Method for demulsification and coagulation of perfluoroether elastomer emulsion, and low-temperature demulsification system

Abstract

The present application provides a method for demulsification and coagulation of a perfluoroether elastomer emulsion, applied to the technical field of perfluoroether elastomers. The method comprises: S1, centrifuging a perfluoroether elastomer emulsion to obtain a perfluoroether elastomer concentrate and a residual liquid; S2, spraying the perfluoroether elastomer concentrate to disperse the perfluoroether elastomer concentrate in the form of droplets into a low-temperature inert liquid for demulsification and coagulation, wherein the temperature of the low-temperature inert liquid is lower than the glass transition temperature of a perfluoroether elastomer; S3, separating the demulsified coagulum in S2, dispersing and washing same in water, and filtering same to obtain a filter cake; and S4, vacuum drying the filter cake to obtain a perfluoroether elastomer powder. The present application further provides a low-temperature demulsification system for implementing the described method. The present application has a high yield by means of a centrifugal concentration-based low-temperature demulsification and coagulation method. After undergoing devolatilization and end group passivation treatment, the obtained perfluoroether elastomer powder can be used for preparing a high-purity perfluoroether elastomer composition for use in a semiconductor manufacturing process.

Description

Method for demulsification and coagulation of perfluoroether elastomer emulsion and low-temperature demulsification system TECHNICAL FIELD

[0001] The present application relates to the technical field of perfluoroether elastomer synthesis, in particular to a method for demulsification and coagulation of perfluoroether elastomer emulsion and a low-temperature demulsification system. BACKGROUND

[0002] When perfluoroether elastomer is synthesized by emulsion polymerization, the obtained first is an emulsion containing perfluoroether elastomer. After degassing, the solid content of the emulsion is usually 20-35%, and the particle size of the perfluoroether elastomer in the emulsion ranges from 0.1 to 1 microns. The emulsion is complex and mainly includes perfluoroether elastomer polymerized from monomers, emulsifiers, initiators, stabilizers, pH buffers, chain transfer agents, small molecule polymers and water. The separation of perfluoroether elastomer and other components in the emulsion is a demulsification and coagulation process. There are various demulsification and coagulation methods, which can be generally divided into chemical demulsification and coagulation (electrolyte method, demulsifier method, etc.) and physical demulsification and coagulation (high-speed centrifugation method, electrostatic demulsification method, heating method, etc.).

[0003] Chemical demulsification requires the addition of flocculants. The existing flocculants mainly include inorganic salts such as magnesium chloride and inorganic acids such as dilute nitric acid. The main problem of flocculation using flocculants is that flocculation occurs rapidly and agglomeration occurs, which makes it difficult to clean the wrapped impurities. At the same time, the large agglomerated particles are not conducive to subsequent processes such as devolatilization and end group passivation. When the particles are large, the internal diffusion in the devolatilization and end group passivation processes is the control step. When the particles are too small or the particle size distribution range is large, the bed pressure drop in the fixed bed is large and channeling is easy to occur. Therefore, it is essential to regulate the size and uniformity of the particles in the coagulation process. In addition, metal ions are easily left over in the flocculation process of chemical demulsification. The left-over metal ions are easy to release metal ions in semiconductor processes such as etching and photolithography, which leads to pollution to the semiconductor process.

[0004] Therefore, the present application provides a new technical solution. SUMMARY

[0005] Therefore, the present application provides a new technical solution.

[0006] The present application provides the following technical solution: a method for demulsification and coagulation of perfluoroether elastomer emulsion, comprising:

[0007] S1, centrifuging perfluoroether elastomer emulsion to obtain perfluoroether elastomer concentrate and residual liquid;

[0008] S2, spraying the perfluoroether elastomer concentrate to disperse the perfluoroether elastomer concentrate in the form of droplets into a low-temperature inert liquid, the temperature of the low-temperature inert liquid being lower than the glass transition temperature of the perfluoroether elastomer;

[0009] S3, separating the demulsified coagulum in S2, dispersing and washing in water, and filtering to obtain a filter cake;

[0010] S4, vacuum drying the filter cake to obtain a perfluoroether elastomer powder.

[0011] Optionally, the centrifugal factor ω in S1 is 10000g-20000g. 2 R is 10000g-20000g.

[0012] Optionally, the spraying in S2 uses compressed air, high-pressure nitrogen or high-pressure argon as the power.

[0013] Optionally, the low-temperature inert liquid in S2 is liquid nitrogen or liquid carbon dioxide.

[0014] Optionally, in S1, a centrifugal separator is used for separation, and a paint cloth is arranged on the inner wall of the centrifugal separator.

[0015] Optionally, in S1, the perfluoroether elastomer emulsion is further washed by centrifugation after centrifugation.

[0016] Optionally, the paint cloth is a hydrophilic modified tetrafluoroethylene, polypropylene or polyvinylidene fluoride.

[0017] Optionally, the surface of the paint cloth has a plurality of holes or grooves.

[0018] The application also provides a low-temperature demulsification system for the above-mentioned method of demulsifying and coagulating any perfluoroether elastomer emulsion, wherein the low-temperature demulsification system comprises a high-pressure gas storage tank, a concentrated emulsion storage tank, a concentrated emulsion temporary storage tank and a low-temperature liquid storage tank, the high-pressure gas storage tank and the concentrated emulsion storage tank are both in communication with the concentrated emulsion temporary storage tank through pipelines;

[0019] The concentrated emulsion storage tank stores perfluoroether elastomer concentrate, the high-pressure gas storage tank stores high-pressure air, nitrogen or argon, the low-temperature liquid storage tank stores liquid nitrogen or liquid carbon dioxide, and the concentrated emulsion temporary storage tank sprays the perfluoroether elastomer concentrate into the low-temperature liquid storage tank through a nozzle.

[0020] Optionally, the high-pressure gas storage tank is in communication with a high-pressure gas cylinder, the high-pressure gas cylinder and the high-pressure gas storage tank are controlled by a valve, the high-pressure gas storage tank and the concentrated emulsion temporary storage tank are controlled by a valve, the concentrated emulsion storage tank and the concentrated emulsion temporary storage tank are controlled by a valve, and the concentrated emulsion temporary storage tank and the nozzle are controlled by a valve.

[0021] Compared with the prior art, the at least one technical solution adopted by the embodiments of the present specification can achieve the beneficial effects at least including:

[0022] The technical solution of the present application concentrates the perfluoroether elastomer emulsion by centrifugation, and then mixes the perfluoroether elastomer concentrate with a low-temperature inert liquid. The perfluoroether elastomer concentrate is rapidly cooled, the perfluoroether elastomer in the emulsion is reduced below the glass transition temperature, the movement of the polymer chain segment is frozen, the stable double-charge structure of the emulsion is destroyed, the emulsion is demulsified in a short time, and the centrifugal concentration can avoid the adverse phenomenon that the perfluoroether elastomer content in the emulsion is low after demulsification due to high moisture content, and the particles are fluffy. It is convenient for subsequent devolatilization and end group passivation treatment of the perfluoroether elastomer.

[0023] In addition, high-speed spraying enables the perfluoroether elastomer concentrate to fully contact with the low-temperature liquid in the form of droplets, rapidly cool and freeze, avoid the agglomeration of perfluoroether elastomer particles, and obtain particles with uniform particle size, which is beneficial to subsequent processes such as washing, freeze-drying, devolatilization and end group passivation. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0025] Figure 1 is a flow process diagram of a method for demulsification and coagulation of perfluoroether elastomer emulsion according to the present application.

[0026] Figure 2 is a schematic diagram of a low-temperature demulsification system according to the present application.

[0027] In the figure: 1, high-pressure gas tank; 2, concentrated emulsion tank; 3, temporary concentrated emulsion tank; 4, low-temperature liquid tank; 5, high-pressure gas cylinder; 6, nozzle. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described in detail below with reference to the drawings.

[0029] The present application is described in detail below with specific reference being made to particular embodiments. Those skilled in the art will readily understand other advantages and benefits of the present application from the description of the embodiments given herein below. It will be apparent to those skilled in the art that the described embodiments are only some of the embodiments of the present application, and are not all the embodiments. The present application can also be implemented or applied in other different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0030] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be apparent that the aspects described herein can be embodied in a wide variety of forms and that any particular structure and / or function described herein is merely illustrative. Based on the present application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. In addition, in the following description, specific details are provided to facilitate a thorough understanding of examples. However, those skilled in the art will understand that the application can be practiced without these specific details.

[0031] Chemical demulsification requires the addition of flocculants, and existing flocculants mainly include inorganic salts such as magnesium chloride and inorganic acids such as dilute nitric acid. The main problem of flocculation using flocculants is that the flocculation process occurs rapidly and agglomeration, and it is not easy to clean the impurities wrapped, and the large agglomerated particles are not conducive to subsequent processing processes such as drying, devolatilization and end group passivation treatment.

[0032] Using rapid cooling technology, the emulsion is atomized and mixed with low-temperature liquid at high speed in the form of droplets. The perfluoroether elastomer in the emulsion is rapidly reduced below the glass transition temperature, and the movement of the polymer chain segment is frozen. The emulsion is demulsified and coagulated in a short time.

[0033] Centrifugal concentration of emulsion can greatly improve the production efficiency of freeze demulsification.

[0034] Centrifugal concentration of low-temperature demulsification can quickly and effectively realize the concentration and demulsification of the emulsion. Centrifugal concentration mainly uses the strong centrifugal force generated during high-speed rotation to realize separation according to the density difference between the target product perfluoroether elastomer and the aqueous solution. The stronger the centrifugal field, the better the concentration effect.

[0035] Based on this, the embodiments of the present specification propose a method for demulsification and coagulation of perfluoroether elastomer emulsion: comprising,

[0036] S1, centrifuging the perfluoroether elastomer emulsion to obtain a perfluoroether elastomer concentrate and a residual liquid;

[0037] S2, spraying the perfluoroether elastomer concentrate to disperse the perfluoroether elastomer concentrate in the form of droplets into a low-temperature inert liquid to break the emulsion and coagulate, the low-temperature inert liquid having a temperature lower than the glass transition temperature of the perfluoroether elastomer;

[0038] S3, separating the coagulum in S2, dispersing and washing in water, and filtering to obtain a filter cake;

[0039] S4, vacuum drying the filter cake to obtain a perfluoroether elastomer powder.

[0040] The centrifugal factor ω in S1 2 R is 10000 g to 20000 g. The separation is performed using a centrifugal separator, the inner wall of which is provided with a lacquer cloth. The lacquer cloth is a hydrophilically modified tetrafluoroethylene, polypropylene or polyvinylidene fluoride. The perfluoroether elastomer emulsion is fed from the bottom of the centrifugal separator, the centrifugal residual liquid is discharged from the top of the centrifugal separator, the centrifuged perfluoroether elastomer concentrate is distributed on the surface of the lacquer cloth, the centrifugal separation direction is perpendicular to the flow direction of the residual liquid, continuous centrifugal separation can be achieved, and the centrifugal efficiency is improved.

[0041] The hydrophilic lacquer cloth can adhere to the perfluoroether elastomer particles mixed with surfactants to concentrate the perfluoroether elastomer. Using a hydrophobic lacquer cloth, the perfluoroether elastomer emulsion is partially broken, but this breaking is uncontrollable, resulting in large particle sizes after breaking or particles sticking together to form a film, which is not conducive to subsequent low-temperature stage spraying and breaking, and is even less conducive to subsequent drying, devolatilization and end group passivation.

[0042] In S2, compressed air, high-pressure nitrogen or high-pressure argon is used as the power for spraying, and liquid nitrogen or liquid carbon dioxide is used as the low-temperature inert liquid. The temperature of liquid nitrogen and liquid carbon dioxide is much lower than the glass transition temperature of the perfluoroether elastomer. The spraying method can fully disperse the perfluoroether elastomer concentrate in the form of droplets, rapidly cool it to below its glass transition temperature, and break the emulsion. At the same time, the impact and cutting brought by the spraying process can effectively destroy the double charge structure of micelles, improving the breaking effect.

[0043] The perfluoroether elastomer emulsion in S1 has a density of 1.21-1.23 g / ml and a viscosity of 2.81-3.02 cp; the concentrated emulsion has a density of 1.27-1.31 g / ml and a viscosity of 30000-35000 cp; and the glass transition temperature of the perfluoroether elastomer is -10℃ to -25℃.

[0044] In the technical solution of the present application, to avoid introducing impurities, the water used is deionized water unless otherwise specified.

[0045] The method for measuring the solid content in the perfluoroether elastomer emulsion is as follows: a certain mass of emulsion w1 is dried in an oven at 120℃ for 24h to obtain a solid, which is weighed after cooling, and the mass is w2, then the solid content is

[0046] The obtained dried solid includes perfluoroether elastomer polymerized from monomers, emulsifier, initiator, stabilizer, pH buffer, chain transfer agent, small molecule polymer and combined water, etc.

[0047] The centrifugal separation and concentration process mainly removes water, and at the same time removes part of free surfactant, initiator, pH buffer, chain transfer agent, small molecule polymer, etc.

[0048] The present application also provides a low-temperature demulsification system for realizing the above method, which comprises a high-pressure gas tank 1, a concentrated emulsion tank 2, a concentrated emulsion temporary tank 3 and a low-temperature liquid tank 4, and the high-pressure gas tank 1 and the concentrated emulsion tank 2 are both in communication with the concentrated emulsion temporary tank 3 through pipelines.

[0049] The concentrated emulsion tank 2 stores perfluoroether elastomer concentrated liquid, the high-pressure gas tank 1 stores high-pressure air, nitrogen or argon, and the low-temperature liquid tank 4 stores liquid nitrogen or liquid carbon dioxide, and the concentrated emulsion temporary tank 3 sprays and disperses the perfluoroether elastomer concentrated liquid into the low-temperature liquid tank through a nozzle 6.

[0050] The high-pressure gas tank 1 is communicated with a high-pressure gas cylinder 5, the high-pressure gas cylinder 5 and the high-pressure gas tank 1 are controlled through valves, the high-pressure gas tank 1 and the concentrated emulsion temporary tank 3 are controlled through valves, the concentrated emulsion tank 2 and the concentrated emulsion temporary tank 3 are controlled through valves, and the concentrated emulsion temporary tank 3 and the nozzle 6 are controlled through valves.

[0051] Example 1

[0052] A method for demulsification and coagulation of perfluoroether elastomer emulsion, comprising

[0053] S1, centrifugal separation of 2500mL (density 1.22g / ml) perfluoroether elastomer emulsion with a solid content of 31.6%, centrifugal factor ω 2 ​R is 13500 g, after centrifugal separation, the raw material remained in the water recovery container and pipeline is recovered with 2000 ml water, to obtain perfluoroether elastomer concentrate liquid v1 = 1027 ml (density 1.29 g / ml, viscosity 32000 cp) and residual liquid v2 = 3350 ml; the inner wall of the centrifugal separator is provided with hydrophilic 10 mesh PTFE cloth (pore size 1.7 mm), the residual liquid is flocculated with 10% MgCl2 flocculant and stirred, and the product is precipitated, and the precipitated product is dried, and the mass is 6.2 g;

[0054] S2, 100 ml of perfluoroether elastomer concentrate liquid is sprayed into open liquid nitrogen (0.5 L, -195℃) with 4.5 bar nitrogen to break emulsion and coagulate;

[0055] S3, after the liquid nitrogen volatilizes, the perfluoroether elastomer particles in S2 are dispersed and washed in water, and a filter cake is obtained by filtration;

[0056] S4, the filter cake is vacuum dried to obtain perfluoroether elastomer powder w3 of 62.7 g, the particle size of the powder is less than 1.0 mm (passing 16 mesh screen), and the glass transition temperature of the perfluoroether elastomer powder is -16.2℃.

[0057] The filtrate in S3 is flocculated with 10% MgCl2 flocculant and stirred, and no product is precipitated, indicating that the emulsion breaking and coagulation is complete.

[0058] Example 2

[0059] A method for breaking emulsion and coagulating perfluoroether elastomer emulsion, comprising

[0060] S1, centrifugal separation of 2500 ml (density 1.22 g / ml) perfluoroether elastomer emulsion with solid content of 31.6%, centrifugal factor ω 2 R is 17500 g, after centrifugal separation, the raw material remained in the water recovery container and pipeline is recovered with 2000 ml water, to obtain perfluoroether elastomer concentrate liquid v1 = 1027 ml (density 1.29 g / ml, viscosity 32000 cp) and residual liquid v2 = 3350 ml; the inner wall of the centrifugal separator is provided with hydrophilic 10 mesh PTFE cloth (pore size 1.7 mm), the residual liquid is flocculated with 10% MgCl2 flocculant and stirred, and the product is precipitated, and the precipitated product is dried, and the mass is 6.2 g.

[0061] S2, 100 ml of perfluoroether elastomer concentrate liquid is sprayed into open liquid nitrogen (0.5 L, -195℃) with 4.5 bar nitrogen to break emulsion;

[0062] S3, after the liquid nitrogen volatilizes, the perfluoroether elastomer particles in S2 are dispersed and washed in water, and a filter cake is obtained by filtration;

[0063] S4, vacuum drying the filter cake to obtain 64.3 g of perfluoroether elastomer powder, the particle size of the powder is less than 1.0 mm (passing 16 mesh sieve), and the glass transition temperature of the perfluoroether elastomer powder is -16.1 °C.

[0064] In S3, the filtrate was flocculated using 10% MgCl2flocculant and stirred, and no product was precipitated, indicating that the demulsification and coagulation were complete.

[0065] Example 3

[0066] The difference between the example of the present application and Example 1 is that the concentrated solution obtained in S1 is demulsified by spraying 5.5 bar nitrogen into sealed liquid carbon dioxide (0.5 L, the saturated pressure and the saturated temperature are 4.5 bar and -56 °C, respectively);

[0067] S3, releasing pressure, dispersing and washing the perfluoroether elastomer particles in S2 in water, and filtering to obtain a filter cake;

[0068] S4, vacuum drying the filter cake to obtain 64.3 g of perfluoroether elastomer powder, the particle size of the powder is less than 1.0 mm (passing 16 mesh sieve), and the glass transition temperature of the perfluoroether elastomer powder is -16.1 °C.

[0069] In S3, the filtrate was flocculated using 10% MgCl2flocculant and stirred, and no product was precipitated, indicating that the demulsification and coagulation were complete.

[0070] Example 4

[0071] The difference between the example of the present application and Example 2 is that the concentrated solution obtained in S1 is demulsified by spraying 5.5 bar nitrogen into sealed liquid carbon dioxide (0.5 L, the saturated pressure and the saturated temperature are 4.5 bar and -56 °C, respectively);

[0072] S3, releasing pressure, dispersing and washing the perfluoroether elastomer particles in S2 in water, and filtering to obtain a filter cake;

[0073] S4, vacuum drying the filter cake to obtain 64.3 g of perfluoroether elastomer powder, the particle size of the powder is less than 1.0 mm (passing 16 mesh sieve), and the glass transition temperature of the perfluoroether elastomer powder is -16.1 °C.

[0074] In S3, the filtrate was flocculated using 10% MgCl2flocculant and stirred, and no product was precipitated, indicating that the demulsification and coagulation were complete.

[0075] Comparative Example 1

[0076] The difference between the example of the present application and Example 1 is that the concentrated solution obtained in S2 is mixed with liquid nitrogen directly without spraying.

[0077] The perfluoroether elastomer after demulsification is aggregated into blocks, which is difficult to wash and to perform subsequent devolatilization and other treatment processes.

[0078] In S3, the filtrate is flocculated by using 10% MgCl2 flocculant and stirring, and no product is precipitated, indicating that the demulsification and coagulation are complete.

[0079] Comparative Example 2

[0080] The difference between the embodiment of the present application and Example 1 is that the paint cloth surface is hydrophobically modified tetrafluoroethylene.

[0081] Part of the obtained concentrated emulsion is directly demulsified to form a film, which is difficult to wash and cannot be subjected to devolatilization and end group passivation post-treatment.

[0082] No subsequent low-temperature demulsification is performed.

[0083] Comparative Example 3

[0084] The difference between the comparative example of the present application and Example 1 is that the concentrated solution in S2 is directly sprayed and mixed with anhydrous ethanol at room temperature.

[0085] A viscous inclusion body is formed, which is difficult to wash and cannot be subjected to devolatilization and end group passivation post-treatment.

[0086] In S4, the filter cake is vacuum dried to obtain perfluoroether elastomer powder w3 of 20 g.

[0087] In S3, the filtrate is flocculated by using 10% MgCl2 flocculant and stirring, and a large amount of product is precipitated, and the dried precipitated product has a mass of 46.8 g, indicating that the demulsification and coagulation by using anhydrous ethanol are not complete.

[0088] Comparative Example 4

[0089] The difference between the embodiment of the present application and Example 1 is that the concentrated solution in S2 is directly sprayed and dispersed and washed with hot water at 80°C.

[0090] In S4, the filter cake is vacuum dried to obtain perfluoroether elastomer powder w3 of 6.6 g. Only a small amount of demulsification and coagulation is performed.

[0091] In S3, the filtrate is flocculated by using 10% MgCl2 flocculant and stirring, and a large amount of product is precipitated, and the dried precipitated product has a mass of 59.8 g, indicating that the demulsification and coagulation by using hot water are not complete.

[0092] Comparative Example 5

[0093] The difference between the embodiment of the present application and Example 1 is that the concentrated solution in S2 is directly sprayed into an ice water mixture at 0°C, that is, a low-temperature liquid dispersion experiment above the glass transition temperature of the perfluoroether elastomer is performed.

[0094] S4, the filter cake was vacuum dried to obtain 13.4 g of perfluoroether elastomer powder w3. Only a small amount of demulsification coagulation occurred.

[0095] In S3, the filtrate was flocculated with 10% MgCl2flocculating agent and stirred, and a large amount of product was precipitated. After drying, the mass of the precipitated product was 53.7 g, indicating that the demulsification coagulation at 0°C was not complete.

[0096] Comparative Example 6

[0097] The difference between this comparative example and Example 1 is that the perfluoroether elastomer emulsion in S1 was not concentrated by centrifugation, but 100 mL of the emulsion was directly sprayed into open liquid nitrogen (0.5 L, -195°C).

[0098] Compared with the centrifugal concentration process, the filter cake obtained in this process was a fluffy body;

[0099] The filter cake was vacuum dried to obtain 27.5 g of perfluoroether elastomer powder, which was difficult to sieve (80 mesh sieve).

[0100] In S3, no product was precipitated when 10% MgCl2flocculating agent was added to the water and stirred, indicating that the demulsification coagulation was complete.

[0101] Let the volume of the perfluoroether elastomer concentrate be v1, the volume of the residual liquid be v2, the volume of the frozen demulsified perfluoroether elastomer concentrate in S2 be v 3 , the mass of the perfluoroether elastomer powder obtained after vacuum drying of the filter cake be w3, in S1, the mass of the product obtained by using 10% MgCl2flocculating agent for the residual liquid be w4 (dry weight), then the product recovery rate η1 of the centrifugal concentration process is

[0102] Let the mass of the product obtained by using 10% MgCl2flocculating agent for the filtrate in S3 be w5 (dry weight), then the demulsification rate η2 of the centrifugal concentration and low-temperature demulsification is

[0103] Table 1 shows the parameters of centrifugal separation concentration and low-temperature demulsification, recovery rate and demulsification rate.

[0104] As can be seen from the comparison between Comparative Example 1 and Example 1, although the direct mixing method can demulsify the perfluoroether elastomer, the particles agglomerate due to the direct mixing of the concentrate, and the subsequent devolatilization process cannot be carried out.

[0105] By comparing the comparative example 2 and the example 1, it can be seen that the hydrophobic modified tetrafluoroethylene is used as the paint cloth, which leads to the demulsification and agglomeration of the perfluoroether elastomer directly spread and bonded on the hydrophobic paint cloth, and finally forms a film, which cannot be subjected to subsequent low-temperature demulsification treatment, and cannot be subjected to subsequent devolatilization treatment.

[0106] By comparing the comparative examples 3, 4, 5 and the example 1, it can be seen that the dispersion is carried out above the glass transition temperature, which can only achieve a small amount of demulsification, and the demulsification is incomplete and low in efficiency.

[0107] By comparing the comparative example 6 and the example 1, it can be seen that the perfluoroether elastomer emulsion is directly subjected to low-temperature demulsification, and due to the existence of a large amount of water in the perfluoroether elastomer emulsion, the filter cake obtained is relatively fluffy, and the bridging and winding phenomenon between particles is easy to occur, which leads to that the perfluoroether elastomer powder is not easy to sieve, the strength is low, and the subsequent devolatilization treatment step in the packed bed cannot be carried out.

[0108] In the specification, the same and similar parts among various embodiments can be referred to each other, and each embodiment focuses on the difference from other embodiments. Especially, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the part of the foregoing embodiments.

[0109] The above is only a specific implementation manner of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for breaking and coagulating perfluoroether elastomer emulsion, characterized in that: S1, centrifuging perfluoroether elastomer emulsion to obtain perfluoroether elastomer concentrate and residual liquid, using a centrifugal separator for separation, the inner wall of the centrifugal separator is provided with a paint cloth, and the paint cloth is hydrophilically modified tetrafluoroethylene, polypropylene or polyvinylidene fluoride; S2, spraying perfluoroether elastomer concentrate to break and coagulate the perfluoroether elastomer concentrate in the form of droplets into a low-temperature inert liquid, the temperature of the low-temperature inert liquid is lower than the glass transition temperature of the perfluoroether elastomer; S3, separating the broken and coagulated product in S2, dispersing and washing in water, and filtering to obtain a filter cake; S4, vacuum drying the filter cake to obtain perfluoroether elastomer powder. In step S2, one of compressed air, high-pressure nitrogen or high-pressure argon is used as power. In step S2, the low-temperature inert liquid is liquid nitrogen or liquid carbon dioxide. In step S1, after centrifugation of the perfluoroether elastomer emulsion, water is used for further centrifugal washing. The surface of the paint cloth has a plurality of holes or grooves.

2. A method of breaking emulsions of perfluoroether elastomer emulsions according to claim 1, characterized in that: The centrifugal factor ω in S1 2 R / g is 10000 to 20000.

3. A method of breaking emulsions of perfluoroether elastomer emulsions according to claim 1, characterized by: The perfluoroether elastomer emulsion is fed from the bottom of the centrifugal separator, the centrifugal residual liquid is discharged from the top of the centrifugal separator, and the centrifuged perfluoroether elastomer concentrate is distributed on the surface of the paint cloth.

4. The method of breaking emulsions of perfluoroether elastomer emulsions according to claim 1, characterized in that: The method for breaking and coagulating perfluoroether elastomer emulsion according to any one of claims 1-7, wherein the low-temperature breaking system comprises a high-pressure gas tank, a concentrated emulsion tank, a temporary concentrated emulsion tank and a low-temperature liquid tank, and the high-pressure gas tank and the concentrated emulsion tank are both in communication with the temporary concentrated emulsion tank through pipelines; 5. The method of breaking emulsions of perfluoroether elastomer emulsions according to claim 1, characterized in that: The concentrated emulsion tank stores perfluoroether elastomer concentrate, the high-pressure gas tank stores one of high-pressure air, nitrogen or argon, the low-temperature liquid tank stores liquid nitrogen or liquid carbon dioxide, and the temporary concentrated emulsion tank sprays perfluoroether elastomer concentrate into the low-temperature liquid tank through a nozzle.

6. The method of breaking emulsions of perfluoroether elastomer emulsions according to claim 1, characterized in that: The high-pressure gas tank is connected with a high-pressure gas cylinder, the high-pressure gas cylinder and the high-pressure gas tank are controlled by valves, the high-pressure gas tank and the temporary concentrated emulsion tank are controlled by valves, the concentrated emulsion tank and the temporary concentrated emulsion tank are controlled by valves, and the temporary concentrated emulsion tank and the nozzle are controlled by valves.

7. The method of breaking emulsions of perfluoroether elastomer emulsions according to claim 1, characterized in that: ​ 8. A low temperature demulsification system characterized by: ​ ​ 9. The cryogenic demulsification system of claim 8, wherein, ​

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