A low-temperature stable organic peroxide emulsion and a safe preparation method thereof

Abstract

The present invention discloses a low-temperature stable organic peroxide emulsion and a safe preparation method thereof. The emulsion comprises diisobutyryl peroxide, a hydroperoxide stabilizer, an organic solvent containing 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and an emulsifying / dispersing agent. By means of a method of coupling low-temperature high-shear dispersion with cyclic emulsification and combining real-time monitoring of combustible gas / oxygen / smoke, the problems of freezing of the emulsion under extremely cold conditions (-40°C) and the decomposition risk during the preparation process are solved. The obtained emulsion has significantly improved storage stability (≥85 days), low viscosity and excellent fluidity, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of fine chemical industry, and particularly relates to a low-temperature stable organic peroxide emulsion and a safe preparation method thereof. Background Art

[0002] Organic peroxides are free radical polymerization initiators and are widely used in industries such as polyethylene, polyvinyl chloride, polystyrene, acrylic resins, ethylene-vinyl acetate copolymers, etc., and are key auxiliaries in the polymer industry. Diisobutyryl peroxide is a low-temperature organic peroxide with a self-accelerating decomposition temperature of 0°C. It has a low use temperature and high initiation efficiency, and has good application value in the field of low-temperature polymerization.

[0003] When the emulsion prepared from diisobutyryl peroxide according to the conventional well-known technology is stored for a period of time, a large amount of gas will be generated in the container storing the emulsion, the container will expand, and the peroxide will decompose, resulting in a decrease in its content. This not only reduces the product quality but also poses a great safety risk. After analyzing the emulsion that generates a large amount of gas, its acidity has a tendency to increase. We found that it is mainly isobutyric acid, the content of diisobutyryl peroxide has also decreased significantly, and the decomposition products also include oxygen, etc. The storage stability period of this emulsion product generally does not exceed 1 month, or even does not exceed 2 weeks, which undoubtedly greatly reduces the service life and significantly limits its industrial production and application.

[0004] At the same time, when the diisobutyryl peroxide emulsion is stored at different temperatures, when the storage temperature is lower than -30°C, the emulsion will freeze and agglomerate into micelles, and the viscosity will also increase significantly, which undoubtedly limits its pumping transmission and application. It is of great significance to provide a diisobutyryl peroxide emulsion that does not freeze at temperatures below -30°C and can be stored, transported, or transmitted under a wider range of temperature conditions, especially having good fluidity under extremely cold conditions (such as -35°C or even -40°C).

[0005] In addition, the diisobutyryl peroxide emulsion is prepared by a conventionally well-known technique, that is, diisobutyryl peroxide, water, methanol, an emulsifier, a dispersant, etc. are added into a kettle and subjected to high-speed shearing. During the preparation process, the high-shearing action of the disperser causes a large amount of heat to be generated in the material. Even if a low-temperature refrigerant is used to cool the emulsified material, the temperature of the material will quickly rise from -10°C to above 0°C. The self-accelerating decomposition temperature of diisobutyryl peroxide is 0°C, so the safety risk during the preparation process increases significantly. At the same time, the organic peroxide decomposes during the emulsion preparation process, resulting in a certain decrease in the product yield. If the over-temperature range is obvious, for example, the temperature exceeds 5°C or even reaches 10°C, the material may decompose, releasing oxygen and combustible gases, generating a large amount of smoke and having an extremely high explosion risk. When considering emulsification at a lower temperature (such as -15°C or lower), it is found that too low an emulsification temperature increases the viscosity of the material, increases the energy consumption under high shear, and at the same time, the material still has a large temperature rise, resulting in poor emulsification. It can be seen that the efficiency of preparing the diisobutyryl peroxide emulsion by the conventional method is relatively reduced and the risk is high.

[0006] In summary, the defects of the prior art are as follows:

[0007] Poor storage stability: Conventional diisobutyryl peroxide emulsions are prone to decompose and generate gas (isobutyric acid / oxygen) during storage, resulting in a risk of container expansion and explosion. The stability period is usually <30 days;

[0008] Insufficient low-temperature adaptability: When the temperature < -30°C, the emulsion freezes and solidifies, with a relatively high viscosity, unable to meet the transportation requirements in extremely cold regions (such as -40°C); when the transmission temperature during use is controlled below -25°C or even -30°C, the emulsion freezes and solidifies, unable to meet the application requirements.

[0009] Production safety hazards: First, the shear heat generation during emulsification makes the temperature of the material easily exceed 0°C (the self-accelerating decomposition temperature of diisobutyryl peroxide), triggering decomposition and explosion. Second, isobutyryl chloride, isobutyric acid, isobutyrate, etc. in the material promote the chain decomposition reaction of diisobutyryl peroxide. Third, the heat exchange efficiency of the traditional emulsification process is low, and the shear heat cannot be removed in time. Summary of the Invention

[0010] In view of the above technical problems, the present invention provides a low-temperature stable organic peroxide emulsion and a safe preparation method thereof, solving the problems of ultra-low temperature storage and product instability of the diisobutyryl peroxide emulsion, as well as the emulsification safety and efficiency problems of the emulsion product.

[0011] The low-temperature stable organic peroxide emulsion of the present invention comprises the following components in mass fractions:

[0012] 23% - 50% of diisobutyryl peroxide;

[0013] 0.5% - 1.0% of a stabilizer hydroperoxide;

[0014] 10% to 18% of an organic solvent, where the organic solvent is a solvent containing 2,2,4-trimethyl-1,3-pentanediol diisobutyrate;

[0015] 15% to 30% of water; 20% to 30% of methanol; 0.5% to 0.9% of an emulsifier; 0.1% to 0.3% of a dispersant.

[0016] The stabilizer hydroperoxide is one or more of tert-amyl hydroperoxide, tert-butyl hydroperoxide, tert-hexyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide. Preferably one or two of tert-amyl hydroperoxide and 1,1,3,3-tetramethylbutyl hydroperoxide. The emulsifier is a fatty alcohol polyoxyethylene ether; the dispersant is a polyvinyl alcohol with a degree of alcoholysis of 50% to 80%. The viscosity of the emulsion is 60 to 80 mPa·s when stored at -40°C, and no freezing or solidification occurs.

[0017] The safe preparation method of the low-temperature stable organic peroxide emulsion of the present invention is to mix the components at a low temperature (-15°C to -5°C) and form an emulsion by a high-shear dispersion coupled with a circulating emulsification method; during the preparation process, the concentration of combustible gas, smoke and oxygen concentration on the surface of the emulsion in the kettle are monitored in real time. Specifically, it includes the following steps:

[0018] (1) Add methanol, water, emulsifier and dispersant to the emulsification kettle, start stirring, and cool down to the low temperature condition of -15°C to -5°C;

[0019] (2) Add diisobutyryl peroxide, organic solvent and stabilizer hydroperoxide, and control the temperature at -15°C to -5°C for 10 to 20 minutes;

[0020] (3) Start the circulating emulsification pump and its pipeline refrigeration, and cool the materials in the kettle to -15 to -5°C;

[0021] (4) Adjust the frequency of the circulating emulsification pump to 20 to 40 Hz, start the high-shear disperser after 15 to 20 minutes for 20 to 40 minutes, and control the rotation speed of the disperser at 1000 to 2000 revolutions per minute;

[0022] (5) Continue to circulate for 10 to 20 minutes after stopping the disperser, stop the circulating emulsification pump, and finally stop stirring to obtain the final emulsion.

[0023] The emulsion is circulated from the bottom of the kettle to the top by the circulating emulsification pump, and the pumping rate is 1 to 3 L / s; the circulating emulsification pump and its pipeline are accompanied by ethylene glycol cold salt, and the temperature is controlled at -25°C to -15°C.

[0024] The concentration of the combustible gas is less than 5% LEL, there is no smoke, and the oxygen concentration is less than 23.5%; the concentrations of the combustible gas, smoke and oxygen are fed back in real time through an on-line monitoring system. If the concentration of the combustible gas ≥ 5% LEL or the oxygen concentration ≥ 23.5%, shearing shall be stopped immediately and refrigeration shall be enhanced.

[0025] To solve the problems of ultra-low temperature storage, transportation and application, an organic solvent accounting for 10%-18% of the mass fraction of the emulsion is added. When necessary, the proportion of methanol is appropriately increased (such as more than 27% of the mass fraction of the emulsion). This emulsion has good anti-low temperature freezing performance, and the emulsion does not freeze when cooled to -40°C. This emulsion also has good fluidity when stored and transported at temperatures below -38 °C, even below -40 °C. According to the method of the present invention, the viscosity of the emulsion is also significantly reduced. The viscosity drops from about 120 mPa·s at -40 °C to less than 80 mPa·s, and the viscosity drop is obvious. At -10 °C, the viscosity of the emulsion mixed with 2,2,4-trimethyl-1,3-pentanediol diisobutyrate with a mass fraction of 5% drops by more than 45% compared with that without adding this solvent. It should be noted at the same time that 2,2,4-trimethyl-1,3-pentanediol diisobutyrate can also be used as an environmentally friendly plasticizer, and it will not have an adverse impact on the polymer materials produced downstream.

[0026] The most common method among existing production technologies for synthesizing diisobutyryl peroxide is to react isobutyryl chloride with hydrogen peroxide under alkaline conditions (Qin Rongguang et al., Synthesis of bis(isobutyryl) peroxide, Journal of Northwest Normal University (Natural Science Edition), No. 2, 1982). Since the reaction occurs in an aqueous system and is mostly alkaline in most cases (Chinese Patent CN116396200A, Chinese Patent CN111072542A, etc.), isobutyryl chloride is extremely prone to hydrolysis and alkali hydrolysis. As a result, isobutyric acid and / or isobutyrate, etc. are formed in the product. And due to incomplete reaction, a small amount of isobutyryl chloride also exists in the organic peroxide, and its decomposition increases the acidity. On the one hand, isobutyric acid and / or isobutyrate, etc. cause the decomposition of the peroxide. On the other hand, the unreacted isobutyryl chloride itself is a volatile and irritating gas. Therefore, the diisobutyryl peroxide synthesized by the existing technology inevitably contains isobutyryl chloride, isobutyric acid and its salts, all of which are the reasons for the decomposition and instability of the product. To solve the above problems and overcome the deficiencies of the existing technology, a small amount of hydroperoxide (such as tert-amyl hydroperoxide, etc.) is innovatively added to react with isobutyryl chloride or isobutyric acid (salt), which can convert it into isobutyric acid peroxide ester (such as tert-amyl isobutyric acid peroxide, etc.). In this way, the formed peroxide is mutually soluble with diisobutyryl peroxide on the one hand, and at the same time can greatly reduce or prevent the material from continuing to decompose to produce acid, thereby reducing or inhibiting the decomposition of the product and stabilizing the diisobutyryl peroxide product (emulsion). Such hydroperoxides include tert-amyl hydroperoxide, tert-hexyl hydroperoxide, tert-butyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide. One or two of tert-amyl hydroperoxide and 1,1,3,3-tetramethylbutyl hydroperoxide are preferred, and the addition amount is 0.5% - 1.0% of the mass of the emulsion, preferably 0.5% - 0.8%.

[0027] To solve the safety risks in the above emulsification process (a large amount of heat is easily generated during the emulsification process, thus having a relatively high risk), as well as the problem of low emulsification efficiency. The inventor chooses to control the material temperature at -15°C to -5°C during high-speed shear dispersion in the emulsification kettle. More preferably, it is controlled at about -10°C. A circulation pump is also introduced to circulate the product, and this circulation pump has the function of emulsification and homogenization. By adding ethylene glycol cold salt for cooling in the circulation pipeline, the problem of continuously maintaining a low temperature during the circulation process is solved. By circulating the product material, the surface renewal of the material is improved, significantly increasing the contact surface area between the material and the jacket and cooling coil of the emulsification kettle, and enhancing the heat exchange area. At the same time, this surface renewal makes the high-shear of the disperser and the homogenization mixing efficiency of the emulsification pump higher and the effect better.

[0028] During the experiment, the inventor found that when the temperature of the diisobutyryl peroxide emulsion exceeded the normal range (greater than 3°C or higher), oxygen (the concentration significantly exceeded 23.5%, sometimes reaching 30%) and combustible gases would be decomposed. When the over-temperature was obvious (greater than 10°C or higher), obvious smoke would be generated, indicating that the emulsion preparation process carried great risks. To monitor the risk of explosion and combustion caused by the possible decomposition of oxygen and combustible gases in the material, resulting in a large amount of smoke, the inventor adopted an online monitoring method using combustible gas alarm instruments, smoke sensing instruments, etc. on the surface of the emulsion in the emulsifying kettle, and transmitted the monitoring data in real time to provide early warnings for taking emergency disposal measures. Among them, the optimal control conditions were that the concentration of combustible gas was less than 5% LEL, there was no smoke, and the oxygen concentration was less than 23.5%. When the concentration of combustible gas was greater than 5% LEL or the oxygen concentration was greater than 23.5%, shear emulsification should be stopped, but stirring and emulsion circulation should not be stopped. At the same time, cooling and refrigeration should be increased. Only when the gas concentration was lower than the control value and the temperature was observed to be lower than the control value could emulsification preparation be carried out again. If visible smoke or a smoke alarm occurred during the emulsion preparation process, emergency measures should be immediately initiated, including immediately stopping the disperser, using water spray, injecting a large amount of cold water, and emptying the material into the emergency pool to avoid subsequent accidents.

[0029] The beneficial effects of the present invention are as follows: By adding hydroperoxide to react with the by-products in the material, the purpose of stabilizing the product is achieved, and the product generated by the reaction is still an organic peroxide, which does not affect the downstream use. At the same time, by using 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, which can be used both as a solvent and a viscosity reducer, the viscosity of the emulsion material decreased by more than 40% at -40°C, and the retention rate of the content after 90 days of storage was greater than 97%, and no freezing occurred. The innovation of the present invention also lies in that both the added stabilizer and the generated product are organic peroxides. Moreover, the present invention adopts high-shear dispersion and a circulating emulsification method at the same time to accelerate the mixing of the material and surface renewal, increase the heat exchange area and efficiency, improve the emulsification efficiency and reduce the safety risk. By online monitoring the concentration of combustible gas, oxygen and smoke, etc., the safety risk control of the corresponding emulsion preparation process is further enhanced. Detailed implementation mode

[0030] To better illustrate the technical method of the present invention, the preparation process is specifically described below and illustrated by examples. Example 1

[0031] (1) Add 602 kg of methanol, 537 kg of water, 60 kg of emulsifier solution (pre-prepared, containing 20 kg of water, 20 kg of methanol and 20 kg of fatty alcohol polyoxyethylene ether emulsifier), and 60 kg of dispersant solution (pre-prepared, containing 48 kg of water, 6 kg of methanol and 6 kg of polyvinyl alcohol dispersant) to the emulsifying kettle, start stirring, with a stirring rate of 180 revolutions per minute, and cool down to -5°C.

[0032] (2) Add 399 kg of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, 587 kg of diisobutyryl peroxide, and 12 kg of 1,1,3,3-tetramethylbutyl hydroperoxide. Control the temperature at -6°C and maintain for 15 minutes.

[0033] (3) Turn on the circulating emulsification pump and its pipeline refrigeration, and control the temperature of the ethylene glycol cold salt for refrigeration at -20°C.

[0034] (4) Cool the materials in the kettle to -10°C, reduce the stirring speed to 150 rpm, adjust the frequency of the circulating emulsification pump to 25 Hz. After 15 minutes, turn on the disperser (rotation speed 1800 rpm) for 35 minutes.

[0035] (5) Stop the disperser, continue to circulate for 15 minutes, then stop the circulating emulsification pump, and finally stop the stirring to obtain a diisobutyryl peroxide emulsion.

[0036] During the preparation process, the concentration of combustible gas is 0% LEL, there is no smoke, and the oxygen concentration is less than 21.5%.

[0037] The content of diisobutyryl peroxide in the emulsion is 24.4%. The viscosity is measured using a DV-1 type BROOKFIELD VISCOMETER (61# rotor, 100 rpm). The viscosity of the emulsion at -10°C is 44 mPa·s. At -35°C, the emulsion flows well, no freezing occurs, the viscosity is 60 mPa·s, and the content is 23.9% after 85 days of storage. The content is 23.6% after 85 days of storage at -25°C. Example 2

[0038] (1) Add 602 kg of methanol, 537 kg of water, 60 kg of emulsifier solution (pre-prepared, containing 20 kg of water, 20 kg of methanol, and 20 kg of fatty alcohol polyoxyethylene ether emulsifier), and 60 kg of dispersant solution (pre-prepared, containing 48 kg of water, 6 kg of methanol, and 6 kg of polyvinyl alcohol dispersant) into the kettle. Turn on the stirring, with a stirring rate of 180 rpm, and cool down to -5°C.

[0039] (2) Add 399 kg of organic solvent (300 kg of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, 99 kg of isododecane), 587 kg of diisobutyryl peroxide, and 12 kg of 1,1,3,3-tetramethylbutyl hydroperoxide. Control the temperature below -6°C and maintain for 15 minutes.

[0040] (3) Turn on the circulating emulsification pump and its pipeline refrigeration, and control the temperature of the ethylene glycol cold salt for refrigeration at -20°C.

[0041] (4)Cool down the materials in the kettle to -10°C, lower the stirring speed to 150 rpm, adjust the frequency of the circulating emulsification pump to 25 Hz. After 15 minutes, start the disperser (rotating speed 1800 rpm) for 35 minutes.

[0042] (5)Stop the disperser. After continuing to circulate for 15 minutes, stop the circulating emulsification pump, and finally stop the stirring to obtain the diisobutyryl peroxide emulsion.

[0043] During the preparation process, the concentration of combustible gas is 0% LEL, there is no smoke, and the oxygen concentration is less than 20.9%.

[0044] The content of diisobutyryl peroxide in the emulsion is 24.2%. The viscosity is measured using a DV-1 type BROOKFIELD VISCOMETER (61# rotor, 100 rpm). The viscosity of the emulsion at -10°C is 46 mPa·s; at -40°C, the emulsion flows well, with a viscosity of 66 mPa·s and no freezing. When stored at different temperatures, the content is 23.7% after 85 days of storage at -40°C; the content is 23.5% after 85 days of storage at -25°C. Example 3

[0045] (1)Add 496.5 kg of methanol, 432 kg of water, 54.5 kg of emulsifier solution (pre-prepared, containing 20 kg of water, 20 kg of methanol, and 14.5 kg of fatty alcohol polyoxyethylene ether emulsifier), and 36 kg of dispersant solution (pre-prepared, containing 29 kg of water, 3.5 kg of methanol, and 3.5 kg of polyvinyl alcohol dispersant) into the kettle. Start stirring at a stirring rate of 180 rpm and cool down to -5°C.

[0046] (2)Add 299 kg of organic solvents (100 kg of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, 199 kg of isododecane) and 1233 kg of diisobutyryl peroxide, 16 kg of tert-amyl hydroperoxide. Control the temperature at -5°C and maintain for 15 minutes.

[0047] (3)Start the refrigeration of the circulating emulsification pump and its pipeline, and control the temperature of the ethylene glycol cold salt for refrigeration at -20°C.

[0048] (4)Cool down the materials in the kettle to -11°C, lower the stirring speed to 150 rpm, adjust the frequency of the circulating emulsification pump to 25 Hz. After 15 minutes, start the disperser (rotating speed 1500 rpm) for 30 minutes.

[0049] (5)Stop the disperser. After continuing to circulate for 10 minutes, stop the circulating emulsification pump, and finally stop the stirring to obtain the diisobutyryl peroxide emulsion.

[0050] During the preparation process, the concentration of combustible gas is 0% LEL, there is no smoke, and the oxygen concentration is less than 21.5%.

[0051] The content of diisobutyryl peroxide in the emulsion is 47.4%. The viscosity was measured using a DV-1 type BROOKFIELD VISCOMETER (61# rotor, 100 rpm). The viscosity of the emulsion was 58 mPa·s at -10 °C; it flowed well at -40 °C, with a viscosity of 79 mPa·s and no freezing occurred. After 90 days of storage, the content was 46.7%.

[0052] Comparative Example 1

[0053] As a comparative example. Otherwise the same as Example 2, without adding the stabilizer 1,1,3,3-tetramethylbutyl hydroperoxide. During the preparation process, the concentration of combustible gas was 2% LEL, there was no smoke, and the oxygen concentration was less than 21.5%.

[0054] The content of diisobutyryl peroxide in the prepared emulsion was 24.6%. The viscosity was measured using a DV-1 type BROOKFIELD VISCOMETER (61# rotor, 100 rpm). The viscosity was 47 mPa·s at -10 °C; it flowed well at -40 °C, with a viscosity of 64 mPa·s and no freezing occurred. When stored at different temperatures, the content was 20.7% after 85 days of storage at -40 °C; the content was 19.3% after 85 days of storage at -25 °C.

[0055] It can be seen that in Comparative Example 1, the content decreased from 24.6% to 20.7% after 85 days of storage at -40 °C, with a decrease rate of 15.8%; the content decreased from 24.6% to 19.3% after 85 days of storage at -25 °C, with a decrease rate of 21.5%.

[0056] In Example 2, the content decreased from 24.2% to 23.7% after 85 days of storage at -40 °C, with a decrease rate of 2%; the content decreased from 24.2% to 23.5% after 85 days of storage at -25 °C, with a decrease rate of 2.9%.

[0057] Comparative Example 2

[0058] As a comparative example. Otherwise the same as Example 3, and the organic solvent added was isododecane. During the preparation process, the concentration of combustible gas was 0% LEL, there was no smoke, and the oxygen concentration was less than 21%.

[0059] The content of diisobutyryl peroxide in the prepared emulsion was 47.6%. The viscosity was measured using a DV-1 type BROOKFIELD VISCOMETER (61# rotor, 100 rpm). The viscosity was 72 mPa·s at -10 °C; the viscosity was 118 mPa·s at -40 °C, with slight freezing. After 90 days of storage, the content was 45.5%. It can be seen from Comparative Example 3 that if only isododecane is added as the organic solvent, the viscosity of the emulsion at -40 °C increases by more than 40%.

Claims

1. A low-temperature stable organic peroxide emulsion, characterized in that, Comprising the following components by mass fraction: Diisobutyryl peroxide 23% - 50%; Stabilizer hydroperoxide 0.5% - 1.0%; the stabilizer hydroperoxide is one or more of tert-amyl hydroperoxide, tert-butyl hydroperoxide, tert-hexyl hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide; Organic solvent 10% - 18%, wherein the organic solvent is a solvent containing 2,2,4-trimethyl-1,3-pentanediol diisobutyrate; Water 15% - 30%; methanol 20% - 30%; emulsifier 0.5% - 0.9%; dispersant 0.1% - 0.3%; The safe preparation method of the low-temperature stable organic peroxide emulsion is to mix each component under low-temperature conditions and form an emulsion by high-shear dispersion coupled with cyclic emulsification method; During the preparation process, the concentration of combustible gas, smoke and oxygen concentration on the surface of the emulsion are monitored in real time; specifically including the following steps: (1) Add methanol, water, emulsifier and dispersant into the emulsification kettle, start stirring, and cool down to the low-temperature condition of -15°C to -5°C; (2) Add diisobutyryl peroxide, organic solvent and stabilizer hydroperoxide, and control the temperature at -15°C to -5°C for 10 - 20 min; (3) Start the cyclic emulsification pump and its pipeline refrigeration, and cool the materials in the kettle to -15 - 5°C; (4) Adjust the frequency of the cyclic emulsification pump to 20 - 40 Hz, start the high-shear disperser after 15 - 20 min for 20 - 40 minutes, and control the rotation speed of the disperser at 1000 - 2000 rpm; (5) After stopping the disperser, continue to circulate for 10 - 20 minutes, stop the cyclic emulsification pump, and finally stop stirring to obtain the final emulsion; When the emulsion is stored at -40°C, its viscosity is 60 - 80 mPa·s and it does not freeze or solidify.

2. The low-temperature stable organic peroxide emulsion according to claim 1, characterized in that, The emulsifier is fatty alcohol polyoxyethylene ether; the dispersant is polyvinyl alcohol with a degree of alcoholysis of 50% - 80%.

3. The low-temperature stable organic peroxide emulsion according to claim 1, wherein The emulsion is circulated from the bottom of the kettle to the top of the kettle through the cyclic emulsification pump, and the pumping rate is 1 - 3 L / s; the cyclic emulsification pump and its pipeline are cooled with ethylene glycol cold salt, and the temperature is controlled at -25°C to -15°C.

4. The low-temperature stable organic peroxide emulsion according to claim 1, wherein, The concentration of combustible gas is less than 5% LEL, there is no smoke, and the oxygen concentration is less than 23.5%; the concentration of combustible gas, smoke and oxygen are fed back in real time through the on-line monitoring system. If the concentration of combustible gas ≥ 5% LEL or the oxygen concentration ≥ 23.5%, then immediately stop shearing and strengthen refrigeration.