Method for preparing perfluoroether elastomer by mixing and grafting

Abstract

The invention provides a method for preparing a perfluoroether elastomer by mixing and grafting, which is applied to the technical field of fluoroelastomers, and comprises the following steps: S1, carrying out emulsion polymerization on perfluoroalkoxy alkyl vinyl ether, tetrafluoroethylene, perfluoroalkyl vinyl ether and a vulcanization point monomer to obtain a perfluoroether elastomer emulsion, and carrying out condensation, washing, drying and devolatilization to obtain a perfluoroether elastomer product; the perfluoroether elastomer micro powder is obtained; s2, mixing the perfluoroether elastomer micro powder with liquid rubber containing active end groups and an acid acceptor at 60-90 DEG C for solid-liquid phase reaction grafting, and then adding PTFE micro powder for continuous mixing and thin-passing to obtain a rubber compound; and S3, adding an acid acceptor into the rubber compound for mixing and thin-passing, carrying out compression molding, and carrying out secondary vulcanization to obtain the low-temperature-resistant perfluoroether elastomer composition. According to the technology adopted by the invention, the glass transition temperature of the perfluoroether elastomer composition is reduced, the low temperature resistance, the mechanical strength and the chemical stability of plasma etching resistance of the perfluoroether elastomer composition are further improved, carbon black does not need to be added, and the cleanliness of the perfluoroether elastomer is improved.

Description

Technical Field

[0001] The present application relates to the technical field of fluoroelastomers, and in particular to a method for preparing perfluoroether elastomers by mixing and grafting. Background Art

[0002] The low temperature resistance of rubber is related to its molecular structure. Generally, rubber with double bonds or / and ether bonds on the main chain has good low temperature resistance, while fluororubber without double bonds on the main chain and with polar groups on the side bonds has poor low temperature resistance. To improve the low temperature resistance of fluororubber, the only way is to change its molecular structure. There are two main approaches to improve it, which are to introduce side groups and modify the main chain: (1) Change the copolymer composition, which can be achieved by changing the main chain structure of the molecule and adjusting the flexibility of the molecular chain. For example, nitroso fluororubber, phosphazene fluororubber, and fluorosilicone rubber belong to this category; (2) Introduce low temperature resistant modified monomers, such as perfluoroalkyl vinyl ether (PAVE), mainly perfluoromethyl vinyl ether PMVE; or perfluoroalkoxyalkyl vinyl ether (PAAVE), mainly perfluoromethoxymethyl vinyl ether (MOVE), to introduce flexible ether bonds in the side chains of fluoroelastomers to reduce the glass transition temperature Tg; (3) Add low molecular weight fluorine-containing polymers with low Tg to the compound rubber.

[0003] Nitroso fluororubber is a fluororubber with NO structure on the main chain, which belongs to heterochain polymer. This type of fluororubber has no groups that react with oxidants such as C=C, =CH 2 Therefore, it has higher chemical stability than fluorinated olefin fluororubber. Because the main chain contains NO bond, the flexibility of the molecular chain is increased, and its cold resistance is improved compared with fluorinated olefin fluororubber. However, due to the low NO bond energy, its heat resistance is worse than that of fluorinated olefin fluororubber.

[0004] Fluorosilicone rubber is a polymer with a main chain formed by silicon-oxygen bonds and trifluoroalkyl groups on the side chains. Since its main chain contains silicon-oxygen bonds and the side groups contain fluorine atoms, it has the advantages of both. Therefore, it can be used in a very wide temperature range of -60-200℃ and has excellent fuel oil resistance. However, its disadvantage is that its physical and mechanical properties are worse than other fluororubbers, and its heat resistance and chemical resistance are not as good as other fluororubbers.

[0005] CN104530292A discloses a low-temperature resistant perfluoroether rubber and a synthesis method thereof. A low-temperature resistant modified monomer is introduced during the synthesis of the emulsion, and the Tg of the prepared perfluoroether rubber reaches -45°C. However, the addition of carbon black affects the cleanliness of the seal, limiting its application in semiconductor processes.

[0006] Based on this, a new technical solution is needed. Summary of the invention

[0007] In view of this, the present specification provides a method for preparing a perfluoroether elastomer by mixing and grafting, which can improve the low-temperature resistance of the elastomer without adding carbon black, thereby improving the cleanliness of the elastomer.

[0008] This specification provides the following technical solution: a method for preparing a perfluoroether elastomer by mixing and grafting, comprising:

[0009] S1. Emulsion polymerize 10-20 parts of perfluoroalkoxyalkyl vinyl ether, 22-59 parts of tetrafluoroethylene, 30-55 parts of perfluoroalkyl vinyl ether and 1-2 parts of bromine- or iodine-containing vulcanization point monomers by weight to obtain a perfluoroether elastomer emulsion, and obtain a perfluoroether elastomer powder after coagulation, washing, drying, devolatilization, end group retention or passivation;

[0010] S2, mixing perfluoroether elastomer powder with 1-15 parts of liquid rubber containing active end groups and 1-7 parts of acid absorbent at 60-90° C. for solid-liquid phase reaction grafting, and then adding 5-20 parts of PTFE powder and continuing to mix to obtain a mixed rubber;

[0011] S3, adding the mixed rubber to the acid absorbent and mixing, and then forming by molding and performing secondary vulcanization to obtain a low-temperature resistant perfluoroether elastomer composition.

[0012] Optionally, the PTFE micropowder contains 80-99 wt% tetrafluoroethylene and 1-20 wt% perfluoroalkyl vinyl ether.

[0013] Optionally, in S2, the liquid rubber containing active end groups is a linear perfluoropolyether.

[0014] Optionally, in S2, the active end group of the liquid rubber is a carboxyl group -COOH or a hydroxymethyl group -CH 2 OH.

[0015] Optionally, in S2, the perfluoroether elastomer is a continuous phase, and the PTFE micropowder is a dispersed phase.

[0016] Optionally, the perfluoroalkoxyalkyl vinyl ether comprises CF 3 OCF 2 OCF 2 CF 2 OCF=CF 2 , C.F. 3 CF 2 CF 2 (OCF 2 CF 2 CF 2 ) 3 OCF=CF 2 , C.F. 3 CF2 OCF 2 OCF=CF 2 , C.F. 3 (OCF 2 CF 2 CF 2 ) 4 OCF=CF 2 One or more of .

[0017] Optionally, the perfluoroalkyl vinyl ether includes one or more of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether and perfluoropropyl vinyl ether.

[0018] Optionally, the vulcanization site monomer is 4-bromo-tetrafluoro-1-butene or 4-iodo-tetrafluoro-1-butene.

[0019] Optionally, in S2, drying includes low temperature drying or vacuum drying, and after drying, liquid or supercritical CO 2 Devolatilization treatment.

[0020] Optionally, the acid absorber is MgO, CaO, ZnO, PbO or dibasic lead phosphite, and the weight of the acid absorber is 5-10wt% of the perfluoroether elastomer.

[0021] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in this specification include at least:

[0022] The present application introduces perfluoroalkoxyalkyl vinyl ether and perfluoroalkyl vinyl ether to achieve the introduction of flexible ether bonds in the side chains of fluoroelastomers to lower the glass transition temperature. The active end groups of liquid rubber are grafted with the main chains of fluoroelastomers to lower the glass transition temperature of the perfluoroether elastomer composition, further improving its low temperature resistance, mechanical strength and chemical stability against plasma etching. No carbon black needs to be added, thereby improving the cleanliness of the elastomer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of the process flow in this application. DETAILED DESCRIPTION

[0025] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0026] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0027] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspect described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0028] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0029] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the examples can be practiced without these specific details.

[0030] Based on this, the present specification proposes a method for preparing a perfluoroether elastomer by mixing and grafting: Figure 1 As shown, including,

[0031] S1. 10-20 parts by weight of perfluoroalkoxyalkyl vinyl ether, 22-59 parts of tetrafluoroethylene, 30-55 parts of perfluoroalkyl vinyl ether and 1-2 parts of bromine- or iodine-containing vulcanization point monomers are subjected to emulsion polymerization to obtain a perfluoroether elastomer emulsion, and after coagulation, washing, drying and devolatilization, end group retention or passivation, a perfluoroether elastomer powder is obtained.

[0032] The reaction temperature of emulsion polymerization is 60-100℃, and the reaction pressure is 1-3MPa. "Maintaining the end group" means maintaining the original end group unchanged without passivation; "passivation" mainly refers to the end group passivation reaction of the -COF end group of fluororubber.

[0033] S2. Mix perfluoroether elastomer powder with 1-15 parts of liquid rubber containing active end groups and 1-7 parts of acid absorbent at 60-90°C for solid-liquid phase reaction grafting, and then add 5-20 parts of PTFE powder and continue mixing to obtain a mixed rubber.

[0034] S3, adding the mixed rubber to the acid absorbent and mixing, and then forming by molding and performing secondary vulcanization to obtain a low-temperature resistant perfluoroether elastomer composition.

[0035] An acid absorber is used to react with perfluoroether elastomer powder to remove HF and form double bonds on the main chain, which then react with liquid rubber containing active end groups. At the same time, the acid absorber can also react with the end groups of the liquid rubber with active end groups to activate them and then react with the double bonds. This is solid phase reaction grafting.

[0036] The present application introduces perfluoroalkoxyalkyl vinyl ether and perfluoroalkyl vinyl ether to achieve the introduction of flexible ether bonds in the side chains of fluoroelastomers to lower the glass transition temperature. The active end groups of liquid rubber are grafted with the main chains of fluoroelastomers to lower the glass transition temperature of the perfluoroether elastomer composition, further improving its low temperature resistance, mechanical strength and chemical stability against plasma etching. No carbon black needs to be added, thereby improving the cleanliness of the elastomer.

[0037] In the embodiment of the present application, the tetrafluoroethylene content in the PTFE micropowder is 80-99wt%, and the perfluoroalkyl vinyl ether content is 1-20wt%. The perfluoroether elastomer is the continuous phase, and the PTFE micropowder is the dispersed phase. The bromine or iodine-containing vulcanization site monomer includes R 1 CH=CR 2 CR 3 , R f -I and IR f -I, where R 1 , R 2 , R 3 Selected from H, Br, F, R f or R f Br, and R 1 , R 2 , R 3 At least one of them is Br or R f Br, R f It is a perfluoroalkyl group.

[0038] In S2, the liquid rubber containing active end groups is a linear perfluoropolyether. The active end groups are carboxyl -COOH or hydroxymethyl -CH 2 OH.

[0039] The perfluoroalkoxyalkyl vinyl ether includes CF 3 OCF 2 OCF 2 CF 2 OCF=CF 2 , C.F. 3 CF 2 CF 2 (OCF 2 CF 2 CF 2 ) 3 OCF=CF 2 , C.F. 3 CF 2 OCF 2 OCF=CF 2 , C.F. 3 (OCF 2 CF 2 CF 2 ) 4 OCF=CF 2 One or more of .

[0040] The perfluoroalkyl vinyl ether includes one or more of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether and perfluoropropyl vinyl ether.

[0041] The sulfurization point monomer is 4-bromo-tetrafluoro-1-butene or 4-iodo-tetrafluoro-1-butene.

[0042] The drying includes low temperature drying or vacuum drying, and then drying with liquid or supercritical CO 2 Devolatilization treatment.

[0043] The acid absorber is MgO, CaO, ZnO, PbO, dibasic lead phosphite, and the weight of the acid absorber is 5-10wt% of the perfluoroether elastomer. The acid absorber can effectively promote the mixing grafting reaction. The grafting reaction includes acylation reaction, etherification reaction and esterification reaction.

[0044] In the present application, the specific processes of emulsion polymerization, mixing and thinning, compression molding, secondary vulcanization and the added vulcanizing agent and co-vulcanizing agent are conventional processes in the industry.

[0045] Example 1

[0046] S1, 11.5g CF 3 OCF 2 OCF 2 CF2 OCF=CF 2 (Cas No 39654-39-2), 42g tetrafluoroethylene

[0047] Ethylene, 45g perfluoromethyl vinyl ether and 1.5g 4-bromo-tetrafluoro-1-butene monomer are subjected to emulsion polymerization to obtain a perfluoroether elastomer emulsion; the perfluoroether elastomer emulsion is condensed, washed and vacuum dried, and supercritical CO is used to 2 Devolatilization is performed to obtain perfluoroether elastomer powder.

[0048] S2. At 60°C, mix the perfluoroether elastomer powder with 8g of liquid rubber FamlbinZ Diac (HOOCCF 2 O(CF 2 CF 2 O) m (CF 2 O) n COOH, molecular weight about 2000) and 5g acid absorber ZnO were mixed for solid-liquid phase reaction grafting, and then 13g PTFE powder was added and continued to be mixed to obtain a mixed rubber. The tetrafluoroethylene content in the PTFE powder was 94.5wt%, and the perfluoropropyl vinyl ether content was 5.5wt%.

[0049] S3. Add 3g MgO to mix the modified perfluoroether elastomer to obtain a rubber mix, and perform secondary vulcanization on the rubber mix to obtain a low-temperature resistant perfluoroether elastomer composition.

[0050] Example 2

[0051] S1, 11.5g CF 3 OCF 2 OCF 2 CF 2 OCF=CF 2 (Cas No 39654-39-2), 42g tetrafluoroethylene

[0052] Ethylene, 45g perfluoromethyl vinyl ether and 1.5g 4-bromo-tetrafluoro-1-butene monomer are subjected to emulsion polymerization to obtain a perfluoroether elastomer emulsion; the perfluoroether elastomer emulsion is condensed, washed and vacuum dried, and supercritical CO is used to 2 Devolatilization, using 40wt% (N 2 As the balance gas) NH 3 After passivation, perfluoroether elastomer powder is obtained.

[0053] S2. At 70°C, mix the perfluoroether elastomer powder with 8g of liquid rubber FamlbinZ Diac (HOOCCF 2 O(CF 2CF 2 O) m (CF 2 O) n COOH, molecular weight about 2000) and 5g acid absorber ZnO were mixed for solid-liquid phase reaction grafting, and then 18g PTFE powder was added and continued to be mixed to obtain a mixed rubber. The PTFE powder contained 94.5wt% tetrafluoroethylene and 5.5wt% perfluoropropyl vinyl ether.

[0054] S3. Add 7 g ZnO to mix the modified perfluoroether elastomer to obtain a rubber mix, and perform secondary vulcanization on the rubber mix to obtain a low-temperature resistant perfluoroether elastomer composition.

[0055] Example 3

[0056] S1, 18.5g CF 3 OCF 2 OCF 2 CF 2 OCF=CF 2 (Cas No 39654-39-2), 15.7g tetra

[0057] Emulsion polymerization of vinyl fluoride, 48 g of perfluoromethyl vinyl ether and 1.8 g of 4-bromo-tetrafluoro-1-butene monomer was performed to obtain a perfluoroether elastomer emulsion; the perfluoroether elastomer emulsion was condensed, washed and vacuum dried, and supercritical CO was used to 2 Devolatilization, using 40wt% (N 2 As the balance gas) NH 3 After passivation, perfluoroether elastomer powder is obtained.

[0058] S2, at 80 ° C, the perfluoroether elastomer powder was mixed with 8g of liquid rubber Famlbin Z Diac (HOOCCF) containing active end groups. 2 O(CF 2 CF 2 O) m (CF 2 O) n COOH, molecular weight about 2000) and 5g acid absorber ZnO were mixed for solid-liquid phase reaction grafting, and then 7g PTFE powder was added and continued to be mixed to obtain a mixed rubber. The PTFE powder contained 91.5wt% tetrafluoroethylene and 8.5wt% perfluoropropyl vinyl ether.

[0059] S3. Add 3g MgO to mix the modified perfluoroether elastomer to obtain a rubber mix, and perform secondary vulcanization on the rubber mix to obtain a low-temperature resistant perfluoroether elastomer composition.

[0060] Example 4

[0061] S1, 14.5g CF 3 CF 2 OCF 2 OCF=CF 2 (Cas No 346662-93-9), 15.7 g tetrafluoroethylene

[0062] The perfluoroether elastomer emulsion was obtained by emulsion polymerization of 48g perfluoromethyl vinyl ether and 1.8g 4-bromo-tetrafluoro-1-butene monomer; the perfluoroether elastomer emulsion was condensed, washed and vacuum dried, and supercritical CO 2 Devolatilization is performed to obtain perfluoroether elastomer powder.

[0063] S2, at 80 ° C, the perfluoroether elastomer powder was mixed with 8g of liquid rubber Famlbin Z Dol (HOCH 2 CF 2 O(CF 2 CF 2 O) m (CF 2 O) n CF 2 CH 2 OH, molecular weight about 2000) and 5g of acid absorbent MgO were mixed for solid-liquid phase reaction grafting, and then 18g of PTFE powder was added for continuous mixing to obtain a mixed rubber. The content of tetrafluoroethylene in the PTFE powder was 81.5wt%, and the content of perfluoropropyl vinyl ether was 18.5wt%.

[0064] S3. Add 4 g MgO to mix the modified perfluoroether elastomer to obtain a rubber mix, and perform secondary vulcanization on the rubber mix to obtain a low-temperature resistant perfluoroether elastomer composition.

[0065] Example 5

[0066] S1, 53.6gCF 3 CF 2 OCF 2 OCF=CF 2 (Cas No 346662-93-9), 15.9 g tetrafluoroethylene

[0067] The perfluoroether elastomer emulsion was obtained by emulsion polymerization of 1.0 g 4-bromo-tetrafluoro-1-butene, 30.5 g perfluoropropyl vinyl ether and 1.0 g 4-bromo-tetrafluoro-1-butene monomer; the perfluoroether elastomer emulsion was condensed, washed and vacuum dried, and supercritical CO 2 Devolatilization is performed to obtain perfluoroether elastomer powder.

[0068] S2, at 80 ° C, the perfluoroether elastomer powder was mixed with 8g of liquid rubber Famlbin Z Dol (HOCH 2 CF 2 O(CF 2 CF 2 O) m (CF 2 O) n CF 2 CH 2 OH, molecular weight about 2000) and 5g of acid absorbent MgO were mixed for solid-liquid phase reaction grafting, and then 10g of PTFE powder was added to continue mixing and thinning to obtain a mixed rubber. The tetrafluoroethylene content in the PTFE emulsion was 94.5wt%, and the perfluoropropyl vinyl ether content was 5.5wt%.

[0069] S3. Add 7g MgO to mix the modified perfluoroether elastomer to obtain a rubber mix, and perform secondary vulcanization on the rubber mix to obtain a low-temperature resistant perfluoroether elastomer composition.

[0070] Comparative Example 1

[0071] 60g of tetrafluoroethylene and 40g of perfluoromethyl vinyl ether were mixed for emulsion polymerization. During the reaction, 1.8g of a vulcanization point monomer, 4-bromo-tetrafluoro-1-butene monomer, was added until the reaction was completed to obtain a perfluoroether elastomer emulsion.

[0072] The perfluoroether elastic emulsion is precipitated and separated, washed, dried, thinned, mixed, molded and secondary vulcanized to obtain a fluorine-containing elastomer composition.

[0073] Comparative Example 2

[0074] S1, 29.05g CF 3 CF 2 OCF 2 OCF=CF 2 (Cas No 346662-93-9), 14.15g tetrafluoroethylene

[0075] Ethylene, 54.8 g perfluoroethyl vinyl ether and 2 g 4-bromo-tetrafluoro-1-butene vulcanization point monomer are subjected to emulsion polymerization to obtain a perfluoroether elastomer emulsion; the perfluoroether elastomer emulsion is condensed, washed and vacuum dried, and supercritical CO is used to 2 Devolatilization is performed to obtain perfluoroether elastomer powder.

[0076] S2, the perfluoroether elastomer powder and 18g PTFE powder are continuously mixed and kneaded to obtain a mixed rubber. The tetrafluoroethylene content in the PTFE emulsion is 98.0wt%, and the perfluoropropyl vinyl ether content is 2.0wt%.

[0077] S3. Add 4 g MgO to thin-pass and mix the modified perfluoroether elastomer to obtain a rubber compound, and perform compression molding and secondary vulcanization on the rubber compound to obtain a low-temperature resistant perfluoroether elastomer composition.

[0078] Comparative Example 3

[0079] S1, 11.5g CF 3 OCF 2 OCF 2 CF 2 OCF=CF 2 (Cas No 39654-39-2), 42g tetrafluoroethylene

[0080] Ethylene, 45g perfluoromethyl vinyl ether and 1.5g 4-bromo-tetrafluoro-1-butene monomer are subjected to emulsion polymerization to obtain a perfluoroether elastomer emulsion; the perfluoroether elastomer emulsion is condensed, washed and vacuum dried, and supercritical CO is used to 2 Devolatilization is performed to obtain perfluoroether elastomer powder.

[0081] S2. At 60°C, mix the perfluoroether elastomer powder with 8g of liquid rubber FamlbinZ Diac (HOOCCF 2 O(CF 2 CF 2 O) m (CF 2 O) n COOH, molecular weight about 2000) and 5g of acid absorber ZnO were mixed for solid-liquid phase reaction grafting, and then 15g of carbon black N990 was added and mixed to obtain a mixed rubber.

[0082] S3. Add 3g MgO to mix the modified perfluoroether elastomer to obtain a rubber mix, and perform secondary vulcanization on the rubber mix to obtain a low-temperature resistant perfluoroether elastomer composition.

[0083] Table 1 Main test results of the examples and comparative examples of this application

[0084]

[0085]

[0086] *Q / SMS 001-2024: Test method for plasma etching resistance of perfluoroether rubber seals.

[0087] The weight loss of the fluorosilicone rubber of Comparative Example 1-2 during plasma etching resistance is 1.52%, which is greater than 1.02-1.2% of Examples 1-5 of the present application.

[0088] The plasma etching conditions are: 13.56 MHz, O2 flow rate 50 sccm, pressure 500 mt, and power 800 w.

[0089] From the comparison between Examples 1-5 and Comparative Examples 1-3, it can be seen that the present application introduces perfluoroalkoxyalkyl vinyl ether and perfluoroalkyl vinyl ether, introduces flexible ether bonds into the side chains of fluoroelastomers to lower the glass transition temperature, and at the same time, reactively grafts flexible blocks onto the surface of fluoroelastomer micropowders to lower the glass transition temperature of the perfluoroether elastomer composition and improve its low temperature resistance. The obtained perfluoroether elastomer composition has a temperature adaptability range of -45-200°C, thereby improving the low temperature resistance, mechanical strength and chemical stability of the perfluoroether elastomer composition against plasma etching.

[0090] The low temperature resistance of Comparative Example 3 is very good, but the cleanliness is poor due to the addition of carbon black.

[0091] In this specification, the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiments described later, the description is relatively simple, and the relevant parts can be referred to the partial description of the previous embodiments.

[0092] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for preparing a perfluoroether elastomer by mixing and grafting, characterized in that: include, S1. Emulsion polymerize 10-20 parts of perfluoroalkoxyalkyl vinyl ether, 22-59 parts of tetrafluoroethylene, 30-55 parts of perfluoroalkyl vinyl ether and 1-2 parts of bromine- or iodine-containing vulcanization point monomers by weight to obtain a perfluoroether elastomer emulsion, and obtain a perfluoroether elastomer powder after coagulation, washing, drying, devolatilization, end group retention or passivation; S2, mixing perfluoroether elastomer powder with 1-15 parts of liquid rubber containing active end groups and 1-7 parts of acid absorbent at 60-90° C. for solid-liquid phase reaction grafting, and then adding 5-20 parts of PTFE powder and continuing to mix to obtain a mixed rubber, wherein the liquid rubber containing active end groups is a linear perfluoropolyether; S3, adding the mixed rubber to the acid absorbent, mixing and thinning, molding, and secondary vulcanization to obtain a low-temperature resistant perfluoroether elastomer composition.

2. The method for preparing a perfluoroether elastomer by mixing and grafting according to claim 1, characterized in that: The PTFE micropowder contains 80-99 wt% tetrafluoroethylene and 1-20 wt% perfluoroalkyl vinyl ether.

3. The method for preparing a perfluoroether elastomer by mixing and grafting according to claim 1, characterized in that: In S2, the active end group of the liquid rubber is a carboxyl group -COOH or a hydroxymethyl group -CH2OH.

4. The method for preparing a perfluoroether elastomer by mixing and grafting according to claim 1, characterized in that: In S2, the perfluoroether elastomer is a continuous phase, and the PTFE powder is a dispersed phase.

5. The method for preparing a perfluoroether elastomer by mixing and grafting according to claim 1, characterized in that: The perfluoroalkoxyalkyl vinyl ether includes one or more of CF3OCF2OCF2CF2OCF=CF2, CF3CF2CF2(OCF2CF2CF2)3OCF=CF2, CF3CF2OCF2OCF=CF2, and CF3(OCF2CF2CF2)4OCF=CF2.

6. The method for preparing a perfluoroether elastomer by mixing and grafting according to claim 1, characterized in that: The perfluoroalkyl vinyl ether includes one or more of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether and perfluoropropyl vinyl ether.

7. The method for preparing a perfluoroether elastomer by mixing and grafting according to claim 1, characterized in that: The sulfurization point monomer is 4-bromo-tetrafluoro-1-butene or 4-iodo-tetrafluoro-1-butene.

8. The method for preparing a perfluoroether elastomer by mixing and grafting according to claim 1, characterized in that: In S2, drying includes low temperature drying or vacuum drying, and after drying, liquid or supercritical CO2 devolatilization treatment is used.

9. The method for preparing a perfluoroether elastomer by mixing and grafting according to claim 1, characterized in that: The acid absorber is MgO, CaO, ZnO, PbO or dibasic lead phosphite, and the weight of the acid absorber is 5-10wt% of the perfluoroether elastomer.

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