A process for the polymerization of polyfluoroethylenepropylene free of pfoa

Abstract

The application discloses a kind of polyfluoroethylene-propylene polymers without PFOA polymerization process, it is related to fluoropolymer field.The specific steps include: in high-pressure reactor, deoxygenated high-purity water is imported, the reactor is stirred, the reactor is oxygen-free replacement, organic metal emulsifier is added, and the reactor is heated;Mixing gas 1 of tetrafluoroethylene and hexafluoropropylene is imported to the reactor pressure to reach reaction pressure, molecular weight regulator and initiator are added, and mixing gas 2 of tetrafluoroethylene and hexafluoropropylene is continuously imported during reaction to maintain reaction pressure, when the emulsion solid content in the reactor reaches 23-27%, the reaction stops, and polyfluoroethylene-propylene is obtained after post-processing procedure.The polyfluoroethylene-propylene resin prepared by the method has stable performance between batches, does not contain PFOA, and the process is green and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of fluoropolymers, and in particular to a PFOA-free process for the polymerization of polyfluoroethylenepropylene. BACKGROUND

[0002] Polyfluoroethylenepropylene (FEP), also known as F-46, is a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP). FEP has excellent weatherability, low coefficient of friction, and can be used from cryogenic temperatures to 392°F (about 200°C). It can be made into pelletized products for extrusion and molding, powders for fluidized bed and electrostatic coating, and aqueous dispersions. Semi-finished products include films, sheets, rods, and monofilaments. Major uses of FEP include making inner liners for pipes and chemical equipment, facings for rolls, and various wires and cables, such as aircraft hanger wire, plenum cable, alarm cable, flat cable, and oil well logging cable. FEP films are also used as thin coatings for solar energy collectors.

[0003] FEP is often used in key parts and harsh environments in the defense industry, aerospace, electronics, semiconductors, construction, medical, automotive, electromechanical, metallurgy, petrochemical, and other industrial sectors due to its excellent performance, and is an indispensable functional material in modern science and technology.

[0004] An extrusion polyfluoroethylenepropylene resin and a preparation method thereof (Patent Application No. CN201810442576.1) includes the following steps: 1) preparing an extrusion polyfluoroethylenepropylene resin crude material by emulsion polymerization under the action of an inorganic initiator; 2) drying and sintering the extrusion polyfluoroethylenepropylene resin crude material at a temperature of 230-255°C until it forms a clump and sticks to the material, and then performing double-screw extrusion processing on the material. The double-screw extrusion includes a melting devolatilization section, and the temperature of the melting devolatilization section is controlled within a range of 350-375°C during the extrusion process. The present invention stabilizes unstable end groups formed by molecular chain segments, such as carboxyl groups (-COOH), double bond unsaturated groups (-CF=CF2), and acyl fluoride groups (-COF), through drying and sintering processing and double-screw extrusion processing of the extrusion polyfluoroethylenepropylene resin, thereby reducing the corrosion of the extrusion polyfluoroethylenepropylene resin product on a metal substrate.

[0005] A molding polyfluoroethylenepropylene resin and a preparation method thereof (Patent Application No. CN201610872586.X) use an emulsion polymerization method to prepare a polyfluoroethylenepropylene resin emulsion using an inorganic initiator. After coagulation and washing, sintering processing is performed, and the molding polyfluoroethylenepropylene resin is obtained. The present invention stabilizes unstable end groups formed by molecular chain segments during the synthesis of the molding polyfluoroethylenepropylene resin using an inorganic initiation system, thereby ensuring that the obtained molding polyfluoroethylenepropylene resin has excellent comprehensive performance and significantly reduces the corrosion of the product on a metal substrate.

[0006] However, the traditional FEP synthesis method often uses perfluorooctanoic acid (PFOA) as an emulsifier, which has potential harm to the environment and human health. With the increasing strictness of environmental regulations, it is urgent to develop a PFOA-free FEP synthesis method. SUMMARY

[0007] The main purpose of the present application is to provide a PFOA-free polyfluoroethylene propylene polymerization process to overcome the shortcomings of the prior art.

[0008] Another purpose of the present application is to provide a polyfluoroethylene propylene resin prepared by the above method.

[0009] To achieve the above-mentioned purposes, the technical solutions adopted by the present application include:

[0010] The present application provides a PFOA-free polyfluoroethylene propylene polymerization process, the operation steps of which are as follows:

[0011] Step one: according to the mass fraction, 30-50 parts of deoxygenated high-purity water are introduced into the high-pressure reaction kettle, the reaction kettle is started to stir, and high-purity nitrogen gas is introduced to displace the gas in the reaction kettle until the oxygen content in the kettle is not higher than 30 ppm, 0.01-0.1 parts of organic metal 3-amino-3-oxopropionate lithium salt and 2-5 parts of tert-butyl alcohol are added, and the reaction kettle is heated by the jacket;

[0012] Step two: the mixed gas of tetrafluoroethylene and hexafluoropropylene is introduced into the reaction kettle 1 until the reaction pressure is reached, 0.01-0.08 parts of a molecular weight regulator and 0.02-0.1 parts of an initiator are added, and the mixed gas of tetrafluoroethylene and hexafluoropropylene is continuously introduced 2 to maintain the reaction pressure during the reaction, when the emulsion solid content in the reaction kettle reaches 23-27%, the reaction is stopped, and the polyfluoroethylene propylene is obtained after the post-processing process.

[0013] The preparation method of the organic metal emulsifier in step one is as follows:

[0014] A1: according to the mass fraction, 5-10 parts of methyltridecafluorooctyl methacrylate, 0.001-0.01 parts of cis-diaminodiodoplatinum, 0.001-0.01 parts of 3-amino-3-oxopropionate lithium salt, and 2-5 parts of sodium tert-butyl alcohol are mixed to carry out amino-acrylic acid addition reaction, the reaction temperature is 70-80℃, and the reaction time is 30-100 minutes, then 100-140 parts of oleylamine polyoxyethylene ether is added, the reaction temperature is 70-80℃, and the reaction time is 30-100 minutes;

[0015] A2: To the product of step A1, 15-22 parts of phosphorus pentoxide is added, and the reaction is continued; the reaction temperature is 40-60℃, and the reaction time is 2-4 hours to obtain the organic metal emulsifier.

[0016] As a preferred technical solution of the present application, the temperature of the reaction kettle in step one is 75-95℃.

[0017] As a preferred technical solution of the present application, the molar ratio of the mixed gas 1 of tetrafluoroethylene and hexafluoropropylene in step two is 5-30:70-95.

[0018] As a preferred technical solution of the present application, the reaction pressure in step two is 3.5-4.5 MPa.

[0019] As a preferred technical solution of the present application, the molecular weight regulator in step two is selected from methane, diethyl malonate or a mixture thereof.

[0020] As a preferred technical solution of the present application, the initiator in step two is selected from ammonium persulfate, potassium persulfate or a mixture thereof.

[0021] As a preferred technical solution of the present application, the molar ratio of the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene in step two is 80-95:5-20.

[0022] As a preferred technical solution of the present application, the post-processing procedure in step two includes condensation, washing and drying.

[0023] Reaction mechanism:

[0024] Cis-diamminediodoplatinum, 3-amino-3-oxopropionate lithium salt and methyltridecafluorooctyl methacrylate undergo amino-acrylic acid addition reaction; then with oleylamine polyoxyethylene ether to undergo amino-acrylic acid addition reaction, and after phosphorus pentoxide reaction, iodine-containing platinum, tridecafluorooctyl ester, and polyoxyethylene ether phosphate are obtained.

[0025] Technical effects:

[0026] 1. Pt(II) complexes usually have large conjugated planes. In emulsion polymerization, these complexes can interact with polymer chains, helping to stabilize growing polymer particles, thereby improving dispersibility. The unsaturated coordination sites of Pt(II) centers can provide opportunities for interaction with other molecules such as solvents, monomers or polymer chains. This interaction can affect the kinetics of polymerization and the final structure of the polymer. Large conjugated planes and ligands can provide steric hindrance to prevent polymer particles from aggregating, thereby improving the stability and dispersibility of the emulsion.

[0027] 2. The use of iodinated platinum, lithium propionate salt, tridecafluorooctyl ester, and polyoxyethylene ether phosphate as emulsifiers can improve the stability during emulsion polymerization. This is mainly because the extremely low surface energy of the fluorine-containing group makes the emulsion droplets less likely to aggregate, thus maintaining stability. In addition, it has excellent anti-pollution performance, which makes it perform well in various surfactant applications. The use of such emulsifiers can also improve the polymerization efficiency, as their special structure can effectively promote the progress of the polymerization reaction. DETAILED DESCRIPTION

[0028] In view of the deficiencies in the prior art, the present inventors have long studied and practiced to come up with the technical solution of the present invention, which will be further explained below in terms of the technical solution, its implementation process and principles.

[0029] Example 1

[0030] A PFOA-free polytetrafluoroethylene-hexafluoropropylene polymerization process, the operation steps of which are as follows:

[0031] Step one: introduce 30 kg of deoxygenated high-purity water into a high-pressure reaction kettle, start stirring the reaction kettle, and introduce high-purity nitrogen gas to displace the gas in the reaction kettle until the oxygen content in the kettle is not higher than 30 ppm, then add 0.01 kg of organic metal emulsifier, and heat the reaction kettle through the jacket;

[0032] Step two: introduce a mixture of tetrafluoroethylene and hexafluoropropylene gas 1 into the reaction kettle until the reaction pressure is reached, then add 0.01 kg of molecular weight regulator and 0.02 kg of initiator, continuously introduce a mixture of tetrafluoroethylene and hexafluoropropylene gas 2 to maintain the reaction pressure during the reaction, and when the emulsion solid content in the reaction kettle reaches 23%, stop the reaction, and obtain polytetrafluoroethylene-hexafluoropropylene after the post-processing procedure.

[0033] The preparation method of the organic metal emulsifier in step one is as follows:

[0034] A1: mix 5 g of tridecafluorooctyl methacrylate, 0.001 g of cis-diamino diiodoplatinum, 0.001 g of 3-amino-3-oxopropionate lithium salt, and 2 g of sodium tert-butoxide to carry out amino-acrylic acid addition reaction, the reaction temperature is 70°C, and the reaction time is 30 minutes, then add 100 g of oil amine polyoxyethylene ether, the reaction temperature is 70°C, and the reaction time is 30 minutes;

[0035] A2: add 15 g of phosphorus pentoxide to the product of step A1 and continue the reaction; the reaction temperature is 40°C, and the reaction time is 2 hours, to obtain the organic metal emulsifier.

[0036] The temperature of the reaction kettle in step one is 75°C.

[0037] The molar ratio of the mixed gas 1 of tetrafluoroethylene and hexafluoropropylene in the step two is 5:95.

[0038] The reaction pressure in the step two is 3.5 MPa.

[0039] The molecular weight regulator in the step two is selected from methane.

[0040] The initiator in the step two is selected from ammonium persulfate.

[0041] The molar ratio of the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene in the step two is 80:20.

[0042] The post-processing procedure in the step two includes coagulation, washing and drying.

[0043] Example 2

[0044] A PFOA-free polytetrafluoroethylene-hexafluoropropylene polymerization process, the operation steps of which are as follows:

[0045] Step one: 40 kg of deoxygenated high-purity water is introduced into a high-pressure reaction kettle, the stirring of the reaction kettle is started, and high-purity nitrogen is introduced to displace the gas in the reaction kettle until the oxygen content in the kettle is not higher than 30 ppm, 0.04 kg of organic metal emulsifier is added, and the reaction kettle is heated through the jacket;

[0046] Step two: the mixed gas 1 of tetrafluoroethylene and hexafluoropropylene is introduced into the reaction kettle until the reaction pressure is reached, 0.03 kg of molecular weight regulator and 0.05 kg of initiator are added, the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene is continuously introduced to maintain the reaction pressure during the reaction, and when the solid content of the emulsion in the reaction kettle reaches 24%, the reaction is stopped, and the polytetrafluoroethylene-hexafluoropropylene is obtained after the post-processing procedure.

[0047] The preparation method of the organic metal emulsifier in the step one is as follows:

[0048] A1: 6.5 g of methacrylic acid tridecafluoro octyl ester, 0.004 g of cis-diamino diiodo platinum, 0.004 g of 3-amino-3-oxopropionate lithium salt, and 3 g of sodium tert-butoxide are mixed to carry out amino-acrylic acid addition reaction, the reaction temperature is 75℃, and the reaction time is 50 minutes, then 115 g of oleylamine polyoxyethylene ether is added, the reaction temperature is 75℃, and the reaction time is 50 minutes;

[0049] A2: 17 g of phosphorus pentoxide is added to the product of step A1, and the reaction is continued; the reaction temperature is 50℃, and the reaction time is 3 hours, to obtain the organic metal emulsifier.

[0050] The temperature of the reaction kettle in the step one is 85℃.

[0051] The molar ratio of the mixed gas 1 of tetrafluoroethylene and hexafluoropropylene in the step two is 15:85.

[0052] The reaction pressure in the step two is 4 MPa.

[0053] The molecular weight regulator in the step two is selected from diethyl malonate.

[0054] The initiator in the step two is selected from ammonium persulfate.

[0055] The molar ratio of the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene in the step two is 85:15.

[0056] The post-processing procedure in the step two includes coagulation, washing and drying.

[0057] Example 3

[0058] A PFOA-free polytetrafluoroethylene-hexafluoropropylene polymerization process, the operation steps of which are as follows:

[0059] Step one: 40 kg of deoxygenated high-purity water is introduced into a high-pressure reaction kettle, the stirring of the reaction kettle is started, and high-purity nitrogen is introduced to displace the gas in the reaction kettle until the oxygen content in the kettle is not higher than 30 ppm, 0.08 kg of organic metal emulsifier is added, and the reaction kettle is heated through the jacket;

[0060] Step two: the mixed gas 1 of tetrafluoroethylene and hexafluoropropylene is introduced into the reaction kettle until the reaction pressure is reached, 0.06 kg of molecular weight regulator and 0.08 kg of initiator are added, the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene is continuously introduced to maintain the reaction pressure during the reaction, and when the solid content of the emulsion in the reaction kettle reaches 25.5%, the reaction is stopped, and the polytetrafluoroethylene-hexafluoropropylene is obtained after the post-processing procedure.

[0061] The preparation method of the organic metal emulsifier in the step one is as follows:

[0062] A1: 8.5 g of methacrylic acid tridecafluoro octyl ester, 0.08 g of cis-diamino diiodoplatinum, 0.08 g of 3-amino-3-oxopropionate lithium salt, and 4 g of sodium tert-butoxide are mixed to carry out amino-acrylic acid addition reaction, the reaction temperature is 75℃, and the reaction time is 80 minutes, then 130 g of oleylamine polyoxyethylene ether is added, the reaction temperature is 75℃, and the reaction time is 80 minutes;

[0063] A2: 20 g of phosphorus pentoxide is added to the product of step A1, and the reaction is continued; the reaction temperature is 50℃, and the reaction time is 3 hours, to obtain the organic metal emulsifier.

[0064] The temperature of the reaction kettle in the step one is 85℃.

[0065] The molar ratio of the mixed gas 1 of tetrafluoroethylene and hexafluoropropylene in the step two is 20:80.

[0066] The reaction pressure in the step two is 4 MPa.

[0067] The molecular weight regulator in the step two is selected from methane.

[0068] The initiator in the step two is selected from ammonium persulfate.

[0069] The molar ratio of the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene in the step two is 90:10.

[0070] The post-processing procedure in the step two includes coagulation, washing and drying.

[0071] Example 4

[0072] A PFOA-free polyfluoroethylene-propylene polymerization process, the operation steps of which are as follows:

[0073] Step one: 50 kg of deoxygenated high-purity water is introduced into a high-pressure reaction kettle, the stirring of the reaction kettle is started, and high-purity nitrogen is introduced to displace the gas in the reaction kettle until the oxygen content in the kettle is not higher than 30 ppm, 0.1 kg of organic metal emulsifier is added, and the reaction kettle is heated through the jacket;

[0074] Step two: the mixed gas 1 of tetrafluoroethylene and hexafluoropropylene is introduced into the reaction kettle until the reaction pressure is reached, 0.08 kg of molecular weight regulator and 0.1 kg of initiator are added, the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene is continuously introduced to maintain the reaction pressure during the reaction, and when the solid content of the emulsion in the reaction kettle reaches 27%, the reaction is stopped, and the polyfluoroethylene-propylene is obtained through a post-processing procedure.

[0075] The preparation method of the organic metal emulsifier in the step one is as follows:

[0076] A1: 10 g of methacrylic acid tridecafluoro octyl ester, 0.01 kg of cis-diamino platinum diiodide, 0.01 kg of 3-amino-3-oxo propionate lithium salt, and 5 kg of sodium tert-butoxide are mixed to carry out amino-acrylic acid addition reaction, the reaction temperature is 80℃, and the reaction time is 100 minutes, then 140 g of oleylamine polyoxyethylene ether is added, the reaction temperature is 80℃, and the reaction time is 100 minutes;

[0077] A2: 22 g of phosphorus pentoxide is added to the product of step A1, and the reaction is continued; the reaction temperature is 60℃, and the reaction time is 4 hours, to obtain the organic metal emulsifier.

[0078] The temperature of the reaction kettle in the step one is 95℃.

[0079] The molar ratio of the mixed gas 1 of tetrafluoroethylene and hexafluoropropylene in the step two is 30:70.

[0080] The reaction pressure in the step two is 4.5 MPa.

[0081] The molecular weight regulator in the step two is selected from diethyl malonate.

[0082] The initiator in the step two is selected from potassium persulfate.

[0083] The molar ratio of the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene in the step two is 95:5.

[0084] The post-processing procedure in the step two includes coagulation, washing and drying.

[0085] Evaluation of examples:

[0086] 1 Melting point: the temperature corresponding to the peak when using a differential scanning calorimetry measuring device with a temperature rise rate of 10°C / min is taken as the melting point.

[0087] 2) Melt index: according to ASTM D-1238, using a melt flow indexer, using a mold with a diameter of 2.1 mm and a length of 8 mm, under the condition of 372°C and 5 kg load, the value at this time is taken as the melt index of the copolymer.

[0088] 3) Thermal gravimetric analysis: using an electric furnace with a rotating disc, using a precision balance, accurately weighing the sample in an aluminum cup (with a weight of A) pre-fired at 372°C for 1 hour in the range of 20±0.1g, and setting the overall weight as B. The sample is placed on the rotating disc of the electric furnace at 372°C, and the rotating speed of the rotating disc is 6 rpm. Keep at 372°C for 30 minutes, and naturally cool for 1 hour, weigh the sample, and set the weight as C. Three parallel samples are taken for each sample, and the test results are averaged.

[0089] The test results of the above examples are as follows:

[0090] Melting point °C Melt index g / 10 min Thermal gravimetric wt % Example 1 255.7 13 0.06 Example 2 254.3 16 0.05 Example 3 255.1 21 0.05 Example 4 254.6 24 0.04

[0091] The polyperfluoroalkylpropylene resin batches prepared by the above specific embodiments are stable in performance, do not contain PFOA, and the process is green and environmentally friendly.

[0092] It should be understood that the above examples are only for illustrating the technical concepts and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and it cannot limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A PFOA-free polyfluoroethylene propylene polymerization process, the operating steps of which are as follows: Step 1: According to the mass fraction, 30-50 parts of deoxygenated high-purity water is introduced into a high-pressure reaction kettle, the reaction kettle is started to stir, and high-purity nitrogen gas is introduced to displace the gas in the reaction kettle until the oxygen content in the kettle is not higher than 30 ppm, 0.01-0.1 parts of an organic metal emulsifier is added, and the reaction kettle is heated through the jacket; Step 2: The mixed gas 1 of tetrafluoroethylene and hexafluoropropylene is introduced into the reaction kettle until the reaction pressure is reached, 0.01-0.08 parts of a molecular weight regulator and 0.02-0.1 parts of an initiator are added, and the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene is continuously introduced to maintain the reaction pressure during the reaction, when the emulsion solid content in the reaction kettle reaches 23-27%, the reaction is stopped, and the polyfluoroethylene propylene is obtained after the post-treatment process; The preparation method of the organic metal emulsifier in step 1 is as follows: A1: According to the mass fraction, 5-10 parts of methyltridecafluorooctyl methacrylate, 0.001-0.01 parts of cis-diamino platinum diiodide, 0.001-0.01 parts of 3-amino-3-oxopropionate lithium salt, and 2-5 parts of sodium tert-butoxide are mixed to carry out amino-acrylic acid addition reaction, the reaction temperature is 70-80℃, and the reaction time is 30-100 minutes, then 100-140 parts of oleylamine polyoxyethylene ether is added, the reaction temperature is 70-80℃, and the reaction time is 30-100 minutes; A2: 15-22 parts of phosphorus pentoxide is added to the product of step A1, and the reaction is continued; the reaction temperature is 40-60℃, and the reaction time is 2-4 hours to obtain the organic metal emulsifier.

2. A PFOA-free FEP polymerization process according to claim 1, characterized in that: The reaction kettle temperature in step 1 is 75-95℃.

3. A PFOA-free FEP polymerization process according to claim 1, characterized in that: The molar ratio of the mixed gas 1 of tetrafluoroethylene and hexafluoropropylene in step 2 is 5-30:70-95.

4. A PFOA-free polyfluoroethylenepropylene polymerization process according to claim 1, characterized in that: The reaction pressure in step 2 is 3.5-4.5 MPa.

5. A PFOA-free polyfluoroethylenepropylene polymerization process according to claim 1, characterized in that: The molecular weight regulator in step 2 is selected from methane, diethyl malonate, or a mixture thereof.

6. A PFOA-free polyfluoroethylenepropylene polymerization process according to claim 1, characterized in that: The initiator in step 2 is selected from ammonium persulfate, potassium persulfate, or a mixture thereof.

7. A PFOA-free polyfluoroethylenepropylene polymerization process according to claim 1, characterized by: The molar ratio of the mixed gas 2 of tetrafluoroethylene and hexafluoropropylene in step 2 is 80-95:5-20.

8. A PFOA-free FEP polymerization process according to claim 1, characterized in that: The post-treatment process in step 2 includes coagulation, washing, and drying.