Perfluoroether fluororubber as well as preparation method and application thereof

Abstract

The invention provides perfluoroether fluororubber as well as a preparation method and application thereof. The perfluoroether fluororubber is in an A-B-A block form; the A block is formed by polymerizing tetrafluoroethylene and perfluoropropyl vinyl ether, and the molar ratio of the tetrafluoroethylene to the perfluoropropyl vinyl ether is (65 to 80): (20 to 35); the block B is formed by polymerizing tetrafluoroethylene and perfluoromethyl vinyl ether, and the molar ratio of the tetrafluoroethylene to the perfluoromethyl vinyl ether is (35-55): (65-45); and the mass fraction of the block B in the perfluoroether fluororubber is 50%-80%. The perfluoroether fluororubber has excellent high temperature resistance, can resist the high temperature of 320 DEG C, has excellent elongation, and is low in hardness, small in compression deformation and good in medium resistance and processability.

Description

Technical Field

[0001] The invention relates to the technical field of rubber materials, and in particular to a perfluoroether fluororubber and a preparation method and application thereof. Background Art

[0002] Perfluoroether fluororubber mainly uses tetrafluoroethylene (TFE) and perfluoroalkyl vinyl ether (PAVE) as the main copolymer monomers, and usually also contains perfluorosulfurization monomers such as bromine, iodine, and cyanide compounds. The vulcanized perfluoroether fluororubber has excellent high temperature resistance and medium resistance. It is favored by industries such as petrochemicals and semiconductor industries. The Tg of general perfluoroether rubber is about -8℃~0℃. However, the high temperature resistance of the currently prepared perfluoroether fluororubber is not good, or the polymerization time in the preparation process is too long, which is not conducive to industrial production. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the prior art at least to a certain extent. To this end, one object of the present invention is to provide a perfluoroether fluororubber and a preparation method and application thereof.

[0004] In one aspect of the present invention, the present invention provides a perfluoroether fluororubber. According to an embodiment of the present invention, the perfluoroether fluororubber is in an ABA block form; The A block is polymerized from tetrafluoroethylene and perfluoropropyl vinyl ether (PPVE), wherein the molar ratio of the tetrafluoroethylene to the perfluoropropyl vinyl ether is (65-80): (20-35); The B block is polymerized from tetrafluoroethylene and perfluoromethyl vinyl ether, wherein the molar ratio of the tetrafluoroethylene to the perfluoromethyl vinyl ether (PMVE) is (35-55): (65-45); The mass fraction of the B block in the perfluoroether fluororubber is 50% to 80%.

[0005] According to the perfluoroether fluororubber of the above embodiment of the present invention, the high temperature resistance of the perfluoroether fluororubber can be significantly improved by selecting the monomers of the A block and the B block, optimizing the molar ratio of each monomer in the A block and the B block, and optimizing the mass fraction of the A block and the B block. Specifically, the perfluoroether fluororubber can withstand a high temperature of 320°C, has excellent elongation, and has a low hardness, a small compression deformation, and good medium resistance and processing performance.

[0006] In some embodiments of the present invention, the mass fractions of the two A blocks in the perfluoroether fluororubber ABA block are independently 10% to 25%. The inventors have found that the high temperature resistance of the perfluoroether fluororubber can be improved by controlling the mass fractions of the two A blocks in the perfluoroether fluororubber ABA block to be independently within the above range.

[0007] In some embodiments of the present invention, the A block is grafted with a vulcanization point monomer. By grafting a vulcanization point monomer on the A block, the high temperature resistance of the perfluoroether fluororubber can be improved.

[0008] In some embodiments of the present invention, the B block is grafted with a vulcanization point monomer. By grafting a vulcanization point monomer on the B block, the high temperature resistance of the perfluoroether fluororubber can be improved.

[0009] In some embodiments of the present invention, the mass of the vulcanization point monomer grafted to the A block accounts for 8‰ to 20‰ of the mass of the A block. By controlling the mass proportion of the vulcanization point monomer grafted to the A block within the above range, the high temperature resistance of the perfluoroether fluororubber can be improved.

[0010] In some embodiments of the present invention, the mass of the vulcanization point monomer grafted to the B block accounts for 5‰ to 12‰ of the mass of the B block. By controlling the mass proportion of the vulcanization point monomer grafted to the B block within the above range, the high temperature resistance of the perfluoroether fluororubber can be improved.

[0011] In some embodiments of the present invention, the vulcanization site monomer includes a cyano-containing compound vulcanization site monomer. A cyano-containing compound vulcanization site monomer is selected and introduced into a polymer so that the perfluoroether fluororubber can be cross-linked and vulcanized using a triazine vulcanization system. The vulcanization site monomer is a perfluoroether cyano-containing vulcanization site monomer, which is beneficial to improving the processing performance of the high-temperature resistant perfluoroether fluororubber to a certain extent.

[0012] In some embodiments of the present invention, the cyano compound sulfurization site monomer includes CF2=CFO(CF2) n CF(CF3)OCF2CF2CN, n=1, 2 or 3; CF2=CFO(CF2)CF(CF3) n OCF2CF2CN, n=1, 2 or 3; CF2=CFO(CF2)CF(CF3)O(CF2) n CN, n=1, 2, 3, 4 or 5, one of them.

[0013] In a second aspect of the present invention, the present invention provides a method for preparing the above-mentioned perfluoroether fluororubber. According to an embodiment of the present invention, the method comprises: (1) Tetrafluoroethylene and perfluoropropyl vinyl ether are subjected to a first polymerization reaction in water to obtain an A block polymer.

[0014] In some embodiments of the present invention, the temperature of the first polymerization reaction is 60°C to 105°C, and the pressure is 2.8MPa to 3.5MPa. The inventors have found that when the temperature and pressure of the first polymerization reaction are controlled within the above range, tetrafluoroethylene and perfluoropropyl vinyl ether can be effectively distributed alternately on the polymer chain segments, so that the polymer has both good processing flexibility and good heat resistance.

[0015] In some embodiments of the present invention, a vulcanization site monomer is also added to the water. Specifically, tetrafluoroethylene, perfluoropropyl vinyl ether and the vulcanization site monomer undergo a first polymerization reaction in water to obtain an A block polymer grafted with the vulcanization site monomer.

[0016] In some embodiments of the present invention, an emulsifier, an initiator and a chain transfer agent are further added to water before the first polymerization reaction is carried out.

[0017] In some embodiments of the present invention, the mass ratio of the emulsifier to the water is (0.01~5):100.

[0018] In some embodiments of the present invention, the emulsifier includes at least one of perfluorooctanoic acid ammonium salt, perfluorooctanoic acid sodium salt and perfluorooctanoic acid potassium salt.

[0019] In some embodiments of the present invention, the mass ratio of the initiator to the water is (0.01-8):100.

[0020] In some embodiments of the present invention, the initiator includes at least one of ammonium persulfate, potassium persulfate and potassium permanganate.

[0021] In some embodiments of the present invention, the ratio of the mass of the chain transfer agent to the total mass of the monomers of the A block and the B block is (0.01-5):100.

[0022] In some embodiments of the present invention, the chain transfer agent includes at least one of 1,2-diiodoperfluoroethane, 1,3-diiodoperfluoropropane and 1,4-diiodoperfluorobutane.

[0023] (2) Tetrafluoroethylene and perfluoromethyl vinyl ether are added to the reaction system of step (1) to undergo a second polymerization reaction to obtain an AB block polymer.

[0024] In some embodiments of the present invention, the temperature of the second polymerization reaction is 70°C to 95°C, and the pressure is 1.6MPa to 2.5MPa. The inventors have found that by controlling the temperature and pressure of the second polymerization reaction within the above range, tetrafluoroethylene and perfluoromethyl vinyl ether can be effectively distributed alternately on the polymer chain segments, so that the polymer has both good processing flexibility and good heat resistance.

[0025] In some embodiments of the present invention, a vulcanization site monomer is added to the system after the reaction in step (1). Specifically, tetrafluoroethylene, perfluoromethyl vinyl ether and a vulcanization site monomer are added to the reaction system in step (1) to undergo a second polymerization reaction to obtain an AB block polymer grafted with a vulcanization site monomer.

[0026] (3) Tetrafluoroethylene and perfluoropropyl vinyl ether are added to the reaction system of step (2) to undergo a third polymerization reaction to obtain an ABA block polymer.

[0027] In some embodiments of the present invention, the temperature of the third polymerization reaction is 60° C. to 105° C., and the pressure is 2.8 MPa to 3.5 MPa.

[0028] In some embodiments of the present invention, a vulcanization site monomer is added to the system after the reaction in step (2). Specifically, tetrafluoroethylene, perfluoropropyl vinyl ether and a vulcanization site monomer are added to the reaction system in step (2) to cause a third polymerization reaction.

[0029] The vulcanization point monomers are grafted onto the A block and the B block in three steps, and different polymerization processes are used in each production stage, which not only makes the vulcanization point monomers evenly distributed in the A block and the B block, but also improves the production efficiency. Specifically, the preparation of the perfluoroether fluororubber can be completed within 5 to 8 hours, which significantly reduces the polymerization time, improves the production efficiency, and is conducive to industrial production. Specifically, the compression permanent deformation value of the obtained high-temperature resistant perfluoroether fluororubber is ≤45% (320℃×24h), the tensile strength is greater than 20MPa, the elongation is about 200%, the hardness is low, and the medium resistance and processing performance are good.

[0030] In the third aspect of the present invention, the present invention proposes the application of the above-mentioned perfluoroether fluororubber or the perfluoroether fluororubber prepared by the above-mentioned method in the fields of petrochemical industry and semiconductor.

[0031] The present invention has at least the following technical effects: (1) The perfluoroether fluororubber prepared by the present invention has excellent high temperature resistance and can withstand a high temperature of 320°C. It has excellent elongation, low hardness, small compression deformation, good medium resistance and processing performance.

[0032] (2) The present invention adopts a three-step segmented process to prepare perfluoroether fluororubber, so that the distribution of the vulcanization point monomer and the A block and the B block is more uniform, thereby improving the high temperature resistance and production efficiency of the perfluoroether fluororubber. Specifically, the production of the entire perfluoroether fluororubber can be completed within 6 to 8 hours, which significantly reduces the polymerization time. The compression permanent deformation value of the prepared high temperature resistant perfluoroether fluororubber is ≤45% (320°C×24h), the tensile strength is greater than 20MPa, the elongation is about 200%, the hardness is relatively low, and the medium resistance and processing performance are good. DETAILED DESCRIPTION

[0033] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0034] Example 1

[0035] Emulsion polymerization was carried out in a 50L reactor. 30L of deionized water was added to the reactor. The reactor should be evacuated, and when the oxygen content was ≤30ppm, 35g of perfluorooctanoic acid ammonia (emulsifier) ​​was added, and the contents in the reactor were heated to 95°C. The monomer ratio of the A stage in the early stage of the polymerization process: the molar ratio of TFE / PPVE was 75:25, the reactor pressure was raised to 3.2MPa, 15g of potassium persulfate (initiator), 25g of 1,2-diiodoperfluoroethane (chain transfer agent) and 38g of CF2=CFOCF2CF (CF3) OCF2CF2CN were added to start the reaction, and the polymerization reaction was carried out. When the amount of monomer added to the reaction reached 2.5kg, the addition of the reaction monomer was stopped. In the middle stage of polymerization, the molar ratio of monomers in the B stage is 45:55 for TFE / PMVE, the polymerization pressure is 2.0MPa, and 53g of high temperature resistant vulcanization point monomer CF2=CFOCF2CF (CF3) OCF2CF2CN is added; when the amount of monomer added to be reacted is 5.3kg, the addition of the reaction monomer is stopped. In the late stage of the polymerization process, the molar ratio of monomers in the A stage is 75:25 for TFE / PPVE, the pressure of the reactor is raised to 3.2MPa, and 38g of high temperature resistant vulcanization point monomer CF2=CFOCF2CF (CF3) OCF2CF2CN is added. When the amount of monomer added to be reacted is 2.5kg, the reaction is terminated, and the emulsion is discharged to the coagulation barrel, coagulated, and washed. Vacuum dried at about 100℃. The polymer produced is about 10.1Kg, and the polymerization time is about 6.5h.

[0036] The obtained high temperature resistant perfluoroether fluororubber has a Mooney viscosity of 55, a fluorine content of 73.2%, a compression set value of 38% (320℃×24h), a tensile strength of 21.5MPa, an elongation of about 210%, and a hardness of 76Ha.

[0037] Example 2

[0038] The difference between Example 2 and Example 1 is: The monomer ratio in the early stage of the polymerization process is: the molar ratio of TFE / PPVE is 65:35.

[0039] In the middle stage of polymerization, the B-stage monomer ratio is added: TFE / PMVE molar ratio is 35:45,

[0040] The monomer ratio in stage A of the late polymerization process: the molar ratio of TFE / PPVE is 65:35.

[0041] The obtained high temperature resistant perfluoroether fluororubber has a Mooney viscosity of 62, a fluorine content of 73.3%, a compression set value of 32% (320℃×24h), a tensile strength of 23.5MPa, an elongation of about 220%, and a hardness of 74Ha.

[0042] Example 3

[0043] The monomer ratio in the early stage of the polymerization process is: the molar ratio of TFE / PPVE is 80:20.

[0044] In the middle stage of polymerization, the B-stage monomer ratio is added: TFE / PMVE molar ratio is 55:65,

[0045] The monomer ratio in stage A of the late polymerization process: the molar ratio of TFE / PPVE is 80:20.

[0046] The obtained high temperature resistant perfluoroether fluororubber has a Mooney viscosity of 67, a fluorine content of 73.5%, a compression set value of 35% (320°C×24h), a tensile strength of 23.2MPa, an elongation of about 200%, and a hardness of 77Ha.

[0047] Example 4

[0048] The difference between Example 4 and Example 1 is: In the early stage A of the polymerization process, when the amount of monomer added to be reacted reaches 2 kg, stop adding the monomer; In the middle stage of polymerization, when the amount of monomer added reaches 6.2 kg, stop adding the monomer; In the late stage A of the polymerization process, when the amount of monomer added reaches 2 kg, the addition of monomer is stopped.

[0049] The obtained high temperature resistant perfluoroether fluororubber has a Mooney viscosity of 52, a fluorine content of 73.0%, a compression set value of 39% (320°C×24h), a tensile strength of 20.5MPa, an elongation of about 230%, and a hardness of 72Ha.

[0050] Example 5

[0051] The difference between Example 5 and Example 1 is: In the early stage A of the polymerization process, when the amount of monomer added to be reacted reaches 1.2 kg, the addition of the monomer to be reacted is stopped; In the middle stage of polymerization, when the amount of monomer added reaches 7.8 kg, stop adding the monomer; In the late stage A of the polymerization process, when the amount of monomer added to be reacted reaches 1.2 kg, the addition of the monomer is stopped.

[0052] The obtained high temperature resistant perfluoroether fluororubber has a Mooney viscosity of 48, a fluorine content of 73.5%, a compression set value of 28% (320°C×24h), a tensile strength of 20.8MPa, an elongation of about 230%, and a hardness of 73Ha.

[0053] Comparative Example 1

[0054] The difference between Comparative Example 1 and Example 1 is: In the early stage of the polymerization process, the monomers in stage A are TFE and PMVE, and PMVE is used to replace PPVE.

[0055] In the later stage of the polymerization process, the monomers in stage A are TFE and PMVE, and PMVE is used to replace PPVE.

[0056] Results: High temperature resistant perfluoroether fluororubber was obtained with Mooney viscosity of 68, fluorine content of 73.3%, compression set of 67% (320℃×24h), tensile strength of 16.2MPa, elongation of about 270%, and hardness of 73Ha.

[0057] Comparative Example 2

[0058] The difference between Comparative Example 2 and Example 1 is: In the middle stage of polymerization, the monomers added in the B stage are TFE and PPVE, and PMVE is replaced by PPVE.

[0059] Results: High temperature resistant perfluoroether fluororubber was obtained with Mooney viscosity of 78, fluorine content of 73.4%, compression set of 48% (320℃×24h), tensile strength of 14.5MPa, elongation of about 200%, and hardness of 82Ha.

[0060] Comparative Example 3

[0061] The difference between Comparative Example 3 and Example 1 is: The monomer ratio in the early stage of the polymerization process is: the molar ratio of TFE / PPVE is 60:40.

[0062] In the middle stage of polymerization, the monomer ratio of stage B is added: TFE / PMVE molar ratio is 60:40,

[0063] The monomer ratio in stage A of the late polymerization process: the molar ratio of TFE / PPVE is 60:40.

[0064] The obtained high temperature resistant perfluoroether fluororubber has a Mooney viscosity of 85, a fluorine content of 73.6%, a compression set value of 47% (320°C×24h), a tensile strength of 15.3MPa, an elongation of about 170%, and a hardness of 85Ha.

[0065] Comparative Example 4

[0066] The difference between Comparative Example 4 and Example 1 is: In the early stage A of the polymerization process, when the amount of monomer added to be reacted reaches 0.5 kg, stop adding the monomer; In the middle stage of polymerization, when the amount of monomer added reaches 9.2 kg, stop adding the monomer; In the late stage A of the polymerization process, when the amount of monomer added reaches 0.5 kg, the addition of monomer is stopped.

[0067] The obtained high temperature resistant perfluoroether fluororubber has a Mooney viscosity of 56, a fluorine content of 73.2%, a compression set value of 57% (320°C×24h), a tensile strength of 22.0MPa, an elongation of about 180%, and a hardness of 76Ha.

[0068] Comparative Example 5

[0069] The difference between Comparative Example 5 and Example 1 is: In the early stage A of the polymerization process, when the amount of monomer added to be reacted reaches 3 kg, stop adding the monomer; In the middle stage of polymerization, when the amount of monomer added reaches 4.2 kg, stop adding the monomer; In the late stage A of the polymerization process, when the amount of monomer added reaches 3 kg, the addition of monomer is stopped.

[0070] The obtained high temperature resistant perfluoroether fluororubber has a Mooney viscosity of 74, a fluorine content of 73.2%, a compression set value of 61% (320°C×24h), a tensile strength of 19.6MPa, an elongation of about 160%, and a hardness of 82Ha.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A perfluoroether fluororubber, characterized in that: The perfluoroether fluororubber is in the form of ABA blocks; The A block is polymerized from tetrafluoroethylene and perfluoropropyl vinyl ether, wherein the molar ratio of the tetrafluoroethylene to the perfluoropropyl vinyl ether is (65-80): (20-35); The B block is polymerized from tetrafluoroethylene and perfluoromethyl vinyl ether, wherein the molar ratio of the tetrafluoroethylene to the perfluoromethyl vinyl ether is (35-55): (65-45); The mass fraction of the B block in the perfluoroether fluororubber is 50% to 80%.

2. The perfluoroether fluororubber according to claim 1, characterized in that: The mass fractions of the two A blocks in the perfluoroether fluororubber ABA block are independently 10% to 25%.

3. The perfluoroether fluororubber according to claim 1 or 2, characterized in that: The A block is grafted with a vulcanization site monomer; And / or, the B block is grafted with a vulcanization site monomer.

4. The perfluoroether fluororubber according to claim 3, characterized in that: The mass of the vulcanization point monomer grafted to the A block accounts for 8‰ to 20‰ of the mass of the A block; and / or, the mass of the vulcanization site monomer grafted to the B block accounts for 5‰ to 12‰ of the mass of the B block; And / or, the vulcanization site monomer includes a cyano compound vulcanization site monomer.

5. The perfluoroether fluororubber according to claim 4, characterized in that: The cyano compound sulfurization point monomer includes CF2=CFO(CF2) n CF(CF3)OCF2CF2CN, n=1, 2 or 3; CF2=CFO(CF2)CF(CF3) n OCF2CF2CN, n=1, 2 or 3; CF2=CFO(CF2)CF(CF3)O(CF2) n CN, n=1, 2, 3, 4 or 5, at least one of them.

6. A method for preparing the perfluoroether fluororubber according to any one of claims 1 to 5, characterized in that: include: (1) subjecting tetrafluoroethylene and perfluoropropyl vinyl ether to a first polymerization reaction in water to obtain an A block polymer; (2) adding tetrafluoroethylene and perfluoromethyl vinyl ether to the reaction system of step (1) to undergo a second polymerization reaction to obtain an AB block polymer; (3) Tetrafluoroethylene and perfluoropropyl vinyl ether are added to the reaction system of step (2) to undergo a third polymerization reaction to obtain an ABA block polymer.

7. The method according to claim 6, characterized in that The temperature of the first polymerization reaction and the third polymerization reaction are independently 60° C. to 105° C., and the pressure is independently 2.8 MPa to 3.5 MPa; And / or, the temperature of the second polymerization reaction is 70° C. to 95° C., and the pressure is 1.6 MPa to 2.5 MPa.

8. The method according to claim 6 or 7, characterized in that: In step (1), a sulfide monomer is also added to the water; And / or, in step (1), at least one of an emulsifier, an initiator and a chain transfer agent is further added to the water; And / or, in step (2), adding a sulfurization site monomer to the system after the reaction in step (1); And / or, in step (3), a sulfide site monomer is added to the system after the reaction in step (2).

9. The method according to claim 8, characterized in that The mass ratio of the emulsifier to the water is (0.01-5):100; And / or, the emulsifier includes at least one of perfluorooctanoic acid ammonium salt, perfluorooctanoic acid sodium salt and perfluorooctanoic acid potassium salt; And / or, the mass ratio of the initiator to the water is (0.01-8):100; and / or, the initiator comprises at least one of ammonium persulfate, potassium persulfate and potassium permanganate; and / or, the ratio of the mass of the chain transfer agent to the total mass of the monomers of the A block and the B block is (0.01-5):100; And / or, the chain transfer agent includes at least one of 1,2-diiodoperfluoroethane, 1,3-diiodoperfluoropropane and 1,4-diiodoperfluorobutane.

10. Use of the perfluoroether fluororubber according to any one of claims 1 to 5 or the perfluoroether fluororubber prepared by the method according to any one of claims 6 to 9 in the fields of petrochemical industry and semiconductor.