A composition for preparing fluororubber latex, fluororubber latex and preparation method

Abstract

The present invention discloses a composition for preparing fluororubber latex, fluororubber latex and a preparation method, relating to the technical field of preparation of fluororubber artificial latex. The composition for preparing fluororubber latex includes a fluorinated rubber solution and an emulsifier with a mass ratio of 1-2.2:1; the raw material composition of the emulsifier includes 5-8 parts by mass of cellulose nanocrystal suspension and 2.2-4.8 parts by mass of a water-absorbing resin; wherein, in the cellulose nanocrystal suspension, the cellulose nanocrystals carry sulfonic acid groups or carboxylic acid groups and are hydrophobically modified. The present invention uses a cellulose nanocrystal suspension as an emulsifier and hydrophobically modifies the cellulose nanocrystals, enhancing the emulsifying ability of the cellulose nanocrystals; and by adding one or more water-absorbing resins such as polyvinyl alcohol, sodium polyacrylate, casein and gelatin, a cavitation effect is formed, further improving the stability of the fluororubber latex.

Description

Technical Field

[0001] The present invention relates to the technical field of preparing fluororubber artificial latex, and specifically relates to a composition for preparing fluororubber latex, a fluororubber latex and a preparation method. Background Art

[0002] Latex is a general term for colloidal emulsions in which polymer microparticles are dispersed in water; among them, fluororubber latex is a kind of latex, which is mainly used as a coating for metals, stones and plastic materials.

[0003] At present, fluororubber latex is mainly prepared by chemical synthesis methods such as emulsion polymerization or suspension polymerization. This preparation method requires the use of a large amount of small molecule monomers, and polymerization reactions are carried out under suitable temperature, stirring speed and initiator, and finally fluororubber emulsion is obtained.

[0004] Regarding the preparation of fluororubber latex by chemical synthesis methods, the inventor believes that the following technical problems exist:

[0005] 1. When preparing fluororubber latex by chemical synthesis methods, it has the disadvantages of having small molecule monomers and polymer residues, high technical difficulty, strict requirements for equipment and complex processes;

[0006] 2. Due to the high density of fluororubber and the large density difference with water, it is extremely easy to settle in the water phase, and the C-F bond is not easy to form an interaction with the lipophilic end of the surfactant. Therefore, the fluororubber emulsion prepared by dry rubber emulsification in the prior art has poor stability and is easy to stratify;

[0007] 3. Emulsifiers are often used in the preparation process of fluororubber latex; for example, in the patent with patent application number CN201510504112.5 and patent name "A nano-emulsion used as a fabric finishing agent and its inverse transition preparation method", an emulsifier is used in the preparation process of the nano-emulsion; the use of emulsifiers will not only cause harm to the environment, but also easily cause irritation to the human eyes, skin and respiratory system.

[0008] Therefore, how to solve the above technical problems, study a production technology for preparing fluororubber latex that is simple, green and efficient, and obtain a fluororubber latex product with good stability is an urgent technical problem to be solved in the current field.

[0009] The information disclosed in this background art section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0010] In view of the above technical problems, embodiments of the present invention provide a composition for preparing fluororubber latex, fluororubber latex and a preparation method to solve the problems raised in the above background art.

[0011] The core of the design concept of the present invention lies in:

[0012] 1. Pickering emulsion is a special emulsion, which is a stable emulsification system composed of tiny solid particles at the liquid interface. It is generally prepared by using solid particles to emulsify rubber latex.

[0013] 2. Cellulose nanocrystals are one-dimensional rod-shaped nanomaterials mainly extracted from natural fibers. They are rich in sources, renewable and degradable. Through research, it is found that cellulose nanocrystals are relatively suitable solid particle emulsifiers. They have amphiphilicity, with a diameter of 5nm - 20nm and a length of 200nm - 400nm. The high aspect ratio of the nanosize enables cellulose nanocrystals to irreversibly adsorb at the oil-water interface, wrapping the oil phase inside to form a dense monolayer interfacial layer.

[0014] 3. Sulfonic acid group or carboxyl group-containing cellulose nanocrystals can be prepared by sulfuric acid acidolysis method, Tempo oxidation method, ammonium persulfate method, potassium permanganate oxidation method, etc. The introduction of sulfonic acid group or carboxyl group can make the surface of cellulose nanocrystals carry negative charges, so that they are more easily dispersed and stabilized in water, thereby enhancing the stability of the emulsion.

[0015] 4. Further research finds that due to the strong interaction between cellulose nanocrystals themselves, they always tend to aggregate. The cellulose nanocrystals can be modified by hydrophobic modification through chemical methods to strengthen the interaction between cellulose nanocrystals and the matrix, prevent the collision and coalescence between adjacent droplets, and improve the emulsion stability.

[0016] 5. At the same time, combined with the cavity stabilization mechanism, one or more water-absorbing resins such as polyvinyl alcohol, sodium polyacrylate, casein and gelatin are added to the system to form a cavity effect. The cavity effect can inhibit the desorption of cellulose nanocrystal particles and prevent the cellulose nanocrystal particles from escaping from the circular latex interface. Once the cellulose nanocrystal particles escape, the cavity effect will press it back to the interface. The cavity effect plays an important role in forming a more stable particle layer at the air / water interface.

[0017] The present invention provides the following technical solutions:

[0018] A composition for preparing fluororubber latex, comprising a fluorine-containing latex and an emulsifier with a mass ratio of 1 - 2.2:1.

[0019] The raw material composition of the emulsifier includes 5-8 parts by mass of cellulose nanocrystal suspension and 2.2-4.8 parts by mass of water-absorbing resin; among them, in the cellulose nanocrystal suspension, the cellulose nanocrystals carry sulfonic acid groups or carboxylic acid groups and are hydrophobically modified.

[0020] Preferably, in the cellulose nanocrystal suspension, the content of cellulose nanocrystals is 1 wt%-5 wt%, the particle size length is 200 nm-400 nm, and the diameter is 5 nm-20 nm.

[0021] A fluororubber latex is prepared from the composition for preparing fluororubber latex described above.

[0022] A method for preparing a fluororubber latex includes the following steps:

[0023] Prepare a fluorine-containing rubber solution;

[0024] Select cellulose nanocrystals with sulfonic acid groups or carboxylic acid groups for hydrophobic modification, and prepare a cellulose nanocrystal suspension;

[0025] Mix the prepared cellulose nanocrystal suspension with the water-absorbing resin to prepare an emulsifier;

[0026] Mix and emulsify the prepared fluorine-containing rubber solution and the emulsifier to prepare a crude latex;

[0027] Perform solvent removal treatment on the prepared crude latex to obtain a fluororubber latex.

[0028] Preferably, preparing the fluorine-containing rubber solution specifically includes:

[0029] Select a high molecular elastomer with fluorine atoms on the main chain or side chain carbon atoms for small piece cutting, and put the cut small pieces into a reaction kettle;

[0030] Add one or more of acetone, toluene and ethyl acetate mixed solution to the reaction kettle, and stir at room temperature to prepare a fluorine-containing rubber solution; specifically, the stirring time at room temperature is 6 h-8 h; the mass concentration of the fluorine-containing rubber solution is 20%-40%.

[0031] Preferably, preparing the cellulose nanocrystal suspension specifically includes:

[0032] Mix ethanol and deionized water with a volume ratio of 9:1 to prepare a mixed solution A;

[0033] Add glacial acetic acid to the mixed solution A for mixing to prepare a mixed solution B, and adjust the pH value range of the mixed solution B to 4-5;

[0034] One or more of modifiers KH550, KH560, and KH570 are added to the mixed solution B for mixing and ultrasonic treatment to prepare a hydrolysis solution; preferably, the dosage of the modifier is 6%-8% relative to the mass of the cellulose nanocrystal suspension.

[0035] The cellulose nanocrystals with sulfonic acid groups or carboxylic acid groups are added to the hydrolysis solution and stirred for modification in a water bath at 65°C - 80°C; and after 3.5 h - 5.5 h, it is transferred to a dialysis bag, soaked in distilled water, and the distilled water is changed every once in a while until the solution is neutral to obtain a cellulose nanocrystal suspension.

[0036] Due to the strong interaction between its own particles, cellulose nanocrystals always tend to aggregate; hydrophobic modification can strengthen the interaction between cellulose nanocrystals and the matrix, enhance its dispersion stability in hydrophobic solutions, and improve the emulsion stability.

[0037] Preferably, preparing an emulsifier by mixing the prepared cellulose nanocrystal suspension with a water-absorbing resin specifically includes:

[0038] Mix 5 - 8 parts of the cellulose nanocrystal suspension and 2.2 - 4.8 parts of the water-absorbing resin and stir to prepare an emulsifier.

[0039] Preferably, the content of cellulose nanocrystals in the cellulose nanocrystal suspension is 1 wt% - 5 wt%, the particle size length is 200 nm - 400 nm, and the diameter is 5 nm - 20 nm.

[0040] 1 wt% - 5 wt% is a suitable concentration of cellulose nanocrystals, and this concentration can ensure the smooth progress of the emulsification process; too low a concentration of cellulose nanocrystals will affect the stability of the emulsion, while too high a concentration will affect the emulsification effect.

[0041] Preferably, preparing a crude latex by mixing and emulsifying the prepared fluororubber latex and an emulsifier specifically includes:

[0042] Mix the fluororubber latex and the emulsifier in a mass ratio of 1 - 2.2:1, and use a high-speed shear mixer to stir the mixed solution for emulsification at a temperature of 23°C - 40°C to obtain a crude latex; specifically, the emulsification time is 8 min - 15 min.

[0043] Preferably, removing the solvent from the prepared crude latex to obtain a fluororubber latex specifically includes:

[0044] Transfer the crude latex to a rotary evaporation flask, and remove the solvent by reduced-pressure rotary evaporation; the initial temperature is 30°C - 60°C, the gauge pressure is 0.08 MPa - 0.1 MPa, and it is gradually heated to 70°C - 75°C. At this temperature, the organic solvent is slowly distilled out. When there is obvious stratification in the recovery flask, it proves that the solvent evaporation is completely finished, and the rotary evaporation is stopped to obtain a fluororubber emulsion.

[0045] The composition for preparing fluororubber latex provided by the embodiment of the present invention has the following beneficial effects:

[0046] 1. The present invention uses cellulose nanocrystal suspension as an emulsifier, and hydrophobically modifies the cellulose nanocrystals, increasing the content of hydrophobic groups in the cellulose nanocrystals, adjusting the proportion of amphiphilic groups, and improving the emulsifying ability; and by adding one or more water-absorbing resins such as polyvinyl alcohol, sodium polyacrylate, casein, and gelatin, a cavitation effect is formed, further improving the stability of the fluororubber latex;

[0047] 2. The emulsion formulation of Pickering emulsion can directly use dry rubber solution to prepare fluororubber latex, with a simple process flow and relatively low requirements for equipment; it solves the technical problems such as the need for chemical reactions such as emulsion polymerization or suspension polymerization in the existing methods for preparing fluororubber emulsion, and the complex production process;

[0048] 3. The present invention abandons traditional externally added anionic emulsifiers, cationic emulsifiers, or nonionic emulsifiers, and uses hydrophobically modified cellulose nanocrystal suspension as an emulsifier for Pickering emulsion emulsification, greatly reducing the usage amount of chemical surfactants, reducing the difficulty of treating production wastewater, reducing energy consumption, reducing the degree of environmental pollution, and protecting the safety of workers;

[0049] 4. The process for preparing Pickering emulsion in the present invention greatly reduces the foaming of the latex in the emulsification stage, increases the actual emulsification quality, and reduces the standing defoaming time;

[0050] 5. The emulsification formulation of the fluororubber latex in the present invention is simple, the formulation mildness is improved, the obtained latex has good stability, and the latex particles still maintain a good dispersed state after standing for half a year, and the particle size distribution of the lower-layer latex changes little. Description of the Drawings

[0051] Figure 1 is the process flow chart for preparing fluororubber latex in the present invention;

[0052] Figure 2 is the static stability effect diagram of the fluororubber latex prepared in Example 1 of the present invention;

[0053] Figure 3 is the static stability effect diagram of the fluororubber latex prepared in Example 2 of the present invention;

[0054] Figure 4 is the static stability effect diagram of the fluororubber latex prepared in Example 3 of the present invention;

[0055] Figure 5 is the particle size distribution diagram of the fluororubber latex prepared in Example 1 of the present invention at different standing times;

[0056] Figure 6 Particle size distribution diagrams of the fluororubber latex prepared in Example 2 of the present invention after standing for different times;

[0057] Figure 7 Particle size distribution diagrams of the fluororubber latex prepared in Example 3 of the present invention after standing for different times;

[0058] Figure 8 Results of preparing fluororubber latex without adding water-absorbing resin in Example 4 of the present invention. Detailed implementation manners

[0059] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0060] In view of the problems mentioned in the above background technology, the embodiments of the present invention provide a composition for preparing fluororubber latex, a fluororubber latex and a preparation method to solve the above technical problems. The specific implementation manners and technical solutions are as follows:

[0061] The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels without special instructions.

[0062] The fluororubber latex and its preparation method involved in the present invention are mainly divided into three parts: 1. Preparation of fluorine-containing rubber solution; 2. Preparation of emulsifier; 3. Emulsification of fluorine-containing rubber solution; For details, please refer to the following embodiments.

[0063] Example 1;

[0064] 1. Preparation of fluorine-containing rubber solution

[0065] Cut the fluororubber, a high molecular elastomer with fluorine atoms on the main chain or side chain carbon atoms, into small rubber blocks and put them into a reaction kettle. Add a certain amount of acetone solution thereto and stir at room temperature for 6 h to prepare a fluorine-containing rubber solution with a concentration of 20%;

[0066] 2. Preparation of emulsifier

[0067] 1) Prepare a cellulose nanocrystal suspension. Mix ethanol and deionized water in a volume ratio of 9:1. Add glacial acetic acid to the solution to adjust the pH value to 5; Add the modifier KH550 (8% of the mass of the cellulose nanocrystal suspension) to the solution; Then ultrasonically treat the mixture for 30 min to obtain a hydrolysis solution; Add cellulose nanocrystals with sulfonate or carboxylate groups to the hydrolysis solution and stir in a 65 °C water bath; After 4 h of modification, transfer it to a dialysis bag and soak it in distilled water, changing the distilled water every once in a while until the solution is neutral;

[0068] 2) Mix and stir a cellulose nanocrystal suspension with a solid content of 3 wt%, a dry weight ratio of 8 parts, 4 parts of polyvinyl alcohol, 0.5 part of sodium polyacrylate, and the rest deionized water to prepare an emulsifier.

[0069] 3. Emulsification of fluorine-containing rubber solution

[0070] 1) Prepare a crude latex: fluorine-containing rubber solution: emulsifier = 1:1 (mass ratio), mix the aqueous phase and the oil phase evenly; at a temperature of 23 °C, use a high-speed shear machine with tooth-to-tooth type to set the rotation speed at 8000 r / min to stir and mix the liquid for emulsification, and the emulsification time is 15 min to obtain a completely emulsified crude latex.

[0071] 2) Perform solvent removal treatment on the crude latex: Transfer the crude latex to a rotary evaporation flask and remove the solvent by reduced-pressure rotary evaporation; the initial temperature is 30 °C, the gauge pressure is 0.08 MPa, and it is gradually heated to 75 °C. At this temperature, the organic solvent is slowly distilled out. When there is obvious stratification in the recovery flask, it proves that the solvent evaporation is completely finished and the rotary evaporation is stopped to obtain fluororubber latex; the latex particle size is 800 nm.

[0072] Conduct a static stability investigation experiment on the above-prepared fluororubber latex, and investigate the change results of the effective particle size distribution after standing for different times. The results are as Figure 2 、 Figure 5 shown.

[0073] Example 2;

[0074] 1. Preparation of fluorine-containing rubber solution

[0075] Cut a fluororubber, a high molecular elastomer with fluorine atoms on the carbon atoms of the main chain or side chain, into small rubber blocks and put them into a reaction kettle. Add a certain amount of ethyl acetate solution thereto and stir at room temperature for 6 h to prepare a fluorine-containing rubber solution with a concentration of 30%.

[0076] 2. Preparation of emulsifier

[0077] 1) Prepare a cellulose nanocrystal suspension. Mix ethanol and deionized water at a volume ratio of 9:1, add glacial acetic acid to the solution to adjust the pH value to 4; add a modifier KH560 (7% of the mass of the cellulose nanocrystal suspension) to the solution; then ultrasonically process the mixture for 45 min to obtain a hydrolysis solution; add cellulose nanocrystals with sulfonic acid groups or carboxylic acid groups to the hydrolysis solution and stir in a 70 °C water bath; after 5.5 h of modification, transfer it to a dialysis bag, soak it with distilled water, and change the distilled water every once in a while until the solution is neutral.

[0078] 2) Prepare an emulsifier by mixing a cellulose nanocrystal suspension with a solid content of 4.2 wt%, a dry weight ratio of 6 parts, 3 parts of gelatin, 0.2 part of sodium polyacrylate, and the rest being deionized water, and stirring them.

[0079] 3. Emulsification of the fluorinated rubber solution

[0080] 1) Prepare a crude latex: the fluorinated rubber solution: emulsifier = 1:1 (mass ratio), mix the aqueous phase and the oil phase evenly; at a temperature of 23 °C, use a high-speed shear mixer with a tooth-to-tooth type to set the rotation speed at 7500 r / min to stir the mixture for emulsification, and the emulsification time is 10 min to obtain a completely emulsified crude latex.

[0081] 2) Remove the solvent from the crude latex: Transfer the crude latex to a rotary evaporation flask and remove the solvent by reduced-pressure rotary evaporation. The initial temperature is 55 °C, the gauge pressure is 0.09 MPa, and it is gradually heated to 70 °C. At this temperature, the organic solvent is slowly distilled out. When there is obvious stratification in the recovery flask, it proves that the solvent evaporation is completely finished and the rotary evaporation is stopped to obtain a fluororubber latex; the latex particle size is 1200 nm.

[0082] Conduct a static stability investigation experiment on the above-prepared fluororubber latex, and investigate the change results of the effective particle size distribution after standing for different times. The results are as Figure 3 、 Figure 6 shown.

[0083] Example 3;

[0084] 1. Preparation of the fluorinated rubber solution

[0085] Cut a fluororubber, a high molecular elastomer with fluorine atoms on the carbon atoms of the main chain or side chain, into small rubber blocks and put them into a reaction kettle. Add a certain amount of ethyl acetate solution thereto and stir at room temperature for 7 h to prepare a fluorinated rubber solution with a concentration of 40%.

[0086] 2. Preparation of the emulsifier

[0087] 1) Prepare a cellulose nanocrystal suspension. Mix ethanol and deionized water at a volume ratio of 9:1, add glacial acetic acid to the solution to adjust the pH value to 5; add a modifier KH570 (7% of the mass of the cellulose nanocrystals) to the solution; then ultrasonically treat the mixture for 55 min to obtain a hydrolyzate; add cellulose nanocrystals with sulfonic acid groups or carboxylic acid groups to the hydrolyzate and stir in a 60 °C water bath; after 3.5 h of modification, transfer it to a dialysis bag, soak it with distilled water, and change the distilled water every once in a while until the solution is neutral.

[0088] 2) Prepare an emulsifier by mixing a cellulose nanocrystal suspension with a solid content of 2.7 wt%, a dry weight ratio of 5 parts, 4 parts of polyvinyl alcohol, 0.6 part of casein, and the rest being deionized water, and stirring them.

[0089] 3. Emulsification of Fluorinated Rubber Solution

[0090] 1) Preparation of crude latex: The mass ratio of fluorinated rubber solution to emulsifier is 1.5:1. Mix the aqueous phase and the oil phase evenly. At a temperature of 40°C, use a high-speed shearing machine with a tooth-to-tooth type to set the rotation speed at 7000 r / min to stir the mixture for emulsification. The emulsification time is 15 min to obtain a completely emulsified crude latex.

[0091] 2) Solvent removal treatment for the crude latex: Transfer the crude latex to a rotary evaporation flask and remove the solvent by reduced-pressure rotary evaporation. The initial temperature is 40°C, the gauge pressure is 0.1 MPa, and it is gradually heated to 75°C. At this temperature, the organic solvent is slowly distilled out. When there is obvious stratification in the recovery flask, it proves that the solvent evaporation is completely finished and the rotary evaporation is stopped to obtain fluororubber latex; the latex particle size is 1000 nm.

[0092] An experiment on the static stability of the above-prepared fluororubber latex was carried out, and the results of the distribution change of the effective particle size after standing for different times were investigated. The results are as Figure 4 、 Figure 7 shown.

[0093] Example 4;

[0094] 1. Preparation of Fluorinated Rubber Solution

[0095] Cut the fluororubber, a high-molecular elastomer with fluorine atoms on the main chain or side chain carbon atoms, into small rubber blocks and put them into a reaction kettle. Add a certain amount of ethyl acetate solution to it and stir at room temperature for 6 h to prepare a fluorinated rubber solution with a concentration of 20%.

[0096] 2. Preparation of Emulsifier

[0097] 1) Prepare a cellulose nanocrystal suspension. Mix ethanol and deionized water in a volume ratio of 9:1, add glacial acetic acid to the solution to adjust the pH value to 4; add the modifier KH550 (7% of the mass of cellulose nanocrystals) to the solution; then ultrasonically treat the mixture for 45 min to obtain a hydrolysis solution; add cellulose nanocrystals with sulfonate or carboxylate groups to the hydrolysis solution and stir in a 65°C water bath; after 5.5 h of modification, transfer it to a dialysis bag, soak it with distilled water, and change the distilled water every once in a while until the solution is neutral.

[0098] 2) Mix and stir the cellulose nanocrystal suspension with a solid content of 5 wt%, 0.2 parts of sodium polyacrylate, and the rest deionized water to prepare an emulsifier.

[0099] 3. Emulsification of Fluorinated Rubber Solution

[0100] 1) Preparation of crude latex: Fluorine-containing rubber solution: emulsifier = 1:1 (mass ratio), mix the aqueous phase and the oil phase evenly; at a temperature of 40 °C, use a high-speed shearing machine with tooth-to-tooth type to set the rotation speed at 8000 r / min to stir the mixture for emulsification, and the emulsification time is 15 min to obtain a completely emulsified crude latex;

[0101] 2) Solvent removal treatment of the crude latex: Transfer the crude latex to a rotary evaporation flask and remove the solvent by reduced-pressure rotary evaporation. The initial temperature is 45 °C, the gauge pressure is 0.1 MPa, and it is gradually heated to 75 °C. At this temperature, the organic solvent is slowly distilled out, and fluororubber precipitates, resulting in demulsification. The demulsification results are as Figure 8 shown.

[0102] From the results of the above Example 1, Example 2 and Example 3, it can be seen that the fluororubber latex prepared by the present invention has good stability. After standing for half a year, the latex particles still maintain a good dispersed state, and the particle size distribution of the lower-layer latex changes little;

[0103] In Example 4, no water-absorbing resin components such as polyvinyl alcohol, sodium polyacrylate, casein and gelatin were added during the preparation of the emulsifier; during the removal of the organic solvent by reduced-pressure rotary evaporation, demulsification occurred; the results of this example confirmed that adding water-absorbing resin during the preparation of fluororubber latex can improve the stability of fluororubber latex.

[0104] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A composition for preparing fluororubber latex, characterized in that, It includes a fluorine-containing glue and an emulsifier in a mass ratio of 1-2.2:1; The raw material composition of the emulsifier includes 5-8 parts of cellulose nanocrystal suspension and 2.2-4.8 parts of water-absorbing resin by weight; wherein, in the cellulose nanocrystal suspension, the cellulose nanocrystal has sulfonate or carboxylate and is hydrophobically modified; The water-absorbing resin is selected from one or more of polyvinyl alcohol, sodium polyacrylate, casein and gelatin; the mass concentration of the fluorine-containing glue is 20%-40%.

2. The composition for preparing fluororubber latex according to claim 1, characterized in that, In the cellulose nanocrystal suspension, the content of cellulose nanocrystals is 1wt%-5wt%, the particle length is 200nm-400nm, and the diameter is 5nm-20nm.

3. A fluororubber latex, characterized in that, The fluororubber latex is prepared from the composition for preparing fluororubber latex according to claim 1 or 2.

4. A preparation method of fluororubber latex, characterized in that The following steps are involved: Prepare fluorine-containing glue; Selecting cellulose nanocrystals with sulfonate groups or carboxylate groups for hydrophobic modification, and preparing a cellulose nanocrystal suspension; The prepared cellulose nanocrystal suspension is mixed with a water-absorbing resin to prepare an emulsifier; The prepared fluorine-containing rubber solution and emulsifier are mixed and emulsified to prepare a crude latex; The prepared crude latex is subjected to a solvent removal treatment to obtain a fluororubber latex; The step of preparing a crude latex by mixing and emulsifying the prepared fluorine-containing rubber solution and an emulsifier specifically comprises: Mixing the fluorine-containing rubber liquid and the emulsifier in a mass ratio of 1-2.2:1, stirring the mixed liquid with a high-speed shearing machine at a temperature of 23°C-40°C for emulsification to obtain a crude latex; The water-absorbing resin is selected from one or more of polyvinyl alcohol, sodium polyacrylate, casein and gelatin; the mass concentration of the fluorine-containing glue is 20%-40%.

5. The preparation method of the fluororubber latex according to claim 4, characterized in that, The preparation of fluorine-containing glue specifically includes: Select a polymer elastomer containing fluorine atoms on the carbon atoms of the main chain or the side chain, cut it into small pieces, and put the cut small pieces into a reaction kettle; One or more mixed solutions of acetone, toluene and ethyl acetate are added into the reaction kettle, and the mixture is stirred at room temperature to prepare the fluorine-containing glue.

6. The preparation method of the fluororubber latex according to claim 4, wherein, The preparation of cellulose nanocrystal suspension specifically includes: Mixing ethanol and deionized water in a volume ratio of 9:1 to prepare a mixed solution A; Add glacial acetic acid to the mixed solution A to prepare the mixed solution B, and adjust the pH value of the mixed solution B to be in the range of 4-5; One or more of the modifiers KH550, KH560 and KH570 are added to the mixed solution B, mixed and ultrasonically treated to prepare a hydrolyzate; Cellulose nanocrystals with sulfonate or carboxylate groups are added to the hydrolyzate, and stirred in a water bath at 65°C-80°C for modification; and after 3.5h-5.5h, they are transferred to a dialysis bag and soaked in distilled water, with the distilled water being replaced at regular intervals until the solution is neutral to obtain a cellulose nanocrystal suspension.

7. The preparation method of the fluororubber latex according to claim 4, characterized in that, The prepared cellulose nanocrystal suspension is mixed with a water-absorbing resin to prepare an emulsifier, specifically comprising: 5-8 parts of cellulose nanocrystal suspension and 2.2-4.8 parts of water-absorbing resin are mixed and stirred to prepare an emulsifier.

8. The preparation method of the fluororubber latex according to claim 7, characterized in that, The content of cellulose nanocrystals in the cellulose nanocrystal suspension is 1wt%-5wt%, the particle length is 200nm-400nm, and the diameter is 5nm-20nm.

9. The preparation method of the fluororubber latex according to claim 4, wherein, The prepared crude latex is subjected to a solvent removal treatment to obtain a fluororubber latex, which specifically comprises: Transfer the crude latex into a rotary evaporation flask and remove the solvent by rotary evaporation under reduced pressure; the initial temperature is 30°C - 60°C, the gauge pressure is 0.08 MPa - 0.1 MPa, and gradually heat up to 70°C - 75°C. Slowly distill out the organic solvent at this temperature. When there is obvious stratification in the recovery flask, it proves that the solvent evaporation is completely finished and the rotary evaporation ends, obtaining a fluororubber emulsion.

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