An injection molding process for high-voltage capacitor housing

Abstract

The present invention relates to the technical field of composite materials, and in particular to an injection molding process for a high-voltage capacitor housing. The present invention uses epoxy resin as the material for the high-voltage capacitor housing, which can fully avoid the problem of aluminum element conductivity faced by aluminum housings, thereby avoiding the addition of insulating filling oil and thus eliminating the problem of leakage. In addition, siloxane is introduced into the epoxy resin housing prepared by the present invention, which can fully enhance the toughness of the epoxy resin and avoid the problem of excessive brittleness and easy cracking of the epoxy resin. In addition, boron is introduced into the epoxy resin to cooperate with the siloxane to further improve the flame retardant performance of the epoxy resin housing prepared by the present invention.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, in particular to an injection molding process for a high-voltage capacitor housing. Background Art

[0002] With the development of electronic technology, various electronic appliances have gradually become popular in thousands of households, which has brought about the development and prosperity of capacitor components. However, existing high-voltage capacitor components often use aluminum shells as the shell material. Aluminum shells, as metal raw materials, have advantages such as good ductility and easy processing. However, aluminum often requires a lot of energy to prepare during the process and brings about serious environmental pollution, which often leads to high aluminum prices. Moreover, when aluminum metal is used as a conductive material to prepare high-voltage capacitors, insulating oil often needs to be injected between it and the capacitor core to prevent damage. However, during use, due to temperature changes and processing problems, the high voltage electricity of the aluminum shell is prone to leakage, causing safety hazards. Therefore, it is necessary to invent a capacitor shell that can solve the above-mentioned drawbacks to meet market demand. Summary of the Invention

[0003] The object of the present invention is to provide an injection molding process for a high-voltage capacitor housing to solve the problems raised in the above background technology.

[0004] In order to solve the above technical problems, the present invention provides the following technical solution: a high-voltage capacitor housing having the following characteristics: the high-voltage capacitor housing comprises the following components, measured by weight: 30-40 parts of bisphenol A epoxy resin, 25-35 parts of branched flame-retardant epoxy resin, 27-35.5 parts of curing agent, 10-15 parts of flame-retardant inorganic filler, 20-30 parts of glass fiber, and 0.1-0.5 parts of antioxidant.

[0005] Furthermore, the curing agent is any one or more of maleic anhydride, phthalic anhydride, and hexahydrophthalic anhydride.

[0006] Furthermore, the flame retardant inorganic filler is antimony trioxide; and the antioxidant is propyl gallate.

[0007] An injection molding process for a high-voltage capacitor housing comprises the following steps:

[0008] S1. Preparation of branched flame-retardant epoxy resin;

[0009] S11. Dissolve 3,4,5-trihydroxybenzoic acid and butyl glycidyl ether in DMF under a nitrogen atmosphere, add tetrabutylammonium bromide, heat to 85-95°C, reflux for 6-12 hours, extract with deionized water, separate the organic phase, dry over anhydrous sodium sulfate overnight, filter, and vacuum dry to constant weight to obtain a hydroxyl-terminated prepolymer;

[0010] S12. The hydroxyl-terminated prepolymer prepared in step S11 is dissolved in DMF, treated in an ice-water bath, and tetrabutylammonium bromide is added. After mixing, the mixture is slowly added dropwise to dichlorodiphenylsilane over a period of 2.5-4 hours. After the addition is complete, the mixture is heated to 50-60° C. and the reaction is continued for 4-8 hours. The mixture is then washed with deionized water until neutral and vacuum dried to a constant weight to obtain a silicon-containing prepolymer.

[0011] S13. Under nitrogen atmosphere, phenylboric acid was dissolved in dichloroethane and treated in an ice-water bath to obtain a phenylboric acid solution; the silicon-containing prepolymer obtained in step S12 was dissolved in dichloroethane and slowly added dropwise to the phenylboric acid solution. After the addition was completed, the temperature was raised to 40-45°C, and the reaction was continued for 4-8 hours. The temperature was then raised to 70-80°C and the reaction was continued for 4-8 hours. After the reaction was completed, the prepolymer was washed with deionized water until neutral and vacuum dried to constant weight to obtain a boron-containing silicon prepolymer;

[0012] S14. Under nitrogen atmosphere, the boron silicon prepolymer prepared in step S13 was dissolved in DMF, trimethylolpropane triglycidyl ether and tetrabutylammonium bromide were added, the temperature was raised to 85-95°C, the reaction was continued for 4-8 hours, and the precipitate was washed 3-5 times with hot deionized water and diethyl ether. The precipitate was collected and vacuum dried to constant weight to obtain a branched flame-retardant epoxy resin;

[0013] S2. The flame retardant inorganic filler, glass fiber, antioxidant is added to the branched flame retardant epoxy resin, stirred and dispersed for 30-45min, bisphenol A epoxy resin is added, mixing is continued for 30-45min, a curing agent is added, and mixed for 10-15min to obtain a mixture;

[0014] S3. Inject the mixture into a mold, heat it to 100-110°C, keep it warm for 2-4 hours, and then remove it from the mold to obtain a high-voltage capacitor housing.

[0015] Furthermore, in step S11, the molar ratio of 3,4,5-trihydroxybenzoic acid, butyl glycidyl ether and tetrabutylammonium bromide is 1:(0.8-1.1):(0.03-0.05) by mole.

[0016] Furthermore, in step S12, the molar ratio of the hydroxyl-terminated prepolymer, tetrabutylammonium bromide and dichlorodiphenylsilane is 1::(0.03-0.05):(3.5-4.5) in terms of molar parts.

[0017] Furthermore, in step S13, the molar ratio of the phenylboric acid to the silicon-containing prepolymer is (3.5-4.2):1 in terms of molar parts.

[0018] Furthermore, in step S14, the molar ratio of the boron-containing silicon prepolymer, trimethylolpropane triglycidyl ether, and tetrabutylammonium bromide is 1:(3.5-4.5):(0.05-0.08) in terms of molar ratio.

[0019] In order to avoid the defects of aluminum shell capacitors, the present invention uses epoxy resin as the shell of high-voltage capacitors. However, simple epoxy resin is not sufficient to meet the requirements of capacitor shells. Therefore, the present invention first prepares a branched flame-retardant epoxy resin with a branched structure and flame retardant function;

[0020] The present invention first uses 3,4,5-trihydroxybenzoic acid as a core molecule and mixes it with butyl glycidyl ether for reaction. Carboxylic acid groups react with epoxy groups to further graft hydroxyl groups onto the 3,4,5-trihydroxybenzoic acid. The 3,4,5-trihydroxybenzoic acid is then mixed with dichlorodiphenylsilane to react the chlorine atoms on the dichlorodiphenylsilane with the hydroxyl groups, thereby grafting the dichlorodiphenylsilane onto the 3,4,5-trihydroxybenzoic acid. In this process, the present invention strictly limits the reaction temperature and the dropwise addition sequence, suppresses the activity of the reaction system in an ice-water bath environment, and dropwise adds a hydroxyl-terminated prepolymer to the dichlorodiphenylsilane, so that the hydroxyl-terminated prepolymer preferentially reacts with the active chlorine atoms in the dichlorodiphenylsilane, thereby ensuring that the dichlorodiphenylsilane is introduced into the 3,4,5-trihydroxybenzoic acid while retaining sufficient reactive groups to participate in subsequent reactions.

[0021] On this basis, the present application further adds phenylboric acid and restricts the dropwise addition order and reaction temperature, thereby introducing the boron element into the reaction system, and then uses trimethylolpropane triglycidyl ether to react with it to prepare a branched flame-retardant epoxy resin with terminal epoxy groups;

[0022] The branched flame-retardant epoxy resin prepared by the present invention has a spherical structure, low viscosity, and high fluidity, and can increase the dispersibility of inorganic flame-retardant particles and glass fibers and other materials in the epoxy resin system. In the preparation process of the present invention, boron and siloxane are also introduced into the branched flame-retardant epoxy resin. The boron element will generate substances such as boric acid or boron oxide during the combustion process, and will combine with unstable carbon atoms generated by the thermal decomposition of the epoxy resin matrix under high temperature conditions, thereby inhibiting its high-temperature volatilization, inhibiting the generation of combustible gases, increasing the residual carbon content, and further protecting the internal matrix of the epoxy resin and preventing the spread of the combustion reaction; siloxane can be distributed in the epoxy resin cross-linked network as a flexible chain segment, improving the problem of large brittleness of the epoxy resin after curing, and during combustion, the silicon element can assist in generating a silicon-carbon shell layer, further increasing the flame retardant properties of the carbon shell layer, thereby improving the flame retardant ability of the epoxy resin.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention uses epoxy resin as the high-voltage capacitor shell material, which can fully avoid the problem of aluminum element conductivity faced by aluminum shells, thereby avoiding the addition of insulating filling oil, thereby eliminating the intrusion of leakage problems, and the epoxy resin shell prepared by the present invention introduces siloxane therein, which can fully enhance the toughness of the epoxy resin and avoid the problems of excessive brittleness and easy cracking of the epoxy resin; and the present invention also introduces boron element into the epoxy resin, which cooperates with siloxane to further improve the flame retardant properties of the epoxy resin shell prepared by the present invention. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0025] The bisphenol A epoxy resin used in the examples of the present invention and the comparative examples is NPEL-128 epoxy resin sold by Kunshan Nanya Electronic Materials; 3,4,5-trihydroxybenzoic acid was purchased from Hubei Honghan Biotechnology Co., Ltd.; butyl glycidyl ether is B152235 butyl glycidyl ether sold by Shanghai Aladdin Biochemical Technology Co., Ltd.; dichlorodiphenylsilane was purchased from Shandong Changyao New Materials Co., Ltd.; phenylboric acid was purchased from Shandong Liang New Materials Technology Co., Ltd.; trimethylolpropane triglycidyl ether was purchased from Wuhan Belleye Biomedical Technology Co., Ltd.; antimony trioxide was purchased from Baiyundu (Shanghai) Biotechnology Co., Ltd.; glass fiber is ZC-6038 glass fiber sold by Henan Gaoze Refractory Co., Ltd.; propyl gallate was purchased from Jiangsu Jiujia Biotechnology Co., Ltd.

[0026] Example 1.

[0027] An injection molding process for a high-voltage capacitor housing comprises the following steps:

[0028] S1. Preparation of branched flame-retardant epoxy resin;

[0029] S11. Based on molar ratios, 1 part of 3,4,5-trihydroxybenzoic acid and 0.8 parts of butyl glycidyl ether were dissolved in DMF under nitrogen atmosphere. 0.03 parts of tetrabutylammonium bromide was added, the temperature was raised to 85°C, and the reaction was refluxed for 6 hours. The mixture was then extracted with deionized water, the organic phase was separated, dried over anhydrous sodium sulfate overnight, filtered, and dried under vacuum at 60°C to constant weight to obtain a hydroxyl-terminated prepolymer. Phthalic anhydride was purchased from Guangzhou Xilong Fine Chemical Technology Co., Ltd.

[0030] S12. Dissolve 1 part of the hydroxyl-terminated prepolymer prepared in step S11 in DMF, protect with a nitrogen atmosphere, and treat in an ice-water bath until the temperature is constant. Then, add 0.03 parts of tetrabutylammonium bromide, mix well, and slowly add dropwise to 3.5 parts of dichlorodiphenylsilane over a period of 2.5 hours. After the addition is complete, raise the temperature to 50°C, continue the reaction for 4 hours, wash with deionized water until neutral, and dry in a vacuum at 60°C to constant weight to obtain a silicon-containing prepolymer.

[0031] S13. Under nitrogen atmosphere, 3.5 parts of phenylboric acid were dissolved in 10 parts of dichloroethane, and the mixture was treated in an ice-water bath to a constant temperature to obtain a phenylboric acid solution; 1 part of the silicon-containing prepolymer obtained in step S12 was dissolved in 5 parts of dichloroethane and slowly added dropwise to the phenylboric acid solution for 2 hours. After the addition was completed, the temperature was raised to 40°C, and the reaction was continued for 4 hours. The temperature was then raised to 70°C again and the reaction was continued for 4 hours. After the reaction was completed, the mixture was washed with deionized water until neutral, and dried in a vacuum at 60°C to constant weight to obtain a boron-containing silicon prepolymer;

[0032] S14. Under nitrogen atmosphere, 1 part of the boron-containing silicon prepolymer prepared in step S13 was dissolved in 10 parts of DMF, 3.5 parts of trimethylolpropane triglycidyl ether and 0.05 parts of tetrabutylammonium bromide were added, and the temperature was raised to 85°C. After reacting for 4 hours, the precipitate was washed three times with hot deionized water and diethyl ether, and the precipitate was collected and dried in vacuo at 80°C to constant weight to obtain a branched flame-retardant epoxy resin;

[0033] S2. In parts by weight, 10 parts of antimony trioxide, 20 parts of glass fiber, 0.1 parts of propyl gallate were added to 25 parts of branched flame-retardant epoxy resin, stirred and dispersed for 30 min, 30 parts of bisphenol A epoxy resin were added, and mixing was continued for 30 min, 27 parts of phthalic anhydride curing agent were added, and mixed for 15 min to obtain a mixture;

[0034] S3. Inject the mixture into a mold, heat it to 100°C, keep it warm for 2 hours, and then remove it from the mold to obtain a high-voltage capacitor housing.

[0035] Example 2.

[0036] Compared with Example 1, this embodiment increases the amount of dichlorodiphenylsilane added in step S12;

[0037] An injection molding process for a high-voltage capacitor housing comprises the following steps:

[0038] S1. Preparation of branched flame-retardant epoxy resin;

[0039] S11. Dissolve 1 part of 3,4,5-trihydroxybenzoic acid and 0.8 parts of butyl glycidyl ether in DMF by molar ratio under nitrogen atmosphere, add 0.03 parts of tetrabutylammonium bromide, heat to 85°C, reflux for 6 hours, extract with deionized water, separate the organic phase, dry it over anhydrous sodium sulfate overnight, filter, and dry it in vacuo at 60°C to constant weight to obtain a hydroxyl-terminated prepolymer;

[0040] S12. Dissolve 1 part of the hydroxyl-terminated prepolymer prepared in step S11 in DMF under nitrogen atmosphere and treat in an ice-water bath until the temperature is constant. Then, add 0.03 parts of tetrabutylammonium bromide, mix well, and slowly add dropwise to 4.5 parts of dichlorodiphenylsilane over a period of 2.5 hours. After the addition is complete, raise the temperature to 50°C and continue the reaction for 4 hours. Wash with deionized water until neutral, and dry in a vacuum at 60°C to constant weight to obtain a silicon-containing prepolymer.

[0041] S13. Under nitrogen atmosphere, 3.5 parts of phenylboric acid were dissolved in 10 parts of dichloroethane, and the mixture was treated in an ice-water bath to a constant temperature to obtain a phenylboric acid solution; 1 part of the silicon-containing prepolymer obtained in step S12 was dissolved in 5 parts of dichloroethane and slowly added dropwise to the phenylboric acid solution for 2 hours. After the addition was completed, the temperature was raised to 40°C, and the reaction was continued for 4 hours. The temperature was then raised to 70°C again and the reaction was continued for 4 hours. After the reaction was completed, the mixture was washed with deionized water until neutral, and dried in a vacuum at 60°C to constant weight to obtain a boron-containing silicon prepolymer;

[0042] S14. Under nitrogen atmosphere, 1 part of the boron-containing silicon prepolymer prepared in step S13 was dissolved in 10 parts of DMF, 3.5 parts of trimethylolpropane triglycidyl ether and 0.05 parts of tetrabutylammonium bromide were added, and the temperature was raised to 85°C. After reacting for 4 hours, the precipitate was washed three times with hot deionized water and diethyl ether, and the precipitate was collected and dried in vacuo at 80°C to constant weight to obtain a branched flame-retardant epoxy resin;

[0043] S2. In parts by weight, 10 parts of antimony trioxide, 20 parts of glass fiber, 0.1 parts of propyl gallate were added to 25 parts of branched flame-retardant epoxy resin, stirred and dispersed for 30 min, 30 parts of bisphenol A epoxy resin were added, and mixing was continued for 30 min, 27 parts of phthalic anhydride curing agent were added, and mixed for 15 min to obtain a mixture;

[0044] S3. Inject the mixture into a mold, heat it to 100°C, keep it warm for 2 hours, and then remove it from the mold to obtain a high-voltage capacitor housing.

[0045] Example 3.

[0046] Compared with Example 1, this example increases the amount of phenylboric acid added in step S13;

[0047] An injection molding process for a high-voltage capacitor housing comprises the following steps:

[0048] S1. Preparation of branched flame-retardant epoxy resin;

[0049] S11. Dissolve 1 part of 3,4,5-trihydroxybenzoic acid and 0.8 parts of butyl glycidyl ether in DMF by molar ratio under nitrogen atmosphere, add 0.03 parts of tetrabutylammonium bromide, heat to 85°C, reflux for 6 hours, extract with deionized water, separate the organic phase, dry it over anhydrous sodium sulfate overnight, filter, and dry it in vacuo at 60°C to constant weight to obtain a hydroxyl-terminated prepolymer;

[0050] S12. Dissolve 1 part of the hydroxyl-terminated prepolymer prepared in step S11 in DMF, protect with a nitrogen atmosphere, and treat in an ice-water bath until the temperature is constant. Then, add 0.03 parts of tetrabutylammonium bromide, mix well, and slowly add dropwise to 3.5 parts of dichlorodiphenylsilane over a period of 2.5 hours. After the addition is complete, raise the temperature to 50°C, continue the reaction for 4 hours, wash with deionized water until neutral, and dry in a vacuum at 60°C to constant weight to obtain a silicon-containing prepolymer.

[0051] S13. Under nitrogen atmosphere, 4.2 parts of phenylboric acid were dissolved in 10 parts of dichloroethane, and the mixture was treated in an ice-water bath to a constant temperature to obtain a phenylboric acid solution; 1 part of the silicon-containing prepolymer obtained in step S12 was dissolved in 5 parts of dichloroethane and slowly added dropwise to the phenylboric acid solution for 2 hours. After the addition was completed, the temperature was raised to 40°C, and the reaction was continued for 4 hours. The temperature was then raised to 70°C again and the reaction was continued for 4 hours. After the reaction was completed, the mixture was washed with deionized water until neutral, and dried in a vacuum at 60°C to constant weight to obtain a boron-containing silicon prepolymer;

[0052] S14. Under nitrogen atmosphere, 1 part of the boron-containing silicon prepolymer prepared in step S13 was dissolved in 10 parts of DMF, 3.5 parts of trimethylolpropane triglycidyl ether and 0.05 parts of tetrabutylammonium bromide were added, and the temperature was raised to 85°C. After reacting for 4 hours, the precipitate was washed three times with hot deionized water and diethyl ether, and the precipitate was collected and dried in vacuo at 80°C to constant weight to obtain a branched flame-retardant epoxy resin;

[0053] S2. In parts by weight, 10 parts of antimony trioxide, 20 parts of glass fiber, 0.1 parts of propyl gallate were added to 25 parts of branched flame-retardant epoxy resin, stirred and dispersed for 30 min, 30 parts of bisphenol A epoxy resin were added, and mixing was continued for 30 min, 27 parts of phthalic anhydride curing agent were added, and mixed for 15 min to obtain a mixture;

[0054] S3. Inject the mixture into a mold, heat it to 100°C, keep it warm for 2 hours, and then remove it from the mold to obtain a high-voltage capacitor housing.

[0055] Example 4.

[0056] Compared with Example 1, this embodiment increases the amount of branched flame retardant epoxy resin added in step S2;

[0057] An injection molding process for a high-voltage capacitor housing comprises the following steps:

[0058] S1. Preparation of branched flame-retardant epoxy resin;

[0059] S11. Dissolve 1 part of 3,4,5-trihydroxybenzoic acid and 0.8 parts of butyl glycidyl ether in DMF by molar ratio under nitrogen atmosphere, add 0.03 parts of tetrabutylammonium bromide, heat to 85°C, reflux for 6 hours, extract with deionized water, separate the organic phase, dry it over anhydrous sodium sulfate overnight, filter, and dry it in vacuo at 60°C to constant weight to obtain a hydroxyl-terminated prepolymer;

[0060] S12. Dissolve 1 part of the hydroxyl-terminated prepolymer prepared in step S11 in DMF, protect with a nitrogen atmosphere, and treat in an ice-water bath until the temperature is constant. Then, add 0.03 parts of tetrabutylammonium bromide, mix well, and slowly add dropwise to 3.5 parts of dichlorodiphenylsilane over a period of 2.5 hours. After the addition is complete, raise the temperature to 50°C, continue the reaction for 4 hours, wash with deionized water until neutral, and dry in a vacuum at 60°C to constant weight to obtain a silicon-containing prepolymer.

[0061] S13. Under nitrogen atmosphere, 3.5 parts of phenylboric acid were dissolved in 10 parts of dichloroethane, and the mixture was treated in an ice-water bath to a constant temperature to obtain a phenylboric acid solution; 1 part of the silicon-containing prepolymer obtained in step S12 was dissolved in 5 parts of dichloroethane and slowly added dropwise to the phenylboric acid solution for 2 hours. After the addition was completed, the temperature was raised to 40°C, and the reaction was continued for 4 hours. The temperature was then raised to 70°C again and the reaction was continued for 4 hours. After the reaction was completed, the mixture was washed with deionized water until neutral, and dried in a vacuum at 60°C to constant weight to obtain a boron-containing silicon prepolymer;

[0062] S14. Under nitrogen atmosphere, 1 part of the boron-containing silicon prepolymer prepared in step S13 was dissolved in 10 parts of DMF, 3.5 parts of trimethylolpropane triglycidyl ether and 0.05 parts of tetrabutylammonium bromide were added, and the temperature was raised to 85°C. After reacting for 4 hours, the precipitate was washed three times with hot deionized water and diethyl ether, and the precipitate was collected and dried in vacuo at 80°C to constant weight to obtain a branched flame-retardant epoxy resin;

[0063] S2. In parts by weight, 10 parts of antimony trioxide, 20 parts of glass fiber, 0.1 parts of propyl gallate were added to 35 parts of branched flame-retardant epoxy resin, stirred and dispersed for 30 min, 30 parts of bisphenol A epoxy resin were added, and mixing was continued for 30 min, 27 parts of phthalic anhydride curing agent were added, and mixed for 15 min to obtain a mixture;

[0064] S3. Inject the mixture into a mold, heat it to 100°C, keep it warm for 2 hours, and then remove it from the mold to obtain a high-voltage capacitor housing.

[0065] Example 5.

[0066] An injection molding process for a high-voltage capacitor housing comprises the following steps:

[0067] S1. Preparation of branched flame-retardant epoxy resin;

[0068] S11. Dissolve 1 part of 3,4,5-trihydroxybenzoic acid and 1.1 parts of butyl glycidyl ether in DMF by molar ratio under nitrogen atmosphere, add 0.05 parts of tetrabutylammonium bromide, heat to 95°C, reflux for 12 hours, extract with deionized water, separate the organic phase, dry it over anhydrous sodium sulfate overnight, filter, and dry it in vacuo at 60°C to constant weight to obtain a hydroxyl-terminated prepolymer;

[0069] S12. Dissolve 1 part of the hydroxyl-terminated prepolymer prepared in step S11 in DMF, protect with a nitrogen atmosphere, and treat in an ice-water bath until the temperature is constant. Then, add 0.05 parts of tetrabutylammonium bromide, mix well, and slowly add dropwise to 4.5 parts of dichlorodiphenylsilane over a period of 4 hours. After the addition is complete, raise the temperature to 60°C and continue the reaction for 8 hours. Wash with deionized water until neutral, and dry in a vacuum at 60°C to constant weight to obtain a silicon-containing prepolymer.

[0070] S13. Under nitrogen atmosphere, 4.2 parts of phenylboric acid were dissolved in 10 parts of dichloroethane, and the mixture was treated in an ice-water bath to a constant temperature to obtain a phenylboric acid solution; 1 part of the silicon-containing prepolymer obtained in step S12 was dissolved in 5 parts of dichloroethane and slowly added dropwise to the phenylboric acid solution for 4 hours. After the addition was completed, the temperature was raised to 45°C, and the reaction was continued for 4 hours. The temperature was then raised to 80°C again and the reaction was continued for 8 hours. After the reaction was completed, the mixture was washed with deionized water until neutral, and dried in a vacuum at 60°C to constant weight to obtain a boron-containing silicon prepolymer;

[0071] S14. Under nitrogen atmosphere, 1 part of the boron-containing silicon prepolymer prepared in step S13 was dissolved in 10 parts of DMF, 4.5 parts of trimethylolpropane triglycidyl ether and 0.08 parts of tetrabutylammonium bromide were added, and the temperature was raised to 95°C. After reacting for 8 hours, the precipitate was washed five times with hot deionized water and diethyl ether, and the precipitate was collected and dried in vacuo at 80°C to constant weight to obtain a branched flame-retardant epoxy resin;

[0072] S2. In parts by weight, 15 parts of antimony trioxide, 30 parts of glass fiber, 0.5 parts of propyl gallate were added to 35 parts of branched flame-retardant epoxy resin, stirred and dispersed for 45 minutes, 40 parts of bisphenol A epoxy resin were added, and mixing was continued for 45 minutes, followed by the addition of 35.5 parts of phthalic anhydride curing agent and mixing for 15 minutes to obtain a mixture;

[0073] S3. Inject the mixture into a mold, heat it to 110°C, keep it warm for 4 hours, and then remove it from the mold to obtain a high-voltage capacitor housing.

[0074] Comparative Example 1.

[0075] Compared with Example 5, this comparative example did not add dichlorodiphenylsilane and phenylboric acid to modify the epoxy resin;

[0076] An injection molding process for a high-voltage capacitor housing comprises the following steps:

[0077] S1. Preparation of branched flame-retardant epoxy resin;

[0078] S11. Dissolve 1 part of 3,4,5-trihydroxybenzoic acid and 1.1 parts of butyl glycidyl ether in DMF by molar ratio under nitrogen atmosphere, add 0.05 parts of tetrabutylammonium bromide, heat to 95°C, reflux for 12 hours, extract with deionized water, separate the organic phase, dry it over anhydrous sodium sulfate overnight, filter, and dry it in vacuo at 60°C to constant weight to obtain a hydroxyl-terminated prepolymer;

[0079] S12. Under nitrogen atmosphere, 1 part of the hydroxyl-terminated prepolymer was dissolved in 10 parts of DMF, 4.5 parts of trimethylolpropane triglycidyl ether and 0.08 parts of tetrabutylammonium bromide were added, and the temperature was raised to 95°C. After reacting for 8 h, the precipitate was washed five times with hot deionized water and diethyl ether. The precipitate was collected and dried in vacuo at 80°C to constant weight to obtain a branched epoxy resin.

[0080] S2. In parts by weight, 15 parts of antimony trioxide, 30 parts of glass fiber, 0.5 parts of propyl gallate were added to 35 parts of branched epoxy resin, stirred and dispersed for 45 minutes, 40 parts of bisphenol A epoxy resin were added, and mixing was continued for 45 minutes, followed by the addition of 35.5 parts of phthalic anhydride curing agent, mixed for 15 minutes to obtain a mixture;

[0081] S3. Inject the mixture into a mold, heat it to 110°C, keep it warm for 4 hours, and then remove it from the mold to obtain a high-voltage capacitor housing.

[0082] Testing: The tensile strength and elongation at break of Examples 1-5 and Comparative Example 1 were tested according to ASTM-D638, with the testing condition being 50 mm / min; the flexural strength and flexural modulus of Examples 1-5 and Comparative Example 1 were tested according to ASTM-D790, with the testing condition being 5 mm / min; the notched impact strength of Examples 1-5 and Comparative Example 1 was tested according to ASTM-D256, with the testing condition being 1 / 8", 23°C; the melt index of Examples 1-5 and Comparative Example 1 was tested according to ASTM-D1238, with the testing condition being 230°C / 2.16 kg; the molding shrinkage of Examples 1-5 and Comparative Example 1 was tested according to ASTM-D955; the heat deformation temperature of Examples 1-5 and Comparative Example 1 was tested according to ASTM-D648, with the testing conditions being 0.46 MPa and 1.82 MPa, respectively; the flame retardancy of Examples 1-5 and Comparative Example 1 was tested according to UL94; the test results are shown in the following table:

[0083]

[0084]

[0085] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A high-voltage capacitor housing, characterized in that: The high-voltage capacitor housing comprises the following components by weight: 30-40 parts of bisphenol A epoxy resin, 25-35 parts of branched flame-retardant epoxy resin, 27-35.5 parts of curing agent, 10-15 parts of flame-retardant inorganic filler, 20-30 parts of glass fiber, and 0.1-0.5 parts of antioxidant; The preparation method of the branched flame retardant epoxy resin comprises the following steps: S11. Dissolve 3,4,5-trihydroxybenzoic acid and butyl glycidyl ether in DMF under a nitrogen atmosphere, add tetrabutylammonium bromide, heat to 85-95°C, reflux for 6-12 hours, extract with deionized water, separate the organic phase, dry over anhydrous sodium sulfate overnight, filter, and vacuum dry to constant weight to obtain a hydroxyl-terminated prepolymer; S12. The hydroxyl-terminated prepolymer prepared in step S11 is dissolved in DMF, treated in an ice-water bath, and tetrabutylammonium bromide is added. After mixing, the mixture is slowly added dropwise to dichlorodiphenylsilane over a period of 2.5-4 hours. After the addition is complete, the mixture is heated to 50-60° C. and the reaction is continued for 4-8 hours. The mixture is then washed with deionized water until neutral and vacuum dried to constant weight to obtain a silicon-containing prepolymer. S13. Under nitrogen atmosphere, phenylboric acid was dissolved in dichloroethane and treated in an ice-water bath to obtain a phenylboric acid solution; the silicon-containing prepolymer obtained in step S12 was dissolved in dichloroethane and slowly added dropwise to the phenylboric acid solution. After the addition was completed, the temperature was raised to 40-45°C, and the reaction was continued for 4-8 hours. The temperature was then raised to 70-80°C and the reaction was continued for 4-8 hours. After the reaction was completed, the prepolymer was washed with deionized water until neutral and vacuum dried to constant weight to obtain a boron-containing silicon prepolymer; S14. Under nitrogen atmosphere protection, dissolve the boron silicon prepolymer obtained in step S13 in DMF, add trimethylolpropane triglycidyl ether and tetrabutylammonium bromide, raise the temperature to 85-95°C, react for 4-8 hours, wash the precipitate with hot deionized water and diethyl ether 3-5 times, collect the precipitate, and vacuum dry it to constant weight to obtain a branched flame retardant epoxy resin.

2. The high-voltage capacitor housing according to claim 1, characterized in that: The curing agent is any one or more of maleic anhydride, phthalic anhydride, and hexahydrophthalic anhydride.

3. The high-voltage capacitor housing according to claim 1, wherein: The flame retardant inorganic filler is antimony trioxide; and the antioxidant is propyl gallate.

4. The high-voltage capacitor housing according to claim 1, wherein: In step S11 , the molar ratio of 3,4,5-trihydroxybenzoic acid, butyl glycidyl ether, and tetrabutylammonium bromide is 1:(0.8-1.1):(0.03-0.05) by mole.

5. The high-voltage capacitor housing according to claim 1, characterized in that: In step S12, the molar ratio of the hydroxyl-terminated prepolymer, tetrabutylammonium bromide and dichlorodiphenylsilane is 1:(0.03-0.05):(3.5-4.5) in terms of molar parts.

6. The high-voltage capacitor housing according to claim 1, characterized in that: In step S13, the molar ratio of the phenylboric acid to the silicon-containing prepolymer is (3.5-4.2):1 in terms of molar parts.

7. The high-voltage capacitor housing according to claim 1, characterized in that: In step S14, the molar ratio of the boron-containing silicon prepolymer, trimethylolpropane triglycidyl ether, and tetrabutylammonium bromide is 1:(3.5-4.5):(0.05-0.08) in terms of molar parts.

8. An injection molding process for a high-voltage capacitor housing according to claim 1, characterized in that: The following steps are involved: S1. Preparation of branched flame-retardant epoxy resin; S2. The flame retardant inorganic filler, glass fiber, antioxidant is added to the branched flame retardant epoxy resin, stirred and dispersed for 30-45min, bisphenol A epoxy resin is added, mixing is continued for 30-45min, a curing agent is added, and mixed for 10-15min to obtain a mixture; S3. Inject the mixture into a mold, heat it to 100-110°C, keep it warm for 2-4 hours, and then remove it from the mold to obtain a high-voltage capacitor housing.

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