A fluorination treatment device for unstable end groups of fluorine-containing thermoplastic polymers

Abstract

The present invention relates to the technical field of fluorine-containing polymer materials, and particularly to a fluorination treatment device for unstable end groups of fluorine-containing thermoplastic polymers, aiming to solve the problems of long reaction time, high reaction temperature, non-recyclable use of fluorination reagents, and poor fluorination effect existing in the existing gas-solid fluorination process. The fluorination treatment device for unstable end groups of fluorine-containing thermoplastic polymers provided by the present invention comprises a storage tank, a first pipeline, a second pipeline, a circulation pump, a fluorination reactor, a third pipeline and a tail gas treatment component; one end of the first pipeline extends into the lower part of the storage tank, and the other end is communicated with the upper part of the fluorination reactor, and a circulation pump is arranged on the first pipeline; one end of the second pipeline extends into the upper part of the storage tank, and the other end is communicated with the bottom of the fluorination reactor; the fluorination reactor is filled with fluorine-containing thermoplastic polymers, and the liquid fluorination reagent enters the fluorination reactor through the first pipeline and undergoes a fluorination reaction with the fluorine-containing thermoplastic polymers; the third pipeline is communicated with the tail gas treatment component.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorine-containing polymer materials, and particularly relates to a fluorination treatment device for unstable end groups of fluorine-containing thermoplastic polymers. Background Art

[0002] Fluorine-containing thermoplastic polymers (such as FEP, PFA, PCTFE, etc.) are widely used in industries with harsh working conditions and extremely high requirements for purity and cleanliness. Especially in the semiconductor field, fluorine-containing thermoplastic polymers can be used to manufacture pipelines, containers, and equipment linings for transporting liquid medicines and ultrapure water, as well as brackets or hanging baskets for silicon wafer etching. Now, they have become essential basic materials for the development of the high-end semiconductor industry.

[0003] Due to the use of inorganic oxides (such as potassium persulfate and ammonium persulfate) as initiators, a large number of unstable end groups (such as -COOH, -COF, -CF=CF2) are formed at the ends of fluorine-containing thermoplastic polymers. During high-temperature processing such as extrusion and injection molding, these unstable end groups are extremely easy to decompose into gases such as CO2, HF, and COF2, corroding metal equipment, causing the fluorine-containing thermoplastic polymer products to bubble and the color to deepen, greatly affecting the performance, appearance, and use of fluorine-containing thermoplastic polymers. In fields such as semiconductor or ultra-high purity reagent production, it is required that the end groups of the fluorine-containing thermoplastic polymers used must be inert. Therefore, it is necessary to perform fluorination treatment on the unstable end groups of the above-mentioned fluorine-containing thermoplastic polymers to convert them into stable trifluoromethyl (-CF3) groups.

[0004] Currently, the method for fluorinating the unstable end groups of fluorine-containing thermoplastic polymers is as follows: In reactors such as conical reactors or stirred reaction kettles, fluorine gas is intermittently introduced to perform fluorination treatment on the unstable end groups of fluorine-containing thermoplastic polymers. This process is a gas-solid reaction. The fluorine-containing thermoplastic polymer materials are extremely easy to agglomerate, the permeability of fluorine gas to fluorine-containing thermoplastic polymers is relatively low, and the contact effect between the gas and solid phases is poor. Usually, it is difficult to achieve full fluorination treatment of the unstable end groups of fluorine-containing thermoplastic polymers. Moreover, the fluorine gas in the fluorination reactor needs to be updated multiple times, and the operation is relatively complex. When using a gas-solid fluidized bed device, although the gas-solid contact effect can be improved to a certain extent, the gas distribution plate is extremely easy to block, and it is difficult to achieve industrialization. The fluorine gas is difficult to recycle, and the tail gas treatment load is large, which is not conducive to the requirements of environmental protection. In addition, the -COF end group is a strong electron-withdrawing end group, and its reaction activity with fluorine gas is relatively low. Usually, it is difficult to be converted into a -CF3 end group, and it requires a relatively high temperature of 250°C to 300°C and a relatively long time of 8h to 16h. However, under the above high-temperature working conditions, the activity of fluorine gas is extremely high, and it is extremely easy to react with the equipment and cause the decomposition of the polymer main chain, resulting in high metal impurities and reduced performance of fluorine-containing thermoplastic polymers. Summary of the Invention

[0005] The object of the present invention is to provide a fluorination treatment device for unstable end groups of fluorine-containing thermoplastics. By using the liquid-solid fluorination treatment device provided by the present invention and adopting a mixed solution of a fluorochloride and an inert perfluorinated solvent as a liquid fluorination reagent to perform liquid-solid fluorination treatment on the fluorine-containing thermoplastics, compared with the existing gas-solid fluorination process, the reaction time is short, the reaction temperature is relatively low, the reaction process is highly efficient, and the fluorination reagent can be reused, solving the problems of long reaction time, high reaction temperature, non-recyclable fluorination reagent, and poor fluorination effect existing in the existing gas-solid fluorination process.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention lies in:

[0007] The present invention provides a fluorination treatment device for unstable end groups of fluorine-containing thermoplastics, comprising: a storage tank, a first pipeline, a second pipeline, a circulation pump, a fluorination reactor, a third pipeline, and a tail gas treatment component;

[0008] The storage tank is used for containing a liquid fluorination reagent, and the liquid fluorination reagent is a mixture of a fluorochloride and an inert perfluorinated solvent;

[0009] One end of the first pipeline extends into the lower part of the storage tank, and the other end is communicated with the upper part of the fluorination reactor. A circulation pump is arranged on the first pipeline;

[0010] One end of the second pipeline extends into the upper part of the storage tank, and the other end is communicated with the bottom of the fluorination reactor;

[0011] The fluorination reactor is filled with fluorine-containing thermoplastics. The liquid fluorination reagent enters the fluorination reactor through the first pipeline and undergoes a fluorination reaction with the fluorine-containing thermoplastics. After the reaction ends, the liquid fluorination reagent in the fluorination reactor flows back to the storage tank through the second pipeline;

[0012] A third pipeline is arranged at the upper end of the fluorination reactor, and the third pipeline is communicated with the tail gas treatment component.

[0013] Furthermore,

[0014] A material component is arranged in the fluorination reactor. The material component is used for containing fluorine-containing thermoplastics, and the material component is provided with sieve holes;

[0015] The aperture of the sieve holes is smaller than the particle size of the fluorine-containing thermoplastics.

[0016] Furthermore,

[0017] The fluorination treatment device for unstable end groups of fluorine-containing thermoplastics further comprises a stirring component;

[0018] The stirring component is arranged above the fluorination reactor. The stirring component is provided with a stirring head which extends into the material piece and is used for stirring the material inside the material piece.

[0019] Furthermore,

[0020] The fluorination treatment device for the unstable end groups of the fluorinated thermoplastic polymer further includes a heating component;

[0021] The heating component is connected to the fluorination reactor and is used to provide the reaction temperature for the fluorination reaction in the fluorination reactor.

[0022] Furthermore,

[0023] The fluorination treatment device for the unstable end groups of the fluorinated thermoplastic polymer further includes a fourth pipeline;

[0024] A fourth pipeline for transporting nitrogen is arranged at the lower end of the fluorination reactor.

[0025] Furthermore,

[0026] The reaction temperature of the fluorination reaction is (20 - 60) °C, and the reaction time is (2 - 4) h.

[0027] Furthermore,

[0028] The fluorochloride is chlorine trifluoride and / or chlorine pentafluoride.

[0029] Furthermore,

[0030] The inert perfluorinated substituted solvent is perfluorinated substituted alkane and / or perfluorinated substituted tertiary amine.

[0031] Furthermore,

[0032] The perfluorinated substituted tertiary amine is perfluorotriethylamine, perfluorotripropylamine, or perfluorotributylamine.

[0033] Furthermore,

[0034] The mass content of the fluorochloride in the liquid fluorination reagent is (10 - 50)%;

[0035] The mass ratio of the liquid fluorination reagent to the fluorinated thermoplastic polymer is (2 - 10):1.

[0036] Based on the above technical solutions, the technical effects that the present invention can achieve are as follows:

[0037] 1. The present invention uses liquid circulation and stirring to fully contact and react a liquid fluorination reagent with a fluorine-containing thermoplastic polymer, which can significantly improve the dispersion degree of the fluorine-containing thermoplastic polymer and the contact area with the fluorination reagent, thereby enhancing the fluorination effect of the unstable end groups of the fluorine-containing thermoplastic polymer. At the same time, the temperature required for the liquid-solid fluorination reaction is low, avoiding the corrosion of the reactor by the fluorination reaction under high temperature conditions, and reducing the metal ion content in the fluorine-containing thermoplastic polymer product.

[0038] 2. The present invention uses a perfluorinated tertiary amine as an inert perfluorinated solvent. The perfluorinated tertiary amine can form an intermolecular dipole moment interaction with the difficult-to-fluorinate -COF end group, increase the electron cloud density of the -COF end group, and promote the fluorination reaction effect.

[0039] 3. In the present invention, the liquid fluorination reagent can be reused, avoiding the waste of the fluorination reagent and reducing the load on the tail gas treatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a schematic structural diagram of a fluorination treatment device for the unstable end groups of a fluorine-containing thermoplastic polymer.

[0042] Reference numerals: 1 - storage tank; 2 - first pipeline; 3 - second pipeline; 4 - circulation pump; 5 - fluorination reactor; 6 - third pipeline; 7 - tail gas treatment component; 8 - material component; 9 - stirring component; 10 - heating component; 11 - fourth pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Generally, the components of the embodiments of the present invention described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the present invention claimed, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0045] The following will describe in detail some embodiments of the present invention with reference to the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0046] The fluorination treatment device for the unstable end groups of the fluorine-containing thermoplastic polymer provided in this embodiment includes: a storage tank 1, a first pipeline 2, a second pipeline 3, a circulation pump 4, a fluorination reactor 5, a third pipeline 6, and a tail gas treatment component 7;

[0047] As Figure 1 shown, the storage tank 1 is used to accommodate the liquid fluorination reagent, and the storage tank 1 can be set as a liquid storage tank 1; one end of the first pipeline 2 extends into the lower part of the storage tank 1, and the other end is communicated with the upper part of the fluorination reactor 5. A circulation pump 4 is arranged on the first pipeline 2; one end of the second pipeline 3 extends into the upper part of the storage tank 1, and the other end is communicated with the bottom of the fluorination reactor 5; wherein, the first pipeline 2 can be set as a first liquid pipeline, and the second pipeline 3 can be set as a second liquid pipeline.

[0048] The fluorination reactor 5 is filled with a fluorine-containing thermoplastic polymer. A material part 8 is arranged in the fluorination reactor 5. The material part 8 is used to hold the fluorine-containing thermoplastic polymer. The material part 8 can be set as a material frame. The material frame 8 is provided with sieve holes, and the aperture of the sieve holes is smaller than the particle size of the fluorine-containing thermoplastic polymer. This setting can ensure that the fluorine-containing thermoplastic polymer is always contained in the material frame, and the liquid fluorination reagent can enter the material frame through the sieve holes to contact and react with the fluorine-containing thermoplastic polymer. In addition, by hoisting the material frame, it is convenient to realize the placement and unloading of the material from the fluorination reactor.

[0049] The liquid fluorination reagent enters the fluorination reactor 5 through the first pipeline 2 and reacts with the fluorine-containing thermoplastic polymer. After the reaction is completed, the liquid fluorination reagent in the fluorination reactor 5 flows back to the storage tank 1 through the second pipeline 3.

[0050] This embodiment is provided with a tail gas treatment component 7; a third pipeline 6 is arranged at the upper end of the fluorination reactor 5, and the third pipeline 6 is communicated with the tail gas treatment component 7. Specifically, the tail gas treatment component 7 can be one or more in series of conventional fluorine-containing tail gas treatment devices such as an alkali solution scrubbing tower, a soda lime adsorption tower, an activated carbon adsorption device, etc.; the third pipeline 6 is a tail gas pipeline, and a gas phase outlet valve is arranged on the fluorination reactor 5. When the gas phase outlet valve is opened, the gas enters the tail gas treatment component 7 through the tail gas pipeline.

[0051] In addition, in this embodiment, the fluorination reagent can be recycled, and the amount of tail gas generated is small. Therefore, the tail gas treatment load of this embodiment is low.

[0052] In an alternative embodiment, in order to increase the liquid-solid contact area, a stirring member 9 is further provided in this embodiment. The stirring member 9 is a device with a stirring function. The stirring member 9 is disposed above the fluorination reactor 5. The stirring member 9 is provided with a stirring head that extends into the material member 8 for stirring the material inside the material member 8. Moreover, the liquid fluorination reagent can be circulated between the fluorination reactor 5 and the storage tank 1 through a circulation pump 4, and liquid-solid stirring is further performed through the stirring member 9, thereby improving the dispersion degree of the fluorinated thermoplastic polymer in the liquid fluorination reagent, and further increasing the contact effect between the liquid fluorination reagent and the unstable end groups of the fluorinated thermoplastic polymer.

[0053] In an alternative embodiment, this embodiment further includes a heating member 10; the heating member 10 is connected to the fluorination reactor 5 and is used to provide a reaction temperature for the fluorination reaction in the fluorination reactor 5. Specifically, the heating member 10 can be set as an electric furnace. The fluorination reactor 5 is placed inside the electric furnace, and the reaction temperature of the fluorination reactor 5 is provided by the electric furnace. The maximum heating temperature of the electric furnace is 200 °C.

[0054] In an alternative embodiment, a fourth pipeline 11 for conveying nitrogen is provided at the lower end of the fluorination reactor 5. Specifically, the fourth pipeline 11 is a nitrogen pipeline, and a nitrogen replacement pipeline valve is provided on the nitrogen pipeline.

[0055] The fluorination treatment method of the fluorination treatment device based on the unstable end groups of the fluorinated thermoplastic polymer provided in this embodiment includes the following process steps:

[0056] Step 1: Material addition. Add the fluorinated thermoplastic polymer pellets into the material member 8, and then hoist the material member 8 filled with the fluorinated thermoplastic polymer into the fluorination reactor 5.

[0057] Step 2: Liquid feeding. Add the liquid fluorination reagent in the storage tank 1 into the fluorination reactor 5 through the circulation pump 4 for liquid-solid fluorination reaction.

[0058] Step 3: Fluorination reaction. The liquid-solid fluorination reaction temperature is (20 - 60) °C, and the reaction time is (2 - 4) h.

[0059] Wherein, the liquid fluorination reagent is circulated in the fluorination reactor 5 through the circulation pump 4. At the same time, start the stirring member 9 to improve the liquid-solid two-phase contact effect.

[0060] Step 4: Liquid recovery. When the fluorination reaction ends, the fluorination reagent in the fluorination reactor 5 returns to the storage tank 1 under the action of gravity.

[0061] Step 5: Material drying. After the liquid in the fluorination reactor 5 is recycled to the liquid storage tank 1, open the gas-phase outlet valve of the fluorination reactor 5. Raise the temperature of the fluorination reactor 5 to 100 - 200 °C to vaporize the small amount of fluorination reagent remaining in the fluorination reactor 5, which then enters the tail gas treatment component 7, thereby drying the fluorine-containing thermoplastic polymer. The drying time is (0.5 - 2) h. After drying, open the nitrogen replacement pipeline valve and replace the fluorination reactor 5 with nitrogen for (1 - 2) h;

[0062] Step 6: Material unloading. After drying is completed, turn off the stirring component 9, disassemble the fluorination reactor 5, lift out the material component 8, and collect the material after the reaction is complete.

[0063] In this embodiment, the fluorine-containing thermoplastic polymer is mixed with a liquid fluorination reagent. In the liquid-solid fluorination reaction system, through methods such as liquid circulation and stirring, the unstable end groups (-COOH, -COF, -CF=CF2, etc.) of the fluorine-containing thermoplastic polymer are brought into full contact with the liquid fluorination reagent, and a liquid-solid fluorination reaction occurs to convert the unstable end groups into stable end groups (-CF3).

[0064] The principle of the fluorination treatment method for the unstable end groups of the fluorine-containing thermoplastic polymer provided in this embodiment is as follows:

[0065] R-CF2-COF + ClF3 → R-CF3 + COF2 + ClF

[0066] R-CF2-COOH + ClF3 → R-CF3 + ClF + CO2 + HF

[0067] R-CF=CF2 + ClF3 → R-CF2-CF3 + ClF

[0068] R-CF2-COF + ClF5 → R-CF3 + COF2 + ClF3

[0069] R-CF2-COOH + ClF5 → R-CF3 + ClF3 + CO2 + HF

[0070] R-CF=CF2 + ClF5 → R-CF2-CF3 + ClF3

[0071] Among them, the liquid fluorination reagent is a mixture of a fluorochloride and an inert perfluorinated solvent; the fluorochloride is chlorine trifluoride and / or chlorine pentafluoride; the inert perfluorinated solvent is a perfluorinated alkane and / or a perfluorinated tertiary amine; the perfluorinated tertiary amine is perfluorotriethylamine, perfluorotripropylamine, or perfluorotributylamine.

[0072] Specifically, the boiling point of chlorine trifluoride is 11.75 °C, and the boiling point of chlorine pentafluoride is -13.1 °C. Compared with conventional gaseous fluorinating agents such as fluorine gas (boiling point -188.1 °C), chlorine trifluoride and chlorine pentafluoride can provide more free radicals, have a stronger fluorination reaction ability for the unstable end groups of fluorinated thermoplastics, and a higher fluorination reaction efficiency. Furthermore, they can convert the active end groups of fluorinated thermoplastics into -CF3 as much as possible. Moreover, chlorine trifluoride and chlorine pentafluoride have lower boiling points and can remain in a liquid state under lower reaction pressures. By using a liquid-solid fluorination process, the dispersibility of the fluorinated thermoplastic polymer material can be improved, the contact effect between fluorine free radicals and the unstable end groups of the fluorinated thermoplastic polymer can be significantly enhanced, and the reaction efficiency can be increased.

[0073] Specifically, the inert perfluoro-substituted solvent can be perfluoro-substituted alkane, perfluoro-substituted tertiary amine, etc. The inert perfluoro-substituted solvent hardly reacts with fluorochloride and fluorinated thermoplastics. During the fluorination reaction process, the inert perfluoro-substituted solvent acts as an inert solvent. The inert perfluoro-substituted solvent has good solubility for fluorochloride and can be made into the liquid fluorinating reagent with a certain ratio. The fluorinated thermoplastic polymer has a certain dispersibility in the inert perfluoro-substituted solvent and can be dispersed or suspended in the inert perfluoro-substituted solvent. The inert perfluoro-substituted solvent provides a good liquid-phase reaction environment for the liquid-solid reaction of the fluorinated thermoplastic polymer and fluorochloride, and can effectively avoid insufficient reaction due to the sticking and agglomeration of materials during the gas-solid reaction. Further, -COF is a strong electron-withdrawing group and is usually difficult to fluorinate. By using perfluoro-substituted tertiary amine as the solvent, since there is a pair of lone pairs of electrons in the perfluoro-substituted tertiary amine molecule, it can form an intermolecular dipole moment interaction with the -COF end group, thereby increasing the electron cloud density on the -COF group, and further increasing the fluorination reaction activity, ensuring that the unstable end groups of the fluorinated thermoplastic polymer can be converted into stable -CF3 end groups as completely as possible at a relatively low reaction temperature and within a relatively short reaction time.

[0074] The intermolecular dipole moment interaction between perfluoro-substituted tertiary amine and fluorinated thermoplastic polymer is as follows:

[0075]

[0076] Among them, the mass content of fluorochloride in the liquid fluorinating reagent is (10 - 50)%.

[0077] Among them, the mass ratio of the liquid fluorinating reagent to the fluorinated thermoplastic polymer is (2 - 10):1.

[0078] Among them, the perfluorinated thermoplastic polymer is a fluorinated thermoplastic polymer obtained by an aqueous emulsion polymerization method, including but not limited to fluorinated thermoplastic polymer pellets such as perfluoroethylene-propylene copolymer (FEP), soluble polytetrafluoroethylene (PFA), and polyvinylidene chloride (PCTFE).

[0079] In the method for fluorination treatment of the unstable end groups of the fully fluorinated thermoplastic polymer provided in this embodiment, compared with fluorine gas, the fluorochloride compound has higher reactivity, can generate more fluorine radicals, has a better fluorination effect on the unstable end groups of the fluorinated thermoplastic polymer, and can significantly reduce the fluorination reaction time and reaction temperature. Moreover, in this embodiment, perfluoro-substituted tertiary amine is used as an inert perfluoro-substituted solvent. The perfluoro-substituted tertiary amine can form an intermolecular dipole moment interaction with the difficult-to-fluorinate -COF end group, increase the electron cloud density of the -COF end group, and promote the fluorination reaction effect.

[0080] Example 1

[0081] (1) Place 100 kg of PFA particles (Sample 1) in a material frame and then hoist them into the fluorination reactor.

[0082] (2) Start the circulating pump on the first liquid pipeline, add 400 kg of liquid fluorination reagent in the liquid storage tank (where the mass of chlorine trifluoride is 100 kg and the mass of perfluoro-substituted triethylamine is 300 kg) to the fluorination reactor through the circulating pump, and return it to the liquid storage tank through the second liquid pipeline to form a liquid circulation. At the same time, start the stirring device in the fluorination reactor and control the reaction temperature at 30 - 40 °C for the fluorination reaction.

[0083] (3) After reacting for 2 h, the fluorination reagent in the fluorination reactor returns to the liquid storage tank by the action of gravity.

[0084] (4) After the fluorination reagent in the fluorination reactor is recovered to the liquid storage tank, raise the temperature of the fluorination reactor to 100 °C, and open the gas-phase outlet valve of the fluorination reactor to vaporize the trace fluorination reagent remaining in the fluorination reactor and enter the tail gas treatment system. The drying time is 1 h.

[0085] (5) After drying, introduce nitrogen for replacement. After 1 h of replacement, turn off the stirring device and take out the PFA particles (Sample 2) in the fluorination reactor.

[0086] Example 2

[0087] (1) Place 100 kg of PFA particles (Sample 1) in a material frame and then hoist them into the fluorination reactor.

[0088] (2) Start the circulating pump on the first liquid pipeline, add 400 kg of liquid fluorination reagent in the liquid storage tank (where the mass of chlorine trifluoride is 100 kg and the mass of perfluorohexane is 300 kg) to the fluorination reactor through the circulating pump, and return it to the liquid storage tank through the second liquid pipeline to form a liquid circulation. At the same time, start the stirring device in the fluorination reactor and control the reaction temperature at 30 - 40 °C for the fluorination reaction.

[0089] (3) After 2 hours of reaction, the fluorination reagent in the fluorination reactor returns to the liquid storage tank by the action of gravity;

[0090] (4) After the fluorination reagent in the fluorination reactor is recovered to the liquid storage tank, the temperature of the fluorination reactor is raised to 100 °C, and the gas-phase outlet valve of the fluorination reactor is opened to vaporize the trace amount of fluorination reagent remaining in the fluorination reactor and enter the tail gas treatment system. The drying time is 1 hour;

[0091] (5) After drying, nitrogen is introduced for replacement. After 1 hour of replacement, the stirring device is turned off, and the PFA particles (Sample 3) in the fluorination reactor are taken out.

[0092] Example 3

[0093] (1) Place 100 kg of PFA particles (Sample 1) in the material frame and then hoist them into the fluorination reactor;

[0094] (2) Start the circulating pump on the first liquid pipeline, add 400 kg of liquid fluorination reagent in the liquid storage tank (where the mass of chlorine trifluoride is 100 kg, the mass of perfluorohexane is 100 kg, and the mass of perfluoro-substituted triethylamine is 200 kg) to the fluorination reactor through the circulating pump, and return it to the liquid storage tank through the second liquid pipeline to form a liquid circulation. At the same time, start the stirring device in the fluorination reactor and control the reaction temperature at 30 - 40 °C for fluorination reaction;

[0095] (3) After 2 hours of reaction, the fluorination reagent in the fluorination reactor returns to the liquid storage tank by the action of gravity;

[0096] (4) After the fluorination reagent in the fluorination reactor is recovered to the liquid storage tank, the temperature of the fluorination reactor is raised to 100 °C, and the gas-phase outlet valve of the fluorination reactor is opened to vaporize the trace amount of fluorination reagent remaining in the fluorination reactor and enter the tail gas treatment system. The drying time is 1 hour;

[0097] (5) After drying, nitrogen is introduced for replacement. After 1 hour of replacement, the stirring device is turned off, and the PFA particles (Sample 4) in the fluorination reactor are taken out.

[0098] Example 4

[0099] (1) Place 100 kg of FEP particles (Sample 5) in the material frame and then hoist them into the fluorination reactor;

[0100] (2) Start the circulation pump on the first liquid pipeline, and add 400 kg of liquid fluorination reagent in the liquid storage tank (where the mass of chlorine pentafluoride is 80 kg and the mass of perfluoro-substituted triethylamine is 320 kg) to the fluorination reactor through the circulation pump, and return it to the liquid storage tank through the second liquid pipeline to form a liquid circulation. At the same time, start the stirring device in the fluorination reactor, and control the reaction temperature at 20 - 30 °C for the fluorination reaction;

[0101] (3) After reacting for 2 h, the fluorination reagent in the fluorination reactor returns to the liquid storage tank by the action of gravity;

[0102] (4) After the fluorination reagent in the fluorination reactor is recovered to the liquid storage tank, raise the temperature of the fluorination reactor to 100 °C, and open the gas-phase outlet valve of the fluorination reactor to vaporize the trace amount of fluorination reagent remaining in the fluorination reactor and enter the tail gas treatment system. The drying time is 1 h;

[0103] (5) After drying, introduce nitrogen for replacement. After 1 h of replacement, turn off the stirring device and take out the FEP particles (Sample 6) in the fluorination reactor;

[0104] Example Five

[0105] (1) Place 100 kg of FEP particles (Sample 5) in the material frame and then hoist them into the fluorination reactor;

[0106] (2) Start the circulation pump on the first liquid pipeline, and add 400 kg of liquid fluorination reagent in the liquid storage tank (where the mass of chlorine pentafluoride is 80 kg and the mass of perfluorohexane is 320 kg) to the fluorination reactor through the circulation pump, and return it to the liquid storage tank through the second liquid pipeline to form a liquid circulation. At the same time, start the stirring device in the fluorination reactor, and control the reaction temperature at 20 - 30 °C for the fluorination reaction;

[0107] (3) After reacting for 2 h, the fluorination reagent in the fluorination reactor returns to the liquid storage tank by the action of gravity;

[0108] (4) After the fluorination reagent in the fluorination reactor is recovered to the liquid storage tank, raise the temperature of the fluorination reactor to 100 °C, and open the gas-phase outlet valve of the fluorination reactor to vaporize the trace amount of fluorination reagent remaining in the fluorination reactor and enter the tail gas treatment system. The drying time is 1 h;

[0109] (5) After drying, introduce nitrogen for replacement. After 1 h of replacement, turn off the stirring device and take out the FEP particles (Sample 7) in the fluorination reactor.

[0110] Example Six

[0111] (1) Place 100 kg of FEP particles (Sample 5) in a material basket and then hoist it into the fluorination reactor;

[0112] (2) Start the circulating pump on the first liquid pipeline, add 400 kg of liquid fluorination reagent in the liquid storage tank (where the mass of chlorine pentafluoride is 80 kg, the mass of perfluorohexane is 220 kg, and the mass of perfluoro-substituted triethylamine is 100 kg) into the fluorination reactor through the circulating pump, and return it to the liquid storage tank through the second liquid pipeline to form a liquid cycle. At the same time, start the stirring device in the fluorination reactor and control the reaction temperature at 20 - 30 °C for the fluorination reaction;

[0113] (3) After reacting for 2 h, the fluorination reagent in the fluorination reactor returns to the liquid storage tank by the action of gravity;

[0114] (4) After the fluorination reagent in the fluorination reactor is recovered to the liquid storage tank, raise the temperature of the fluorination reactor to 100 °C, and open the gas-phase outlet valve of the fluorination reactor to vaporize the trace fluorination reagent remaining in the fluorination reactor and enter the tail gas treatment system. The drying time is 1 h;

[0115] (5) After drying, introduce nitrogen for replacement. After 1 h of replacement, turn off the stirring device and take out the FEP particles (Sample 8) in the fluorination reactor

[0116] Comparative Example 1

[0117] (1) Place 100 kg of PFA particles (Sample 1) in a material basket and then hoist it into the fluorination reactor;

[0118] (2) Introduce a 20% fluorine-nitrogen mixed gas into the fluorination reactor, keep the reaction pressure at 0.1 MPa, gauge pressure, and the reaction temperature at 200 °C. Under the stirring action, make the fluorine gas contact and react with the PFA particles. The fluorine-nitrogen mixed gas needs to be updated every 0.5 h;

[0119] (3) After reacting for 12 h, introduce nitrogen to replace the reactor. After 1 h of replacement, turn off the stirring device and take out the PFA particles (Sample 9) in the fluorination reactor.

[0120] Comparative Example 2

[0121] (1) Place 100 kg of FEP particles (Sample 5) in a material basket and then hoist it into the fluorination reactor;

[0122] (2) Introduce a 30% fluorine-nitrogen mixed gas into the reactor, maintain the reaction pressure at 0.1 MPa, gauge pressure, and the reaction temperature at 150 °C. Under the stirring action, make the fluorine gas contact and react with the FEP particles. The fluorine-nitrogen mixed gas is updated every 0.5 h;

[0123] (3) After reacting for 10 h, nitrogen was introduced to displace the reactor. After 1 h of displacement, the stirring device was turned off, and the FEP particles (Sample 10) in the fluorination reactor were taken out.

[0124] Experimental Example

[0125] The content of unstable end groups of the sample was analyzed by infrared spectroscopy analysis.

[0126] The polymer powder was pressed into a thin film of (0.1 - 0.2) mm at 200 °C - 350 °C, and the Nicolet 380 Fourier transform infrared spectrometer was used to determine the content of unstable end groups of the fluorinated thermoplastic polymer. The infrared absorption wavelengths of the unstable end groups are shown in Table 1.

[0127] Table 1. List of characteristic infrared absorption spectral numbers corresponding to the types of unstable end groups of fluorinated thermoplastic polymers

[0128] End group type Infrared absorption spectrum number 1 -COOH 1814 2 -COF 1883 3 <![CDATA[-CF=CF2]]> 1795

[0129] The Nicolet 380 Fourier transform infrared spectrometer was used to analyze the content of unstable end groups of the above sample, and the analysis results are shown in Table 2.

[0130] Table 2. Statistical table of the content of unstable end groups of the sample determined by infrared spectroscopy analysis

[0131]

[0132] From the data in Table 2, it can be seen that when the fluorinated thermoplastic polymer selects soluble polytetrafluoroethylene (PFA), compared with Comparative Example 1, after reacting by the fluorination treatment method of the unstable end groups of the fluorinated thermoplastic polymer provided in this example, the content of unstable end groups of the product is greatly reduced, and the fluorination effect of the unstable end groups of the fluorinated thermoplastic polymer in this example is better. At the same time, from the data in Table 2, it can be seen that when the fluorinated thermoplastic polymer selects perfluoroethylene-propylene copolymer (FEP), compared with Comparative Example 2, after reacting by the fluorination treatment method of the unstable end groups of the fluorinated thermoplastic polymer provided in this example, the content of unstable end groups of the product is greatly reduced, and the fluorination effect of the unstable end groups of the fluorinated thermoplastic polymer in this example is better. Moreover, when reacting by the fluorination treatment method provided in this example, when the inert perfluoro-substituted solvent selects perfluoro-substituted tertiary amine and perfluoro-substituted alkane, compared with the case where the inert perfluoro-substituted solvent selects a single-component perfluoro-substituted tertiary amine or perfluoro-substituted alkane, the fluorination effect of the unstable end groups of the fluorinated thermoplastic polymer is better.

[0133] Compared with the gas-solid fluorination reaction, in this embodiment, a liquid fluorochloride and a fluorinated thermoplastic polymer are used to carry out a liquid-solid fluorination reaction in a liquid phase environment of an inert perfluoro-substituted solvent. The fluorinated thermoplastic polymer has a higher degree of dispersion and is in more sufficient contact with the fluorochloride, which can effectively avoid insufficient reaction due to material adhesion and agglomeration during the gas-solid reaction. In addition, the fluorochloride has a higher reaction activity, and the fluorination reaction activity of the unstable end groups of the fluorinated thermoplastic polymer is higher, requiring a lower reaction temperature and a shorter reaction time. In addition, the degree of dispersion of the fluorinated thermoplastic polymer in perfluoro-substituted alkanes is higher than that in perfluoro-substituted tertiary amines. At the same time, due to the intermolecular dipole moment of perfluoro-substituted tertiary amines, the reaction activity of the difficult-to-fluorinate group -COF can be improved, and the fluorination treatment effect of the unstable end groups of the fluorinated thermoplastic polymer is better. Therefore, when the inert perfluoro-substituted solvent is selected as perfluoro-substituted tertiary amine and perfluoro-substituted alkane, the fluorination effect of the unstable end groups of the fluorinated thermoplastic polymer is better.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fluorination treatment method for unstable end groups of a fluorinated thermoplastic polymer, characterized in that, A fluorination treatment device using unstable end groups of fluorinated thermoplastic polymers, the fluorination treatment device comprising a storage tank, a first pipeline, a second pipeline, a circulation pump, a fluorination reactor and a stirring component; The storage tank is used for containing a liquid fluorination reagent, and the liquid fluorination reagent is a mixture of a fluorochloride compound and an inert perfluorinated substituted solvent; One end of the first pipeline extends into the lower part of the storage tank, and the other end is communicated with the upper part of the fluorination reactor, and a circulation pump is arranged on the first pipeline; One end of the second pipeline extends into the upper part of the storage tank, and the other end is communicated with the bottom of the fluorination reactor; The fluorination reactor is filled with fluorinated thermoplastic polymers. The liquid fluorination reagent enters the fluorination reactor through the first pipeline and undergoes a fluorination reaction with the fluorinated thermoplastic polymers. After the reaction ends, the liquid fluorination reagent in the fluorination reactor flows back to the storage tank through the second pipeline; A material frame is arranged in the fluorination reactor, and the material frame is used for containing fluorinated thermoplastic polymers; the material frame is provided with sieve holes, and the aperture of the sieve holes is smaller than the particle size of the fluorinated thermoplastic polymers; The stirring component is arranged above the fluorination reactor, the stirring component is provided with a stirring head, and the stirring head extends into the material frame for stirring the materials inside the material frame; The storage tank is set as a liquid storage tank; the first pipeline is set as a first liquid pipeline, and the second pipeline is set as a second liquid pipeline; Comprising the following steps: Place 100 kg of fusible polytetrafluoroethylene particles in the material frame, and then hoist them into the fluorination reactor; Start the circulation pump on the first liquid pipeline, add 400 kg of liquid fluorination reagent in the liquid storage tank to the fluorination reactor through the circulation pump, and form a liquid circulation by flowing back to the liquid storage tank through the second liquid pipeline. At the same time, start the stirring component and control the reaction temperature at 30 - 40 °C for the fluorination reaction; among the 400 kg of liquid fluorination reagent, the mass of chlorine trifluoride is 100 kg, and the mass of perfluorinated triethylamine is 300 kg; After reacting for 2 h, the fluorination reagent in the fluorination reactor returns to the liquid storage tank under the action of gravity; After the fluorination reagent in the fluorination reactor is recovered to the liquid storage tank, raise the temperature of the fluorination reactor to 100 °C, and open the gas-phase outlet valve of the fluorination reactor to vaporize the remaining fluorination reagent in the fluorination reactor and enter the tail gas treatment system, and the drying time is 1 h; After drying, introduce nitrogen for replacement. After replacing for 1 h, turn off the stirring component and take out the fusible polytetrafluoroethylene particles in the fluorination reactor.

2. The fluorination treatment method for unstable end groups of fluorinated thermoplastic polymers according to claim 1, wherein, The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers further comprises a heating component; The heating component is connected to the fluorination reactor and is used to provide a reaction temperature for the fluorination reaction in the fluorination reactor.

3. The fluorination treatment method for unstable end groups of fluorinated thermoplastic polymers according to claim 2, wherein, The fluorination treatment device for the unstable end groups of the fluorinated thermoplastic polymer further includes a fourth pipeline; A fourth pipeline for transporting nitrogen gas is arranged at the lower end of the fluorination reactor.

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