Preparation method of diisopropyl peroxydicarbonate and application of diisopropyl peroxydicarbonate

Abstract

The application belongs to the technical field of chemical synthesis, and particularly relates to a preparation method of diisopropyl peroxydicarbonate and application of the diisopropyl peroxydicarbonate. The preparation method comprises the following steps: firstly, isopropyl chloroformate and an ester-soluble organic solution are added into a three-necked flask, stirring is started, hydrogen peroxide solution is added, when the temperature of the mixture in the flask is stabilized at-5 DEG C, sodium hydroxide solution is slowly added into the three-necked flask, and the time and temperature in the reaction process are controlled; finally, the organic phase is separated, washed with water, dried with anhydrous sodium sulfate, and obtained. The preparation method is safe and controllable, the yield of the diisopropyl peroxydicarbonate is high, the stability is good, the diisopropyl peroxydicarbonate can be directly used for the preparation of polyvinylidene fluoride, a chain transfer agent is not needed, polymerization can be carried out under low-temperature conditions, the molecular chain regularity of the polyvinylidene fluoride is improved, abnormal structures are few, the crystallinity is high, and the comprehensive performance is good.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis technology, specifically relating to a method for preparing diisopropyl peroxide and the application of diisopropyl peroxide. Background Technology

[0002] Dicarbon peroxide is a commonly used initiator in free radical polymerization. It has a low decomposition temperature and can initiate polymerization reactions at relatively low temperatures. It is particularly sensitive to temperature, impact, and chemicals such as acids and alkalis, and is extremely prone to decomposition, which can cause explosions. It usually needs to be diluted and stored at low temperatures.

[0003] Polyvinylidene fluoride (PVDF) is a high-performance fluoropolymer with excellent chemical resistance, high-temperature resistance, oxidation resistance, weather resistance, UV resistance, and radiation resistance. It also possesses high mechanical strength, low surface energy, excellent processability, and unique electrical properties such as piezoelectricity, thermoelectricity, and ferroelectricity, making it widely used in aerospace, high-performance membrane modules, lithium batteries, the automotive industry, electronics, and biomedicine. However, the molecular chain structure of PVDF contains abnormal head-to-head and tail-to-tail connections. An increase in these abnormal structures can affect the crystallinity of the polymer, creating defects within the crystals, increasing swelling in solvents, and lowering the melting point. The proportion of these abnormal connections depends on the polymerization conditions, especially the polymerization temperature. Therefore, it is essential to develop a peroxide dicarbonate initiator that exhibits good initiation activity at low temperatures and can improve the molecular chain regularity of PVDF. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a method for preparing diisopropyl peroxide and its applications. This preparation method optimizes and precisely controls the preparation process conditions, ensuring a safe and controllable process. The resulting diisopropyl peroxide exhibits high yield and good stability, and can be directly used in the preparation of polyvinylidene fluoride (PVDF). It requires no chain transfer agent, polymerizes at low temperatures, improves the regularity of PVDF molecular chains, reduces abnormal structures, increases crystallinity, and enhances overall performance.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] The first objective of this invention is to provide a method for preparing diisopropyl peroxide dicarbonate, comprising the following steps:

[0007] S1. Add isopropyl chloroformate and ester-soluble organic solution to a dried and cooled three-necked flask, turn on the stirrer, add hydrogen peroxide solution, and when the temperature of the mixture in the flask stabilizes at -5℃, add sodium hydroxide solution to the dropping funnel, and then slowly add it dropwise to the three-necked flask, controlling the dropping time at 60-90 min, and controlling the reaction temperature below 10℃ during the reaction. After the sodium hydroxide solution is added, continue the reaction for 30-35 min.

[0008] S2. Pour the mixed solution after the reaction in S1 is completed into a separatory funnel to separate the organic phase. Wash it with water 2-3 times and dry it with anhydrous sodium sulfate to obtain the final product.

[0009] Isopropyl chloroformate is a toxic, colorless liquid with an irritating odor. It reacts exothermically with water or steam, or forms explosive mixtures, making its use quite dangerous. This invention strictly controls the order and conditions of raw material addition. By pre-treating the three-necked flask and then dissolving isopropyl chloroformate in an ester-soluble organic solvent to reduce its concentration, the risk of use is significantly reduced. Simultaneously, hydrogen peroxide solution is added first at low temperature, followed by pre-cooled sodium hydroxide via titration. The diisopropyl peroxide (diisopropyl peroxide) generated during the reaction dissolves directly into the organic phase, further reducing its concentration and potential risks of decomposition and explosion. The titration of sodium hydroxide also reduces the decomposition of diisopropyl peroxide, increasing the final yield. The final product, an organic phase solution, can be directly used to prepare polyvinylidene fluoride (PVDF) without storage, thus reducing structural defects in PVDF resin.

[0010] Furthermore, in the above technical solution, in S1, the molar ratio of isopropyl chloroformate, sodium hydroxide, and hydrogen peroxide is 1:1.02-1.05:0.55-0.7.

[0011] Furthermore, in the above technical solution S1, the ester-soluble organic solution is any one or more of ethyl acetate, diethyl malonate, and diethyl carbonate, and the amount added is 1-3 times the mass of isopropyl chloroformate. Adding the ester-soluble organic solution directly before the reaction reduces the risk associated with isopropyl chloroformate. Simultaneously, as a solvent for the final product, it can directly dilute the generated product, reducing the risk of decomposition and explosion of diisopropyl peroxide, resulting in high stability.

[0012] Furthermore, in the above technical solution S1, before turning on the stirrer, the flask is first cooled to -5°C using an ice-salt bath. Pre-cooling the flask allows the raw material, isopropyl chloroformate, to be in a low-temperature environment, improving its stability and providing low-temperature conditions for subsequent reactions.

[0013] Furthermore, in the above technical solution S1, the mass concentration of the hydrogen peroxide solution is 27%; and the mass concentration of the sodium hydroxide solution is 32%.

[0014] Furthermore, in the above technical solution S1, the sodium hydroxide solution is pre-cooled to 0°C using an ice-water bath. Since the reaction process is exothermic and releases a large amount of heat, pre-cooling the sodium hydroxide solution not only improves reaction efficiency but also significantly reduces the risk of explosion in order to better control the temperature of the reaction solution.

[0015] Furthermore, in the above technical solution S2, the water used for washing is ice water. Specifically, ice water is water with a temperature below 5°C that does not freeze. Using ice water to wash the organic phase of the product can not only remove water-soluble impurities, but also further reduce the product temperature and prevent its decomposition.

[0016] The second objective of this invention is to provide an application of the diisopropyl peroxide prepared by the above-mentioned preparation method in the preparation of polyvinylidene fluoride (PVDF). The application method is as follows: deionized water is added to a closed polymerization reactor, the air inside the reactor is evacuated and replaced with nitrogen until the oxygen content inside the reactor is less than 10 ppm, methylcellulose is added, the temperature of the polymerization reactor is controlled at 10±2℃, VDF (vinylidene fluoride) monomer is added at once, the above-prepared diisopropyl peroxide solution is added, the pressure is increased to 1-1.2 MPa, the polymerization reaction is started, the temperature of the polymerization reactor is controlled to slowly rise to 20-35℃, the reaction is carried out for 5-8 hours, when the pressure inside the polymerization reactor is lower than 0.5 MPa, the polymerization reaction is stopped, the remaining VDF monomer in the reactor is recovered, and the polymer in the reactor is centrifuged, washed, and dried to obtain powdered resin. This invention uses an organic phase to dissolve diisopropyl peroxide dicarbonate in advance during its preparation, reducing its concentration and improving its stability. The resulting product has a high yield, low risk of decomposition and explosion, and can be directly used for the preparation of polyvinylidene fluoride (PVDF) without storage or usage risks. Furthermore, no additional chain transfer agent is required, making it more convenient to use. In addition, the reaction can be carried out at lower temperatures, resulting in lower risk and fewer defective structures in the obtained PVDF resin, with good molecular chain regularity, high crystallinity, and excellent performance.

[0017] Furthermore, in the above technical solution, the amount of deionized water added is 1-2 times the weight of the VDF monomer; the amount of methylcellulose added is 0.08-0.4‰ of the weight of the VDF monomer.

[0018] Furthermore, in the above technical solution, the amount of diisopropyl peroxide dicarbonate solution added is 4.2-8.3‰ of the weight of the VDF monomer.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention, by strictly controlling the order and conditions of raw material addition, first pre-cools the three-necked flask, then dissolves isopropyl chloroformate in an ester-soluble organic solvent to reduce its concentration, which greatly reduces the risk of its use. At the same time, hydrogen peroxide solution is added first at low temperature, followed by pre-cooled sodium hydroxide by titration. This not only controls the reaction rate, but also ensures that the generated diisopropyl peroxide dissolves directly in the organic phase. Diluting it reduces potential risks such as product decomposition and explosion. Furthermore, the titration of sodium hydroxide reduces the decomposition of diisopropyl peroxide by sodium hydroxide, thus improving the final yield.

[0021] The diisopropyl peroxide dicarbonate prepared by this invention is a solution soluble in the organic phase, exhibiting good stability and a lower risk of decomposition and explosion. It can be directly used to prepare polyvinylidene fluoride (PVDF), or prepared on demand without storage, greatly reducing storage risks. Furthermore, it does not require the addition of chain transfer agents, can react at lower temperatures, and yields PVDF resin with fewer structural defects, good molecular chain regularity, high crystallinity, and excellent overall performance, making it highly competitive in the market. Detailed Implementation

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the raw materials used in the following examples are all commercially available products and can be purchased from the market.

[0023] The above-described technical features of the present invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions.

[0024] The raw materials involved in the various embodiments of the present invention are either existing commercially available products or can be prepared according to existing methods, and the testing methods are industry-standard methods.

[0025] Example 1

[0026] A method for preparing diisopropyl peroxide dicarbonate includes the following steps:

[0027] S1. Add isopropyl chloroformate and ethyl acetate to a dried and cooled three-necked flask. Cool the flask to -5°C using a salt bath. Turn on the stirrer and add a 27% hydrogen peroxide solution. When the temperature of the mixture in the flask stabilizes at -5°C, add a 32% sodium hydroxide solution to a dropping funnel and then slowly add it dropwise to the three-necked flask. Control the dropping time to 60 min and keep the reaction temperature below 10°C during the reaction. After the sodium hydroxide solution is added, continue the reaction for 35 min. The molar ratio of isopropyl chloroformate, sodium hydroxide, and hydrogen peroxide is 1:1.02:0.55. The amount of ethyl acetate used is twice the mass of isopropyl chloroformate.

[0028] S2. Pour the mixed solution after the reaction in S1 into a separatory funnel to separate the organic phase. Wash it twice with ice water at a temperature below 5°C and dry it with anhydrous sodium sulfate to obtain the diisopropyl peroxide organic phase solution.

[0029] The content of organic peroxides was determined by iodometric titration according to GB / T 32102-2015. The mass ratio of diisopropyl dicarbonate to ethyl acetate in the organic phase solution of diisopropyl dicarbonate was 29:71, and the yield of diisopropyl dicarbonate was 98.0%.

[0030] Example 2

[0031] A method for preparing diisopropyl peroxide dicarbonate includes the following steps:

[0032] S1. Add isopropyl chloroformate and ethyl acetate to a dried and cooled three-necked flask. Cool the flask to -5°C using a salt bath. Turn on the stirrer and add a 27% hydrogen peroxide solution. When the temperature of the mixture in the flask stabilizes at -5°C, add a 32% sodium hydroxide solution to a dropping funnel and then slowly add it dropwise to the three-necked flask. Control the dropping time to 75 min and keep the reaction temperature below 10°C during the reaction. After the sodium hydroxide solution is added, continue the reaction for 32 min. The molar ratio of isopropyl chloroformate, sodium hydroxide, and hydrogen peroxide is 1:1.03:0.6. The amount of ethyl acetate used is 3 times the mass of isopropyl chloroformate.

[0033] S2. Pour the mixed solution after the reaction in S1 into a separatory funnel to separate the organic phase. Wash it three times with ice water at a temperature below 5°C and dry it with anhydrous sodium sulfate to obtain the diisopropyl peroxide organic phase solution.

[0034] The content of organic peroxides was determined by iodometric titration according to GB / T 32102-2015. The mass ratio of diisopropyl peroxide to ethyl acetate in the organic phase solution of diisopropyl peroxide was 30:70, and the yield of diisopropyl peroxide was 98.3%.

[0035] Example 3

[0036] A method for preparing diisopropyl peroxide dicarbonate includes the following steps:

[0037] S1. Isopropyl chloroformate and diethyl malonate were added to a dried and cooled three-necked flask. The flask was cooled to -5°C using a salt bath. The stirrer was turned on, and a 27% hydrogen peroxide solution was added. When the temperature of the mixture in the flask stabilized at -5°C, a 32% sodium hydroxide solution was added to a dropping funnel and then slowly added dropwise to the three-necked flask. The dropping time was controlled at 90 min, and the reaction temperature was controlled to be below 10°C during the reaction. After the sodium hydroxide solution was added, the reaction was continued for 30 min. The molar ratio of isopropyl chloroformate, sodium hydroxide, and hydrogen peroxide was 1:1.05:0.7. The amount of diethyl malonate used was 1 times the mass of isopropyl chloroformate.

[0038] S2. Pour the mixed solution after the reaction in S1 into a separatory funnel to separate the organic phase. Wash it twice with ice water at a temperature below 5°C and dry it with anhydrous sodium sulfate to obtain the diisopropyl peroxide organic phase solution.

[0039] The content of organic peroxides was determined by iodometric titration according to GB / T 32102-2015. The mass ratio of diisopropyl peroxide to diethyl malonate in the organic phase solution of diisopropyl peroxide was 44:56, and the yield of diisopropyl peroxide was 97.2%.

[0040] Example 4

[0041] The preparation method of polyvinylidene fluoride includes the following steps:

[0042] 20L of deionized water was added to a 40L sealed polymerization reactor. The air inside the reactor was evacuated and replaced with nitrogen until the oxygen content inside the reactor was less than 10ppm. 2g of methylcellulose was added, and the temperature of the polymerization reactor was controlled at 10±2℃. 12kg of VDF monomer was added at once, along with 75g of the diisopropyl peroxide organic phase solution prepared in Example 2 (containing 22.5g of diisopropyl peroxide and 52.5g of ethyl acetate). The pressure was increased to 1MPa, and the polymerization reaction was started. The temperature of the polymerization reactor was slowly increased to 20℃, and the reaction was carried out for 8 hours. When the pressure inside the polymerization reactor was lower than 0.5MPa, the polymerization reaction was stopped, and the remaining VDF monomer in the reactor was recovered. After centrifugation, washing, and drying, 11.5kg of polyvinylidene fluoride powdered resin was obtained. The yield was 95.8%, and the defect structure with head-to-tail connections was 4.3%.

[0043] Example 5

[0044] The preparation method of polyvinylidene fluoride includes the following steps:

[0045] 20L of deionized water was added to a 40L sealed polymerization reactor. The air inside the reactor was evacuated and replaced with nitrogen until the oxygen content inside the reactor was less than 10ppm. 5g of methylcellulose was added, and the temperature of the polymerization reactor was controlled at 10±2℃. 12kg of VDF monomer was added at once, along with 100g of the diisopropyl peroxide organic phase solution prepared in Example 2 (containing 30g of diisopropyl peroxide and 70g of ethyl acetate). The pressure was increased to 1.1MPa, and the polymerization reaction was started. The temperature of the polymerization reactor was slowly increased to 30℃, and the reaction was carried out for 6 hours. When the pressure inside the polymerization reactor was lower than 0.5MPa, the polymerization reaction was stopped. The remaining VDF monomer in the reactor was recovered. After centrifugation, washing, and drying, 11.7kg of polyvinylidene fluoride powdered resin was obtained. The yield was 97.5%, and the defect structure with head-to-tail connections was less than 4.7%.

[0046] Example 6

[0047] The preparation method of polyvinylidene fluoride includes the following steps:

[0048] 20L of deionized water was added to a 40L sealed polymerization reactor. The air inside the reactor was evacuated and replaced with nitrogen until the oxygen content inside the reactor was less than 10ppm. 1g of methylcellulose was added, and the temperature of the polymerization reactor was controlled at 10±2℃. 12kg of VDF monomer was added at once, along with 50g of the organic phase solution of diisopropyl peroxide prepared in Example 2 (containing 15g of diisopropyl peroxide and 35g of ethyl acetate). The pressure was increased to 1.2MPa, and the polymerization reaction was started. The temperature of the polymerization reactor was slowly increased to 35℃, and the reaction was carried out for 5 hours. When the pressure inside the polymerization reactor was lower than 0.5MPa, the polymerization reaction was stopped. The remaining VDF monomer in the reactor was recovered. After centrifugation, washing, and drying, 11.3kg of polyvinylidene fluoride powdered resin was obtained. The yield was 94.2%, and the defect structure with head-to-head and tail-to-tail connections was less than 4.5%.

[0049] Comparative Example 1

[0050] A method for preparing diisopropyl peroxide dicarbonate includes the following steps:

[0051] Isopropyl chloroformate was added to a dried and cooled three-necked flask. The flask was cooled to -5°C using a salt bath. A stirrer was turned on, and a 27% hydrogen peroxide solution was added. When the temperature of the mixture in the flask stabilized at -5°C, a 32% sodium hydroxide solution was added to a dropping funnel and then slowly added dropwise to the three-necked flask. The addition time was controlled at 75 min, and the reaction temperature was controlled to be below 10°C during the reaction. After the sodium hydroxide solution was added, the reaction was continued for 32 min to obtain diisopropyl peroxide. The molar ratio of isopropyl chloroformate, sodium hydroxide, and hydrogen peroxide was 1:1.03:0.6.

[0052] The yield of diisopropyl peroxide was 78.9% according to the iodometric method for the determination of organic peroxide content in GB / T 32102-2015.

[0053] Comparative Example 2

[0054] A method for preparing diisopropyl peroxide dicarbonate includes the following steps:

[0055] Isopropyl chloroformate and ethyl acetate were added to a three-necked flask. The stirrer was turned on, and a 27% hydrogen peroxide solution and a 32% sodium hydroxide solution were added sequentially. The reaction was continued for 32 minutes to obtain diisopropyl peroxide. The molar ratio of isopropyl chloroformate, sodium hydroxide, and hydrogen peroxide was 1:1.03:0.6, and the amount of ethyl acetate used was 3 times the mass of isopropyl chloroformate.

[0056] The content of organic peroxides was determined by iodometric titration according to GB / T 32102-2015, and the yield of diisopropyl peroxide dicarbonate was 10%.

[0057] Comparative Example 3

[0058] The preparation method of polyvinylidene fluoride includes the following steps:

[0059] 20L of deionized water was added to a 40L sealed polymerization reactor. The air inside the reactor was evacuated and replaced with nitrogen until the oxygen content was less than 10ppm. 2g of methylcellulose was added, and the temperature of the polymerization reactor was controlled at 10±2℃. 12kg of VDF monomer, 30g of diisopropyl peroxide dicarbonate prepared in Comparative Example 1, and 70g of chain transfer agent were added all at once. After mixing evenly, the pressure was increased to 1.1MPa to start the polymerization reaction. The temperature of the polymerization reactor was slowly increased to 30℃ and the reaction was carried out for 6 hours. When the pressure inside the polymerization reactor was lower than 0.5MPa, the polymerization reaction was stopped. The remaining VDF monomer in the reactor was recovered. After centrifugation, washing, and drying, 10.8g of polyvinylidene fluoride powdered resin was obtained. The yield was 90.0%, and the defect structure with head-to-head and tail-to-tail connections was 5.2%.

[0060] Comparative Example 4

[0061] The preparation method of polyvinylidene fluoride includes the following steps:

[0062] 20L of deionized water was added to a 40L sealed polymerization reactor. The air inside the reactor was evacuated and replaced with nitrogen until the oxygen content was less than 10ppm. 2g of methylcellulose was added, and the temperature of the polymerization reactor was controlled at 10±2℃. 12kg of VDF monomer was added at once, along with 100g of the organic phase solution of diisopropyl peroxide prepared in Comparative Example 2 (containing 10g of diisopropyl peroxide and 90g of ethyl acetate). The pressure was increased to 1.1MPa to start the polymerization reaction. The temperature of the polymerization reactor was slowly increased to 30℃, and the reaction was carried out for 6 hours. When the pressure inside the polymerization reactor was lower than 0.5MPa, the polymerization reaction was stopped. The remaining VDF monomer in the reactor was recovered. After centrifugation, washing, and drying, 5.9g of polyvinylidene fluoride powdered resin was obtained. The yield was 49.2%, and the defect structure with head-to-head and tail-to-tail connections accounted for 5.5%.

[0063] Comparative Example 5

[0064] The preparation method of polyvinylidene fluoride (refer to the relevant method in existing patent CN103524647A) includes the following steps:

[0065] 20L of deionized water and 2g of methylcellulose were added to a 40L sealed polymerization reactor. 12kg of VDF monomer was added at once, followed by 100g of the diisopropyl peroxide organic solution prepared in Example 2 (containing 30g of diisopropyl peroxide and 70g of ethyl acetate). The polymerization reaction was started, and the temperature of the polymerization reactor was slowly increased to 30℃. The polymerization reaction was stopped after 20h. The remaining VDF monomer in the reactor was recovered. The polymer in the reactor was centrifuged, washed, and dried to obtain 10.5kg of polyvinylidene fluoride powder resin. The yield was 87.5%, and the defective structure with head-to-tail connections was 5.9%.

[0066] As can be seen from the results of Examples 1-3, by strictly controlling the order, method and process conditions of adding raw materials, this invention not only has high safety, but also yields high and stable diisopropyl peroxide. It can be directly used in the preparation of polyvinylidene fluoride without the addition of chain transfer agents, and can be polymerized at lower temperatures, thereby improving the regularity of the polyvinylidene fluoride molecular chain, reducing abnormal structures and greatly improving the overall performance of polyvinylidene fluoride.

[0067] In contrast, Comparative Example 1 did not use an ester-soluble organic solvent in the preparation of diisopropyl peroxide dicarbonate. Not only was there a risk of explosion during the reaction, but the product yield was also low. Furthermore, the preparation of polyvinylidene fluoride required the addition of a chain transfer agent, making the process more complex and increasing the preparation risk. In addition, its defects were also increased to some extent.

[0068] In Comparative Example 2, the raw materials were directly mixed without adding sodium hydroxide solution dropwise to prepare diisopropyl peroxide. This not only increased the reaction risk but also seriously affected the yield. Directly using it to prepare polyvinylidene fluoride resulted in a low yield and further increased defects.

[0069] In Comparative Example 5, polyvinylidene fluoride was prepared using existing methods. Although it used diisopropyl peroxide dicarbonate prepared in this invention, the lack of control over the air content and temperature in the polymerization reactor in the early stages increased the preparation risk, reduced the yield, and increased defects, directly affecting its performance.

[0070] In summary, this invention, through strict control of the order, method, and process conditions of raw material addition, not only ensures high safety and yield, but also produces diisopropyl peroxide dicarbonate, a solution soluble in the organic phase with good stability and a lower risk of decomposition and explosion. It can be directly used to prepare polyvinylidene fluoride (PVDF), or prepared on demand without storage, significantly reducing storage risks. Furthermore, it eliminates the need for additional chain transfer agents, resulting in PVDF resin with fewer structural defects, good molecular chain regularity, high crystallinity, and excellent overall performance, giving it strong market competitiveness.

[0071] Finally, it should be emphasized that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing diisopropyl peroxide dicarbonate, characterized in that, Includes the following steps: S1. Add isopropyl chloroformate and an ester-soluble organic solution to a dried and cooled three-necked flask. Turn on the stirrer and add hydrogen peroxide solution. When the temperature of the mixture in the flask stabilizes at -5°C, add sodium hydroxide solution to a dropping funnel and then slowly add it dropwise to the three-necked flask. Control the dropping time to 60-90 minutes and keep the reaction temperature below 10°C during the reaction. After the sodium hydroxide solution is added, continue the reaction for 30-35 minutes. The molar ratio of isopropyl chloroformate, sodium hydroxide, and hydrogen peroxide is 1:1.02-1.05:0.55-0.

7. The ester-soluble organic solution is any one or more of ethyl acetate, diethyl malonate, and diethyl carbonate, and the amount added is 1-3 times the mass of isopropyl chloroformate. S2. Pour the mixed solution after the reaction in S1 is completed into a separatory funnel to separate the organic phase. Wash it with water 2-3 times and dry it with anhydrous sodium sulfate to obtain the final product.

2. The preparation method according to claim 1, characterized in that, In S1, before turning on the stirrer, the flask is cooled to -5°C using an ice-salt bath.

3. The preparation method according to claim 1, characterized in that, In S1, the mass concentration of the hydrogen peroxide solution is 27%; the mass concentration of the sodium hydroxide solution is 32%.

4. The preparation method according to claim 1, characterized in that, In S1, the sodium hydroxide solution is pre-cooled to 0°C using an ice-water bath.

5. The preparation method according to claim 1, characterized in that, In S2, the water used for washing is ice water.

6. The application of diisopropyl peroxide prepared by the preparation method according to any one of claims 1-5 in the preparation of polyvinylidene fluoride, characterized in that, The application method is as follows: Deionized water is added to a closed polymerization reactor, the air inside the reactor is evacuated, and the oxygen content inside the reactor is replaced with nitrogen until it is less than 10 ppm. Methylcellulose is added, the temperature of the polymerization reactor is controlled at 10±2℃, VDF monomer is added all at once, and diisopropyl peroxide dicarbonate solution prepared by any one of claims 1-5 is added. The pressure is increased to 1-1.2 MPa to start the polymerization reaction. The temperature of the polymerization reactor is controlled to rise slowly to 20-35℃, and the reaction is carried out for 5-8 hours. When the pressure inside the polymerization reactor is lower than 0.5 MPa, the polymerization reaction is stopped, the remaining VDF monomer in the reactor is recovered, and the polymer in the reactor is centrifuged, washed, and dried to obtain powdered resin.

7. The application according to claim 6, characterized in that, The amount of deionized water added is 1-2 times the weight of the VDF monomer; the amount of methylcellulose added is 0.08-0.4‰ of the weight of the VDF monomer.

8. The application according to claim 6, characterized in that, The amount of diisopropyl peroxide dicarbonate solution added is 4.2-8.3‰ of the weight of the VDF monomer.