Fluorination Treatment Device for Unstable End Groups of Fluorine-Containing Thermoplastic Polymers

Abstract

The present invention relates to the field of fluororesin materials, and in particular to a fluorination treatment device for unstable end groups of fluorine-containing thermoplastic polymers. The device comprises: an amide reaction device, used for an amide reaction of the fluorine-containing thermoplastic polymer, so as to convert the difficult-to-fluorinate -COF end groups in the fluorine-containing thermoplastic polymer into easily-fluorinated -CONHR end groups, thereby obtaining an amidated fluorine-containing thermoplastic polymer; a fluorination reaction device, connected to the amide reaction device, used for a fluorination reaction of the amidated fluorine-containing thermoplastic polymer, so as to convert the -CONHR end groups, -COOH end groups and -CF=CF2 end groups in the amidated fluorine-containing thermoplastic polymer into -CF3 end groups, thereby obtaining a fluorinated fluorine-containing thermoplastic polymer; and a melt granulation device, connected to the fluorination reaction device, used for extruding and granulating the fluorinated fluorine-containing thermoplastic polymer to obtain a granular product.

Description

Technical Field

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

[0002] Fluorinated thermoplastic polymers (FEP, PFA, PCTFE, etc.) are nearly identical to PTFE in terms of thermal / chemical stability, physical and mechanical properties, electrical insulation, aging resistance, and low friction. Compared to PTFE, these fluorinated thermoplastic polymers can be melt-processed, overcoming PTFE's drawback of being unable to be injection molded. Consequently, fluorinated thermoplastic polymers are widely used in industries with demanding working conditions and extremely high purity and cleanliness requirements. In particular, in the semiconductor sector, fluorinated thermoplastic polymers can be used to make pipes, containers, and equipment linings for transporting liquid chemicals and ultrapure water, as well as brackets or hanging baskets for silicon wafer etching. They have become an essential cornerstone material for the development of the high-end semiconductor industry.

[0003] The use of inorganic oxides (such as potassium persulfate and ammonium persulfate) as initiators results in the formation of numerous thermally unstable end groups (e.g., -COOH, -COF, and -CF=CF2) at the ends of fluorinated thermoplastic polymers. These thermally unstable end groups easily decompose during high-temperature processing, such as extrusion and injection molding, to produce gases such as CO2, HF, and COF2. These gases corrode metal equipment, cause blistering, and darken the color of fluorinated thermoplastic polymer products, and significantly impact the performance, appearance, and usability of the fluorinated thermoplastic polymers. Therefore, in the semiconductor industry, where cleanliness and sanitization requirements are becoming increasingly stringent, these unstable end groups in fluorinated thermoplastic polymers must be stabilized. Summary of the Invention

[0004] Based on this, the present invention proposes a fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers. The fluorination treatment process combines amide reaction and fluorination reaction under microwave heating conditions, which has the advantages of mild reaction conditions, high selectivity, and fast reaction rate.

[0005] According to one aspect of the present invention, a fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers is provided, which adopts a fluorination treatment process combining an amide reaction and a fluorination reaction, and uses microwave heating to provide the activation energy required for the amide reaction and the fluorination reaction; the device comprises:

[0006] An amide reaction device is used for the amide reaction of the fluorinated thermoplastic polymer to convert the difficult-to-fluorinate -COF end group in the fluorinated thermoplastic polymer into the easily fluorinated -CONHR end group to obtain an amidated fluorinated thermoplastic polymer;

[0007] a fluorination reaction device connected to the amide reaction device, used for fluorination reaction of the amidated fluorine-containing thermoplastic polymer, converting the -CONHR end group, -COOH end group and -CF=CF2 end group in the amidated fluorine-containing thermoplastic polymer into a -CF3 end group to obtain a fluorinated fluorine-containing thermoplastic polymer;

[0008] The melt granulation device is connected to the fluorination reaction device and is used for extruding and granulating the fluorinated thermoplastic polymer to obtain a granular product.

[0009] According to an embodiment of the present invention, the amide reaction device comprises:

[0010] a first microwave reaction device, for subjecting the fluorine-containing thermoplastic polymer to an amide reaction to obtain the amidated fluorine-containing thermoplastic polymer, comprising an amide reactor and a microwave emitting device disposed outside the amide reactor;

[0011] a first powder feeding device, used for storing and feeding the fluorinated thermoplastic polymer, wherein the first powder feeding device introduces the fluorinated thermoplastic polymer in the silo into a first ejection device through a first star feeder, and the first ejection device then sprays the fluorinated thermoplastic polymer into the amide reactor;

[0012] The first gas supply device is used to provide a mixed gas during the amide reaction of the fluorine-containing thermoplastic polymer, comprising:

[0013] The first gas mixing device is used to transport nitrogen and organic amine gas into the first gas mixing device through a pipeline and mix them to obtain a mixed gas. The outlet end of the first gas mixing device is connected to the amide reactor through a pipeline.

[0014] According to an embodiment of the present invention, the fluorination reaction device includes:

[0015] a second microwave reaction device, for subjecting the amidated fluorinated thermoplastic polymer to a fluorination reaction to obtain the fluorinated fluorinated thermoplastic polymer, comprising a fluorination reactor and a microwave emitting device arranged outside the amidation reactor;

[0016] a second powder feeding device, configured to transfer the amidated fluorinated thermoplastic polymer in the first microwave reaction device to the second microwave reaction device, and the second powder feeding device sprays the amidated fluorinated thermoplastic polymer into the fluorination reactor via the second ejecting device;

[0017] The second gas supply device is used to provide a mixed gas during the fluorination reaction of the fluorine-containing thermoplastic polymer, comprising:

[0018] The second gas mixing device is used to transport nitrogen and fluorine into the second gas mixing device through a pipeline and mix them to obtain a mixed gas. The outlet end of the second gas mixing device is connected to the fluorination reactor through a pipeline.

[0019] According to an embodiment of the present invention, the melt granulation device includes:

[0020] a feeding bin for receiving the fluorinated fluorinated thermoplastic polymer obtained from the second microwave reaction device;

[0021] A twin-screw extrusion granulation device is connected to the feed bin pipeline.

[0022] According to an embodiment of the present invention, the present invention further includes:

[0023] a third ejection device, for transferring the fluorinated fluorinated thermoplastic polymer in the second microwave reaction device to the melt granulation device;

[0024] The gas-solid separation device is arranged between the third ejection device and the melting granulation device.

[0025] According to an embodiment of the present invention, the feed bin is provided with a second star-shaped feeder for transferring the fluorinated fluorine-containing thermoplastic polymer to the twin-screw extrusion granulation device.

[0026] According to an embodiment of the present invention, a waste alkali gas treatment system is further included, one end of which is connected to the gas phase outlet pipeline of the amide reaction device, and the other end is connected to the waste alkali gas treatment device.

[0027] According to an embodiment of the present invention, a waste fluorine gas treatment system is further included, one end of which is connected to the gas phase outlet pipeline of the fluorination reaction device, and the other end is connected to the waste fluorine gas treatment device.

[0028] According to an embodiment of the present invention, a gas filtering device is provided on the top of the amide reaction device and the fluorination reaction device.

[0029] It can be seen from the above technical solution that the fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers provided by the present invention has the following beneficial effects:

[0030] (1) The fluorination treatment device for unstable end groups of fluorine-containing thermoplastic polymers provided by the present invention adopts a two-step treatment method of amide reaction combined with fluorination reaction, supplemented by microwaves as a heating source. Since the microwave heating method is from the inside to the outside and only heats the polar end groups, the -COF polar end groups are converted into -CONHR end groups, and the polar end groups such as -CONHR, -COOH, and -CF=CF2 can be quickly activated after absorbing microwaves to achieve the energy required for the reaction, significantly improving the rates of amide reaction and fluorination reaction, and greatly shortening the reaction time.

[0031] (2) The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers provided by the present invention uses microwaves as a heating source. The easily fluorinated polar end groups of the fluorinated thermoplastic polymers can be activated by heat and react with fluorine gas, while the main chain of the fluorinated thermoplastic polymer with a non-polar structure does not absorb microwaves and almost no chain breaking and decomposition will occur.

[0032] (3) The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers provided by the present invention uses microwaves as a heating source, so that the temperature of the reaction system can be maintained at room temperature, which can significantly reduce the problem of high metal impurity content caused by equipment corrosion under high-temperature conditions.

[0033] (4) The present invention provides a fluorination treatment device for unstable end groups of fluorine-containing thermoplastic polymers. By adopting a fluidized bed reactor, the raw materials are subjected to a fluidized reaction mode, which ensures sufficient contact between the reaction gas and the fluorine-containing thermoplastic polymer. Compared with the use of stirring reactors, rotary drum reactors and other reactors, it can effectively avoid the problems of fluorine-containing thermoplastic polymers sticking together and agglomerating and insufficient reaction, and has a good fluorination end-capping effect.

[0034] (5) The present invention provides a fluorination treatment device for unstable end groups of fluorine-containing thermoplastic polymers. The device has a reasonable structure and design, and has the characteristics of low energy consumption, good fluorination end-capping effect, and convenient operation. It can realize continuous production and is suitable for large-scale industrial applications. The total content of unstable end groups in the fluorine-containing polymers prepared by using this process device is less than 10 / million carbon atoms, which meets the indicators of the semiconductor industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0036] Figure 1 It is a schematic structural diagram of a fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers according to an embodiment of the present invention.

[0037] In the above drawings, the meanings of the reference numerals are as follows:

[0038] 1-silo; 2-star feeder; 3-first ejector; 4-amide reactor; 5-first gas mixing device; 6-second ejector; 7-circulation pump; 8-fluorination reactor; 9-membrane press; 10-second gas mixing device; 11-third ejector; 12-gas-solid separation device; 13-star feeder; 14-temporary storage silo; 15-twin-screw extrusion granulation device; 16-flow meter. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0040] Currently, wet heat treatment methods typically use alkali metals or their corresponding bases or alkaline salts in the presence of water vapor at a heating temperature of 250°C-300°C to convert the -COF and -COOH end groups of fluorinated thermoplastic polymers into the relatively stable -CF2H. However, alkali metals easily remain in fluorinated thermoplastic polymers, resulting in reduced thermal stability and making them unusable in the semiconductor industry.

[0041] Currently, there is a method that uses ammonia gas or ammonia water to convert -COF and -COOH end groups into -CONH2. The -CONH2-terminated fluorinated thermoplastic polymer prepared by this method will still be destroyed and decomposed at a processing temperature of 300°C-400°C.

[0042] There is another method that uses fluorine gas to stabilize the end groups of fluorinated thermoplastic polymers, which can convert the above-mentioned unstable end groups into stable -CF3 end groups. Compared with -COOH, CONH2, and -CF=CF2 end groups, the -COF end group is a strong electron-withdrawing end group with low fluorination activity, and is the least likely to be converted into a -CF3 end group. To ensure that -COF can react completely to the greatest extent, the fluorination end-capping reaction usually requires a higher temperature of 250℃-300℃ and a longer time of 8h-16h to convert it into -CF3. However, under the above-mentioned high-temperature working conditions, the activity of fluorine gas is extremely high, and it is very easy to react with the equipment and cause the decomposition of the polymer main chain, resulting in high metal impurities and reduced performance of fluorinated thermoplastic polymers.

[0043] Therefore, a fluorination treatment technology for unstable end groups of fluorinated thermoplastic polymers is needed to improve the problem of high metal impurity content caused by equipment corrosion under high-temperature conditions, so that it has higher purity and thermal stability and can be further applied in semiconductor-level process.

[0044] According to the general inventive concept of the first aspect of the present invention, Figure 1 As shown, a fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers is provided, which adopts a fluorination treatment process combining amide reaction and fluorination reaction, and uses microwave heating to provide the activation energy required for amide reaction and fluorination reaction; it includes:

[0045] An amide reaction device is used for the amide reaction of a fluorinated thermoplastic polymer to convert the difficult-to-fluorinate -COF end group in the fluorinated thermoplastic polymer into the easily fluorinated -CONHR end group to obtain an amidated fluorinated thermoplastic polymer;

[0046] A fluorination reaction device connected to the amide reaction device is used for the fluorination reaction of the amidated fluorine-containing thermoplastic polymer, converting the -CONHR end group, -COOH end group and -CF=CF2 end group in the amidated fluorine-containing thermoplastic polymer into a -CF3 end group to obtain a fluorinated fluorine-containing thermoplastic polymer;

[0047] The melt granulation device is connected to the fluorination reaction device and is used to extrude and granulate the fluorinated thermoplastic polymer to obtain a granular product.

[0048] According to an embodiment of the present invention, the amide reaction device comprises:

[0049] The first microwave reaction device is used to make the fluorine-containing thermoplastic polymer undergo an amide reaction to obtain an amidated fluorine-containing thermoplastic polymer, and includes an amide reactor 4 and a microwave emitting device arranged outside the amide reactor 4 .

[0050] The first powder feeding device is used for storing and feeding the fluorinated thermoplastic polymer. The first powder feeding device introduces the fluorinated thermoplastic polymer in the silo 1 into the first ejecting device 3 through the first star feeder 2, and then the first ejecting device 3 sprays the fluorinated thermoplastic polymer into the amide reactor 4.

[0051] The first gas feeding device is used to provide a mixed gas during the amide reaction of the fluorine-containing thermoplastic polymer, including: a first gas mixing device 5, which transports nitrogen and organic amine gas into the first gas mixing device 5 through a pipeline and mixes them to obtain a mixed gas, and the outlet end of the first gas mixing device 5 is connected to the amide reactor 4 through a pipeline.

[0052] The powder feeding device mainly adds the fluorinated thermoplastic polymer powder into the silo 1 for storage, and then quantitatively discharges the powder to the first ejection device 3 at the lower end through the first star feeder 2, thereby quantitatively transporting the fluorinated thermoplastic polymer powder to the amide reactor 4 to realize the powder feeding function.

[0053] According to an embodiment of the present invention, the silo 1 includes: a silo body, a level meter, and a vibration module. The silo 1 can adopt a circular, square, diamond-shaped, conical, cylindrical structure, etc., preferably an inverted conical cylindrical structure, made of 316L. A feed port and a discharge port are respectively provided at the upper and lower parts of the silo body. A valve is provided on the feed port pipeline, and a star-shaped feeding valve is provided at the discharge port. The feeding amount is controlled by controlling the rotation speed of the star-shaped feeding valve. The level meter is provided on the side of the silo 1 to monitor the amount of material in the silo. The vibration module is provided on the side of the lower section of the silo 1 to control the smoothness of the discharge process through vibration to avoid material blockage.

[0054] According to an embodiment of the present invention, the fluorination reaction device includes:

[0055] The second microwave reaction device is used to carry out a fluorination reaction on the amidated fluorine-containing thermoplastic polymer to obtain a fluorinated fluorine-containing thermoplastic polymer, and includes a fluorination reactor 8 and a microwave emitting device arranged outside the amide reactor 4.

[0056] The second powder feeding device is used to transfer the amidated fluorinated thermoplastic polymer in the first microwave reaction device to the second microwave reaction device. The second powder feeding device sprays the amidated fluorinated thermoplastic polymer into the fluorination reactor 8 through the second ejecting device 6.

[0057] The second gas feeding device is used to provide a mixed gas during the fluorination reaction of the fluorine-containing thermoplastic polymer, including: a second gas mixing device 10, nitrogen and fluorine are transported into the second gas mixing device 10 through a pipeline and mixed to obtain a mixed gas, and the outlet end of the second gas mixing device 10 is connected to the fluorination reactor 8 through a pipeline.

[0058] In the second microwave reaction device, under microwave heating conditions, the fluorine-nitrogen mixed gas and the amidated fluorine-containing thermoplastic polymer powder undergo contact reaction within the fluorination reactor 8, thereby achieving the fluorination reaction process. The material is then discharged through the lower outlet of the fluorination reactor 8 to the gas-solid separation device 12 for gas-solid separation. The separated gas is then piped to the waste fluorine gas treatment device, thus achieving gas circulation and waste gas treatment functions.

[0059] According to an embodiment of the present invention, the device used in the amide reactor 4 and the fluorination reactor 8 is a fluidized bed, the material of which can be pure nickel, Inconel, Hastelloy, etc., considering the corrosion resistance and metal composition, Hastelloy is preferably used as the material of the fluidized bed reactor; the fluidized bed structure is mainly composed of a shell, a feed port, an air inlet, an air outlet, a discharge port and a lower gas distribution plate, wherein the shell adopts a straight cylindrical type, the feed port is arranged on the top side wall of the reactor, the air inlet and the gas distribution plate are arranged at the bottom of the reactor, the air outlet is arranged above the top of the reactor, and the discharge port is arranged at the bottom of the reactor; a filter is provided at the top of the fluidized bed reactor, preferably a sintered nickel metal filter, and the filter outlet is connected to the tail gas pipeline and the circulation pipeline;

[0060] According to an embodiment of the present invention, microwave introduction holes are provided on the outer walls of the amide reactor 4 and the fluorination reactor 8, and the activation energy required for the reaction is provided by heating the reactor with microwaves, thereby carrying out the amide and fluorination reaction processes.

[0061] According to an embodiment of the present invention, the first gas mixing device 5 and the second gas mixing device 10 are mainly composed of a shell and an inner cavity. The shell is made of stainless steel and lined with polytetrafluoroethylene. The inner cavity is a cavity.

[0062] According to an embodiment of the present invention, the first gas supply device and the second gas supply device further include a nitrogen pipeline and an organic amine gas pipeline.

[0063] According to an embodiment of the present invention, the nitrogen pipeline and the organic amine gas pipeline are provided with flow meters to measure the gas flow.

[0064] According to an embodiment of the present invention, the melt granulation device includes:

[0065] A feeding bin 14 is used to receive the fluorinated fluorinated thermoplastic polymer obtained from the second microwave reaction device;

[0066] The twin-screw extruder granulation device 15 is connected to the feed bin 14 via a pipeline.

[0067] According to an embodiment of the present invention, the twin-screw extrusion granulation device 15 adopts a screw extruder for extrusion molding, and its type can be single screw, twin screw and multi-screw, etc. Considering the comprehensive process conditions, the preferred extruder is a twin-screw extrusion granulation device 15, and the extruder speed is 5kg / h-25kg / h, preferably 10kg / h-15kg / h.

[0068] According to an embodiment of the present invention, the present invention further includes:

[0069] The third ejector 11 is used to transfer the fluorinated thermoplastic polymer in the second microwave reaction device to the melt granulation device;

[0070] The gas-solid separation device 12 is arranged between the third ejector device 11 and the melting granulation device.

[0071] According to an embodiment of the present invention, the gas-solid separation device 12 preferably adopts a cyclone separator; a sintered nickel filter is provided on the top of the shell to achieve the function of separating the gas and the fluorine-containing thermoplastic polymer.

[0072] According to an embodiment of the present invention, the feed bin 14 is provided with a second star-shaped feeder 13 for transferring the fluorinated fluorine-containing thermoplastic polymer to the twin-screw extrusion granulation device 15 .

[0073] According to an embodiment of the present invention, a waste alkali gas treatment system is further included, one end of which is connected to the gas phase outlet pipeline of the amide reactor, and the other end is connected to the waste alkali gas treatment device.

[0074] According to an embodiment of the present invention, a waste fluorine gas treatment system is further included, one end of which is connected to the gas phase outlet pipe of the fluorination reactor, and the other end is connected to the waste fluorine gas treatment device.

[0075] According to an embodiment of the present invention, a gas filtering device is provided on the top of the amide reaction device and the fluorination reaction device.

[0076] According to an embodiment of the present invention, a gas filtration device is provided on the upper part of the amide reactor 4, the outlet end of the gas filtration device is connected to the pipeline of the waste alkali gas treatment device, and the pipeline of the waste alkali gas treatment device is connected to the organic amine gas circulation pipeline; wherein a circulation pump 7 is provided on the organic amine gas circulation pipeline, and the organic amine gas circulation pipeline is connected to the first gas mixing device 5 to realize the circulation and transportation of the gas.

[0077] According to an embodiment of the present invention, a gas filtering device is provided on the upper part of the fluorination reactor 8, the outlet end of the gas filtering device is connected to the pipeline of the waste fluorine gas treatment device, and the fluorine gas circulation pipeline is connected to the pipeline of the waste fluorine gas treatment device; wherein a diaphragm compressor 9 is provided on the fluorine gas circulation pipeline, and the fluorine gas circulation pipeline is connected to the second gas mixing device 10 to realize the circulation and transportation of fluorine gas.

[0078] According to an embodiment of the present invention, the fluorinated thermoplastic polymer is a fluorinated polymer obtained by aqueous emulsion polymerization, including but not limited to polyperfluoroethylene propylene (FEP), fusible polytetrafluoroethylene (PFA), polychlorotrifluoroethylene (PCTFE), etc. The unfluorinated end-capped fluorinated thermoplastic polymer raw material includes but is not limited to powder, and may also be in blocks, strips, sheets, irregular shapes, etc., preferably in powder form.

[0079] According to an embodiment of the present invention, the organic amine gas is a low-level organic amine gas (methylamine, ethylamine, propylamine, butylamine, pentylamine), etc., and taking into account the boiling point, nucleophilicity and steric hindrance of the organic amine, ethylamine or propylamine is preferably used as the organic amine gas. Furthermore, nitrogen is preferably used to dilute the organic amine. The volume ratio of the organic amine to nitrogen can generally be (1-10)%, and further preferably (2-4)%.

[0080] According to an embodiment of the present invention, the activation energy required for the amide reaction is provided by microwave heating, the microwave heating frequency is 915 MHz and 2450 MHz, and the microwave heating time is (0.5-2) h. It is further preferred that the microwave heating frequency is 2450 MHz and the microwave heating time is (0.5-1) h.

[0081] According to an embodiment of the present invention, since the fluorination reaction is an exothermic reaction with a huge amount of heat released, it is relatively dangerous to use pure fluorine gas as a fluorination reagent. Therefore, nitrogen gas is used to dilute the pure fluorine. The volume ratio of fluorine gas to nitrogen gas can generally be (5-50)%, and further preferably (10-30)%.

[0082] According to an embodiment of the present invention, the activation energy required for the fluorination reaction is provided by microwave heating, the microwave heating frequency is 915 MHz and 2450 MHz, and the microwave heating time is (1-2) h. More preferably, the microwave heating frequency is 2450 MHz, and the microwave heating time is (1-1.5) h.

[0083] According to an embodiment of the present invention, the present invention provides a process flow using the device, comprising:

[0084] After the entire device is dehydrated and deoxygenated to an acceptable range, the feeding valve switch at the lower end of the fluorine-containing thermoplastic powder silo 1 is opened, and the vibration module is turned on for vibration feeding. The fluorine-containing thermoplastic polymer powder is quantitatively added to the amide reactor 4 through the first star feeder 2 and measured with a weighing sensor;

[0085] Before adding the materials to the amide reaction device, the valves on the nitrogen pipeline and the valves on the organic amine gas pipeline are opened respectively. The two gases are metered and proportioned by the flow meter 16, so that the nitrogen and organic amine gases enter the first gas mixing device 5 for full mixing to obtain a certain proportion of organic amine mixed gas with a flow rate of (6-10) m 3 / h, then open the outlet valve of the first gas mixing device 5 to allow the organic amine mixed gas to enter the amide reactor 4, open the tail gas valve, and the gas in the reactor enters the waste alkali gas treatment device.

[0086] After the addition of materials, the feed flow rate was increased and microwave was introduced to carry out amide reaction. The materials were kept in a stable fluidized state in the reactor for about 10 minutes. The stabilized flow rate was (30-40) m 3 / h, close the nitrogen pipeline valve, the organic amine gas pipeline valve, and the tail gas valve, open the valve on the first circulation pipeline and the circulation pump 7, and circulate the organic amine gas in the reactor through the circulation pump 7.

[0087] After the amide reaction is completed, the nitrogen pipeline valve and the tail gas pipeline valve at the front end of the first mixer are opened, the circulation pipeline valve and the circulation pump 7 are closed, and the gas in the amide reactor 4 is replaced with nitrogen for 30 minutes.

[0088] After the replacement is completed, the outlet valve at the lower end of the amide reactor 4 is opened to allow the amidated fluorinated thermoplastic polymer powder to enter the second ejector device 6 and be transported to the fluorination reactor 8;

[0089] Before adding the materials to the fluorination reaction device, the valves on the nitrogen pipeline and the fluorine pipeline are opened respectively. The two gases are measured and proportioned by the flow meter 16, so that the nitrogen and fluorine gases enter the second gas mixing device 10 for full mixing, and the flow rate of the fluorine-nitrogen mixed gas with a certain proportion is (6-10)m 3 / h, then open the outlet valve of the second gas mixing device 10 to allow the fluorine-nitrogen mixed gas to enter the fluorination reactor 8, open the tail gas valve, and the gas in the reactor enters the waste fluorine gas treatment device.

[0090] After the amidated material is added, the feed flow rate is increased and microwaves are introduced to carry out the fluorination reaction. The amidated material is in a stable fluidized state in the reactor for about 10 minutes. The stabilized flow rate is (30-40) m 3 / h Close the nitrogen pipeline valve, the fluorine pipeline valve, and the tail gas valve, open the valve on the second circulation pipeline and the diaphragm compressor 9, and circulate the fluorine-nitrogen mixed gas in the reactor through the diaphragm compressor 9.

[0091] After the fluorination reaction is completed, the nitrogen pipeline valve and the tail gas pipeline valve at the front end of the second mixer are opened, the circulation pipeline valve and the membrane press 9 are closed, and the gas in the fluorination reactor 8 is replaced with nitrogen for 30 minutes.

[0092] After the replacement is completed, the outlet valve at the lower end of the fluorination reactor 8 is opened to allow the fluorinated fluorinated thermoplastic polymer powder to enter the third ejector 11 and be transported to the gas-solid separation device 12;

[0093] The sintered nickel filter device at the upper end of the gas-solid separation device 12 and the valve on the pipeline are opened to treat the tail gas. The fluorine-containing thermoplastic polymer powder is added to the feed bin 14 through the first star feeder 2. The tail gas in the gas-solid separation device 12 is sent to the waste fluorine gas treatment device through the waste fluorine gas treatment pipeline for further deep treatment.

[0094] The outlet valve at the lower end of the feeding bin 14 is opened, and the fluorinated fluorinated thermoplastic polymer powder is fed at a certain rate by quantitative feeding, and enters the twin-screw extruder granulation device 15 for molding, and finally a fluorinated and end-capped fluorinated thermoplastic polymer product is obtained.

[0095] The technical solutions of the present invention are described in detail below through preferred embodiments. It should be noted that the specific embodiments below are only for illustration and are not intended to limit the present invention.

[0096] Example:

[0097] High-purity nitrogen is introduced to remove water and oxygen from the process equipment.

[0098] When the water and oxygen contents in the device are lower than 10 ppm and 100 ppm respectively, stop introducing high-purity nitrogen, then open the pneumatic valve on the inlet pipe of silo 1, add 300 kg of PFA powder (sample 1) into silo 1 for storage, and then close the pneumatic valve at the inlet end of silo 1.

[0099] Open the feeding valve switch at the lower end of the silo 1 filled with PFA powder, and turn on the vibration module for vibration feeding. Then, the first star feeder 2 is used in conjunction with the weighing sensor to achieve metering. The PFA powder is quantitatively delivered to the amide reactor 4 at an input rate of 120 kg / h through the first ejector 3. The delivery time is 30 minutes and the feeding amount is 60 kg.

[0100] Before adding PFA powder to the amide reaction device, open the inlet valve of the first gas mixing device 5, and measure the nitrogen and organic amine gas respectively through the rotor flowmeter. Then, open the valve on the nitrogen pipeline and the valve on the ethylamine gas pipeline to allow nitrogen and fluorine gas to enter the first gas mixing device 5 for full mixing to obtain a 3% (volume ratio) ethylamine and nitrogen mixed gas. The feed flow rate is 8m 3 / h, then open the outlet valve of the first gas mixing device 5 to allow the mixed gas of ethylamine and nitrogen to enter the amide reactor 4, and open the tail gas valve on the waste alkali gas pipeline.

[0101] When the PFA powder is delivered, increase the feed flow rate. At this time, the feed flow rate is 30m 3 / h, and at the same time, the microwave heating frequency of the microwave device is turned on to 2450 MHz and the microwave heating power is 3 kW; after the PFA powder is in a stable fluidized state in the amide reactor 4 for about 10 minutes, the valve on the nitrogen pipeline, the valve on the ethylamine gas pipeline, the inlet valve of the first mixing device, and the tail gas valve on the waste alkali device pipeline are closed; then the valve on the ethylamine circulation pipeline and the circulation pump 7 are opened, and the mixed gas of ethylamine and nitrogen is circulated in the amide reactor 4 through the circulation pump 7.

[0102] After the amide reaction was carried out for 1 hour, the sintered nickel filter at the upper end of the amide reactor 3 and the valves on the nitrogen pipeline and the tail gas pipeline were opened, the ethylamine circulation pipeline valve and the circulation pump 7 were closed, and nitrogen was introduced into the amide reactor 4 for replacement for 30 minutes.

[0103] After the replacement is completed, close the valve on the nitrogen pipeline and the tail gas valve, open the outlet valve at the lower end of the amide reactor 4, and transport the amidated PFA powder to the second ejector fluorination reactor 8. The feed rate is 120 kg / h and the feeding time is about 30 min.

[0104] Before the amidated PFA powder is added to the fluorination reaction device, the inlet valve of the second gas mixing device 10 is opened, and the nitrogen and fluorine gases are respectively measured by the rotor flowmeter. Then, the valves on the nitrogen pipeline and the fluorine pipeline are opened to allow the fluorine and nitrogen gases to enter the second gas mixing device 10 for full mixing to obtain a fluorine-nitrogen mixed gas with a volume ratio of 15%. The feed flow rate is 3m 3 / h, then open the outlet valve of the second gas mixing device 10 and the valve on the fluorine gas circulation pipeline at the top of the fluorination reactor 8, so that the fluorine-nitrogen mixed gas with a volume ratio of 15% enters the fluorination reactor 8, and open the tail gas valve on the waste fluorine gas pipeline.

[0105] When the amidated PFA powder is delivered, increase the flow rate of the fluorine-nitrogen mixed gas. At this time, the flow rate is 30m 3 / h, and simultaneously start microwave heating to heat the fluorination reactor 8 at room temperature, with a microwave heating frequency of 2450 MHz and a microwave heating power of 3 kW; after the amidated PFA powder is in a stable fluidized state in the fluorination reactor 8 for about 10 minutes, close the valves on the nitrogen pipeline, the valves on the fluorine pipeline, and the tail gas valve, open the valve on the fluorine gas circulation pipeline and the diaphragm compressor 9, and circulate the fluorine-nitrogen mixed gas in the fluorination reactor 8 through the diaphragm compressor 9.

[0106] After the fluorination reaction was carried out for 1 hour, the valve on the nitrogen pipeline and the tail gas valve were opened, the valve on the fluorine gas circulation pipeline and the membrane press 9 were closed, and nitrogen was introduced into the fluorination reactor 8 for replacement for 30 minutes.

[0107] After the replacement is completed, close the valve on the nitrogen pipeline and the tail gas valve, open the outlet valve at the lower end of the fluorination reactor 8, and transport the fluorinated PFA powder to the third ejector 11 to the feed port of the gas-solid separation device 12;

[0108] Open the sintered nickel filter device at the upper end of the gas-solid separation device 12 and the valve on the tail gas pipeline to allow the fluorinated PFA powder to fall naturally into the gas-solid separation device by gravity.

[0109] The second star-shaped feeder 13 at the lower end of the gas-solid separation device 12 is opened to discharge the material. The fluorinated PFA powder is added to the temporary storage bin 14 through the second star-shaped feeder 13. The trace fluorine gas in the gas-solid separation device 12 is sent to the waste fluorine gas treatment device through the waste fluorine gas treatment pipeline for further deep treatment.

[0110] Open the outlet valve at the lower end of the temporary storage bin 14 and simultaneously start the twin-screw extruder granulator 15. Feed the fluorinated PFA powder at a rate of 20-30 kg / h through quantitative feeding and feed it into the twin-screw extruder granulator for granulation, ultimately obtaining the fluorinated end-capped PFA sample 2.

[0111] Comparative Example:

[0112] The PFA raw material (sample 1) was subjected to the following operation:

[0113] Close all valves on the pipeline in the amide reaction unit

[0114] Introduce high-purity nitrogen to remove water and oxygen from the fluorination reaction unit and melt extrusion unit

[0115] When the water and oxygen contents in the device were lower than 10 ppm and 100 ppm respectively, the introduction of high-purity nitrogen was stopped, the valve on the pipeline was closed, and then 60 kg of PFA powder (sample 1) was manually added to the fluorination reactor 8.

[0116] Before adding PFA powder to the fluorination reaction device, open the inlet valve of the second gas mixing device 10, and allow nitrogen and fluorine to be measured by the rotor flowmeter respectively. Then, open the valve on the nitrogen pipeline and the valve on the fluorine pipeline to allow fluorine and nitrogen to enter the second gas mixing device 10 for full mixing to obtain a fluorine-nitrogen mixed gas with a volume ratio of 15%. The feed flow rate is 3m 3 / h, then open the outlet valve of the second gas mixing device 10 and the valve on the fluorine gas circulation pipeline at the top of the fluorination reactor 8, so that the fluorine-nitrogen mixed gas with a volume ratio of 15% enters the fluorination reactor 8, and open the tail gas valve on the waste fluorine gas pipeline.

[0117] When the PFA powder is delivered, increase the flow rate of the fluorine-nitrogen mixed gas. At this time, the flow rate is 30m 3 / h, and simultaneously start microwave heating to heat the fluorination reactor 8 at room temperature, with a microwave heating frequency of 2450 MHz and a microwave heating power of 3 kW; after the PFA powder is in a stable fluidized state in the fluorination reactor 8 for about 10 minutes, close the valves on the nitrogen pipeline, the valves on the fluorine pipeline, and the tail gas valve, open the valve on the fluorine gas circulation pipeline and the membrane press 9, and circulate the fluorine and nitrogen mixed gas in the fluorination reactor 8 through the circulation pump 9.

[0118] After the fluorination reaction was carried out for 1 hour, the valve on the nitrogen pipeline and the tail gas valve were opened, the valve on the fluorine gas circulation pipeline and the membrane press 9 were closed, and nitrogen was introduced into the fluorination reactor 8 for replacement for 30 minutes.

[0119] After the replacement is completed, close the valve on the nitrogen pipeline and the tail gas valve, open the outlet valve at the lower end of the fluorination reactor 8, and transport the fluorinated PFA powder to the third ejector 11 to the feed port of the gas-solid separation device 12;

[0120] Open the sintered nickel filter device at the upper end of the gas-solid separation device 12 and the valve on the tail gas pipeline to allow the fluorinated PFA powder to fall naturally into the gas-solid separation device by gravity.

[0121] The second star-shaped feeder 13 at the lower end of the gas-solid separation device 12 is opened to discharge the material. The fluorinated PFA powder is added to the temporary storage bin 14 through the second star-shaped feeder 13. The trace fluorine gas in the gas-solid separation device 12 is sent to the waste fluorine gas treatment device through the waste fluorine gas treatment pipeline for further deep treatment.

[0122] Open the outlet valve at the lower end of the temporary storage silo 14, and at the same time start the twin-screw extrusion granulation device 15. Through quantitative feeding, the fluorinated PFA powder is discharged at a rate of 20-30 kg / h and enters the twin-screw extrusion granulation device for granulation, and finally the fluorinated end-capped PFA sample 3 is obtained.

[0123] Experimental example:

[0124] The unstable end group content of the samples was analyzed by infrared spectroscopy.

[0125] The polymer powders of Sample 1, Sample 2, and Sample 3 were pressed into (0.1-0.2) mm sheets at 250°C-350°C. The unstable end group contents of the three groups of samples were analyzed using a Nicolet 380 Fourier transform infrared spectrometer. The analysis results are shown in Table 1.

[0126] Table 1. Statistics of unstable end group content of samples determined by infrared spectroscopy

[0127]

[0128] As shown in Table 1, the content of unstable end groups in Sample 2 is significantly reduced compared to the raw material and Samples 1 and 3. Therefore, it can be seen that in the present invention, a two-step fluorination process combining an amide reaction and a fluorination reaction is adopted, supplemented by microwave heating as a heating heat source for the amidation reaction and the fluorination reaction, providing the activation energy required for the amide reaction and the fluorination reaction, wherein the amidation reaction converts the difficult-to-fluorinate -COF end group into an easily fluorinated polar end group, and then the fluorination reaction is carried out to convert the polar end group in the fluorinated thermoplastic polymer into a -CF3 end group to the greatest extent, thereby obtaining a fluorinated fluorinated thermoplastic polymer. In addition, microwave heating is used as the heating heat source for the above-mentioned amide reaction and fluorination reaction, and the reaction provides the required activation energy, which can effectively increase the reaction rate of the amide reaction and fluorination reaction of the fluorinated thermoplastic polymer, reduce the reaction temperature, and convert the unstable end group of the fluorinated thermoplastic polymer into -CF3, thereby maximizing the fluorination treatment of the thermally unstable end group of the fluorinated thermoplastic polymer.

[0129] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers, characterized in that: The fluorination process combines amide reaction and fluorination reaction, and uses microwave heating to provide the activation energy required for amide reaction and fluorination reaction; including: An amide reaction device is used for the amide reaction of the fluorinated thermoplastic polymer to convert the difficult-to-fluorinate -COF end group in the fluorinated thermoplastic polymer into the easily fluorinated -CONHR end group to obtain an amidated fluorinated thermoplastic polymer; a fluorination reaction device connected to the amide reaction device, used for fluorination reaction of the amidated fluorine-containing thermoplastic polymer, converting the -CONHR end group, -COOH end group and -CF=CF2 end group in the amidated fluorine-containing thermoplastic polymer into a -CF3 end group to obtain a fluorinated fluorine-containing thermoplastic polymer; a melt granulation device, connected to the fluorination reaction device, for extruding and granulating the fluorinated thermoplastic polymer to obtain a granular product; The amide reaction device comprises: a first microwave reaction device, for subjecting the fluorine-containing thermoplastic polymer to an amide reaction to obtain the amidated fluorine-containing thermoplastic polymer, comprising an amide reactor and a microwave emitting device disposed outside the amide reactor; a first powder feeding device, used for storing and feeding the fluorinated thermoplastic polymer, wherein the first powder feeding device introduces the fluorinated thermoplastic polymer in the silo into the first ejecting device via a first star-shaped feeder, and the first ejecting device then sprays the fluorinated thermoplastic polymer into the amide reactor; The first gas supply device is used to provide a mixed gas during the amide reaction of the fluorine-containing thermoplastic polymer, comprising: The first gas mixing device is used to transport nitrogen and organic amine gas into the first gas mixing device through a pipeline and mix them to obtain a mixed gas. The outlet end of the first gas mixing device is connected to the amide reactor through a pipeline.

2. The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers according to claim 1, characterized in that: The fluorination reaction device comprises: a second microwave reaction device, for subjecting the amidated fluorinated thermoplastic polymer to a fluorination reaction to obtain the fluorinated fluorinated thermoplastic polymer, comprising a fluorination reactor and a microwave emitting device arranged outside the amidation reactor; a second powder feeding device, configured to transfer the amidated fluorinated thermoplastic polymer in the first microwave reaction device to the second microwave reaction device, and the second powder feeding device sprays the amidated fluorinated thermoplastic polymer into the fluorination reactor via a second ejecting device; The second gas supply device is used to provide a mixed gas during the fluorination reaction of the fluorine-containing thermoplastic polymer, comprising: The second gas mixing device is used to transport nitrogen and fluorine into the second gas mixing device through a pipeline and mix them to obtain a mixed gas. The outlet end of the second gas mixing device is connected to the fluorination reactor through a pipeline.

3. The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers according to claim 2, characterized in that: The melt granulation device comprises: a feeding bin for receiving the fluorinated fluorinated thermoplastic polymer obtained from the second microwave reaction device; A twin-screw extrusion granulation device is connected to the feed bin pipeline.

4. The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers according to claim 2, characterized in that: Also includes: a third ejection device, for transferring the fluorinated fluorinated thermoplastic polymer in the second microwave reaction device to the melt granulation device; The gas-solid separation device is arranged between the third ejection device and the melting granulation device.

5. The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers according to claim 3, characterized in that: The feeding bin is provided with a second star-shaped feeder for transferring the fluorinated fluorine-containing thermoplastic polymer to the twin-screw extrusion granulation device.

6. The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers according to claim 1, characterized in that: It also includes a waste alkali gas treatment system, one end of which is connected to the gas phase outlet pipeline of the amide reaction device, and the other end is connected to the waste alkali gas treatment device.

7. The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers according to claim 2, characterized in that: It also includes a waste fluorine gas treatment system, one end of which is connected to the gas phase outlet pipeline of the fluorination reaction device, and the other end is connected to the waste fluorine gas treatment device.

8. The fluorination treatment device for unstable end groups of fluorinated thermoplastic polymers according to claim 6 or 7, characterized in that: A gas filtering device is provided on the top of the amide reaction device and the fluorination reaction device.

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