Highly efficient method for preparing polyfluoroalkoxy (PFA)

Abstract

The present disclosure discloses a highly efficient method for preparing polyfluoroalkoxy (PFA) and relates to the technical field of fluoropolymers. The method comprises the following steps: adding highly pure water to a polymerization reactor, starting stirring and adding a surfactant, a dispersion aid, a chain transfer agent, and perfluoroalkyl vinyl ether monomers, controlling the temperature and pressure of the polymerization reactor, adding an initiator solution to the reactor to initiate a copolymerization reaction, after the polymerization reaction is started, continuously adding a gas mixture of tetrafluoroethylene and the perfluoroalkyl vinyl ether into the polymerization reactor while continuously adding the initiator solution into the reactor at a constant speed, and after the reaction is complete, recovering unreacted monomers from the polymerization reactor to obtain a polyfluoroalkoxy (PFA) resin emulsion. The present disclosure overcomes the problem of low polymerization efficiency caused by a small filling coefficient and a long solvent recovery period with conventional solvent-phase PFA polymerization, thereby improving the utilization of the starting materials.

Description

A method for preparing high-efficiency meltable polytetrafluoroethylene (PFA)

[0001] Cross-reference to related applications

[0002] This disclosure is based on and claims priority to Chinese Patent Application No. 202411579725.0, filed on November 7, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of fluoropolymer technology, and in particular to a method for preparing highly efficient meltable polytetrafluoroethylene (PFA). Background Technology

[0004] Meltable polytetrafluoroethylene (PFA) is a copolymer of tetrafluoroethylene (TFE) and a small amount of perfluoroalkyl vinyl ether (PAVE). Its main chain structure gives it properties very similar to those of polytetrafluoroethylene, exhibiting excellent chemical stability, physical and mechanical properties, electrical insulation, lubricity, non-stickiness, aging resistance, non-flammability, and thermal stability. The presence of perfluoroalkoxy side groups in the main chain significantly improves the flexibility of the polymer chain, reduces the crystallinity of the polymer, and improves the melt viscosity of the polymer, giving PFA good thermoplasticity.

[0005] CN113501904A discloses a method for preparing a perfluoroalkyl vinyl ether copolymer. The method involves adding 10-28 parts by weight of tetrafluoroethylene monomer, 2-5 parts by weight of perfluoroalkyl vinyl ether, 0.01-0.1 parts by weight of alkenyl ionic liquid, 0.01-0.1 parts by weight of vinyl ferrocene, and 0.2-1.2 parts by weight of initiator to 100-200 parts of solvent for polymerization. The reaction temperature is 20-50℃, and the reaction pressure is 120-500 kPa. After the reaction, the solvent is recovered to obtain the perfluoroalkyl vinyl ether copolymer. However, this method has the following technical problems: 1. The reaction rate is slow, and the reactor filling coefficient is low; 2. The solvent recovery cycle after the reaction is long. Further optimization of the design is needed.

[0006] Current melt-polymerizable polytetrafluoroethylene (PFA) polymerization processes typically use organic solvents as the medium and acyl fluorides as initiators, employing solvent-phase polymerization to carry out the free radical copolymerization reaction of tetrafluoroethylene (TFE) and perfluoroalkyl vinyl ethers (PAVE). This process is widely used; however, the PFA product obtained from typical polymerization processes requires solvent recovery, with a recovery cycle of approximately 20 hours, resulting in very low operating efficiency for individual reactors.

[0007] In view of this, this disclosure is hereby made. Summary of the Invention

[0008] This disclosure provides a method for preparing highly efficient meltable polytetrafluoroethylene (PFA). By optimizing the process, it overcomes the problems of low polymerization efficiency caused by the low filling coefficient and long solvent recovery cycle in the original solvent-phase PFA polymerization reaction.

[0009] To achieve the aforementioned objectives, this disclosure proposes the following solution:

[0010] A method for preparing high-efficiency meltable polytetrafluoroethylene (PFA), comprising the following steps:

[0011] S1: Add 2000-3000 parts by weight of high-purity water to the polymerization reactor, start stirring, control the speed at 10-120 rpm, add 10-50 parts of surfactant, 2-5 parts of dispersant, 0.01-10 parts of chain transfer agent, and 5-40 parts of perfluoroalkyl vinyl ether monomer. Adjust the temperature of the polymerization reactor to 60-120℃, add 100-200 parts of tetrafluoroethylene monomer, and make the pressure inside the reactor reach 1.5-5.0 MPa. Add 1-10 parts of initiator solution to the reactor to initiate the copolymerization reaction.

[0012] S2: After the polymerization reaction begins, a gas mixture of tetrafluoroethylene and perfluoroalkyl vinyl ether is continuously added to the polymerization reactor to maintain the reactor pressure at 1.5–5.0 MPa. At the same time, an initiator solution is continuously added to the reactor at a constant rate, while the reaction temperature is controlled at 60–120°C. When the amount of mixed monomers added reaches 600–1200 parts, the addition of monomers and initiator is stopped, and the copolymerization reaction is terminated. After recovering the unreacted monomers in the polymerization reactor, a fusible polytetrafluoroethylene (PFA) resin emulsion is obtained. The emulsion is semi-transparent milky white.

[0013] Furthermore, the surfactant is one or more of ammonium perfluorooctanoate, ammonium perfluorooctyl sulfonate, perfluorooctyl sulfonamide, ammonium perfluorohexanoate, and ammonium perfluoro-2,5-dimethyl-3,6-dioxanonate.

[0014] Furthermore, the surfactant is an aqueous solution with a concentration of 10-30%.

[0015] Furthermore, the chain transfer agent is a straight-chain alkane; the straight-chain alkane has the molecular formula C1. n H 2n+2 , where n = 1 to 4.

[0016] Furthermore, the perfluoroalkyl vinyl ether is one or a mixture of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, and perfluoron-propyl vinyl ether.

[0017] Furthermore, the initiator is an aqueous solution or a mixture of potassium persulfate and ammonium persulfate.

[0018] Furthermore, the concentration of the initiator solution is 0.1% to 5%.

[0019] Furthermore, the initiator is added at a rate of 3 to 10 parts per hour.

[0020] Furthermore, the ratio of tetrafluoroethylene to perfluoroalkyl vinyl ether in the mixed monomer is 8 to 25.

[0021] Furthermore, the method for preparing the dispersing agent is as follows:

[0022] H1: Add 10–17 parts by weight of 6-mercaptobenzo[C][1,2]oxaborone heterocyclic-1(3H)-ol (CAS: 2130753-08-9), 2–5 parts by weight of 10,13-epoxy-10,12-octadecadienoic acid, 500–600 parts by weight of DMF, and 10–15 parts by weight of triethylamine. React at 40–50 °C for 100–150 minutes.

[0023] H2: Add 50-70 parts of perfluoropolyether (meth)acrylate and 2-5 parts of triethylamine, react at 70-80°C for 120-180 minutes, and then remove DMF by vacuum distillation to obtain the dispersing agent.

[0024] Furthermore, the perfluoropolyether (meth)acrylate has a viscosity of 300–1000.

[0025] Reaction mechanism:

[0026] 1. Addition reactions of mercapto-olefins and ring-opening reactions of mercapto-epoxy groups:

[0027] In the initial stage, the thiol (-SH) group in 6-mercaptobenzo[C][1,2]oxaboronic heterocyclic-1(3H)-ol undergoes an addition reaction with the olefinic moiety in 10,13-epoxy-10,12-octadecadienoic acid. This step generates an intermediate product by opening the double bond and forming a new sulfur-carbon bond with the thiol group.

[0028] Next, the thiol group undergoes a ring-opening reaction with the epoxy group, forming a more complex polycyclic ring structure. This step may involve a nucleophilic attack of the epoxy group by the thiol group, leading to ring-opening of the epoxy group and the formation of a new chemical bond with the thiol group.

[0029] 2. Continued addition reaction of mercapto-olefins:

[0030] Building on the previous step, the remaining thiol groups continue to undergo a thiol-olefin addition reaction with perfluoropolyether (meth)acrylate. This step is also accomplished by breaking the double bonds in the perfluoropolyether (meth)acrylate and forming new sulfur-carbon bonds with the thiol groups.

[0031] Technical effects:

[0032] Compared with traditional methods, this method has the following advantages:

[0033] 1. Improve polymerization efficiency and fill factor:

[0034] The use of this novel dispersant can significantly improve the polymerization reaction. Because the dispersant can more effectively disperse and stabilize the reaction mixture, it can increase the filling factor, i.e., the proportion of monomer in the polymerization system, thereby shortening the polymerization reaction time and improving production efficiency. It also solves the problem of demulsified powder generated during PFA emulsion polymerization, reducing product waste and improving raw material utilization.

[0035] 2. Simplify solvent recovery and reduce environmental impact:

[0036] The use of new dispersants also helps simplify the solvent recovery process after polymerization. This is because dispersants reduce the generation of unstable components in the reaction system, minimizing side reactions and pollutant formation. Furthermore, using water as a solvent and dispersant further reduces the environmental impact, making the production process greener and more environmentally friendly. Attached Figure Description

[0037] Figure 1 is a DSC diagram of the PFA prepared in Example 4.

[0038] Figure 2 shows the Fourier transform infrared spectrum of the PFA prepared in Example 4.

[0039] Figure 3 shows the nuclear magnetic resonance spectrum of the PFA prepared in Example 4. Detailed Implementation

[0040] Embodiments of this disclosure are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this disclosure, and should not be construed as limiting it.

[0041] Example 1

[0042] A method for preparing high-efficiency meltable polytetrafluoroethylene (PFA), comprising the following steps:

[0043] S1: Add 2000g of high-purity water to the polymerization reactor, start stirring, control the speed at 30rpm, add 10g of surfactant, 2g of dispersant, 0.01g of chain transfer agent, and 5g of perfluoroalkyl vinyl ether monomer. Adjust the temperature of the polymerization reactor to 60℃, add 100g of tetrafluoroethylene monomer, and make the pressure inside the reactor reach 1.5MPa. Add 3g of initiator solution to the reactor to initiate the copolymerization reaction.

[0044] S2: After the polymerization reaction begins, a gas mixture of tetrafluoroethylene and perfluoroalkyl vinyl ether is continuously added to the polymerization reactor to maintain the reactor pressure at 1.5 MPa. At the same time, an initiator solution is continuously added to the reactor at a constant rate, while the reaction temperature is controlled at 60°C. When the amount of mixed monomers added reaches 600 g, the addition of monomers and initiator is stopped, and the copolymerization reaction is terminated. The unreacted monomers in the polymerization reactor are recovered to obtain a fusible polytetrafluoroethylene (PFA) resin emulsion, which is semi-transparent milky white.

[0045] The surfactant is ammonium perfluorooctanoate.

[0046] The surfactant is an aqueous solution with a concentration of 10%.

[0047] The chain transfer agent is methane.

[0048] The perfluoroalkyl vinyl ether is a perfluoromethyl vinyl ether.

[0049] The initiator is an aqueous solution of potassium persulfate.

[0050] The concentration of the initiator solution is 1%.

[0051] The initiator is added at a rate of 3 g / h.

[0052] The ratio of tetrafluoroethylene to perfluoroalkyl vinyl ether in the mixed monomer is 8:1.

[0053] The dispersing agent is prepared by the following method:

[0054] H1: Add 10g of 6-mercaptobenzo[C][1,2]oxaborone heterocyclic-1(3H)-ol (CAS: 2130753-08-9), 2g of 10,13-epoxy-10,12-octadecadienoic acid, 500g of DMF, and 10g of triethylamine. React at 40°C for 100 minutes.

[0055] H2: Add 50g of perfluoropolyether (meth)acrylate and 2g of triethylamine, react at 70℃ for 120 minutes, and then remove DMF by vacuum distillation to obtain the dispersing agent.

[0056] The perfluoropolyether (meth)acrylate has a viscosity of 300.

[0057] The final emulsion product had a specific gravity of 1.19 g / ml and a solid content of 27.3% w / w, with no broken emulsion powder on the surface.

[0058] Example 2

[0059] A method for preparing high-efficiency meltable polytetrafluoroethylene (PFA), comprising the following steps:

[0060] S1: Add 2500g of high-purity water to the polymerization reactor, start stirring, control the speed at 60rpm, add 25g of surfactant, 3g of dispersant, 5g of chain transfer agent, and 15g of perfluoroalkyl vinyl ether monomer. Adjust the temperature of the polymerization reactor to 80℃, add 125g of tetrafluoroethylene monomer, and make the pressure inside the reactor reach 2.5MPa. Add 5g of initiator solution to the reactor to initiate the copolymerization reaction.

[0061] S2: After the polymerization reaction begins, a gas mixture of tetrafluoroethylene and perfluoroalkyl vinyl ether is continuously added to the polymerization reactor to maintain the reactor pressure at 2.5 MPa. At the same time, an initiator solution is continuously added to the reactor at a constant rate, while the reaction temperature is controlled at 80°C. When the amount of mixed monomers added reaches 800 g, the addition of monomers and initiator is stopped, and the copolymerization reaction is terminated. The unreacted monomers in the polymerization reactor are recovered to obtain a fusible polytetrafluoroethylene (PFA) resin emulsion, which is semi-transparent milky white.

[0062] The surfactant is ammonium perfluorooctyl sulfonate.

[0063] The surfactant is an aqueous solution with a concentration of 20%.

[0064] The chain transfer agent is ethane.

[0065] The perfluoroalkyl vinyl ether is a perfluoroethyl vinyl ether.

[0066] The initiator is an aqueous solution of ammonium persulfate.

[0067] The concentration of the initiator solution is 2.5%.

[0068] The initiator is added at a rate of 5 g / h.

[0069] The ratio of tetrafluoroethylene to perfluoroalkyl vinyl ether in the mixed monomers is 14:1.

[0070] The dispersing agent is prepared by the following method:

[0071] H1: Add 12.5 g of 6-mercaptobenzo[C][1,2]oxaborone heterocyclic-1(3H)-ol (CAS: 2130753-08-9), 3 g of 10,13-epoxy-10,12-octadecadienoic acid, 550 g of DMF, and 11.5 g of triethylamine. React at 45 °C for 125 minutes.

[0072] H2: Add 60g of perfluoropolyether (meth)acrylate and 3g of triethylamine, react at 75℃ for 140 minutes, and then remove DMF by vacuum distillation to obtain the dispersing agent.

[0073] The perfluoropolyether (meth)acrylate has a viscosity of 500.

[0074] The final emulsion product has a specific gravity of 1.20 g / ml and a solid content of 30.4% w / w, with no broken emulsion powder on the surface.

[0075] Example 3

[0076] A method for preparing high-efficiency meltable polytetrafluoroethylene (PFA), comprising the following steps:

[0077] S1: Add 2500g of high-purity water to the polymerization reactor, start stirring, control the speed at 100rpm, add 40g of surfactant, 4g of dispersant, 8g of chain transfer agent, and 30g of perfluoroalkyl vinyl ether monomer. Adjust the temperature of the polymerization reactor to 100℃, add 165g of tetrafluoroethylene monomer, and make the pressure inside the reactor reach 4.0MPa. Add 8g of initiator solution to the reactor to initiate the copolymerization reaction.

[0078] S2: After the polymerization reaction begins, a gas mixture of tetrafluoroethylene and perfluoroalkyl vinyl ether is continuously added to the polymerization reactor to maintain the reactor pressure at 4.0 MPa. At the same time, an initiator solution is continuously added to the reactor at a constant rate, while the reaction temperature is controlled at 100°C. When the amount of mixed monomers added reaches 1000 g, the addition of monomers and initiator is stopped, and the copolymerization reaction is terminated. The unreacted monomers in the polymerization reactor are recovered to obtain a fusible polytetrafluoroethylene (PFA) resin emulsion, which is semi-transparent milky white.

[0079] The surfactant is perfluorooctylsulfonamide.

[0080] The surfactant is an aqueous solution with a concentration of 20%.

[0081] The chain transfer agent is propane.

[0082] The perfluoroalkyl vinyl ether is a perfluoroethyl vinyl ether.

[0083] The initiator is an aqueous solution of potassium persulfate.

[0084] The concentration of the initiator solution is 4%.

[0085] The initiator is added at a rate of 8 g / h.

[0086] The ratio of tetrafluoroethylene to perfluoroalkyl vinyl ether in the mixed monomers is 20:1.

[0087] The dispersing agent is prepared by the following method:

[0088] H1: Add 15g of 6-mercaptobenzo[C][1,2]oxaborone heterocyclic-1(3H)-ol (CAS: 2130753-08-9), 4g of 10,13-epoxy-10,12-octadecadienoic acid, 550g of DMF, and 14g of triethylamine. React at 45°C for 140 minutes.

[0089] H2: Add 60g of perfluoropolyether (meth)acrylate and 4g of triethylamine, react at 75℃ for 160 minutes, and then remove DMF by vacuum distillation to obtain the dispersing agent.

[0090] The perfluoropolyether (meth)acrylate has a viscosity of 800.

[0091] The final emulsion product had a specific gravity of 1.19 g / ml and a solid content of 28.6% w / w, with no broken emulsion powder on the surface.

[0092] Example 4

[0093] A method for preparing high-efficiency meltable polytetrafluoroethylene (PFA), comprising the following steps:

[0094] S1: Add 3000g of high-purity water to the polymerization reactor and start stirring at 120rpm. Add 50g of surfactant, 5g of dispersant, 10g of chain transfer agent, and 40g of perfluoroalkyl vinyl ether monomer. Adjust the temperature of the polymerization reactor to 120℃. Add 200g of tetrafluoroethylene monomer to make the pressure inside the reactor reach 5.0MPa. Add 10g of initiator solution to the reactor to initiate the copolymerization reaction.

[0095] S2: After the polymerization reaction begins, a gas mixture of tetrafluoroethylene and perfluoroalkyl vinyl ether is continuously added to the polymerization reactor to maintain the reactor pressure at 5.0 MPa. At the same time, an initiator solution is continuously added to the reactor at a constant rate, while the reaction temperature is controlled at 120°C. When the amount of mixed monomers added reaches 1200 g, the addition of monomers and initiator is stopped, and the copolymerization reaction is terminated. The unreacted monomers in the polymerization reactor are recovered to obtain a fusible polytetrafluoroethylene (PFA) resin emulsion, which is semi-transparent milky white.

[0096] The surfactant is perfluoro-2,5-dimethyl-3,6-dioxanonate ammonium.

[0097] The surfactant is an aqueous solution with a concentration of 30%.

[0098] The chain transfer agent is n-butane.

[0099] The perfluoroalkyl vinyl ether is a perfluoropropyl vinyl ether.

[0100] The initiator is an aqueous solution of ammonium persulfate.

[0101] The concentration of the initiator solution is 5%.

[0102] The initiator is added at a rate of 10 g / h.

[0103] The ratio of tetrafluoroethylene to perfluoroalkyl vinyl ether in the mixed monomers is 25:1.

[0104] The dispersing agent is prepared by the following method:

[0105] H1: Add 17g of 6-mercaptobenzo[C][1,2]oxaborone heterocyclic-1(3H)-ol (CAS: 2130753-08-9), 5g of 10,13-epoxy-10,12-octadecadienoic acid, 600g of DMF, and 15g of triethylamine. React at 50°C for 150 minutes.

[0106] H2: Add 70g of perfluoropolyether (meth)acrylate and 5g of triethylamine, react at 80℃ for 180 minutes, and then remove DMF by vacuum distillation to obtain the dispersing agent.

[0107] The perfluoropolyether (meth)acrylate has a viscosity of 1000.

[0108] The final emulsion product had a specific gravity of 1.21 g / ml and a solid content of 33.1% w / w, with no broken emulsion powder on the surface.

[0109] Comparative Example

[0110] A method for preparing high-efficiency meltable polytetrafluoroethylene (PFA), comprising the following steps:

[0111] S1: Add 2000g of high-purity water to the polymerization reactor, start stirring, control the speed at 30rpm, add 10g of surfactant, 2g of chain transfer agent, and 5g of perfluoroalkyl vinyl ether monomer. Adjust the temperature of the polymerization reactor to 60℃, add 100g of tetrafluoroethylene monomer, and make the pressure inside the reactor reach 1.5MPa. Add 3g of initiator solution to the reactor to initiate the copolymerization reaction.

[0112] S2: After the polymerization reaction begins, a gas mixture of tetrafluoroethylene and perfluoroalkyl vinyl ether is continuously added to the polymerization reactor to maintain the reactor pressure at 1.5 MPa. At the same time, an initiator solution is continuously added to the reactor at a constant rate, while the reaction temperature is controlled at 60°C. When the amount of mixed monomers added reaches 600 g, the addition of monomers and initiator is stopped, and the copolymerization reaction is terminated. The unreacted monomers in the polymerization reactor are recovered to obtain a fusible polytetrafluoroethylene (PFA) resin emulsion, which is semi-transparent milky white.

[0113] The surfactant is ammonium perfluorooctanoate.

[0114] The surfactant is an aqueous solution with a concentration of 10%.

[0115] The chain transfer agent is propane.

[0116] The perfluoroalkyl vinyl ether is a perfluoromethyl vinyl ether.

[0117] The initiator is an aqueous solution of potassium persulfate.

[0118] The concentration of the initiator solution is 1%.

[0119] The initiator is added at a rate of 3 g / h.

[0120] The ratio of tetrafluoroethylene to perfluoroalkyl vinyl ether in the mixed monomer is 8:1.

[0121] The final emulsion product had a specific gravity of 1.18 g / ml and a solid content of 22.0% w / w, with no broken emulsion powder on the surface.

[0122] As can be seen from the above specific implementation methods, this method effectively increases the solid content of the emulsion and improves production efficiency.

[0123] The applicant declares that the above embodiments are used to further illustrate this disclosure, but this disclosure is not limited to the above embodiments, that is, it does not mean that this disclosure must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this disclosure, equivalent substitutions of the raw materials of the disclosed products, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this disclosure.

Claims

1. A method for preparing high-efficiency meltable polytetrafluoroethylene (PFA), comprising the following steps: S1: Add 2000-3000 parts by weight of high-purity water to the polymerization reactor, start stirring, control the speed at 10-120 rpm, add 10-50 parts of surfactant, 2-5 parts of dispersant, 0.01-10 parts of chain transfer agent, and 5-40 parts of perfluoroalkyl vinyl ether monomer. Adjust the temperature of the polymerization reactor to 60-120℃, add 100-200 parts of tetrafluoroethylene monomer, and make the pressure inside the reactor reach 1.5-5.0 MPa. Add 1-10 parts of initiator solution to the reactor to initiate the copolymerization reaction. S2: After the polymerization reaction begins, a gas mixture of tetrafluoroethylene and perfluoroalkyl vinyl ether is continuously added to the polymerization reactor to maintain the reactor pressure at 1.5–5.0 MPa. At the same time, an initiator solution is continuously added to the reactor at a constant rate, while the reaction temperature is controlled at 60–120°C. When the amount of mixed monomers added reaches 600–1200 parts, the addition of monomers and initiator is stopped, and the copolymerization reaction is terminated. After recovering the unreacted monomers in the polymerization reactor, a fusible polytetrafluoroethylene (PFA) resin emulsion is obtained. The emulsion is semi-transparent milky white.

2. The method for preparing a high-efficiency fusible polytetrafluoroethylene (PFA) according to claim 1, wherein the surfactant is one or more of ammonium perfluorooctanoate, ammonium perfluorooctyl sulfonate, perfluorooctyl sulfonamide, ammonium perfluorohexanoate, and ammonium perfluoro-2,5-dimethyl-3,6-dioxanonate.

3. The method for preparing a high-efficiency fusible polytetrafluoroethylene (PFA) according to claim 1 or 2, wherein the surfactant is an aqueous solution with a concentration of 10-30%.

4. A method for preparing a high-efficiency fusible polytetrafluoroethylene (PFA) according to any one of claims 1-3, wherein the chain transfer agent is a straight alkane; wherein the straight alkane has the molecular formula CnH2n+2, where n = 1 to 4.

5. A method for preparing a high-efficiency fusible polytetrafluoroethylene (PFA) according to any one of claims 1-4, wherein the perfluoroalkyl vinyl ether is one or a mixture of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, and perfluoropropyl vinyl ether.

6. A method for preparing a high-efficiency fusible polytetrafluoroethylene (PFA) according to any one of claims 1-5, wherein the initiator is an aqueous solution or a mixture of potassium persulfate, ammonium persulfate, or potassium persulfate.

7. A method for preparing a high-efficiency fusible polytetrafluoroethylene (PFA) according to claim 1 or 6, wherein the concentration of the initiator solution is 0.1-5%.

8. A method for preparing a high-efficiency fusible polytetrafluoroethylene (PFA) according to claim 1, 6 or 7, wherein the initiator is added at a rate of 3 to 10 parts / h.

9. A method for preparing a high-efficiency meltable polytetrafluoroethylene (PFA) according to any one of claims 1-8, wherein the ratio of tetrafluoroethylene to perfluoroalkyl vinyl ether in the mixed monomer is 8-25.

10. A method for preparing a high-efficiency meltable polytetrafluoroethylene (PFA) according to any one of claims 1-9, wherein the method for preparing the dispersing agent is as follows: H1: Add 10–17 parts by weight of 6-mercaptobenzo[C][1,2]oxaborone-1(3H)-ol, 2–5 parts by weight of 10,13-epoxy-10,12-octadecadienoic acid, 500–600 parts by weight of DMF, and 10–15 parts by weight of triethylamine. React at 40–50 °C for 100–150 minutes. H2: Add 50-70 parts of perfluoropolyether (meth)acrylate and 2-5 parts of triethylamine, react at 70-80°C for 120-180 minutes, and then remove DMF by vacuum distillation to obtain the dispersing agent.

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