Ethylene-tetrafluoroethylene copolymer and preparation method thereof

Abstract

According to the ethylene-tetrafluoroethylene copolymer and the preparation method provided by the invention, cyclohexyl vinyl ether is adopted as a third monomer during preparation of the copolymer, and a rigid structure and thermal stability of a molecular six-membered ring of the cyclohexyl vinyl ether are utilized, so that the movement trend of a polymer molecular chain can be reduced, and the strength of ETFE can be improved; and moreover, the strength and heat resistance of the ETFE can be greatly improved, and the application range of the ETFE is expanded. The tensile strength of the ETFE is 60-70 MPa, the 1wt% thermal weight loss temperature is 430 DEG C or above, and the ETFE has excellent mechanical properties and heat resistance. The preparation method provided by the invention is simple, is simple and convenient to operate, is convenient for large-scale production, can be used for preparing cables, films and the like, and improves the application performance of ETFE.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorine-containing polymer materials and relates to an ethylene-tetrafluoroethylene copolymer and a preparation method thereof. Background Art

[0002] Ethylene-tetra-fluoro-ethylene (ETFE) is a semi-crystalline fluorine-containing polymer formed by the copolymerization of ethylene and tetrafluoroethylene. It is the toughest fluoroplastic. ETFE contains tetrafluoroethylene monomer, so it has excellent corrosion resistance, weather resistance, high temperature resistance, aging resistance, radiation resistance and other properties. In addition, ETFE also has the characteristics of light weight, high transparency, and environmental protection. It can be processed into coatings, films, cables, etc., and is widely used in many fields such as aerospace, construction, agriculture, chemical industry, and underground.

[0003] However, ETFE has great alternation and high crystallinity, which leads to poor crack resistance. In order to solve these shortcomings, a small amount of a third monomer is usually added to copolymerize with tetrafluoroethylene and ethylene when synthesizing ETFE to improve the mechanical properties of ETFE. For example, in the patent with application number CN03104145.0, ETFE polymerized with itaconic anhydride as the third monomer has good performance in adhesion and flame retardancy, but the strength is not much improved. For example, in the patent with application number CN200810138051.5, ETFE prepared with 1,2,2-trifluorostyrene as the third monomer improves its heat resistance and mechanical properties, but 1,2,2-trifluorostyrene has not been industrially mass-produced and is expensive, which is not conducive to the large-scale production of ETFE.

[0004] As ETFE is used more and more widely and its application conditions become more and more demanding, ETFE with higher strength and better heat resistance is increasingly needed. Therefore, it is necessary to research and develop an ETFE with higher strength and better heat resistance. Summary of the invention

[0005] The purpose of the present invention is to provide an ethylene-tetrafluoroethylene copolymer and a preparation method thereof, so as to solve the problem that the existing ETFE has low structural strength.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present application provides an ethylene-tetrafluoroethylene copolymer, which is prepared by emulsion polymerization using ethylene, tetrafluoroethylene and cyclohexyl vinyl ether as raw materials. Specifically, the polymer uses a surfactant as an emulsifier, and ethylene, tetrafluoroethylene and cyclohexyl vinyl ether are uniformly dispersed in micelles of the emulsifier, and the ethylene-tetrafluoroethylene copolymer is formed by free radical polymerization.

[0007] In the prepared ethylene-tetrafluoroethylene copolymer, the molar ratio of ethylene to tetrafluoroethylene is 35:65-65:35, and the molar proportion of cyclohexyl vinyl ether in the copolymer is 0.1-15%.

[0008] Preferably, in the prepared ethylene-tetrafluoroethylene copolymer, the molar ratio of ethylene to tetrafluoroethylene is 45:55-55:45, and the molar proportion of cyclohexyl vinyl ether in the copolymer is 0.5-10%.

[0009] The present application also provides a method for preparing an ethylene-tetrafluoroethylene copolymer, the method comprising: S01: In a reactor under negative pressure, cyclohexyl vinyl ether, surfactant and deionized water are mixed and heated to 65°C.

[0010] The autoclave was evacuated, and an inert gas was introduced into the autoclave for at least 3 times until the oxygen in the autoclave was removed, and the autoclave was evacuated to 0.01 MPa. The inert gas in the present application is nitrogen.

[0011] Cyclohexyl vinyl ether, surfactant and deionized water are added to the autoclave, and the autoclave is started to stir and heated to 65° C. In the present application, the surfactant is used as an emulsifier to form an emulsion and provide a polymerization site for the polymerization reaction. The surfactant is selected from one of sodium dodecyl sulfonate, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, etc.

[0012] S02: Initially, a mixed gas of ethylene and tetrafluoroethylene is introduced to a pressure of 1.5 MPa.

[0013] A mixed gas of ethylene and tetrafluoroethylene is initially introduced into the autoclave until the pressure in the autoclave reaches 1.5 MPa. In the present application, the molar ratio of the initially added ethylene and tetrafluoroethylene is 10:90-90:10. The initial addition amount of cyclohexyl vinyl ether in the present application is 0.5%-10% of the total molar amount of the initially added ethylene and tetrafluoroethylene.

[0014] S03: After the temperature and pressure are stabilized at 65°C and 1.5 MPa, an initiator is added to carry out an emulsion polymerization reaction; during the emulsion polymerization reaction, cyclohexyl vinyl ether, ethylene and tetrafluoroethylene are continuously added, and the reaction temperature and pressure are maintained stable at 65°C and 1.5 MPa.

[0015] When the temperature and pressure in the autoclave are stabilized at 65°C and 1.5MPa, an initiator is added to the autoclave to initiate an emulsion polymerization reaction between cyclohexyl vinyl ether, ethylene and tetrafluoroethylene. In the present application, cyclohexyl vinyl ether is used as the third monomer, and the rigid structure and thermal stability of the six-membered ring of the molecule are utilized to not only reduce the movement tendency of the polymer molecular chain and increase the strength of ETFE, but also greatly improve the strength and heat resistance of ETFE and expand its application range.

[0016] In the present application, only when the temperature reaches 65°C and the pressure reaches 1.5MPa, the copolymer formed by the polymerization reaction of cyclohexyl vinyl ether, ethylene and tetrafluoroethylene can achieve the requirements of a molar ratio of ethylene to tetrafluoroethylene of 35:65-65:35 and a molar proportion of cyclohexyl vinyl ether in the copolymer of 0.1-15%, thereby exhibiting good tensile strength and heat resistance.

[0017] In the present application, the initiator is selected from di-tert-butylcyclohexyl peroxydicarbonate or diperfluoropropionyl peroxide.

[0018] During the polymerization reaction, cyclohexyl vinyl ether, ethylene and tetrafluoroethylene need to be continuously added to the autoclave to ensure that the reaction temperature and pressure in the autoclave are stable at 65°C and 1.5 MPa. In the present application, the molar ratio of the added ethylene and tetrafluoroethylene is 35:65-65:35, and the added amount of cyclohexyl vinyl ether is 0.5%-10% of the total molar amount of ethylene and tetrafluoroethylene added.

[0019] S04: When the total mass of the added ethylene and tetrafluoroethylene reaches 28 kg, the polymerization reaction is stopped to obtain a reaction slurry.

[0020] When the total mass of ethylene and tetrafluoroethylene added to the autoclave reaches 28 kg, the addition of cyclohexyl vinyl ether, ethylene and tetrafluoroethylene is stopped, and the autoclave is cooled and depressurized to stop the polymerization reaction and obtain a reaction slurry.

[0021] S05: The reaction slurry is washed with hot water and dried to obtain an ethylene-tetrafluoroethylene copolymer.

[0022] The reaction slurry was washed with hot water to obtain a white powder product, which was placed in an oven at 150° C. and dried for 8 h to obtain an ethylene-tetrafluoroethylene copolymer.

[0023] The present invention has the following beneficial effects: (1) In the present application, cyclohexyl vinyl ether is used as the third monomer. By utilizing the rigid structure and thermal stability of the six-membered ring of the molecule, not only can the movement tendency of the polymer molecular chain be reduced and the strength of ETFE be increased, but also the strength and heat resistance of ETFE can be greatly improved, thereby expanding its scope of application.

[0024] (2) In the present application, when the emulsion polymerization temperature is 65°C and the pressure is 1.5 MPa, the copolymer formed by the polymerization reaction of cyclohexyl vinyl ether, ethylene and tetrafluoroethylene can meet the requirements that the molar ratio of ethylene to tetrafluoroethylene is 35:65-65:35 and the molar proportion of cyclohexyl vinyl ether in the copolymer is 0.1-15%, thereby making the copolymer exhibit good tensile strength and heat resistance.

[0025] (3) The ethylene-tetrafluoroethylene copolymer prepared in the present application has a tensile strength of 60-70 MPa and a 1 wt% thermal weight loss temperature of above 430°C, and has excellent mechanical properties and heat resistance.

[0026] (4) The preparation method provided in this application is simple, easy to operate, and convenient for large-scale production. It can be used to prepare cables, films, etc., thereby improving the application performance of ETFE. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0028] Example 1 The present application provides an ethylene-tetrafluoroethylene copolymer, and the preparation method of the copolymer comprises: S101: evacuate the 500L autoclave, introduce nitrogen into the autoclave, and replace it at least 3 times until the oxygen in the autoclave is removed, and evacuate the autoclave to 0.01MPa. Add 1.436kg cyclohexyl vinyl ether, 5kg sodium dodecyl sulfonate and 250L deionized water into the autoclave, start stirring the autoclave and heat it to 65°C.

[0029] S102: initially introducing a mixture of tetrafluoroethylene and ethylene in a molar ratio of 80:20 into the autoclave until the pressure in the autoclave reaches 1.5 MPa.

[0030] S103: When the temperature and pressure in the autoclave are stabilized at 65°C and 1.5MPa, 25g of di-tert-butyl cyclohexyl peroxydicarbonate is added to the autoclave as an initiator to initiate an emulsion polymerization reaction between cyclohexyl vinyl ether, ethylene and tetrafluoroethylene. During the polymerization reaction, cyclohexyl vinyl ether, ethylene and tetrafluoroethylene are continuously added to the autoclave, wherein the molar ratio of the added tetrafluoroethylene to ethylene is 52:48, and the added amount of cyclohexyl vinyl ether is 2% of the total molar amount of the added ethylene and tetrafluoroethylene.

[0031] S104: When the total mass of ethylene and tetrafluoroethylene added to the autoclave reaches 28 kg, the addition of cyclohexyl vinyl ether, ethylene and tetrafluoroethylene is stopped, and the autoclave is cooled and depressurized to stop the polymerization reaction and obtain a reaction slurry.

[0032] S105: The reaction slurry is washed with hot water to obtain a white powder product. The white powder product is placed in an oven at 150° C. and dried for 8 hours to obtain an ethylene-tetrafluoroethylene copolymer.

[0033] Example 2 The present application provides an ethylene-tetrafluoroethylene copolymer, and the preparation method of the copolymer comprises: S201: evacuate the 500L autoclave, introduce nitrogen into the autoclave, and replace it at least 3 times until the oxygen in the autoclave is removed, and evacuate the autoclave to 0.01MPa. Add 1.436kg cyclohexyl vinyl ether, 5kg sodium dodecyl sulfate and 250L deionized water into the autoclave, start stirring the autoclave and heat it to 65°C.

[0034] S202: initially introducing a mixture of tetrafluoroethylene and ethylene in a molar ratio of 83:17 into the autoclave until the pressure in the autoclave reaches 1.5 MPa.

[0035] S203: When the temperature and pressure in the autoclave are stabilized at 65°C and 1.5MPa, 25g of diperfluoropropionyl peroxide is added to the autoclave as an initiator to initiate an emulsion polymerization reaction between cyclohexyl vinyl ether, ethylene and tetrafluoroethylene. During the polymerization reaction, cyclohexyl vinyl ether, ethylene and tetrafluoroethylene are continuously added to the autoclave, wherein the molar ratio of the added tetrafluoroethylene to ethylene is 54:46, and the added amount of cyclohexyl vinyl ether is 2% of the total molar amount of the added ethylene and tetrafluoroethylene.

[0036] S204: When the total mass of ethylene and tetrafluoroethylene added to the autoclave reaches 28 kg, the addition of cyclohexyl vinyl ether, ethylene and tetrafluoroethylene is stopped, and the autoclave is cooled and depressurized to stop the polymerization reaction and obtain a reaction slurry.

[0037] S205: The reaction slurry is washed with hot water to obtain a white powder product. The white powder product is placed in an oven at 150° C. and dried for 8 hours to obtain an ethylene-tetrafluoroethylene copolymer.

[0038] Example 3 The present application provides an ethylene-tetrafluoroethylene copolymer, and the preparation method of the copolymer comprises: S301: evacuate the 500L autoclave, introduce nitrogen into the autoclave, and replace it at least 3 times until the oxygen in the autoclave is removed, and evacuate the autoclave to 0.01MPa. Add 1.436kg cyclohexyl vinyl ether, 5kg fatty alcohol polyoxyethylene ether and 150L deionized water into the autoclave, start stirring the autoclave and heat it to 65°C.

[0039] S302: initially introducing a mixture of tetrafluoroethylene and ethylene in a molar ratio of 90:10 into the autoclave until the pressure in the autoclave reaches 1.5 MPa.

[0040] S303: When the temperature and pressure in the autoclave are stabilized at 65°C and 1.5MPa, 25g of di-tert-butyl cyclohexyl peroxydicarbonate is added to the autoclave as an initiator to initiate an emulsion polymerization reaction between cyclohexyl vinyl ether, ethylene and tetrafluoroethylene. During the polymerization reaction, cyclohexyl vinyl ether, ethylene and tetrafluoroethylene are continuously added to the autoclave, wherein the molar ratio of the added tetrafluoroethylene to ethylene is 65:35, and the added amount of cyclohexyl vinyl ether is 10% of the total molar amount of the added ethylene and tetrafluoroethylene.

[0041] S304: When the total mass of ethylene and tetrafluoroethylene added to the autoclave reaches 28 kg, the addition of cyclohexyl vinyl ether, ethylene and tetrafluoroethylene is stopped, and the autoclave is cooled and depressurized to stop the polymerization reaction and obtain a reaction slurry.

[0042] S305: The reaction slurry is washed with hot water to obtain a white powder product. The white powder product is placed in an oven at 150° C. and dried for 8 hours to obtain an ethylene-tetrafluoroethylene copolymer.

[0043] Example 4 The present application provides an ethylene-tetrafluoroethylene copolymer, and the preparation method of the copolymer comprises: S401: evacuate the 500L autoclave, introduce nitrogen into the autoclave, replace at least 3 times, until the oxygen in the autoclave is removed, and evacuate the autoclave to 0.01MPa. Add 1.436kg cyclohexyl vinyl ether, 5kg sodium dodecyl sulfonate and 150L deionized water into the autoclave, start stirring the autoclave and heat it to 65°C.

[0044] S402: initially introducing a mixture of tetrafluoroethylene and ethylene in a molar ratio of 10:90 into the autoclave until the pressure in the autoclave reaches 1.5 MPa.

[0045] S403: When the temperature and pressure in the autoclave are stabilized at 65°C and 1.5MPa, 25g of diperfluoropropionyl peroxide is added to the autoclave to initiate an emulsion polymerization reaction between cyclohexyl vinyl ether, ethylene and tetrafluoroethylene. During the polymerization reaction, cyclohexyl vinyl ether, ethylene and tetrafluoroethylene are continuously added to the autoclave, wherein the molar ratio of the added tetrafluoroethylene to ethylene is 35:65, and the added amount of cyclohexyl vinyl ether is 0.5% of the total molar amount of the added ethylene and tetrafluoroethylene.

[0046] S404: When the total mass of cyclohexyl vinyl ether, ethylene and tetrafluoroethylene added to the autoclave reaches 28 kg, the addition of cyclohexyl vinyl ether, ethylene and tetrafluoroethylene is stopped, and the autoclave is cooled and depressurized to stop the polymerization reaction and obtain a reaction slurry.

[0047] S405: The reaction slurry is washed with hot water to obtain a white powder product. The white powder product is placed in an oven at 150° C. and dried for 8 hours to obtain an ethylene-tetrafluoroethylene copolymer.

[0048] Comparative Example 1 The preparation method of the ethylene-tetrafluoroethylene copolymer provided in Comparative Example 1 comprises: D101: Evacuate the 500L autoclave and introduce nitrogen into the autoclave for at least 3 times until the oxygen in the autoclave is removed. Evacuate the autoclave to 0.01MPa. Add 1.664kgCH 2 =CH(CF 2 ) 2 F. Add 5 kg sodium dodecyl sulfate and 250 L deionized water, start stirring the autoclave and heat to 65 °C.

[0049] D102: A mixed gas of tetrafluoroethylene and ethylene in a molar ratio of 80:20 was initially introduced into the autoclave until the pressure in the autoclave reached 1.5 MPa.

[0050] D103: When the temperature and pressure in the autoclave are stabilized at 65°C and 1.5 MPa, 25 g of di-tert-butyl cyclohexyl peroxydicarbonate is added to the autoclave as an initiator to initiate CH 2 =CH(CF 2 ) 2 F, an emulsion polymerization reaction occurs between ethylene and tetrafluoroethylene. During the polymerization reaction, CH 2=CH(CF 2 ) 2 F, ethylene and tetrafluoroethylene, wherein the molar ratio of the added tetrafluoroethylene to ethylene is 54:46, CH 2 =CH(CF 2 ) 2 The amount of F added is 2% of the total molar amount of ethylene and tetrafluoroethylene added.

[0051] D104: When the total mass of ethylene and tetrafluoroethylene added to the autoclave reaches 28 kg, stop adding CH 2 =CH(CF 2 ) 2 F, ethylene and tetrafluoroethylene, and at the same time, the high-pressure reactor is cooled and depressurized to stop the polymerization reaction and obtain a reaction slurry.

[0052] D105: The reaction slurry was washed with hot water to obtain a white powder product, which was placed in an oven at 150° C. and dried for 8 h to obtain an ethylene-tetrafluoroethylene copolymer.

[0053] Comparative Example 2 The preparation method of the ethylene-tetrafluoroethylene copolymer provided in Comparative Example 2 comprises: D201: Evacuate the 500L autoclave and introduce nitrogen into the autoclave for at least 3 times until the oxygen in the autoclave is removed. Evacuate the autoclave to 0.01MPa. Add 1.664kgCH 2 =CH(CF 2 ) 2 F. Add 5 kg of sodium dodecyl sulfate and 250 L of deionized water, start stirring the autoclave and heat to 65 °C.

[0054] D202: A mixture of tetrafluoroethylene and ethylene in a molar ratio of 83:17 was initially introduced into the autoclave until the pressure in the autoclave reached 1.5 MPa.

[0055] D203: When the temperature and pressure in the autoclave are stabilized at 65°C and 1.5 MPa, 25 g of diperfluoropropionyl peroxide is added to the autoclave as an initiator to initiate CH 2 =CH(CF 2 ) 2 F, an emulsion polymerization reaction occurs between ethylene and tetrafluoroethylene. During the polymerization reaction, CH 2 =CH(CF 2 ) 2 F, ethylene and tetrafluoroethylene, wherein the molar ratio of the added tetrafluoroethylene to ethylene is 54:46, CH 2 =CH(CF 2) 2 The amount of F added is 2% of the total molar amount of ethylene and tetrafluoroethylene added.

[0056] D204: When the total mass of ethylene and tetrafluoroethylene added to the autoclave reaches 28 kg, stop adding CH 2 =CH(CF 2 ) 2 F, ethylene and tetrafluoroethylene, and at the same time, the high-pressure reactor is cooled and depressurized to stop the polymerization reaction and obtain a reaction slurry.

[0057] D205: The reaction slurry was washed with hot water to obtain a white powder product, which was placed in an oven at 150° C. and dried for 8 h to obtain an ethylene-tetrafluoroethylene copolymer.

[0058] The ethylene-tetrafluoroethylene copolymers prepared in Examples 1-4 and Comparative Examples 1 and 2 were subjected to heat resistance tests and tensile strength tests, respectively, and the test results shown in Table 1 were obtained.

[0059] The heat resistance test process is as follows: using a thermogravimetric analyzer, in an air atmosphere, 3 mg of ethylene-tetrafluoroethylene copolymer is heated from room temperature to 500°C at a rate of 10°C / min, and the temperature at which the weight loss is 1wt% is taken to evaluate the thermal stability of the polymer.

[0060] The tensile strength test process is as follows: the prepared ethylene-tetrafluoroethylene copolymer is pressed into a 1.3-1.5 mm thick sheet at 300°C; the sheet is punched into a specimen using the same mold as ASTMD3159-10, and the measured value of each tensile specimen is the average value of the tensile test results of 5 specimens.

[0061] Table 1: Performance test results of ethylene-tetrafluoroethylene copolymers prepared in Examples 1-4 and Comparative Examples 1 and 2 As can be seen from Table 1, the 1wt% thermal weight loss temperature of the ethylene-tetrafluoroethylene copolymer prepared in Comparative Examples 1 and 2 is 411-416°C, and the tensile strength is 52-56MPa; the 1wt% thermal weight loss temperature of the ethylene-tetrafluoroethylene copolymer prepared in Examples 1-4 reaches about 430°C, and the tensile strength is 60-70MPa. That is, relative to Comparative Examples 1 and 2, the 1wt% thermal weight loss temperature and tensile strength of the ethylene-tetrafluoroethylene copolymer prepared in the examples of the present application are significantly increased. This shows that cyclohexyl vinyl ether as the third monomer can significantly improve the heat resistance and tensile strength of ethylene-tetrafluoroethylene polymers, showing excellent mechanical properties and heat resistance, and further expanding the scope of use of ETFE.

[0062] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An ethylene-tetrafluoroethylene copolymer, characterized in that The copolymer is prepared by emulsion polymerization using ethylene, tetrafluoroethylene and cyclohexyl vinyl ether as raw materials; in the copolymer, the molar ratio of ethylene to tetrafluoroethylene is 35:65-65:35, and the molar proportion of cyclohexyl vinyl ether in the copolymer is 0.1-15%.

2. The ethylene-tetrafluoroethylene copolymer according to claim 1, characterized in that The molar ratio of ethylene to tetrafluoroethylene is 45:55-55:

45.

3. The ethylene-tetrafluoroethylene copolymer according to claim 1, characterized in that The molar proportion of the cyclohexyl vinyl ether in the copolymer is 0.5-10%.

4. A method for preparing an ethylene-tetrafluoroethylene copolymer, characterized in that: include: In a reactor under negative pressure, cyclohexyl vinyl ether, surfactant and deionized water are mixed and heated to 65°C; Initially, a mixed gas of ethylene and tetrafluoroethylene is introduced until the pressure reaches 1.5 MPa; After the temperature and pressure are stabilized at 65°C and 1.5 MPa, an initiator is added to carry out an emulsion polymerization reaction; during the emulsion polymerization reaction, cyclohexyl vinyl ether, ethylene and tetrafluoroethylene are continuously added, and the reaction temperature and pressure are maintained stable at 65°C and 1.5 MPa; When the total mass of the added ethylene and tetrafluoroethylene reaches 28 kg, the polymerization reaction is stopped to obtain a reaction slurry; The reaction slurry is washed with hot water and dried to obtain an ethylene-tetrafluoroethylene copolymer.

5. The method for preparing an ethylene-tetrafluoroethylene copolymer according to claim 4, characterized in that: The molar ratio of the ethylene and tetrafluoroethylene initially added is 10:90-90:

10.

6. The method for preparing an ethylene-tetrafluoroethylene copolymer according to claim 4, characterized in that: The initial addition amount of cyclohexyl vinyl ether is 0.5%-10% of the total molar amount of ethylene and tetrafluoroethylene initially added.

7. The method for preparing an ethylene-tetrafluoroethylene copolymer according to claim 4, characterized in that: The molar ratio of the added ethylene to tetrafluoroethylene is 35:65-65:

35.

8. The method for preparing an ethylene-tetrafluoroethylene copolymer according to claim 4, characterized in that: The amount of cyclohexyl vinyl ether added is 0.5%-10% of the total molar amount of ethylene and tetrafluoroethylene added.

9. The method for preparing an ethylene-tetrafluoroethylene copolymer according to claim 4, characterized in that: The surfactant is selected from sodium dodecyl sulfonate, sodium dodecyl sulfate, and fatty alcohol polyoxyethylene ether.

10. The method for preparing ethylene-tetrafluoroethylene copolymer according to claim 4, characterized in that: The initiator is selected from di-tert-butyl cyclohexyl peroxydicarbonate or diperfluoropropionyl peroxide.

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