Raw fluororubber and preparation method thereof

Abstract

The invention relates to raw fluororubber and a preparation method thereof, and the preparation method comprises the following steps: (1) mixing a dispersant, an initiator, a molecular weight regulator, a pH regulator and water to obtain an aqueous solution; and (2) introducing liquid vinylidene fluoride, a liquid fluoropropylene compound and the aqueous solution prepared in the step (1) into a microreactor for reaction, and performing separation and purification to obtain the raw fluororubber, the preparation method of the raw fluororubber can realize efficient heat transfer and mass transfer, can accurately control reaction parameters, also has the advantages of small occupied area, high safety performance, continuous production and the like, and does not have the risk of gas leakage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, and particularly relates to a fluororubber raw rubber and a preparation method thereof. BACKGROUND

[0002] The fluororubber (FKM) has excellent heat resistance, oxidation resistance, oil resistance, corrosion resistance and atmospheric aging resistance, and is widely used in the fields of aerospace, aviation, automobile, petroleum and household appliances. For example, sealing materials in aircraft hydraulic systems, sealing materials in oil fields, sealing materials in flexible connections of mechanical equipment, etc.

[0003] At present, many fluorine chemical production manufacturers at home and abroad synthesize fluororubber through a reaction kettle. However, since the reaction raw materials (such as vinylidene fluoride, tetrafluoroethylene and perfluoropropylene) are gaseous, the sealing performance of the reaction kettle is required to be high, the sealing performance of the traditional reaction kettle is relatively poor, the temperature control precision is low, there is a risk of gas leakage, and there is a certain safety hazard. Moreover, the reaction raw materials need to be added according to the reaction condition during the reaction, the controllability is poor, and time and labor are consumed.

[0004] Therefore, it is necessary to develop a preparation method of fluororubber raw rubber with high safety and good controllability. SUMMARY

[0005] To solve the above technical problems, the present application provides a fluororubber raw rubber and a preparation method thereof. The preparation method of the fluororubber raw rubber can realize efficient heat and mass transfer, can accurately control the reaction parameters, has the advantages of small occupied area, high safety performance, continuous production, etc., has no risk of gas leakage, and the prepared fluororubber raw rubber has the advantages of small molecular weight distribution coefficient and large tensile strength.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a preparation method of a fluororubber raw rubber, which comprises the following steps:

[0008] (1) mixing a dispersing agent, an initiator, a molecular weight regulator, a pH regulator and water to obtain an aqueous solution;

[0009] (2) passing liquid vinylidene fluoride and liquid fluoropropylene compound into the microreactor to react with the aqueous solution prepared in step (1), and separating and purifying to obtain the fluororubber raw rubber.

[0010] In the present application, the preparation method of the fluoro rubber raw rubber can realize efficient heat and mass transfer, can accurately control the reaction parameters, has the advantages of small occupied area, high safety performance, continuous production, etc., has no risk of gas leakage, does not need to use surfactants or dispersing aids, and does not need to add reaction monomers to the reaction kettle according to the reaction situation; the prepared fluoro rubber raw rubber has the characteristics of small molecular weight distribution coefficient and large tensile strength.

[0011] Preferably, the dispersant includes perfluorooctanoic acid.

[0012] Preferably, the initiator includes any one or a combination of at least two of sodium phosphate, ammonium persulfate or sodium sulfite.

[0013] Preferably, the molecular weight regulator includes an alcohol molecular weight regulator.

[0014] Preferably, the alcohol molecular weight regulator includes any one or a combination of at least two of methanol, ethanol or trifluoromethanol.

[0015] Preferably, the pH regulator includes any one or a combination of at least two of sodium carbonate, sodium bicarbonate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate or dipotassium hydrogen phosphate.

[0016] Preferably, the liquid vinylidene fluoride is stored in a pressure storage tank, the pressure of the pressure storage tank is 4.5-5 MPa (for example, 4.55 MPa, 4.6 MPa, 4.65 MPa, 4.7 MPa, 4.75 MPa, 4.8 MPa, 4.85 MPa, 4.9 MPa or 4.95 MPa, etc.), and the temperature is 20-30°C (for example, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C or 29°C, etc.).

[0017] Preferably, the liquid fluorinated propylene compound is stored in a pressure storage tank, the pressure of the pressure storage tank is 1.5-2 MPa (for example, 1.55 MPa, 1.6 MPa, 1.65 MPa, 1.7 MPa, 1.75 MPa, 1.8 MPa, 1.85 MPa, 1.9 MPa or 1.95 MPa, etc.), and the temperature is 20-30°C (for example, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C or 29°C, etc.).

[0018] Preferably, the liquid fluorinated propylene compound includes liquid hexafluoropropylene.

[0019] Preferably, the water includes deionized water.

[0020] Preferably, the mass fraction of the dispersant in step (1) is 0.001-0.5 parts, for example 0.01 parts, 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts or 0.45 parts, etc., based on 100 parts of the mass of water.

[0021] Preferably, the mass fraction of the initiator in step (1) is 0.01-0.1 parts, for example 0.02 parts, 0.03 parts, 0.04 parts, 0.05 parts, 0.06 parts, 0.07 parts, 0.08 parts or 0.09 parts, etc., based on 100 parts of the mass of water.

[0022] Preferably, the mass fraction of the molecular weight regulator in step (1) is 0.05-0.3 parts, for example 0.08 parts, 0.11 parts, 0.14 parts, 0.17 parts, 0.20 parts, 0.25 parts or 0.28 parts, etc., based on 100 parts of the mass of water.

[0023] Preferably, the mass fraction of the pH regulator in step (1) is 0.15-0.3 parts, for example 0.17 parts, 0.19 parts, 0.21 parts, 0.23 parts, 0.25 parts, 0.27 parts or 0.29 parts, etc., based on 100 parts of the mass of water.

[0024] Preferably, the temperature of the reaction in step (2) is 20-80℃, for example 30℃, 40℃, 50℃, 60℃ or 70℃, etc.

[0025] Preferably, the time of the reaction is 4-6h, for example 4.2h, 4.4h, 4.6h, 4.8h, 5.0h, 5.2h, 5.4h, 5.6h or 5.8h, etc.

[0026] In the present application, the time of the reaction means the residence time of the material in the microreactor.

[0027] Preferably, the pressure in the microreactor is 4.5-5MPa (for example 4.55MPa, 4.6MPa, 4.65MPa, 4.7MPa, 4.75MPa, 4.8MPa, 4.85MPa, 4.9MPa or 4.95MPa, etc.).

[0028] In the present application, the pressure in the microreactor is preferably 4.5-5MPa, which ensures that the liquid vinylidene fluoride and the liquid fluorinated propylene compound are in liquid state in the microreactor and fully participate in the reaction. If the pressure in the microreactor is too high, the reaction rate is too fast and the molecular weight distribution coefficient of the product is too large. If the pressure in the microreactor is too low, part of the raw materials become gaseous, the reaction ratio deviates greatly and the molecular weight distribution coefficient of the product is too large.

[0029] Preferably, the ratio of the total mass flow rate of the liquid vinylidene fluoride and liquid fluoropropylene compound to the mass flow rate of the aqueous solution is (18-42): (58-82), for example, 20:80, 22:78, 24:76, 28:72, 30:70, 32:68, 34:66, 32:68, 34:66, 36:64, 38:62 or 40:60, etc.

[0030] Preferably, the ratio of the mass flow rate of the liquid vinylidene fluoride to the mass flow rate of the liquid fluoropropylene compound is (9-21):(9-21), for example, 9:21, 11:19, 13:17, 15:15, 17:13, 19:11 or 21:9. Preferably, the separation and purification comprises the steps of freeze coagulation, washing, extrusion dehydration, vacuum drying and plasticizing.

[0031] In a second aspect, the present invention provides a fluororubber raw rubber, which is prepared by the preparation method described in the first aspect.

[0032] Preferably, the number average molecular weight of the fluororubber raw rubber is 70,000 to 110,000, for example, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000 or 105,000.

[0033] Preferably, the molecular weight distribution coefficient of the fluororubber raw rubber is 2.2 to 4.1, for example, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8 or 4.0.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] The present invention uses liquid vinylidene fluoride and liquid fluoropropylene compounds to react in a microreactor, thereby achieving efficient heat and mass transfer and accurately controlling reaction parameters such as temperature, pressure, flow rate, residence time, etc., and also has the advantages of small footprint, high safety performance, continuous production, and no risk of gas leakage. The yield of the prepared fluororubber raw rubber is ≥61%, the number average molecular weight is 70,000 to 110,000, the molecular weight distribution coefficient is 2.2 to 4.1, and the tensile strength is 16.9 to 19.9 MPa. In a preferred embodiment, the yield is ≥77%, the number average molecular weight is 90,000 to 100,000, the molecular weight distribution coefficient is 2.2 to 2.5, and the tensile strength is 19.0 to 19.9 MPa. The invention has the advantages of small molecular weight distribution coefficient, high tensile strength, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the infrared spectrum of the fluororubber raw rubber obtained in Example 1. DETAILED DESCRIPTION

[0037] The technical solutions of the present application are further illustrated below in conjunction with the accompanying drawings and through specific embodiments. However, the following examples are merely simple examples of the present application and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.

[0038] Embodiment 1

[0039] The present embodiment provides a fluororubber raw rubber and a preparation method thereof, the preparation method comprising the following steps:

[0040] (1) 0.09 parts by mass of a dispersing agent (perfluorooctanoic acid), 0.25 parts by mass of a pH regulator (sodium carbonate), 0.2 parts by mass of a molecular weight regulator (methanol), 0.04 parts by mass of an initiator (ammonium persulfate), and 100 parts by mass of deionized water are mixed, stirred uniformly for dissolution, filtered through a filter, and then a water solution is obtained and stored in a storage tank;

[0041] (2) Vinylidene fluoride is introduced into a pressure storage tank for pressurization, the pressure of the pressure storage tank is 4.5 MPa, and the temperature is 25°C, so as to form liquid vinylidene fluoride;

[0042] Hexafluoropropylene is introduced into a pressure storage tank for pressurization, the pressure of the pressure storage tank is 2 MPa, and the temperature is 25°C, so as to form liquid hexafluoropropylene;

[0043] The liquid vinylidene fluoride, the liquid hexafluoropropylene, and the water solution obtained in step (1) are introduced into a microreactor (the size of the reaction channel is 5 mm) through a metering pump according to a mass flow ratio of 18:12:70 for reaction, the temperature of the reaction is 60°C, the pressure in the microreactor is 4.5 MPa, and the residence time of the material in the microreactor is 5 h, then the emulsion obtained by the reaction is subjected to freezing coagulation, washing, extrusion dehydration, vacuum drying, and plastication, so as to obtain the fluororubber raw rubber.

[0044] Embodiment 2

[0045] The present embodiment provides a fluororubber raw rubber and a preparation method thereof, the preparation method comprising the following steps:

[0046] Step (1) is to mix 0.4 parts by mass of a dispersing agent (perfluorooctanoic acid), 0.3 parts by mass of a pH regulator (sodium bicarbonate), 0.15 parts by mass of a molecular weight regulator (methanol), 0.06 parts by mass of an initiator (ammonium persulfate), and 100 parts by mass of deionized water, stir uniformly for dissolution, filter through a filter, and then a water solution is obtained and stored in a storage tank;

[0047] (2) Vinylidene fluoride is introduced into a pressure storage tank for pressurization, the pressure of the pressure storage tank is 4.5 MPa, and the temperature is 25°C, so as to form liquid vinylidene fluoride;

[0048] The liquid hexafluoropropylene and the aqueous solution prepared in step (1) are introduced into a micro-reactor through a metering pump at a mass flow ratio of 12:13:75 to react at a temperature of 70°C, a pressure of 5 MPa in the micro-reactor, and a residence time of 5 h in the micro-reactor, and then the emulsion obtained by the reaction is subjected to freezing coagulation, washing, extrusion dewatering, vacuum drying, and plasticizing to obtain the fluororubber raw rubber.

[0049] The liquid hexafluoropropylene and the aqueous solution prepared in step (1) are introduced into a micro-reactor through a metering pump at a mass flow ratio of 12:13:75 to react at a temperature of 70°C, a pressure of 5 MPa in the micro-reactor, and a residence time of 5 h in the micro-reactor, and then the emulsion obtained by the reaction is subjected to freezing coagulation, washing, extrusion dewatering, vacuum drying, and plasticizing to obtain the fluororubber raw rubber.

[0050] Example 3

[0051] The present embodiment provides a fluororubber raw rubber and a preparation method thereof, and the preparation method comprises the following steps:

[0052] Step (1) is to mix 0.2 parts by mass of a dispersant (perfluorooctanoic acid), 0.15 parts by mass of a pH regulator (sodium dihydrogen phosphate), 0.08 parts by mass of a molecular weight regulator (methanol), 0.08 parts by mass of an initiator (sodium sulfite), and 100 parts by mass of deionized water, stir and dissolve uniformly, filter through a filter, and obtain an aqueous solution, which is stored in a storage tank;

[0053] (2) The liquid hexafluoropropylene and the aqueous solution prepared in step (1) are introduced into a micro-reactor through a metering pump at a mass flow ratio of 12:13:75 to react at a temperature of 70°C, a pressure of 5 MPa in the micro-reactor, and a residence time of 5 h in the micro-reactor, and then the emulsion obtained by the reaction is subjected to freezing coagulation, washing, extrusion dewatering, vacuum drying, and plasticizing to obtain the fluororubber raw rubber.

[0054] The liquid hexafluoropropylene and the aqueous solution prepared in step (1) are introduced into a micro-reactor through a metering pump at a mass flow ratio of 12:13:75 to react at a temperature of 70°C, a pressure of 5 MPa in the micro-reactor, and a residence time of 5 h in the micro-reactor, and then the emulsion obtained by the reaction is subjected to freezing coagulation, washing, extrusion dewatering, vacuum drying, and plasticizing to obtain the fluororubber raw rubber.

[0055] The liquid hexafluoropropylene and the aqueous solution prepared in step (1) are introduced into a micro-reactor through a metering pump at a mass flow ratio of 12:13:75 to react at a temperature of 70°C, a pressure of 5 MPa in the micro-reactor, and a residence time of 5 h in the micro-reactor, and then the emulsion obtained by the reaction is subjected to freezing coagulation, washing, extrusion dewatering, vacuum drying, and plasticizing to obtain the fluororubber raw rubber.

[0056] Example 4

[0057] The present embodiment provides a fluororubber raw rubber and a preparation method thereof, and the preparation method comprises the following steps:

[0058] Example 5

[0059] The embodiment provides a fluororubber raw rubber and a preparation method thereof, which are different from the embodiment 1 only in that the mass flow ratio of liquid vinylidene fluoride, liquid hexafluoropropylene and aqueous solution is adjusted to 12:8:80, and other conditions are the same as those in the embodiment 1.

[0060] Embodiment 6

[0061] The embodiment provides a fluororubber raw rubber and a preparation method thereof, which are different from the embodiment 1 only in that the mass fraction of the molecular weight regulator (methanol) is adjusted to 0.3 parts, and other conditions are the same as those in the embodiment 1.

[0062] Embodiment 7

[0063] The embodiment provides a fluororubber raw rubber and a preparation method thereof, which are different from the embodiment 1 only in that the mass fraction of the molecular weight regulator (methanol) is adjusted to 0.05 parts, and other conditions are the same as those in the embodiment 1.

[0064] Embodiment 8

[0065] The embodiment provides a fluororubber raw rubber and a preparation method thereof, which are different from the embodiment 1 only in that the reaction temperature is adjusted to 20 DEG C, and other conditions are the same as those in the embodiment 1.

[0066] Embodiment 9

[0067] The embodiment provides a fluororubber raw rubber and a preparation method thereof, which are different from the embodiment 1 only in that the reaction temperature is adjusted to 80 DEG C, and other conditions are the same as those in the embodiment 1.

[0068] Embodiment 10

[0069] The embodiment provides a fluororubber raw rubber and a preparation method thereof, which are different from the embodiment 1 only in that the molecular weight regulator (methanol) is replaced by the same mass of the molecular weight regulator (ethanol), and other conditions are the same as those in the embodiment 1.

[0070] Embodiment 11

[0071] The embodiment provides a fluororubber raw rubber and a preparation method thereof, which are different from the embodiment 1 only in that the molecular weight regulator (methanol) is replaced by the same mass of the molecular weight regulator (trifluoromethanol), and other conditions are the same as those in the embodiment 1.

[0072] Embodiment 12

[0073] The embodiment provides a fluororubber raw rubber and a preparation method thereof, which are different from the embodiment 1 only in that the molecular weight regulator (methanol) is replaced by the same mass of the molecular weight regulator (diethyl malonate), and other conditions are the same as those in the embodiment 1.

[0074] Comparative example 1

[0075] The embodiment provides a fluororubber raw rubber and a preparation method thereof, which are only different from those of embodiment 1 in that step (2) is adjusted as follows: the aqueous solution prepared in step (1) is added into a reaction kettle, the reaction kettle is deoxygenated and heated to 60 DEG C, gaseous vinylidene fluoride and hexafluoropropylene are introduced into the reaction kettle, the mass flow ratio of the vinylidene fluoride and the hexafluoropropylene is 18:12, the pressure of the reaction kettle is 0.7 MPa, the vinylidene fluoride and the hexafluoropropylene are additionally added during the reaction to maintain the constant pressure of the reaction kettle, the vinylidene fluoride and the hexafluoropropylene are not continuously introduced when the mass ratio of the introduced vinylidene fluoride and hexafluoropropylene to the aqueous solution is 30:70, and the reaction is ended. The emulsion obtained in the reaction is subjected to freezing coagulation, washing, extrusion dewatering, vacuum drying and plasticating to obtain the fluororubber raw rubber. Other conditions are the same as those of embodiment 1.

[0076] The fluororubber raw rubbers prepared in embodiments 1-12 and the fluororubber raw rubber prepared in comparative example 1 are subjected to the following tests.

[0077] (1) Number average molecular weight and molecular weight distribution: a gel permeation chromatograph (GPC) is used for testing, the model is Agilent 1260Infinity II, and an Agilent Polargel-M single column is used, 50 DEG C, a flow rate of 1 mL / min. PS and PMMA standards are supported, and the measurement interval is Mn=200-100W.

[0078] (2) Tensile strength and elongation at break: the tensile strength and elongation at break of a molded sample are determined by using a universal tensile testing machine (ETM503A, Shenzhen Wan Test Equipment Co., Ltd.) according to the method described in ASTM D638. The experimental environment temperature is 23 DEG C ± 2 DEG C, the tensile speed is 50 mm / min ± 5 mm / min, and the clamp spacing is 24 mm.

[0079] (3) Mooney viscosity: the cavity of a mold is first heated to (100 ± 1) DEG C, then the sample is placed in the mold cavity and preheated for a certain period of time, and then the viscometer starts to work. When the rotor rotates, the scale value of the instrument is observed, and the value is the Mooney viscosity value of the rubber, which is simply referred to as Mooney viscosity.

[0080] (4) Thermal decomposition temperature: about 10 mg of the fluororubber raw rubber sample is taken, a thermogravimetric analyzer (TGA 2SF / 1100, METELER) is used, the temperature is raised from 50 DEG C to 600 DEG C at a rate of 10 DEG C / min under a nitrogen atmosphere, and the thermal weight loss curve is recorded. The temperature at which 1% (wt) of the weight is lost is taken as the decomposition temperature.

[0081] Table 1

[0082]

[0083]

[0084] " / " in Table 1 represents that the test is not performed.

[0085] As can be seen from the test results in Table 1, the fluororubber raw rubber prepared by the preparation method provided in Examples 1-12 has a yield of ≥ 61%, a number average molecular weight of 70,000-110,000, a molecular weight distribution coefficient of 2.2-4.1, a tensile strength of 16.9-19.9 MPa, a Mooney viscosity of 42.3-60.2 M, and a thermal decomposition temperature of 439-452°C.

[0086] Figure 1 the infrared spectrum of the fluororubber raw rubber prepared in Example 1 is shown in Fig. 1, Figure 1 the peak at 1150 cm -1 is a characteristic peak of C-F, the peak at 2922 cm -1 is a characteristic peak of methylene, and the fluororubber raw rubber is successfully prepared.

[0087] Compared with Example 1, if the ratio of the mass flow rate of the liquid vinylidene fluoride and the liquid fluorinated propylene compound to the mass flow rate of the aqueous solution is too high (Example 4), the yield, the number average molecular weight, and the physical properties are reduced, and the molecular weight distribution coefficient is too large; if the ratio of the mass flow rate of the liquid vinylidene fluoride and the liquid fluorinated propylene compound to the mass flow rate of the aqueous solution is too low (Example 5), the number average molecular weight and the physical properties are reduced, and thus it is preferred that the ratio of the mass flow rate of the liquid vinylidene fluoride and the liquid fluorinated propylene compound to the mass flow rate of the aqueous solution is (25-35):(65-75), and the fluororubber raw rubber prepared is better.

[0088] Compared with Example 1, if the mass fraction of the molecular weight regulator is too high (Example 6), the number average molecular weight and the physical properties are reduced; if the mass fraction of the molecular weight regulator is too low (Example 7), the molecular weight distribution coefficient is too large and the physical properties are reduced, and thus it is preferred that the mass fraction of the molecular weight regulator is 0.15-0.25 based on 100 parts of water, and the fluororubber raw rubber prepared is better.

[0089] Compared with Example 1, if the reaction temperature is too low (Example 8), the yield, the number average molecular weight, and the physical properties are reduced, and the molecular weight distribution coefficient is too large; if the reaction temperature is too high (Example 9), the yield and the physical properties are reduced, and the molecular weight distribution coefficient is too large, and thus it is preferred that the reaction temperature is 50-70°C, and the fluororubber raw rubber prepared is better.

[0090] Compared with Example 1, Example 10, Example 11, and Example 12, the fluororubber raw rubber prepared by using the alcohol molecular weight regulator as the molecular weight regulator is better.

[0091] The fluoroelastomer raw rubber of Example 1 has a greater tensile strength than that of Comparative Example 1.

[0092] The applicant states that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and it should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all of them fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing fluororubber raw rubber, characterized in that: The preparation method comprises the following steps: (1) mixing a dispersant, an initiator, a molecular weight regulator, a pH regulator, and water to obtain an aqueous solution; (2) Liquid vinylidene fluoride, liquid fluoropropylene compound and the aqueous solution prepared in step (1) are introduced into a microreactor for reaction, and separated and purified to obtain the fluororubber raw rubber.

2. The preparation method according to claim 1, characterized in that The dispersant includes perfluorooctanoic acid; Preferably, the initiator comprises any one or a combination of at least two of sodium phosphate, ammonium persulfate or sodium sulfite; Preferably, the molecular weight regulator comprises an alcohol molecular weight regulator; Preferably, the alcohol molecular weight regulator includes any one of methanol, ethanol or trifluoromethanol or a combination of at least two thereof; Preferably, the pH adjuster includes any one of sodium carbonate, sodium bicarbonate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate or dipotassium hydrogen phosphate, or a combination of at least two thereof.

3. The preparation method according to claim 1 or 2, characterized in that The liquid vinylidene fluoride is stored in a pressure storage tank with a pressure of 4.5-5 MPa and a temperature of 20-30°C; Preferably, the liquid fluoropropylene compound is stored in a pressure storage tank, and the pressure of the pressure storage tank is 1.5-2 MPa and the temperature is 20-30°C.

4. The preparation method according to any one of claims 1 to 3, characterized in that The liquid fluoropropylene compound includes liquid hexafluoropropylene; Preferably, the water comprises deionized water.

5. The preparation method according to any one of claims 1 to 4, characterized in that In the step (1), the mass fraction of the dispersant is 0.001 to 0.5 parts based on the mass fraction of water being 100 parts; Preferably, in step (1), the mass fraction of the initiator is 0.01 to 0.1 parts based on 100 parts by mass of water; Preferably, in step (1), the mass fraction of the molecular weight regulator is 0.05 to 0.3 parts based on 100 parts by mass of water; Preferably, in step (1), the mass fraction of the pH regulator is 0.15 to 0.3 parts based on 100 parts by mass of water.

6. The preparation method according to any one of claims 1 to 5, characterized in that The reaction temperature in step (2) is 20-80° C. Preferably, the reaction time is 3 to 8 hours; Preferably, the pressure in the microreactor is 4.5-5 MPa.

7. The preparation method according to any one of claims 1 to 6, characterized in that The ratio of the total mass flow rate of the liquid vinylidene fluoride and liquid fluoropropylene compound to the mass flow rate of the aqueous solution is (18-42): (58-82); Preferably, the ratio of the mass flow rate of the liquid vinylidene fluoride to the mass flow rate of the liquid fluoropropylene compound is (9-21):(9-21).

8. The preparation method according to any one of claims 1 to 7, characterized in that The separation and purification comprises the steps of freezing and condensing, washing, extrusion dehydration, vacuum drying and plasticizing and molding.

9. A fluororubber raw rubber, characterized in that: The fluororubber raw rubber is prepared by the preparation method according to any one of claims 1 to 8.

10. The fluororubber raw rubber according to claim 9, characterized in that: The number average molecular weight of the fluororubber raw rubber is 70,000 to 110,000; Preferably, the molecular weight distribution coefficient of the fluororubber raw rubber is 2.2 to 4.1.

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