An insulated busbar and a manufacturing method thereof

Abstract

This invention belongs to the technical field of insulating materials, specifically relating to an insulating busbar and its preparation method. The preparation method of the insulating busbar of this invention includes the following steps: coating the surface of a busbar substrate with adhesive, and drying to obtain a busbar with an adhesive layer; mixing 40-60 parts of silicone resin, 20-40 parts of grafted silica, 10-20 parts of alumina, and 2-4 parts of 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane to obtain a binder; placing the busbar with the adhesive layer in a mold, then adding the binder, and pressing to obtain the insulating busbar; the preparation method of the grafted silica includes: stirring and reacting m-aminobenzoic acid and 3-aminopropyltriethoxysilane to obtain a grafting solution, adding silica to the grafting solution to carry out a grafting reaction, and obtaining grafted silica.

Description

Technical Field

[0001] This invention belongs to the field of insulating materials technology, specifically relating to an insulating busbar and its preparation method. Background Technology

[0002] Substations are crucial hubs in power transmission systems, and busbars, as the main power supply lines in power distribution equipment, play an irreplaceable role in substation operation. Power busbars are primarily used to connect the main switchgear in the power supply system to switches in various branch circuits. In power transmission systems, power busbars are used in high and low voltage switchgear, transformers, power panels, and other infrastructure, playing a vital role in the power supply system. Insulation protection of busbars is key to ensuring the safe and stable operation of the power system. Currently, the main method for insulation protection of power busbars is to wrap them with heat-shrinkable materials. Heat-shrinkable materials are widely used in the connection and termination treatment of wires and cables, insulation protection of electrical equipment and components, and protection of gas and liquid pipeline connections.

[0003] Chinese patent (publication number CN114121344B) discloses an insulating busbar, its preparation method, and its application. The insulating busbar of this invention comprises a first adhesive layer, a first adhesive layer, a busbar, a second adhesive layer, and a second adhesive layer, stacked sequentially. The insulating busbar features good appearance consistency, high insulation strength, excellent high-temperature resistance and fire resistance, high mechanical properties, and outstanding weather resistance, exhibiting excellent overall performance. Furthermore, its preparation process is simple. However, existing insulating busbars suffer from insufficient breakdown voltage and require improvement in tensile strength, severely impacting their further use.

[0004] Therefore, optimizing the composition of insulating busbars to effectively improve their breakdown voltage while obtaining good mechanical properties has become a key research direction. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an insulating busbar and its preparation method. The invention first coats the surface of the busbar substrate with an adhesive to form an adhesive layer. Then, epoxy-modified phenyl silicone resin and methyl vinyl MQ silicone resin are used as compound silicone resins, along with grafted silica, alumina, and 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane to prepare an adhesive compound. By pressing the adhesive compound onto the busbar with the adhesive layer, an insulating busbar is prepared, which can improve the breakdown voltage while achieving good mechanical properties.

[0006] A first aspect of the present invention provides a method for preparing an insulating busbar, comprising the following steps:

[0007] An adhesive is coated on the surface of the busbar substrate and dried to obtain a busbar with an adhesive layer. 40-60 parts by weight of silicone resin, 20-40 parts by weight of grafted silica, 10-20 parts by weight of alumina, and 2-4 parts by weight of 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane are mixed to obtain a rubber compound. The busbar with the adhesive layer is placed in a mold, and then the rubber compound is added and pressed to obtain an insulating busbar.

[0008] As a preferred embodiment of the present invention, the weight parts of the silicone resin may be 40 parts, 45 parts, 50 parts, 55 parts or 60 parts.

[0009] As a preferred embodiment of the present invention, the grafted silica may be in the following weight proportions: 20 parts, 25 parts, 30 parts, 35 parts, or 40 parts.

[0010] As a preferred embodiment of the present invention, the alumina may be in the following weight proportions: 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, or 20 parts.

[0011] As a preferred embodiment of the present invention, the weight parts of the 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane may be 2 parts, 2.5 parts, 3 parts, 3.5 parts, or 4 parts.

[0012] As a preferred embodiment of the present invention, the method for preparing grafted silica includes: stirring and reacting m-aminobenzoic acid and 3-aminopropyltriethoxysilane to obtain a grafting solution, adding silica to the grafting solution to carry out a grafting reaction, and obtaining grafted silica.

[0013] In this invention, a grafting solution is first prepared by liquid-phase reaction of the voltage stabilizer m-aminobenzoic acid and the silane coupling agent 3-aminopropyltriethoxysilane. Then, nano-silica is added to carry out a grafting reaction. By fixing the stabilizer on the surface of nano-silica, grafted silica capable of capturing high-energy electrons is prepared.

[0014] As a preferred embodiment of the present invention, the preparation steps of the grafting solution include: adding 12-16 parts of m-aminobenzoic acid to 200-240 parts of toluene and stirring evenly, then adding 18-22 parts of 3-aminopropyltriethoxysilane and stirring the reaction at 70-80°C for 2-4 hours to obtain the grafting solution.

[0015] As a preferred embodiment of the present invention, the grafting reaction steps include: adding 20-40 parts of silica to 200-240 parts of the grafting solution, then adding 20-30 parts of deionized water, stirring at 65-75°C for 24-28 hours, centrifuging, washing with water, and drying to obtain grafted silica.

[0016] As a preferred embodiment of the present invention, the particle size of the silicon dioxide is 10~50nm.

[0017] The present invention introduces the voltage stabilizer m-aminobenzoic acid into the surface of grafted silica. It has a conjugated π-bond structure, which is beneficial for dispersing the energy of electrons. At the same time, under the accelerating electric field, electrons continuously accumulate energy and move at high speed. m-aminobenzoic acid can capture the continuously accumulating collision electrons, avoiding the secondary electrons generated between collisions, and ultimately effectively enhancing the breakdown voltage of the material. At the same time, aminobenzoic acid can also act as a curing agent for epoxy groups in epoxy-modified phenyl silicone resin. Through the ring-opening reaction between amino and epoxy groups, a cross-linked network is formed, thereby improving the tensile strength of the material.

[0018] As a preferred embodiment of the present invention, the silicone resin is an epoxy-modified phenyl silicone resin and a methyl vinyl MQ silicone resin.

[0019] As a preferred embodiment of the present invention, the mass ratio of the epoxy-modified phenyl silicone resin to the methyl vinyl MQ silicone resin is (1~2):1.

[0020] This invention utilizes a compound of epoxy-modified phenyl silicone resin and methyl vinyl MQ silicone resin. The crosslinking network of the epoxy-modified phenyl silicone resin and the elastic structure of the methyl vinyl MQ silicone resin work synergistically to reduce internal porosity and defects in the material, thereby reducing the risk of partial discharge and increasing the breakdown voltage. In addition, the rigid crosslinking network of the epoxy-modified phenyl silicone resin provides tensile support, while the elastic structure of the methyl vinyl MQ silicone resin can absorb external mechanical impacts. Together, they disperse stress, delay crack propagation, and thus improve tensile strength.

[0021] As a preferred embodiment of the present invention, the alumina is modified alumina;

[0022] The method for preparing the modified alumina includes: surface modification of commercially available alumina using vinyltrimethoxysilane to obtain modified alumina.

[0023] As a preferred technical solution of the present invention, the surface modification step includes: dispersing 2-4 parts by weight of commercially available alumina in 400-500 parts by weight of anhydrous ethanol, then adding 4-6 parts by weight of vinyltrimethoxysilane, stirring at 60-70°C for 24-30 hours, centrifuging, washing with anhydrous ethanol, and vacuum drying to obtain modified alumina.

[0024] The modified alumina of this invention introduces carbon-carbon double bonds on its surface via vinyltrimethoxysilane. During high-temperature pressing, 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane decomposes and generates free radicals, which initiate the bonding of the carbon-carbon double bonds on the modified alumina surface with methyl vinyl MQ silicone resin. This effectively improves the dispersibility of alumina in the matrix, enhances interfacial interactions, and effectively improves mechanical properties. At the same time, alumina particles can fill micropores and defects in insulating materials, reduce local electric field concentration, thereby blocking electron migration paths and increasing breakdown voltage.

[0025] As a preferred embodiment of the present invention, the adhesive is Chemlock 608 adhesive.

[0026] As a preferred embodiment of the present invention, the conditions for the mixing process include: a rotation speed of 40~60 r / min and a time of 50~60 min.

[0027] As a preferred embodiment of the present invention, the pressing conditions include: a temperature of 150~170℃, a pressure of 20~24MPa, and a time of 10~20min.

[0028] A second aspect of the present invention provides an insulating busbar prepared by the method described in the first aspect.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The insulating busbar of the present invention is composed of a busbar substrate, an adhesive layer and an insulating adhesive. The adhesive is a compound silicone resin system of epoxy modified phenyl silicone resin and methyl vinyl MQ silicone resin. Grafted silica is bonded to form a first cross-linking network through m-aminobenzoic acid epoxy modified phenyl silicone resin. Methyl vinyl MQ silicone resin reacts with the double bonds on the surface of modified alumina under the action of 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane to form a second cross-linking network. The breakdown voltage is effectively improved and the tensile strength is increased through the dual network structure.

[0031] (2) The present invention uses epoxy-modified phenyl silicone resin and methyl vinyl MQ silicone resin to compound the epoxy-modified phenyl silicone resin. The cross-linking network of the epoxy-modified phenyl silicone resin and the elastic structure of the methyl vinyl MQ silicone resin work together to reduce the internal porosity and defects of the material, thereby reducing the risk of partial discharge and increasing the breakdown voltage. In addition, the rigid cross-linking network of the epoxy-modified phenyl silicone resin provides tensile support, while the elastic structure of the methyl vinyl MQ silicone resin can absorb external mechanical impact. The two together disperse stress and delay crack propagation, thereby improving tensile strength.

[0032] (3) The grafted silica surface of the present invention introduces the voltage stabilizer m-aminobenzoic acid, which has a conjugated π bond structure, which is beneficial to disperse the energy of electrons. At the same time, under the acceleration electric field, electrons continuously accumulate energy and move at high speed. m-aminobenzoic acid can capture the continuously accumulating collision electrons, avoiding the secondary electrons generated between collisions, and ultimately effectively enhancing the breakdown voltage of the material. At the same time, aminobenzoic acid can also be used as a curing agent for epoxy groups in epoxy modified phenyl silicone resin. Through the ring-opening reaction between amino and epoxy groups, a cross-linked network is formed, thereby improving the tensile strength of the material.

[0033] (4) The modified alumina of the present invention introduces carbon-carbon double bonds on the surface through vinyltrimethoxysilane. During the high-temperature pressing process, 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane decomposes and generates free radicals, which initiate the combination of carbon-carbon double bonds on the surface of modified alumina with methyl vinyl MQ silicone resin, effectively improving the dispersibility of alumina in the matrix, enhancing interfacial interaction, and effectively improving mechanical properties. At the same time, alumina particles can fill the micropores and defects in the insulating material, reduce the concentration of local electric field, thereby blocking the electron migration path and improving the breakdown voltage. Detailed Implementation

[0034] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0035] The sources of some components in the examples and comparative examples are as follows:

[0036] Epoxy-modified phenyl silicone resin, model DY-EB401, was purchased from Shandong Dayi Chemical Co., Ltd.

[0037] Methyl vinyl MQ silicone resin, model DY-VMQ101, was purchased from Shandong Dayi Chemical Co., Ltd.

[0038] Silica I, product number S433693, with a particle size of 15nm, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0039] Silica II, product number S433680, with a particle size of 1μm, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0040] m-Aminobenzoic acid, CAS No. 99-05-8, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0041] 3-Aminopropyltriethoxysilane, CAS No. 919-30-2, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0042] Alumina, product number A431930, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0043] Vinyltrimethoxysilane, CAS No. 2768-02-7, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0044] 2,5-Dimethyl-2,5-bis-(tert-butylperoxy)hexane, catalog number T110273, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0045] The adhesive, Chemlock 608 glue, was purchased from Yueyang Baoling Industry and Trade Co., Ltd.

[0046] Example 1

[0047] This embodiment provides a method for preparing an insulating busbar, including the following steps:

[0048] A busbar substrate is coated with Chemlock 608 adhesive and dried to obtain a busbar with an adhesive layer. 60 parts by weight of silicone resin (40 parts epoxy-modified phenyl silicone resin and 20 parts methyl vinyl MQ silicone resin), 40 parts grafted silica, 20 parts modified alumina, and 4 parts 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane are mixed (at a speed of 60 r / min for 50 min) to obtain a binder. The busbar with the adhesive layer is placed in a mold, and then the binder is added and pressed (at a temperature of 170℃, a pressure of 24 MPa, and a time of 10 min) to obtain an insulating busbar.

[0049] Preparation of the grafted silica: By weight, 16 parts of m-aminobenzoic acid were added to 240 parts of toluene and stirred evenly, then 22 parts of 3-aminopropyltriethoxysilane were added, and the mixture was stirred at 80°C for 2 hours to obtain a grafting solution; 40 parts of silica I (product number S433693, particle size 15nm) were added to 240 parts of the grafting solution, then 30 parts of deionized water were added, and the mixture was stirred at 75°C for 24 hours, centrifuged, washed with water, and dried to obtain grafted silica.

[0050] Preparation of modified alumina: By weight, 4 parts of commercially available alumina were dispersed in 500 parts of anhydrous ethanol, and then 6 parts of vinyltrimethoxysilane were added. The mixture was stirred at 70°C for 24 hours, centrifuged, washed with anhydrous ethanol, and vacuum dried to obtain modified alumina.

[0051] Example 2

[0052] This embodiment provides a method for preparing an insulating busbar, including the following steps:

[0053] A busbar substrate is coated with Chemlock 608 adhesive and dried to obtain a busbar with an adhesive layer. 40 parts by weight of silicone resin (20 parts epoxy-modified phenyl silicone resin and 20 parts methyl vinyl MQ silicone resin), 20 parts grafted silica, 10 parts modified alumina, and 2 parts 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane are mixed (40 r / min for 60 min) to obtain a binder. The busbar with the adhesive layer is placed in a mold, and then the binder is added and pressed (150℃, 20 MPa, for 20 min) to obtain an insulating busbar.

[0054] Preparation of the grafted silica: By weight, 12 parts of m-aminobenzoic acid were added to 200 parts of toluene and stirred evenly, then 18 parts of 3-aminopropyltriethoxysilane were added, and the mixture was stirred at 70°C for 4 hours to obtain a grafting solution; 20 parts of silica I (product number S433693, particle size 15nm) were added to 200 parts of the grafting solution, then 20 parts of deionized water were added, and the mixture was stirred at 65°C for 28 hours, centrifuged, washed with water, and dried to obtain grafted silica.

[0055] Preparation of modified alumina: By weight, 2 parts of commercially available alumina were dispersed in 400 parts of anhydrous ethanol, and then 4 parts of vinyltrimethoxysilane were added. The mixture was stirred at 60°C for 30 h, centrifuged, washed with anhydrous ethanol, and vacuum dried to obtain modified alumina.

[0056] Example 3

[0057] This embodiment provides a method for preparing an insulating busbar, including the following steps:

[0058] A busbar substrate is coated with Chemlock 608 adhesive and dried to obtain a busbar with an adhesive layer. 50 parts by weight of silicone resin (30 parts epoxy-modified phenyl silicone resin and 20 parts methyl vinyl MQ silicone resin), 30 parts grafted silica, 15 parts modified alumina, and 3 parts 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane are mixed (50 r / min for 55 min) to obtain a binder. The busbar with the adhesive layer is placed in a mold, and then the binder is added and pressed (160℃, 22 MPa, 15 min) to obtain an insulating busbar.

[0059] Preparation of the grafted silica: By weight, 14 parts of m-aminobenzoic acid were added to 220 parts of toluene and stirred until homogeneous. Then, 20 parts of 3-aminopropyltriethoxysilane were added and stirred at 75°C for 3 hours to obtain a grafting solution. 30 parts of silica I (product number S433693, particle size 15 nm) were added to the 220 parts of the grafting solution, followed by 25 parts of deionized water. The mixture was stirred at 70°C for 26 hours, centrifuged, washed with water, and dried to obtain grafted silica.

[0060] Preparation of modified alumina: 3 parts by weight of commercially available alumina were dispersed in 450 parts of anhydrous ethanol, and then 5 parts of vinyltrimethoxysilane were added. The mixture was stirred at 65°C for 28 h, centrifuged, washed with anhydrous ethanol, and vacuum dried to obtain modified alumina.

[0061] Comparative Example 1

[0062] The difference between this comparative example and Example 1 is that the amount of epoxy-modified phenyl silicone resin in the silicone resin is changed to 50 parts, and the amount of methyl vinyl MQ silicone resin is changed to 10 parts.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 1 is that the amount of epoxy-modified phenyl silicone resin in the silicone resin is changed to 20 parts, and the amount of methyl vinyl MQ silicone resin is changed to 40 parts.

[0065] Comparative Example 3

[0066] The difference between this comparative example and Example 1 is that silica I (item number S433693, particle size 15nm) was used instead of grafted silica.

[0067] Comparative Example 4

[0068] The difference between this comparative example and Example 1 is that silica II (product number S433680, particle size 1 μm) was used instead of silica I (product number S433693, particle size 15 nm) in the preparation of grafted silica.

[0069] Comparative Example 5

[0070] The difference between this comparative example and Example 1 is that commercially available alumina (product number A431930) was used instead of modified alumina.

[0071] The performance of the above embodiments and comparative examples was tested using the following methods:

[0072] (1) Density test: The test shall be conducted in accordance with the requirements of GB / T 533-2008 Determination of density of vulcanized rubber or thermoplastic rubber.

[0073] (2) Water absorption test: The test shall be conducted in accordance with the requirements of GB / T 1034-2008 Determination of water absorption of plastics.

[0074] (3) Breakdown voltage test: The test shall be conducted in accordance with the requirements of GB / T 1695-2005 Determination of power frequency breakdown voltage strength and withstand voltage of vulcanized rubber.

[0075] (4) Tensile strength test: The test shall be conducted in accordance with the requirements of GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber.

[0076] The performance test data above are shown in Table 1.

[0077] Table 1 Performance Test Results

[0078]

[0079] As can be seen from the above, the adhesive of the present invention adopts a compound silicone resin system of epoxy-modified phenyl silicone resin and methyl vinyl MQ silicone resin. In this system, grafted silica is bonded to epoxy-modified phenyl silicone resin through m-aminobenzoic acid to form a first crosslinking network. Methyl vinyl MQ silicone resin reacts with the double bonds on the surface of modified alumina under the action of 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane to form a second crosslinking network. The dual network structure effectively improves the breakdown voltage and increases the tensile strength.

[0080] Compared to Example 1, the amount of epoxy-modified phenyl silicone resin in the silicone resin was changed to 50 parts, and the amount of methyl vinyl MQ silicone resin was changed to 10 parts. The compounding effect of the silicone resin was poor, resulting in a lower breakdown voltage and lower tensile strength (Comparative Example 1). Compared to Example 1, the amount of epoxy-modified phenyl silicone resin in the silicone resin was changed to 20 parts, and the amount of methyl vinyl MQ silicone resin was changed to 40 parts. The compounding effect of the silicone resin was poor, resulting in a lower breakdown voltage and lower tensile strength (Comparative Example 2). Compared to Example 1, silica I (product number S433693, particle size 15nm) was used instead of grafted silica. The reduced effect of the surface voltage stabilizer m-aminobenzoic acid resulted in a lower breakdown voltage and lower tensile strength (Comparative Example 3). Compared to Example 1, the use of silica II (product number S433680, particle size 1 μm) instead of silica I (product number S433693, particle size 15 nm) for the preparation of grafted silica resulted in a lower breakdown voltage and lower tensile strength due to the excessively large particle size of silica II and poor modification effect (Comparative Example 4). Compared to Example 1, the use of commercially available alumina (product number A431930) instead of modified alumina resulted in a lower breakdown voltage and lower tensile strength (Comparative Example 5).

Claims

1. A method for preparing an insulating busbar, characterized in that, Includes the following steps: An adhesive is coated onto the surface of the busbar substrate, and after drying, a busbar with an adhesive layer is obtained. 40-60 parts by weight of silicone resin, 20-40 parts by weight of grafted silica, 10-20 parts by weight of modified alumina, and 2-4 parts by weight of 2,5-dimethyl-2,5-bis-(tert-butylperoxy)hexane are mixed to obtain a rubber compound. The busbar with the adhesive layer is placed in a mold, then the rubber compound is added, and the mixture is pressed to obtain an insulating busbar. The method for preparing grafted silica includes: stirring and reacting m-aminobenzoic acid and 3-aminopropyltriethoxysilane to obtain a grafting solution, adding silica to the grafting solution to carry out a grafting reaction, and obtaining grafted silica. The silicone resin is an epoxy-modified phenyl silicone resin and a methyl vinyl MQ silicone resin; the mass ratio of the epoxy-modified phenyl silicone resin and the methyl vinyl MQ silicone resin is (1~2):1; The method for preparing the modified alumina includes: surface modification of commercially available alumina using vinyltrimethoxysilane to obtain modified alumina.

2. The method for preparing an insulating busbar according to claim 1, characterized in that, The preparation steps of the grafting solution include: adding 12-16 parts by weight of m-aminobenzoic acid to 200-240 parts by weight of toluene and stirring evenly, then adding 18-22 parts by weight of 3-aminopropyltriethoxysilane and stirring the reaction at 70-80°C for 2-4 hours to obtain the grafting solution.

3. The method for preparing an insulating busbar according to claim 1, characterized in that, The grafting reaction steps include: adding 20-40 parts by weight of silica to 200-240 parts by weight of the grafting solution, then adding 20-30 parts by weight of deionized water, stirring at 65-75°C for 24-28 hours, centrifuging, washing with water, and drying to obtain grafted silica.

4. The method for preparing an insulating busbar according to claim 1, characterized in that, The particle size of the silica is 10~50nm.

5. The method for preparing an insulating busbar according to claim 1, characterized in that, The surface modification steps include: dispersing 2-4 parts by weight of commercially available alumina in 400-500 parts by weight of anhydrous ethanol, then adding 4-6 parts by weight of vinyltrimethoxysilane, stirring at 60-70°C for 24-30 hours, centrifuging, washing with anhydrous ethanol, and vacuum drying to obtain modified alumina.

6. The method for preparing an insulating busbar according to claim 1, characterized in that, The pressing conditions include: temperature of 150~170℃, pressure of 20~24MPa, and time of 10~20min.

7. An insulating busbar, characterized in that, Prepared by the method according to any one of claims 1 to 6.

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