different contents of diallyl small molecule epoxy compounds and DCP double crosslinked XLPE prepared in Examples 1-4 above was tested, and the specific test results are as follows: (1) The molecular structure of the above materials was tested, analyzed, and characterized using a Fourier transform infrared spectroscopy (FT / IR 6100) to verify whether they successfully participated in the cross-linking reaction. The selected samples were all 100 μm thick sheets, and the test spectral wavenumber range was 640-4000 cm⁻¹. -1 The scanning accuracy is 2cm. -1 The scan was performed 30 times, and the results are as follows: Figure 1 As shown.

[0038] Depend on Figure 1 It can be seen that, compared with the uncrosslinked P / DCP / EAA / LDPE blend material, the modified high-voltage DC cable material has a crosslinking performance of 1702 cm⁻¹. -1 The absorption peak of the nearby carbonyl group broadens significantly (the carbonyl group of -COOH in EAA coincides with the newly formed ester carbonyl group), indicating that EAA has completed cross-linking with the epoxy ring in the small molecule epoxy compound. The uncross-linked peak is at 1604 cm⁻¹. -1 The C=C stretching vibration peak that appeared was at 908 cm⁻¹ -1 The disappearance of the out-of-plane rocking vibration peak of the carbon-hydrogen bond in the carbon-carbon double bond indicates that the dielyl group in LDPE and epoxy molecules has been successfully crosslinked.

[0039] (2) Prepare dumbbell specimens and measure cross-sectional area according to the test method specified in GB / T 2951.11-2008. Cut the modified high-voltage DC cable material specimens into dumbbell-shaped specimens with a thickness of 1 mm using a cutter. The total length is 75 mm and the width of the effective test part is 4 ± 0.2 mm. The surface is smooth and free of defects visible to the naked eye. Mark the narrow section with 20 mm spacing markings using a marker. The test is conducted in a 200℃ natural ventilation oven. The specimen is suspended from the upper clamp and clamped with the lower clamp. A weight is added to the lower clamp. The counterweight = 20.4 × specimen thickness × specimen width (including clamps, support rods and weights). The specimen is kept at 200℃ in the oven. After 15 minutes, the distance between the markings is measured and the elongation is calculated.

[0040] According to GB / T12527-2008, the thermal elongation of XLPE insulated cables must not exceed 175%. Figure 2It can be seen that the cable materials prepared by the present invention all meet the standard requirements, and the thermal elongation rate decreases significantly with the increase of EAA. When the EAA content is 9%, the thermal elongation rate is only 38%.

[0041] (3) The DC breakdown field strength of the above materials was tested using cylindrical electrodes at 30°C with a voltage ramp rate of 1 kV / s and a sample thickness of 50 μm. The sample and electrodes were immersed in transformer oil throughout the test, and 10 sets of samples were selected for repeated experiments under each experimental condition.

[0042] The experimental data on DC breakdown strength were statistically analyzed using a two-parameter Weibull distribution, and the results are described below: P(E) = 1 - exp(-(E / E) b ) β ) In the formula: P(E) is the cumulative failure probability, E is the measured breakdown field strength, and E b β represents the characteristic breakdown field strength when the breakdown probability is 63.2%, and β is the shape parameter.

[0043] The Weibull distributions of the DC breakdown strength of the above four materials are as follows: Figure 3 As shown.

[0044] Depend on Figure 3 It can be seen that the DC breakdown strength of the four modified high-voltage DC cable materials is improved to varying degrees compared with that before modification. After modification with epoxy compounds, the characteristic breakdown field strength at each content is significantly improved. Compared with the unmodified material, the breakdown strength of the modified high-voltage DC cable material reaches a maximum of 469.4 kV / mm at a 5% EAA content, which is higher than that of pure LDPE, LE5, and LE5D. 0.7 The four blank components, LE5E, were increased by 56.8%, 42.7%, 14%, and 22.5%, respectively. High-voltage DC cable materials at this content exhibit good breakdown characteristics.

[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the present 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 method for preparing a double-crosslinked cable material containing diallyl bisphenol A diglycidyl ether and DCP, characterized in that, The specific steps are as follows: S1: Dicumyl peroxide (DCP), ethylene-acrylic acid copolymer (EAA), low-density polyethylene (LDPE) and diallyl bisphenol A diglycidyl ether were melt-blended in a torque rheometer to obtain a mixed material. S2: The mixed material is placed in a flat vulcanizing machine for pressing and molding, and then subjected to heating and cross-linking, followed by vacuum drying and cooling; S3: After vacuum drying and cooling, a high-voltage DC cable material with significantly improved breakdown strength and tensile strength is obtained.

2. The preparation method according to claim 1, characterized in that, The dual crosslinking system is composed of dicumyl peroxide (DCP) and diallyl bisphenol A diglycidyl ether as crosslinking agents.

3. The preparation method according to claim 1, characterized in that, EAA accounts for 3%-9% of the total mass of the composite material.

4. The preparation method according to claim 1, characterized in that, LDPE accounts for 87%-95% of the total mass of the composite material.

5. The preparation method according to claim 1, characterized in that, The DCP content is 0.7% of the total mass of the composite material.

6. The preparation method according to claim 1, characterized in that, 2,2'-Dialylbisphenol A diglycidyl ether accounts for 0.7%-2.1% of the total mass of the composite material.

7. The preparation method according to claim 1, characterized in that, In step S1, LDPE is added to a torque rheometer and melted at 115°C at a speed of 60 r / min. After mixing for 5 min, EAA and epoxy compound 2,2'-diallylbisphenol A diglycidyl ether (P) are added and mixed for another 10 min. Finally, DCP is added and mixed for 3 min to obtain the blended composite material. In step S2, the pressing temperature is 115℃ and the pressure is 15MPa; the heating crosslinking temperature is 175℃ and the pressure is 15MPa; the vacuum drying temperature is 80℃ and the time is 24h. In step S2, the temperature is cooled to below 25°C.

8. A cable material containing diallyl bisphenol A diglycidyl ether and DCP double crosslinked EAA and LDPE, prepared according to any one of claims 1-7, characterized in that, The DC breakdown strength can reach 469.4KV / mm, and the thermal elongation is only 23%.

9. An application of the cable material containing diallyl bisphenol A diglycidyl ether and DCP double crosslinked EAA and LDPE according to claim 8, characterized in that, It is mainly used in high-voltage DC cable materials.

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