CN116836494B - Composition for preparing fluororubber latex, fluororubber latex and preparation method - Google Patents
Composition for preparing fluororubber latex, fluororubber latex and preparation methodInfo
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- CN116836494B CN116836494B CN202310663790.0A CN202310663790A CN116836494B CN 116836494 B CN116836494 B CN 116836494B CN 202310663790 A CN202310663790 A CN 202310663790A CN 116836494 B CN116836494 B CN 116836494B
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- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/02—Making solutions, dispersions, lattices or gels by other methods than by solution, emulsion or suspension polymerisation techniques
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- C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
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- C08J2429/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
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- C08J2433/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
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Abstract
The invention discloses a composition for preparing fluororubber latex, fluororubber latex and a preparation method thereof, and relates to the technical field of fluororubber artificial latex preparation. The composition for preparing the fluororubber latex comprises a fluororubber solution and an emulsifier in a mass ratio of 1-2.2:1, wherein the raw materials of the emulsifier comprise 5-8 parts of cellulose nanocrystal suspension and 2.2-4.8 parts of water-absorbent resin in parts by mass, and the cellulose nanocrystal suspension is hydrophobically modified by the presence of sulfonate or carboxylate. The invention adopts the cellulose nanocrystalline suspension as an emulsifying agent, carries out hydrophobic modification on cellulose nanocrystalline, enhances the emulsifying capacity of the cellulose nanocrystalline, forms a cavity effect by adding one or more water-absorbing resins such as polyvinyl alcohol, sodium polyacrylate, casein, gelatin and the like, and further improves the stability of the fluororubber latex.
Description
Technical Field
The invention relates to the technical field of fluororubber artificial latex preparation, in particular to a composition for preparing fluororubber latex, fluororubber latex and a preparation method.
Background
The latex is a general term for colloidal emulsions formed by dispersing polymer particles in water, and the fluororubber latex is one of the latices and is mainly used as a coating layer of metal, stone and plastic materials.
At present, fluororubber latex is mainly prepared by adopting chemical synthesis methods such as emulsion polymerization or suspension polymerization, and the preparation method needs to use a large amount of small-molecule monomers to carry out polymerization under the action of proper temperature, stirring speed and initiator, so that fluororubber emulsion is finally obtained.
For the preparation of fluororubber latex by chemical synthesis, the inventors consider the following technical problems:
1. the fluororubber latex prepared by the chemical synthesis method has the defects of small molecular monomer and polymer residues, high technical difficulty, severe requirements on equipment and complex process;
2, fluororubber is extremely easy to settle in water phase due to high density and large water density difference, and C-F bond and the oil-friendly end of the surfactant are not easy to form interaction, so that fluororubber emulsion prepared by adopting dry latex in the prior art has poor stability and is easy to delaminate;
3. An emulsifier is often used in the preparation process of fluororubber latex, for example, the patent application number is CN201510504112.5, the patent name is a nanometer latex used as a textile finishing agent and a phase inversion preparation method thereof, the emulsifier is used in the preparation process of the nanometer latex, and the use of the emulsifier is harmful to the environment and is easy to cause irritation to eyes, skin and respiratory systems of human bodies.
Therefore, how to solve the above technical problems, to study a production technology of fluororubber latex with simple preparation and green and high efficiency, and to obtain a fluororubber latex product with good stability, is a technical problem that needs to be solved in the field at present.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.
Disclosure of Invention
In view of the above technical problems, embodiments of the present invention provide a composition for preparing fluororubber latex, fluororubber latex and preparation method thereof, so as to solve the problems set forth in the background art.
The core of the design concept of the invention is that:
1. Pickering emulsion (Pickering emulsion) is a special emulsion, which is a stable emulsifying system consisting of solid particles with small particle sizes on a liquid interface, and is generally prepared by emulsifying rubber glue solution by solid particles;
2. The cellulose nanocrystalline is a nanoscale one-dimensional rod-shaped material which is mainly extracted from natural fibers, has rich sources, can be regenerated and can be degraded, is a relatively suitable solid particle emulsifier through research, has amphipathy, has the diameter of 5nm-20nm, the length of 200nm-400nm and the nanoscale with high length-diameter ratio, enables the cellulose nanocrystalline to be irreversibly adsorbed at an oil-water interface, and wraps an oil phase into the oil phase to form a compact single-layer interface layer;
3. The cellulose nanocrystalline with sulfonate or carboxylate can be prepared by a sulfuric acid hydrolysis method, a Tempo oxidation method, an ammonium persulfate method, a potassium permanganate oxidation method and the like, and the introduction of sulfonate or carboxylate can lead the surface of the cellulose nanocrystalline to have negative charges, so that the cellulose nanocrystalline is easier to disperse and stabilize in water, and the stability of emulsion is enhanced;
4. Further research shows that the cellulose nanocrystals always tend to aggregate due to stronger acting force among the self particles, and the cellulose nanocrystals can be subjected to hydrophobic modification by a chemical method to strengthen the action between the cellulose nanocrystals and a matrix, prevent collision and coalescence between adjacent liquid drops and improve emulsion stability;
5. Simultaneously, one or more water-absorbing resins such as polyvinyl alcohol, sodium polyacrylate, casein, gelatin and the like are added into the system to form a cavitation effect by combining a cavitation stabilization mechanism, the cavitation effect can inhibit desorption of cellulose nanocrystalline particles and prevent the cellulose nanocrystalline particles from escaping from a circular latex interface, once the cellulose nanocrystalline particles escape, the cavitation effect presses the cellulose nanocrystalline particles back to the interface, and the cavitation effect plays an important role in forming a more stable particle layer on an air/water interface.
The invention provides the following technical scheme:
a composition for preparing fluororubber latex comprises a fluororubber solution and an emulsifier in a mass ratio of 1-2.2:1;
the raw materials of the emulsifier comprise, by mass, 5-8 parts of cellulose nanocrystalline suspension and 2.2-4.8 parts of water-absorbent resin, wherein in the cellulose nanocrystalline suspension, cellulose nanocrystalline carries sulfonate or carboxylate and is subjected to hydrophobic modification.
Preferably, in the cellulose nanocrystalline suspension, the content of cellulose nanocrystalline is 1wt% -5wt%, the particle size length is 200nm-400nm, and the diameter is 5nm-20nm.
A fluororubber latex is prepared from the composition for preparing the fluororubber latex.
A method for preparing fluororubber latex, comprising the following steps:
Preparing fluorine-containing glue solution;
Selecting cellulose nanocrystalline with sulfonate or carboxylate to carry out hydrophobic modification, and preparing cellulose nanocrystalline suspension;
mixing the prepared cellulose nanocrystalline suspension with water-absorbent resin to prepare an emulsifier;
mixing and emulsifying the prepared fluorine-containing glue solution and an emulsifier to prepare coarse latex;
And (3) removing the solvent from the prepared coarse latex to obtain the fluororubber latex.
Preferably, the preparation of the fluorine-containing glue solution specifically comprises the following steps:
selecting a high polymer elastomer containing fluorine atoms on carbon atoms of a main chain or a side chain to cut small blocks, and placing the cut small blocks into a reaction kettle;
Adding one or more mixed solutions of acetone, toluene and ethyl acetate into a reaction kettle, stirring at room temperature to prepare fluorine-containing glue solution, wherein the stirring time at room temperature is specifically 6-8 h, and the mass concentration of the fluorine-containing glue solution is 20-40%.
Preferably, the preparation of the cellulose nanocrystalline suspension specifically comprises:
mixing ethanol and deionized water in the volume ratio of 9:1 to prepare a mixed solution A;
Adding glacial acetic acid into the mixed solution A to prepare a mixed solution B, and adjusting the pH value range of the mixed solution B to be 4-5;
one or more of modifiers KH550, KH560 and KH570 are added into the mixed solution B to prepare hydrolysis solution by mixing and ultrasonic treatment, and the dosage of the modifier is preferably 6-8% relative to the mass of the cellulose nanocrystal suspension.
Adding cellulose nanocrystalline with sulfonate or carboxylate into hydrolysate, stirring in water bath at 65-80 deg.C for modification, transferring into dialysis bag after 3.5-5.5 hr, soaking in distilled water, and changing distilled water once at intervals until the solution is neutral to obtain cellulose nanocrystalline suspension.
The cellulose nanocrystalline always tends to aggregate due to the strong acting force among the self particles, and the effect between the cellulose nanocrystalline and the matrix can be enhanced through hydrophobic modification, so that the dispersion stability of the cellulose nanocrystalline in a hydrophobic solution is enhanced, and the emulsion stability is improved.
Preferably, the emulsifier prepared by mixing the prepared cellulose nanocrystalline suspension with the water-absorbent resin specifically comprises:
mixing 5-8 parts of cellulose nanocrystalline suspension and 2.2-4.8 parts of water-absorbing resin, and stirring to prepare the emulsifier.
Preferably, the content of cellulose nanocrystalline in the cellulose nanocrystalline suspension is 1wt% to 5wt%, the grain size length is 200nm to 400nm, and the diameter is 5nm to 20nm.
The concentration of the cellulose nanocrystals is 1-5 wt% of the proper concentration, which can ensure that the emulsification process can be smoothly carried out, and the stability of the emulsion can be affected by the too low concentration of the cellulose nanocrystals, and the emulsification effect can be affected by the too high concentration.
Preferably, the preparation of the coarse latex by mixing and emulsifying the prepared fluorine-containing glue solution and the emulsifier specifically comprises the following steps:
mixing fluorine-containing glue solution with the mass ratio of 1-2.2:1 with an emulsifying agent, and emulsifying the mixed solution by using a high-speed shearing machine at the temperature of 23-40 ℃ to obtain coarse latex, wherein the specific emulsifying time is 8-15 min.
Preferably, the method for removing solvent from the prepared crude latex to obtain the fluororubber latex specifically comprises the following steps:
Transferring the crude rubber emulsion into a rotary evaporation bottle, removing the solvent by adopting reduced pressure rotary evaporation, gradually heating to 70-75 ℃ at the initial temperature of 30-60 ℃ and the gauge pressure of 0.08-0.1 MPa, slowly distilling off the organic solvent at the temperature, and obtaining the fluororubber emulsion after obvious layering in the recovery bottle and proving that the solvent evaporation is completely finished.
The composition for preparing the fluororubber latex provided by the embodiment of the invention has the following beneficial effects:
1. The invention adopts the cellulose nanocrystalline suspension as an emulsifying agent, carries out hydrophobic modification on cellulose nanocrystalline, increases the content of hydrophobic groups of the cellulose nanocrystalline, adjusts the ratio of amphiphilic groups, improves the emulsifying capacity, forms a cavity effect by adding one or more water-absorbing resins such as polyvinyl alcohol, sodium polyacrylate, casein, gelatin and the like, and further improves the stability of the fluororubber latex;
2. the emulsion formula of the Pickering emulsion can directly prepare the fluororubber latex by using the dry rubber solution, has simple process flow and relatively low requirements on equipment, and solves the technical problems that the existing fluororubber emulsion preparation method needs emulsion polymerization or suspension polymerization and the like and the production process is complex;
3. According to the invention, the traditional externally added anionic emulsifier, cationic emulsifier or nonionic emulsifier is omitted, the hydrophobic modified cellulose nanocrystalline suspension is adopted as the emulsifier to carry out Pickering emulsion emulsification, so that the use amount of chemical surfactants is greatly reduced, the treatment difficulty of production wastewater is reduced, the energy consumption is reduced, the environmental pollution degree is reduced, and the safety of workers is protected;
4, the process for preparing the Pickering emulsion greatly reduces the foaming condition of the latex in the emulsification stage, increases the actual emulsification quality and reduces the standing defoaming time;
5. The fluororubber latex has the advantages of simple emulsion formula, mild formula, good stability, good dispersion state of latex particles after standing for half a year, and little change of the particle size distribution of the lower latex.
Drawings
FIG. 1 is a flow chart of a process for preparing a fluororubber latex according to the present invention;
FIG. 2 is a graph showing the effect of the fluororubber latex prepared in the first embodiment of the present invention on the static stability;
FIG. 3 is a graph showing the effect of the fluororubber latex prepared in example II of the present invention on the standing stability;
FIG. 4 is a graph showing the effect of the fluororubber latex prepared in example III of the present invention on the standing stability;
FIG. 5 is a graph showing the particle size distribution of fluororubber latex prepared in example I of the present invention at rest for different times;
FIG. 6 is a graph showing the particle size distribution of fluororubber latex prepared in example II of the present invention at rest for different times;
FIG. 7 is a graph showing the particle size distribution of fluororubber latex prepared in example III of the present invention at rest for different times;
FIG. 8 shows the result of preparing fluororubber latex without adding water-absorbent resin in example IV of the present invention.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person skilled in the art without making any inventive effort are within the scope of the present invention.
Aiming at the problems mentioned in the background art, the embodiment of the invention provides a composition for preparing fluororubber latex, fluororubber latex and a preparation method thereof, so as to solve the technical problems, and the technical scheme of the specific implementation scheme is as follows:
Materials, reagents and the like used in the examples described below are commercially available unless otherwise specified.
The fluororubber latex and the preparation method thereof mainly comprise three parts, namely 1, preparation of fluorine-containing glue solution, 2, preparation of emulsifying agent, 3, emulsification of the fluorine-containing glue solution, and specific reference is made to the following examples.
Embodiment one;
1. Preparation of fluorine-containing glue solution
Cutting the high polymer elastomer fluororubber containing fluorine atoms on carbon atoms of a main chain or a side chain into small rubber blocks, putting the small rubber blocks into a reaction kettle, adding a certain amount of acetone solution into the small rubber blocks, stirring the small rubber blocks at room temperature for 6 hours, and preparing into fluorine-containing glue solution with the concentration of 20%;
2. Preparation of emulsifiers
1) Preparing cellulose nanocrystalline suspension, mixing ethanol and deionized water in a volume ratio of 9:1, adding glacial acetic acid into the solution to adjust the pH value to 5, adding a modifier KH550 (8% of the mass of the cellulose nanocrystalline suspension) into the solution, then carrying out ultrasonic treatment on the mixture for 30min to obtain hydrolysate, adding cellulose nanocrystalline with sulfonate or carboxylate into the hydrolysate, stirring in a water bath at 65 ℃, transferring into a dialysis bag after modification for 4h, soaking in distilled water, and changing distilled water once at intervals until the solution is neutral;
2) Mixing and stirring cellulose nanocrystalline suspension with 3wt% of solid content, 8 parts of dry weight, 4 parts of polyvinyl alcohol, 0.5 part of sodium polyacrylate and the balance of deionized water to prepare an emulsifier;
3. Emulsification of fluorine-containing glue solution
1) Preparing coarse latex, namely preparing fluorine-containing glue solution, namely mixing water phase and oil phase uniformly, wherein the emulsifier is=1:1 (mass ratio), and emulsifying the mixed solution by stirring at the rotating speed of 8000r/min by using a tooth-to-tooth type high-speed shearing machine at the temperature of 23 ℃ for 15min to obtain the completely emulsified coarse latex;
2) The crude latex is subjected to solvent removal treatment, namely the crude latex is transferred into a rotary evaporation bottle, the solvent is removed by adopting reduced pressure rotary evaporation, the initial temperature is 30 ℃, the gauge pressure is 0.08MPa, the temperature is gradually increased to 75 ℃, the organic solvent is slowly distilled off at the temperature, obvious delamination exists in the recovery bottle, the solvent evaporation is proved to be completely finished, the fluororubber latex is obtained, and the particle size of the latex is 800nm.
The fluororubber latex prepared as described above was subjected to a test for examining the stability at rest, and the results of the change in the distribution of the effective particle diameter after standing for different periods were examined, and the results are shown in fig. 2 and 5.
Embodiment two;
1. Preparation of fluorine-containing glue solution
Cutting the high polymer elastomer fluororubber containing fluorine atoms on carbon atoms of a main chain or a side chain into small rubber blocks, putting the small rubber blocks into a reaction kettle, adding a certain amount of ethyl acetate solution into the small rubber blocks, stirring the small rubber blocks at room temperature for 6 hours, and preparing fluorine-containing glue solution with the concentration of 30%;
2. Preparation of emulsifiers
1) Preparing cellulose nanocrystalline suspension, mixing ethanol and deionized water in a volume ratio of 9:1, adding glacial acetic acid into the solution to adjust the pH value to 4, adding a modifier KH560 (7% relative to the mass of the cellulose nanocrystalline suspension) into the solution, then performing ultrasonic treatment on the mixture for 45min to obtain hydrolysate, adding cellulose nanocrystalline with sulfonate or carboxylate into the hydrolysate, stirring in a 70 ℃ water bath, transferring into a dialysis bag after modification for 5.5h, soaking in distilled water, and changing distilled water once at intervals until the solution is neutral;
2) Mixing and stirring cellulose nanocrystalline suspension with a solid content of 4.2wt%, a dry weight ratio of 6 parts, gelatin of 3 parts, sodium polyacrylate of 0.2 part and deionized water of the rest to prepare an emulsifier;
3. Emulsification of fluorine-containing glue solution
1) Preparing coarse latex, namely preparing fluorine-containing glue solution, namely emulsifying agent=1:1 (mass ratio), uniformly mixing the water phase and the oil phase, and emulsifying the mixed solution by stirring at the speed of 7500r/min by using a tooth-to-tooth type high-speed shearing machine at the temperature of 23 ℃ for 10min to obtain the coarse latex completely emulsified.
2) And (3) removing the solvent from the crude latex, namely transferring the crude latex into a rotary evaporation bottle, and removing the solvent by adopting reduced pressure rotary evaporation. The initial temperature is 55 ℃, the gauge pressure is 0.09MPa, the temperature is gradually increased to 70 ℃, the organic solvent is slowly distilled off at the temperature, obvious layering is carried out in a recovery bottle, the solvent evaporation is proved to be completely finished, the fluororubber latex is obtained, and the latex particle size is 1200nm.
The fluororubber latex prepared as described above was subjected to a test for examining the stability at rest, and the results of the change in the distribution of the effective particle diameter after standing for different periods were examined, and the results are shown in fig. 3 and 6.
Embodiment three;
1. Preparation of fluorine-containing glue solution
Cutting the high polymer elastomer fluororubber containing fluorine atoms on carbon atoms of a main chain or a side chain into small rubber blocks, putting the small rubber blocks into a reaction kettle, adding a certain amount of ethyl acetate solution into the small rubber blocks, stirring the small rubber blocks at room temperature for 7 hours, and preparing into fluorine-containing glue solution with the concentration of 40%;
2. Preparation of emulsifiers
1) Preparing cellulose nanocrystalline suspension, mixing ethanol and deionized water in a volume ratio of 9:1, adding glacial acetic acid into the solution to adjust the pH value to 5, adding a modifier KH570 (7% relative to the mass of the cellulose nanocrystalline) into the solution, then carrying out ultrasonic treatment on the mixture for 55min to obtain hydrolysate, adding cellulose nanocrystalline with sulfonate or carboxylate into the hydrolysate, stirring in a 60 ℃ water bath, transferring into a dialysis bag after modification for 3.5h, soaking in distilled water, and changing distilled water once every other time until the solution is neutral;
2) Mixing and stirring cellulose nanocrystalline suspension with a solid content of 2.7wt%, a dry weight ratio of 5 parts, 4 parts of polyvinyl alcohol, 0.6 part of casein and the balance of deionized water to prepare an emulsifier;
3. Emulsification of fluorine-containing glue solution
1) Preparing coarse latex, namely preparing fluorine-containing glue solution, namely mixing an aqueous phase and an oil phase uniformly, wherein the emulsifier is=1.5:1 (mass ratio), and stirring the mixed solution at a rotating speed of 7000r/min by using a tooth-to-tooth high-speed shearing machine at a temperature of 40 ℃ for emulsification for 15min to obtain completely emulsified coarse latex;
2) And (3) removing the solvent from the crude latex, namely transferring the crude latex into a rotary evaporation bottle, and removing the solvent by adopting reduced pressure rotary evaporation. The initial temperature is 40 ℃, the gauge pressure is 0.1MPa, the temperature is gradually increased to 75 ℃, the organic solvent is slowly distilled off at the temperature, obvious layering is carried out in a recovery bottle, the solvent evaporation is proved to be completely finished, the fluororubber latex is obtained, and the particle size of the latex is 1000nm.
The fluororubber latex prepared as described above was subjected to a test for examining the stability at rest, and the results of the change in the distribution of the effective particle diameter after standing for different periods were examined, and the results are shown in fig. 4 and 7.
Fourth embodiment;
1. Preparation of fluorine-containing glue solution
Cutting the high polymer elastomer fluororubber containing fluorine atoms on carbon atoms of a main chain or a side chain into small rubber blocks, putting the small rubber blocks into a reaction kettle, adding a certain amount of ethyl acetate solution into the small rubber blocks, stirring the small rubber blocks at room temperature for 6 hours, and preparing the fluorine-containing rubber solution with the concentration of 20%.
2. Preparation of emulsifiers
1) Preparing cellulose nanocrystalline suspension, mixing ethanol and deionized water in a volume ratio of 9:1, adding glacial acetic acid into the solution to adjust the pH value to 4, adding a modifier KH550 (7% relative to the mass of the cellulose nanocrystalline) into the solution, then performing ultrasonic treatment on the mixture for 45min to obtain hydrolysate, adding cellulose nanocrystalline with sulfonate or carboxylate into the hydrolysate, stirring in a water bath at 65 ℃, transferring into a dialysis bag after modification for 5.5h, soaking in distilled water, and changing distilled water once every other time until the solution is neutral;
2) Mixing and stirring cellulose nanocrystalline suspension with solid content of 5wt%, sodium polyacrylate of 0.2 part and deionized water of the rest to prepare an emulsifier;
3. Emulsification of fluorine-containing glue solution
1) Preparing coarse latex, namely preparing fluorine-containing glue solution, namely mixing water phase and oil phase uniformly, wherein the emulsifier is=1:1 (mass ratio), and emulsifying the mixed solution by stirring at a rotating speed of 8000r/min by using a tooth-to-tooth type high-speed shearing machine at a temperature of 40 ℃ for 15min to obtain the completely emulsified coarse latex;
2) And (3) removing the solvent from the crude latex, namely transferring the crude latex into a rotary evaporation bottle, and removing the solvent by adopting reduced pressure rotary evaporation. The initial temperature is 45 ℃, the gauge pressure is 0.1MPa, the temperature is gradually increased to 75 ℃, the organic solvent is slowly distilled off at the temperature, fluororubber is separated out, and the demulsification result is shown in figure 8.
As is clear from the results of the first, second and third embodiments, the fluororubber latex prepared by the method has good stability, the latex particles still keep a good dispersion state after standing for half a year, and the particle size distribution of the lower latex has little change;
in the fourth example, the components of water-absorbent resin such as polyvinyl alcohol, sodium polyacrylate, casein and gelatin are not added in the preparation process of the emulsifier, the demulsification phenomenon occurs in the process of removing the solvent by reduced pressure rotary evaporation of the organic solvent, and the result of the example proves that the stability of the fluororubber latex is improved by adding the water-absorbent resin in the preparation process of the fluororubber latex.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A composition for preparing fluororubber latex is characterized by comprising a fluororubber solution and an emulsifier in a mass ratio of 1-2.2:1;
The raw materials of the emulsifier comprise, by mass, 5-8 parts of a cellulose nanocrystalline suspension and 2.2-4.8 parts of a water-absorbent resin, wherein in the cellulose nanocrystalline suspension, cellulose nanocrystalline carries sulfonate or carboxylate and is subjected to hydrophobic modification;
The water-absorbing resin is one or more selected from polyvinyl alcohol, sodium polyacrylate, casein and gelatin, and the mass concentration of the fluorine-containing glue solution is 20-40%.
2. The composition for preparing a fluororubber latex according to claim 1, wherein the content of cellulose nanocrystals in the suspension of cellulose nanocrystals is 1 to 5wt%, the particle size length is 200 to 400nm, and the diameter is 5 to 20nm.
3. A fluororubber latex prepared from the composition for preparing a fluororubber latex according to claim 1 or 2.
4. A method for preparing fluororubber latex, characterized by comprising the following steps:
Preparing fluorine-containing glue solution;
Selecting cellulose nanocrystalline with sulfonate or carboxylate to carry out hydrophobic modification, and preparing cellulose nanocrystalline suspension;
mixing the prepared cellulose nanocrystalline suspension with water-absorbent resin to prepare an emulsifier;
mixing and emulsifying the prepared fluorine-containing glue solution and an emulsifier to prepare coarse latex;
removing solvent from the prepared crude latex to obtain fluororubber latex;
the step of preparing the coarse latex by mixing and emulsifying the prepared fluorine-containing glue solution and the emulsifier specifically comprises the following steps:
mixing fluorine-containing glue solution with the mass ratio of 1-2.2:1 with an emulsifier, and stirring the mixed solution by using a high-speed shearing machine at the temperature of 23-40 ℃ to emulsify to obtain coarse latex;
The water-absorbing resin is one or more selected from polyvinyl alcohol, sodium polyacrylate, casein and gelatin, and the mass concentration of the fluorine-containing glue solution is 20-40%.
5. The method for preparing a fluororubber latex according to claim 4, wherein preparing the fluororubber latex comprises:
selecting a high polymer elastomer containing fluorine atoms on carbon atoms of a main chain or a side chain to cut small blocks, and placing the cut small blocks into a reaction kettle;
Adding one or more mixed solutions of acetone, toluene and ethyl acetate into a reaction kettle, and stirring at room temperature to prepare fluorine-containing glue solution.
6. The method for preparing a fluororubber latex according to claim 4, wherein preparing a suspension of cellulose nanocrystals comprises:
mixing ethanol and deionized water in the volume ratio of 9:1 to prepare a mixed solution A;
Adding glacial acetic acid into the mixed solution A to prepare a mixed solution B, and adjusting the pH value range of the mixed solution B to be 4-5;
adding one or more of modifiers KH550, KH560 and KH570 into the mixed solution B, mixing and performing ultrasonic treatment to prepare hydrolysate;
Adding cellulose nanocrystalline with sulfonate or carboxylate into hydrolysate, stirring in water bath at 65-80 deg.C for modification, transferring into dialysis bag after 3.5-5.5 hr, soaking in distilled water, and changing distilled water once at intervals until the solution is neutral to obtain cellulose nanocrystalline suspension.
7. The method for preparing a fluororubber latex according to claim 4, wherein the step of mixing the prepared cellulose nanocrystal suspension with a water-absorbent resin to prepare an emulsifier comprises:
mixing 5-8 parts of cellulose nanocrystalline suspension and 2.2-4.8 parts of water-absorbing resin, and stirring to prepare the emulsifier.
8. The method for producing a fluororubber latex according to claim 7, wherein the content of cellulose nanocrystals in the suspension of cellulose nanocrystals is 1 to 5wt%, the particle size length is 200 to 400nm, and the diameter is 5 to 20nm.
9. The method for producing a fluororubber latex according to claim 4, wherein the step of subjecting the prepared crude latex to a solvent removal treatment to obtain a fluororubber latex comprises:
transferring the crude rubber emulsion into a rotary evaporation bottle, removing the solvent by adopting reduced pressure rotary evaporation, gradually heating to 70-75 ℃ at the initial temperature of 30-60 ℃ and the gauge pressure of 0.08-0.1 MPa, slowly distilling off the organic solvent at the temperature, and obtaining the fluororubber emulsion after obvious layering in the recovery bottle, wherein the solvent evaporation is completely finished.
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| CN105419012A (en) * | 2015-12-19 | 2016-03-23 | 华南理工大学 | Preparation method for straw-based crystalline cellulose nanocrystals and rubber composite material of straw-based crystalline cellulose nanocrystals |
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