Modified fluororubber, method for producing the same, and semiconductor sealing assembly

Abstract

The present application relates to the technical field of rubber sealing material, and particularly relates to a modified fluorine rubber, a preparation method thereof and a semiconductor sealing assembly. The preparation method provided by the present application comprises the following steps: mixing vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, long-chain modified flexible monomers and vulcanization point monomers in a predetermined proportion to obtain mixed monomers; mixing the mixed monomers, a solvent and a fluorine-containing surfactant, and then performing first stirring treatment to obtain a monomer pre-emulsion; mixing the monomer pre-emulsion, an additive and the solvent, and then performing second stirring treatment to obtain a product to be treated; placing the product to be treated at a first temperature, heating to a second temperature under predetermined conditions, and then performing reaction to obtain a reaction product; recovering the mixed monomers that do not participate in the reaction in the reaction product, adding a magnesium nitrate aqueous solution, performing third stirring treatment, and then drying to obtain the modified fluorine rubber. Under the premise of maintaining the excellent chemical resistance of the fluorine rubber, the present application significantly improves the elastic recovery performance of the fluorine rubber in a wide temperature range.

Description

Technical Field

[0001] This invention relates to the field of rubber sealing materials technology, and in particular to a modified fluororubber, its preparation method, and a semiconductor sealing component. Background Technology

[0002] Fluororubber (FKM) is a core material for sealing components in semiconductor manufacturing processes due to its excellent chemical resistance, high-temperature resistance, and processability. Semiconductor manufacturing involves contact with highly corrosive gases and plasma, requiring sealing materials to maintain elasticity under extreme conditions for extended periods, with low particle release and low compression set. To address the insufficient elastic recovery of existing fluororubber under wide temperature range conditions, current technologies attempt to modify it by introducing long-chain flexible monomers. A common method involves mixing vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, and a small amount of long-chain modifying monomers according to a formulation ratio, followed by intermittent, single-feed emulsion polymerization. However, the large steric hindrance of the modified monomers results in rigid molecular chain segments, a high glass transition temperature, and insufficient elastic recovery under wide temperature range cycling conditions. Summary of the Invention

[0003] In order to significantly improve the elastic recovery performance of fluororubber over a wide temperature range while maintaining its excellent chemical resistance, this invention provides a modified fluororubber, its preparation method, and a semiconductor sealing component.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing modified fluororubber, wherein the method for preparing modified fluororubber includes the following steps: The raw materials are provided as vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomers and sulfurization point monomers, and the raw materials are mixed to obtain mixed monomers; Solvents and fluorinated surfactants are provided. After mixing the mixed monomers, solvents and fluorinated surfactants, a first stirring treatment is performed to obtain a monomer preemulsion. An additive is provided, and the monomer preemulsion, additive and solvent are mixed and then subjected to a second stirring treatment to obtain the product to be treated; The product to be processed is placed at a first temperature and heated to a second temperature to react and obtain the reaction product; A magnesium nitrate aqueous solution is provided. After recovering the unreacted mixed monomers from the reaction product, the magnesium nitrate aqueous solution is added back in, and the mixture is stirred a third time before drying to obtain modified fluororubber.

[0005] Preferably, mixing raw materials to obtain a mixed monomer includes: The molar ratio of vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomer and sulfur point monomer provided is (40-60):(15-30):(5-20):(0.1-2).

[0006] Preferably, the process of mixing raw materials to obtain a mixed monomer further includes: providing tetrafluoroethylene, using vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomer, sulfidation point and tetrafluoroethylene as raw materials, mixing the raw materials to obtain a mixed monomer, and adding tetrafluoroethylene to the mixed raw materials.

[0007] Preferably, the long-chain modified flexible monomer is any one or a combination of two of perfluorohexyl vinyl ether and perfluorooctyl vinyl ether; the sulfidation point monomer is a bromine- or iodine-functionalized fluorinated olefin, wherein the sulfidation point monomer is any one or a combination of two of 2-bromo-1,1,2,3,3,3-hexafluoropropene and perfluoro(2-iodoethyl) vinyl ether.

[0008] Preferably, the step of mixing the monomer, solvent, and fluorinated surfactant and then performing a first stirring treatment to obtain the monomer preemulsion includes: Deionized water is used as the first solvent, and perfluoropolyether ammonium carboxylate is used as the fluorinated surfactant. The mixed monomers, deionized water and perfluoropolyether ammonium carboxylate are stirred at a speed of 400 r / min-600 r / min for 30-40 min to obtain a monomer pre-emulsion. The mass ratio of the mixed monomers, perfluoropolyether ammonium carboxylate and deionized water is 1:(5%-8%):(30%-40%).

[0009] Preferably, the second stirring process yields the following product: Additives include fluorinated surfactants, pH adjusters, perfluorodiiodoethane, and initiators; Deionized water is provided as the second solvent. The monomer preemulsion, additives and solvents are mixed and stirred at 300r / min-500r / min for 20-30min. The pH is then adjusted to 7.0-8.5 to obtain the product to be treated. The total mass of deionized water in the first and second solvents is w. The mass of the fluorinated surfactant in the additives is (0.1%-1.0%)w, the mass of the pH adjuster is (0.1%-0.2%)w, the mass of perfluorodiiodoethane is (0.05%-0.3%)w, and the mass of the initiator is (0.02%-0.1%)w.

[0010] Preferably, the product to be processed is placed at a first temperature and heated to a second temperature to react and obtain the reaction product, comprising: We provide polymerization reactor equipment to heat the reactor to 44-45℃ and maintain a reactor pressure of 1.5-2.5MPa. The product to be processed is placed in a polymerization reactor and heated to 50-55℃ at a heating rate of 1℃ / h. The copolymerization reaction is carried out under constant pressure. During the copolymerization reaction, the stirring rate is maintained at 200-300r / min until the solid content of the emulsion is 30%-40%, at which point the copolymerization reaction is terminated.

[0011] Preferably, the modified fluororubber obtained by adding unreacted mixed monomers from the recovered reaction product to a magnesium nitrate aqueous solution, followed by a third stirring treatment and drying, comprises: Unreacted monomer mixtures are volatilized into recovered gas. After recovering the gas, magnesium nitrate aqueous solution is added to the reaction product and stirred at 140-150 r / min for 10-12 min to obtain a condensate. Deionized water is provided, and the condensate is washed 4-5 times with deionized water. The washed condensate is then subjected to gradient drying to obtain fluororubber.

[0012] To solve the above-mentioned technical problems, the present invention provides another technical solution as follows: a modified fluororubber, wherein the components of the modified fluororubber, in molar amounts, include: 40-60 parts of vinylidene fluoride, 15-30 parts of hexafluoropropylene, 5-20 parts of long-chain modified flexible monomer, and 0.1-2 parts of vulcanization point monomer.

[0013] To solve the above-mentioned technical problems, the present invention provides another technical solution as follows: a semiconductor sealing assembly, wherein at least a portion of the semiconductor sealing assembly is made of the above-mentioned modified fluororubber.

[0014] To solve the above-mentioned technical problems, the present invention provides another technical solution as follows: a computer device applied to the above-mentioned method for preparing modified fluororubber, comprising a memory, a processor, and a computer program stored in the memory, wherein the processor executes the above-mentioned computer program to realize the method for preparing modified fluororubber.

[0015] To solve the above-mentioned technical problems, the present invention provides another technical solution as follows: a computer program product, comprising a computer program or instructions, wherein the computer program or instructions, when executed by a processor, implement the above-mentioned method for preparing modified fluororubber.

[0016] Compared with the prior art, the modified fluororubber and its preparation method, as well as the semiconductor sealing assembly provided by the present invention, have the following beneficial effects: 1. This invention provides a method for preparing modified fluororubber, comprising the following steps: providing vinylidene fluoride, hexafluoropropylene, a long-chain modified flexible monomer, and a vulcanization point monomer as raw materials; mixing the raw materials to obtain a mixed monomer; providing a solvent and a fluorinated surfactant; mixing the mixed monomer, solvent, and fluorinated surfactant and performing a first stirring treatment to obtain a monomer pre-emulsion; providing an additive; mixing the monomer pre-emulsion, additive, and solvent and performing a second stirring treatment to obtain a product to be treated; placing the product to be treated at a first temperature and heating it to a second temperature to react to obtain a reaction product; providing a magnesium nitrate aqueous solution; recovering the unreacted mixed monomer from the reaction product; adding the magnesium nitrate aqueous solution; performing a third stirring treatment; and drying to obtain modified fluororubber. Monomer pre-emulsification solves the problem of large differences in copolymerization reactivity between the long-chain modified flexible monomer and vinylidene fluoride, and their poor compatibility, thereby significantly improving the elastic recovery performance of fluororubber over a wide temperature range while maintaining its excellent chemical resistance.

[0017] 2. This invention also provides a modified fluororubber, wherein the components of the modified fluororubber, in molar amounts, include: 40-60 parts vinylidene fluoride, 15-30 parts hexafluoropropylene, 5-20 parts long-chain modified flexible monomer, and 0.1-2 parts vulcanization point monomer. This formulation allows each monomer to work synergistically during polymerization, ensuring both the processability and mechanical rigidity of the fluororubber, while significantly improving the flexibility of the molecular chain through the internal plasticizing effect of the long-chain perfluoroether. Simultaneously, the uniformly distributed vulcanization sites provide a structural basis for the formation of a stable cross-linked network during subsequent vulcanization, thus providing a modified fluororubber with a low glass transition temperature and low high-temperature compression set.

[0018] 3. This invention also provides a semiconductor sealing assembly, wherein at least a portion of the semiconductor sealing assembly is made of the aforementioned modified fluororubber. This solves the technical problem that existing sealing materials struggle to maintain stable sealing performance over long periods under the multiple harsh conditions involved in semiconductor manufacturing processes, such as wide-temperature cycling, exposure to highly corrosive media, and high cleanliness requirements, thus achieving an improvement in the overall service performance of the sealing assembly under extreme operating conditions. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic flowchart of a method for preparing modified fluororubber provided in the first embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the semiconductor sealing assembly provided in the third embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] In the embodiments provided by this invention, it should be understood that "B corresponding to A" means that B is associated with A, and B can be determined based on A. However, it should also be understood that determining B based on A does not mean determining B solely based on A; B can also be determined based on A and / or other information.

[0024] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also recognize that the embodiments described in the specification are optional embodiments, and the actions and modules involved are not necessarily essential to the invention.

[0025] In various embodiments of the present invention, it should be understood that the sequence number of each process does not necessarily imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0026] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. It is particularly important to note that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0027] Existing semiconductor fluororubbers are mostly binary copolymers of vinylidene fluoride (VDF) and hexafluoropropylene (HCF) or ternary copolymers of VDF, tetrafluoroethylene (TEF), and hexafluoropropylene (TEF). However, these monomers have significant steric hindrance on the -CF3 side groups and insufficient chain segment flexibility, resulting in generally high glass transition temperatures (Tg), typically in the range of -15℃ to -40℃. This makes it difficult to further improve sealing performance under temperature cycling conditions. Furthermore, the commonly used preparation process is emulsion polymerization, which involves emulsion polymerization of various monomers in an aqueous medium, followed by coagulation, washing, and drying to obtain the fluororubber elastomer. However, due to the large differences in the reactivity ratios of monomers such as VDF, HCF, and TEF, and the lack of precise control over the uniformity of the copolymer composition, there are significant batch-to-batch variations in the finished rubber compound. Therefore, there is an urgent need to develop a fluororubber with high chain segment flexibility, low glass transition temperature, and low compression set, and to find a suitable emulsion polymerization process for controlling the reactivity ratio.

[0028] Please see Figure 1 The first embodiment of the present invention provides a method for preparing modified fluororubber, the method comprising the following steps: S1. Provide vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomer and sulfurization point monomer as raw materials, and mix the raw materials to obtain mixed monomer; S2. Provide solvent and fluorinated surfactant, and after mixing the mixed monomer, solvent and fluorinated surfactant, perform a first stirring treatment to obtain monomer preemulsion; S3. Provide additives, mix monomer pre-emulsion, additives and solvent, and then perform a second stirring treatment to obtain the product to be treated; S4. The product to be processed is placed at a first temperature and heated to a second temperature to react and obtain the reaction product; S5. Provide an aqueous solution of magnesium nitrate, recover the unreacted mixed monomers from the reaction product, add the aqueous solution of magnesium nitrate, stir for a third time, and then dry to obtain modified fluororubber.

[0029] Specifically, in step S1, vinylidene fluoride (VDF), hexafluoropropylene (HFP), long-chain modified flexible monomers, and vulcanization point monomers are provided as raw materials and mixed. Long-chain modified flexible monomers have relatively long flexible side chains, which can significantly improve the flexibility of the molecular chain through internal plasticizing effects, thereby reducing the glass transition temperature of fluororubber and improving its wide-temperature-range elasticity. However, the copolymerization reactivity ratios of these long-chain modified flexible monomers and vinylidene fluoride differ significantly, and their compatibility is poor. If a direct copolymerization reaction is carried out, it is very easy to cause uneven distribution of the copolymer sequence, resulting in batch-to-batch fluctuations in key properties of the final product, such as low-temperature elasticity and high-temperature compression set. In this example, in step S2, a solvent and a fluorinated surfactant are introduced. After mixing the monomers, solvent, and fluorinated surfactant, a first stirring treatment is performed to obtain a monomer pre-emulsion. The fluorinated surfactant can reduce the interfacial tension between the monomer and the aqueous phase, allowing the oil-soluble long-chain modified flexible monomer to be dispersed into tiny micelles, uniformly suspended in the aqueous system. Through emulsification, long-chain monomers that were originally poorly compatible and prone to local enrichment are made fully compatible with the aqueous phase, effectively avoiding the shift in copolymer composition caused by uneven monomer dispersion. Further, in step S4, the product to be treated is placed at a first temperature and heated to a second temperature to obtain the reaction product. The heating process aims to simultaneously control the polymerization rate of different reactive monomers: in the initial first temperature stage, the polymerization of highly reactive vinylidene fluoride monomers is somewhat inhibited, preventing excessively rapid self-polymerization; as the temperature slowly rises to the second temperature, the copolymerization reactivity of the moderately reactive long-chain modified flexible monomers is gradually activated. Through this temperature gradient control, the polymerization rates of two monomers with significantly different reactivity tend to match in the isothermal stage, enabling them to participate in the chain growth process simultaneously, thereby achieving uniform random copolymerization of each monomer. In addition, in step S5, after recovering the unreacted mixed monomers, a magnesium nitrate aqueous solution is added for a third stirring treatment, followed by drying to obtain modified fluororubber. The magnesium ions provided by the magnesium nitrate aqueous solution neutralize the negative charge on the surface of latex particles, compress the electric double layer, and cause the fluororubber particles to aggregate into solid flocs, thus achieving the separation of the polymer from the aqueous phase. Combined with subsequent multiple washings and gradient temperature drying, residual surfactants, salts, unreacted additives, and other impurities can be effectively removed, ensuring the low particle release characteristics of the raw rubber.

[0030] It should be understood that this example addresses the significant difference in copolymerization reactivity between long-chain modified flexible monomers and vinylidene fluoride, as well as their poor compatibility, through monomer pre-emulsification. This significantly improves the elastic recovery performance of fluororubber over a wide temperature range while maintaining its excellent chemical resistance.

[0031] Specifically, in step S1, mixing the raw materials to obtain a mixed monomer includes: The molar ratio of vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomer and sulfurization point monomer is (40-60): (15-30): (5-20): (0.1-2).

[0032] Specifically, in this example, vinylidene fluoride (VDF), as the core hard segment monomer of the fluororubber molecular backbone, contains carbon-hydrogen bonds in its molecular structure, providing the necessary processability and mechanical rigidity for the fluororubber raw rubber. If the proportion of VDF is too low, the mechanical strength and processing performance of the rubber will be insufficient to meet the requirements for sealing applications; if the proportion of VDF is too high, the molecular chain rigidity will be too strong, weakening the rubber's elastic recovery ability. By controlling the proportion range, sufficient space can be reserved for the introduction of flexible monomers while ensuring processing performance and mechanical rigidity.

[0033] Specifically, hexafluoropropylene, as a basic flexible monomer, effectively reduces the crystallinity of fluororubber due to its -CF3 side group in its molecular chain. The -CF2- structure in the hexafluoropropylene molecular chain has a similar spatial configuration and polarity to the -CH2-CF2- unit of vinylidene fluoride (PVDF), resulting in good free radical copolymerization activity between the two. Simultaneously, the -CF3 side group of hexafluoropropylene also exhibits a high copolymerization tendency towards long-chain modified flexible monomers. Therefore, within this ratio range, hexafluoropropylene can stably construct the main chain backbone and act as a link between PVDF and long-chain modified flexible monomers, enabling uniform copolymerization and thus solving the problem of uneven copolymerization caused by the strong self-polymerization tendency of PVDF and the low copolymerization activity of long-chain monomers.

[0034] Specifically, long-chain modified flexible monomers can significantly improve the overall flexibility of the molecular chain through internal plasticizing effects, lower the glass transition temperature of fluororubber, and improve its elasticity retention under low-temperature conditions and sealing stability over a wide temperature range. If the proportion of long-chain monomers is too low, the modification effect will be insignificant; if the proportion is too high, it may affect the mechanical rigidity and media resistance of the rubber. A defined ratio range can improve flexibility while maintaining the inherent chemical corrosion resistance and mechanical strength of fluororubber.

[0035] Specifically, the vulcanizing monomer can uniformly distribute bromine or iodine active crosslinking sites in the molecular chain, ensuring the formation of a stable crosslinking network during subsequent vulcanization. Because the crosslinking sites are evenly distributed and in appropriate proportions, the crosslinking network formed after vulcanization provides sufficient crosslinking density to ensure the seal's resistance to compression set, while avoiding excessively dense crosslinking points that could hinder chain segment movement. Thus, while maintaining rubber flexibility, it also possesses high-temperature resistance to compression set.

[0036] It should be understood that this example limits the molar ratio range between vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomers, and vulcanization point monomers, enabling each monomer to work synergistically during polymerization. This ensures both the processability and mechanical rigidity of the fluororubber, while significantly improving the flexibility of the molecular chain through the internal plasticizing effect of the long-chain perfluoroether. In addition, the uniformly distributed crosslinking sites contribute to the preparation of modified fluororubber with low glass transition temperature and low high-temperature compression set.

[0037] It should be noted that the molar ratio of vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomer and sulfurization point monomer can also be 55:25:19:1, 50:30:19.5:0.5 or 60:20:19:1.

[0038] Specifically, obtaining a mixed monomer by mixing raw materials also includes: providing tetrafluoroethylene, using vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomers, sulfidation point and tetrafluoroethylene as raw materials, mixing the raw materials to obtain a mixed monomer, and adding tetrafluoroethylene to the mixed raw materials. Specifically, the molar content of tetrafluoroethylene as a monomer for adjusting fluorine content can be 0.5% to 20% of the total molar content of the mixed monomers.

[0039] Specifically, this example introduces tetrafluoroethylene (TEF) as a component of the mixed monomers, building upon the existing monomers: vinylidene fluoride (VDF), hexafluoropropylene (HFA), long-chain modified flexible monomers, and sulfurization point monomers. TEF's molecular structure lacks carbon-hydrogen bonds, instead consisting of a perfluorinated structure composed of carbon-fluorine bonds. Its introduction significantly increases the fluorine content of the copolymer molecular chain. The chemical corrosion resistance of fluororubber is closely related to its fluorine content: higher fluorine content results in a larger proportion of carbon-fluorine bonds in the molecular chain, strengthening the material's resistance to strong oxidizing media, highly corrosive gases, and various chemical reagents. In semiconductor manufacturing processes, sealing materials frequently come into contact with highly corrosive gases such as hydrogen fluoride, nitrogen trifluoride, and chlorine trifluoride, as well as plasma environments. Higher fluorine content effectively inhibits the erosion of the polymer chain by the medium, extending the service life of the seals. By mixing TEF with other monomers and using a subsequent emulsion polymerization process with controlled polymerization ratios, TEF can be uniformly embedded into the copolymer molecular chain. Because the copolymerization activity of TEF differs from that of monomers such as VDF and hexafluoropropylene, direct polymerization can easily lead to uneven copolymer composition. Tetrafluoroethylene (TEF) can achieve uniform random copolymerization with other monomers, thereby achieving a uniform distribution of fluorine content at the molecular chain level and avoiding the problem of poor corrosion resistance caused by insufficient local fluorine content. The introduction of TEF does not change the core design idea of ​​this example, which is to improve the flexibility of chain segments by modifying flexible monomers with long chains. Instead, it serves as a supplementary means of adjusting fluorine content, working synergistically with flexible monomers to obtain a modified fluororubber that possesses both excellent wide-temperature elasticity and low compression set.

[0040] Optionally, with the total molar amount of the mixed monomers being 100%, the content of tetrafluoroethylene as a fluorine content adjusting monomer can be 10% or 15%.

[0041] Specifically, the long-chain modified flexible monomer is any one or a combination of two of perfluorohexyl vinyl ether and perfluorooctyl vinyl ether; the sulfidation point monomer is a bromine- or iodine-functionalized fluorinated olefin, and the sulfidation point monomer is any one or a combination of two of 2-bromo-1,1,2,3,3,3-hexafluoropropene and perfluoro(2-iodoethyl) vinyl ether.

[0042] Understandably, in this example, the long-chain modified flexible monomer is selected from perfluorohexyl vinyl ether or perfluorooctyl vinyl ether. Compared with the short-chain monomers commonly used in the prior art, perfluorohexyl vinyl ether (C6VE) and perfluorooctyl vinyl ether (C8VE) have longer perfluoroether flexible side chains in their molecular structures, which can significantly enhance the mobility of molecular chains through internal plasticizing effects, thereby effectively reducing the glass transition temperature of fluororubber and improving its wide-temperature elasticity. However, the copolymerization reactivity ratios of the long-chain modified flexible monomer and vinylidene fluoride differ greatly, and their miscibility is poor. If used alone or without appropriate copolymerization control methods, it is very easy to lead to uneven distribution of copolymer sequences. In this example, perfluorohexyl vinyl ether or perfluorooctyl vinyl ether is used in combination with hexafluoropropylene. Hexafluoropropylene acts as a bridging monomer in the copolymerization process: the -CF2- structure in the hexafluoropropylene molecular chain has a similar spatial configuration and polarity to the vinylidene fluoride unit of vinylidene fluoride, resulting in good free radical copolymerization activity. Simultaneously, the -CF3 side group of hexafluoropropylene also exhibits a high copolymerization tendency with perfluorohexyl vinyl ether or perfluorooctyl vinyl ether. Therefore, with the bridging effect of hexafluoropropylene, perfluorohexyl vinyl ether or perfluorooctyl vinyl ether can achieve uniform copolymerization with vinylidene fluoride, ensuring a uniform distribution of the long-chain perfluoroether structure within the molecular chain, thereby fully utilizing its internal plasticizing effect and improving chain segment flexibility.

[0043] Specifically, in this example, the vulcanizing point monomer is selected from 2-bromo-1,1,2,3,3,3-hexafluoropropylene or perfluoro(2-iodoethyl) vinyl ether, both of which are bromine- or iodine-functionalized fluorinated olefins. Compared with conventional vulcanizing point monomers, bromine or iodine atoms have higher reactivity and can form a stable cross-linking network in the peroxide vulcanization system. Using these specific types of bromine- or iodine-containing fluorinated olefins allows the vulcanizing point monomer to copolymerize uniformly with other monomers during polymerization, thereby forming uniformly distributed bromine or iodine active cross-linking sites in the molecular chain. This uniformly distributed cross-linking site structure can form a uniform and stable cross-linking network during subsequent vulcanization, ensuring that the seal has sufficient cross-linking density to resist compression set under high-temperature conditions and avoiding the shielding of molecular chain mobility due to local aggregation of cross-linking points or excessively high cross-linking density. Furthermore, in this example, there is no mutual interference between perfluorohexyl vinyl ether or perfluorooctyl vinyl ether and the selected vulcanizing point monomer. The flexible side chains of long-chain modified flexible monomers endow the molecular chains with good mobility, while the uniformly distributed bromine or iodine crosslinking sites form a moderately constrained crosslinking network after vulcanization. The synergistic effect of these two factors allows the vulcanized rubber to maintain good flexibility while possessing excellent high-temperature resistance to compression set.

[0044] Specifically, in step S2 above, the process of mixing the monomers, solvent, and fluorinated surfactant and then first stirring to obtain the monomer preemulsion includes: Deionized water is used as the first solvent, and perfluoropolyether ammonium carboxylate is used as the fluorinated surfactant. The mixed monomers, deionized water and perfluoropolyether ammonium carboxylate are stirred at a speed of 400 r / min-600 r / min for 30-40 min to obtain a monomer pre-emulsion. The mass ratio of the mixed monomers, perfluoropolyether ammonium carboxylate and deionized water is 1:(5%-8%):(30%-40%).

[0045] Understandably, this example uses deionized water as the first solvent and perfluoropolyether ammonium carboxylate as the fluorinated surfactant. Deionized water, as the reaction medium, provides a clean aqueous environment for the polymerization reaction, avoiding interference from impurities. Perfluoropolyether ammonium carboxylate is an environmentally friendly fluorinated surfactant whose molecular structure contains both hydrophilic ammonium carboxylate groups and hydrophobic perfluoropolyether segments. This effectively reduces the interfacial tension between the oil-phase monomer and the aqueous medium, allowing the hydrophobic fluorinated monomer to be stably dispersed in the aqueous phase. In this example, the mass ratio of mixed monomers, perfluoropolyether ammonium carboxylate, and deionized water is limited to 1:(5%-8%):(30%-40%), and the mixture is stirred at 400-600 rpm for 30-40 minutes. Under this limited mass ratio, the amount of fluorinated surfactant provides sufficient interfacial activity, causing the mixed monomers to break into tiny droplets under shear; simultaneously, the deionized water ensures sufficient dispersion space for the monomer droplets. The surfactant molecules can fully cover the surface of the newly formed monomer droplets, forming a stable interfacial film. At a stirring speed of 400-600 rpm, shear force can uniformly disperse the mixed monomers into tiny micelles with a particle size of 50-100 nm. If the stirring speed is too low, the shear force is insufficient, and the monomers are difficult to break down sufficiently, resulting in larger and unevenly distributed droplets. If the stirring speed is too high, too many air bubbles may be introduced or excessive shearing may be applied to the droplets. A stirring time of 30-40 minutes ensures that the emulsification process can proceed fully, enabling all monomer droplets to achieve a uniform particle size distribution and forming a monomer pre-emulsion with a uniform appearance. Specifically, through the above pre-emulsification treatment, the long-chain modified flexible monomers that are originally incompatible with the aqueous phase are uniformly encapsulated in tiny micelles and suspended in a stable state within the aqueous system, effectively avoiding copolymerization shifts caused by localized monomer enrichment.

[0046] It should be noted that the mass ratio of the mixed monomers, perfluoropolyether ammonium carboxylate and deionized water can also be 1:(6%-7%):(35%-40%) or 1:(7%-8%):(30%-32%).

[0047] Furthermore, in step S3 above, the second stirring process to obtain the product to be processed includes: The additives include fluorinated surfactants, pH adjusters, perfluorodiiodoethane, and initiators. Deionized water is provided as the second solvent. After mixing the monomer pre-emulsion, additives, and solvents, the mixture is stirred at 300-500 rpm for 20-30 minutes and then the pH is adjusted to 7.0-8.5 to obtain the product to be treated. The mass ratio of the mixed monomers to the second solvent is 1:(60%-70%). The total mass of deionized water in the first and second solvents is w. The mass of the fluorinated surfactants in the additives is (0.1%-1.0%)w, the mass of the pH adjusters is (0.1%-0.2%)w, the mass of the perfluorodiiodoethane is (0.05%-0.3%)w, and the mass of the initiator is (0.02%-0.1%)w.

[0048] Understandably, the additives in this example comprise four components: a fluorinated surfactant, a pH adjuster, perfluorodiiodoethane, and an initiator. The fluorinated surfactant is perfluoropolyether ammonium carboxylate, which stabilizes the latex particles generated during polymerization, preventing particle aggregation during growth. It synergistically works with the surfactant in the pre-emulsification step to achieve emulsion stability throughout the polymerization process. The pH adjuster is a 1:1 mass ratio of sodium bicarbonate and disodium hydrogen phosphate, neutralizing the hydrogen fluoride released from the fluorinated monomers during polymerization and preventing a drop in the pH of the aqueous phase. If the pH is too low, it will accelerate the decomposition rate of the initiator, leading to uncontrolled reaction; it will also disrupt the stability range of the fluorinated surfactant, causing emulsion demulsification and equipment sticking. By adjusting the pH to 7.0–8.5, the aqueous environment is maintained within a slightly alkaline range, ensuring the controllability of the initiator decomposition rate and the stability of the emulsion.

[0049] Specifically, in this example, perfluorodiiodoethane is used as a molecular weight regulator, with a dosage of 0.05%-0.3% of the total aqueous phase mass. During polymerization, perfluorodiiodoethane can transfer the active ends of growing chain radicals to itself through chain transfer reactions, forming new active centers and effectively controlling the molecular chain length. Within this dosage range, the molecular weight regulator can precisely control the Mooney viscosity of the raw rubber within a suitable processing range, ensuring that the modified fluororubber possesses both good mechanical properties and meets the requirements of subsequent compounding, vulcanization, and other processing techniques. If the dosage is too low, the molecular weight will be too high, resulting in poor processing performance of the raw rubber; if the dosage is too high, the molecular weight will be too low, leading to insufficient mechanical strength of the vulcanized rubber. The initiator is an ammonium persulfate-sodium bisulfite redox system, with a dosage of 0.02%-0.1% of the total aqueous phase mass. This redox initiation system can generate free radicals at a low temperature of 45-55℃, avoiding the high-temperature conditions required by a single thermal initiator, effectively suppressing the risk of monomer burst polymerization, and ensuring a stable and controllable chain initiation stage.

[0050] Specifically, in this example, the total mass of deionized water in the first and second solvents is denoted as w, and the mass ratio of each additive relative to w is precisely defined. The amount of fluorinated surfactant is 0.1%-1.0% w, a ratio that provides sufficient latex particle stabilization while avoiding excessive surfactant residue that could affect product cleanliness. The amount of pH adjuster is 0.1%-0.2% w, sufficient to neutralize the hydrogen fluoride generated during polymerization and maintain pH stability. The amount of perfluorodiiodoethane is 0.05%-0.3% w, ensuring a moderate molecular weight adjustment effect. The amount of initiator is 0.02%-0.1% w, ensuring that the free radical generation rate matches the monomer consumption rate. The synergistic effect of each component within this proportional range allows the aqueous system to reach a clear, homogeneous, and stable state before polymerization. In this example, the mixture is stirred at 300-500 rpm for 20-30 minutes, a stirring intensity and time sufficient to fully dissolve and uniformly disperse all additives in the aqueous phase, forming a homogeneous reaction medium. After stirring, adjust the pH to 7.0~8.5 to bring the aqueous environment into the stable range most suitable for the polymerization reaction.

[0051] It should be noted that the mass ratio of the mixed monomer and the second solvent can also be 1:63%, 1:65%, or 1:68%, and the pH can be adjusted to 7.2~7.5 or 7.6~8.2.

[0052] Furthermore, in step S4 above, the process of placing the product to be processed at a first temperature and heating it to a second temperature to obtain the reaction product includes: Provide polymerization reactor equipment, heat the polymerization reactor to 44-45℃, and pressurize it to 1.5-2.5MPa; place the product to be processed in the polymerization reactor equipment and heat it to 50-55℃ at a heating rate of 1℃ / h. Carry out the copolymerization reaction under constant pressure. During the copolymerization reaction, maintain a stirring rate of 200-300r / min until the solid content of the emulsion is 30%-40% and then end the copolymerization reaction.

[0053] Specifically, in this example, the polymerization reactor was heated to 44-45℃ as the initial reaction temperature, and the reactor pressure was controlled at 1.5-2.5 MPa. The initial temperature of 44-45℃ is set within the suitable activity temperature range of the ammonium persulfate-sodium bisulfite redox initiation system. At this temperature, the initiator can decompose smoothly to generate free radicals, initiating the chain initiation stage, while avoiding excessively high temperatures that could lead to rapid initiation and explosive polymerization. The reactor pressure control of 1.5-2.5 MPa provides a sufficient pressure environment for the dissolution of the gaseous monomer vinylidene fluoride in the reaction system, allowing the gaseous monomer to fully dissolve in the aqueous phase and participate in the polymerization reaction, maintaining a stable monomer concentration in the reaction system. Furthermore, the polymerization reactor temperature was slowly increased from 44-45℃ to 50-55℃ at a heating rate of 1℃ / h. Vinylidene fluoride (VDF) exhibits high polymerization reactivity. If directly polymerized under isothermal conditions, VDF will be preferentially consumed and rapidly self-polymerize. Meanwhile, long-chain modified flexible monomers such as perfluorohexyl vinyl ether (PFHE) or perfluorooctyl vinyl ether (PFOCE) have relatively low polymerization reactivity, making it difficult to obtain sufficient copolymerization opportunities after the rapid consumption of VDF. By slowly increasing the temperature at a rate of 1℃ / h, the polymerization of highly reactive VDF is inhibited to some extent in the initial low-temperature stage of 44-45℃, preventing its rapid consumption. As the temperature gradually increases, when it enters the 50-55℃ range, for example, at 53℃, the copolymerization reactivity of the moderately reactive long-chain modified flexible monomers is gradually activated. This temperature gradient design allows the polymerization rates of the two monomers with significantly different reactivity to tend to match during temperature changes, enabling them to participate in the chain growth reaction simultaneously, thereby achieving uniform random copolymerization of each monomer. If the heating rate is too fast, VDF will still preferentially polymerize; if the heating rate is too slow, the reaction cycle will be too long, affecting production efficiency.

[0054] It should be noted that a stirring rate of 200-300 rpm is maintained during the copolymerization reaction. Compared to the higher stirring rate of 450-500 rpm during the pre-emulsification and additive mixing stages, the stirring rate during the reaction stage is moderately reduced to minimize the impact of shear force on the stability of latex particles while ensuring the homogeneity of the reaction system and avoiding demulsification due to excessive shear. During the reaction, the reactor pressure is maintained at a constant 1.5-2.5 MPa by continuously adding monomer pre-emulsion. This constant pressure control method allows for the estimation of the amount of monomer consumed in polymerization based on the rate of pressure drop, and the corresponding pre-emulsion is replenished to maintain a stable concentration ratio of each monomer in the reaction system, ensuring the homogeneity of the copolymer composition. Specifically, in this example, the copolymerization reaction endpoint is defined as the emulsion solid content reaching 30%-40%. Solid content is a direct indicator of polymerization conversion rate in this reaction system. When the solid content reaches 30%-40%, for example, 35%, it indicates that the conversion rate of the mixed monomers has reached a suitable level. Within this solid content range, terminating the reaction can yield a modified fluororubber emulsion with stable performance.

[0055] It should be noted that when controlling the reactor pressure at 1.5-2.5 MPa, vinylidene fluoride (VDF) exhibits the highest reactivity, is consumed the fastest, and constitutes the largest proportion in the gas phase, making it the absolute dominant factor causing the pressure drop. Hexafluoropropylene and tetrafluoroethylene react more slowly and contribute less to the pressure decrease. Therefore, the VDF consumption rate represents the overall pressure change trend, and the total pressure is maintained stable by replenishing the pre-emulsion. Simultaneously, hexafluoropropylene and tetrafluoroethylene monomers are also replenished to ensure the stability of the copolymer composition. Specifically, the reactor pressure gradually decreases due to the consumption of VDF gas phase monomers; therefore, a metering pump is used to continuously replenish the monomer pre-emulsion to maintain the reactor pressure stable at 1.5-2.5 MPa. The copolymerization reaction includes the following processes: Chain initiation: The initiator undergoes a redox reaction to generate sulfate radicals. These radicals then abstract electrons from the double bonds of the monomers, forming monomeric radicals. The reaction equation is as follows: S2O8 2- +HSO3 - →SO4 2- +SO4 - +HSO3 SO4 +CH2=CF2→ - O3SO CH2 CF2

[0056] Chain growth: Monomer radicals continuously add to the double bond, causing the molecular chain to elongate, while various monomers randomly insert. The reaction formula is: -O3SO CH2 CF2 +CF2=CF-CF3→-O3SO CH2 CF2-CF2-CF -CF3 ~-CF -CF3+CF2=CF-O-(CF2)5→~-CF-CF3-CF2-CF -O-(CF2)5 ~-CF -~+CF2=CF-Br→~-CF -Br Chain transfer stage: Perfluorodiiodoethane, acting as a chain transfer agent, can terminate chain growth by abstracting the active end of chain free radicals, thereby controlling the molecular chain length. The reaction formula is: ~-CF -+I-(CF2)2-I→~CF-I+ I-(CF2)2-I Chain termination: When two chain radicals meet, the chain terminates through coupling or disproportionation, and the molecular chain stops growing. The coupling reaction equation is: ~-CF -~+~-CF -~→~-CF-CF-~ Furthermore, the amount of monomer preemulsion continuously added is essentially based on the value of pressure drop to infer the polymerization rate, thereby ensuring that the amount of monomer preemulsion added is exactly enough to make up for the amount of monomer preemulsion consumed by polymerization, thus avoiding the problem of copolymerization ratio deviation caused by the difference in activity of different monomers when the polymerization rate is out of control or insufficient addition.

[0057] Further, in step S5 above, the process of recovering the unreacted mixed monomers from the reaction product, adding magnesium nitrate aqueous solution, stirring for a third time, and then drying to obtain modified fluororubber includes: the unreacted mixed monomers volatilizing into recovered gas; after recovering the recovered gas, adding magnesium nitrate aqueous solution to the reaction product and stirring at 140-150 r / min for 10-12 min to obtain a coagulant; providing deionized water; washing the coagulant 4-5 times with deionized water; and then subjecting the washed coagulant to gradient drying to obtain the modified fluororubber. The gradient drying involves placing the washed coagulant at 40℃ for a first drying time of 3.5-4 h, placing the washed coagulant at 60℃ for a second drying time of 7.5-8 h, and placing the washed coagulant at 70℃ for a third drying time of 7.5-8 h.

[0058] Specifically, in this example, unreacted mixed monomers are volatilized into a recoverable gas and then recycled. The gaseous monomers (vinylidene fluoride / hexafluoropropylene / TFE) are liquefied and mixed together under pressure; the monomer pre-emulsion is heated at 45°C, causing the vinylidene fluoride / hexafluoropropylene / TFE to volatilize into a gaseous recoverable gas; the recovered gas is then condensed to form a liquid crude monomer, which is then purified according to its different boiling points to complete the recovery process. It should be understood that the gaseous monomers remaining in the system after the polymerization reaction are separated and collected, and after condensation and purification, can be recycled for subsequent production, reducing raw material waste. After recovering the unreacted monomers, the remaining component in the reaction system is mainly a fluororubber polymer emulsion, containing latex particles and impurities such as surfactants, salts, and unreacted additives dispersed in the aqueous phase. Further, an aqueous solution of magnesium nitrate is added to the reaction product after gas recovery, and the mixture is stirred at a stirring rate of 140-150 r / min for 10-12 min to obtain a coagulant. The magnesium ions provided by the magnesium nitrate aqueous solution neutralize the negative charge formed on the surface of latex particles due to the adsorption of fluorinated surfactants, compress the electric double layer of the latex particles, and eliminate the electrostatic repulsion between the particles. Under stirring, the fluororubber particles, which were originally stably dispersed in the aqueous phase, flocculate and aggregate into solid flocs, achieving the separation of the polymer from the aqueous phase. A stirring rate of 140-150 r / min provides moderate shear force, which promotes the full formation of agglomerates without breaking them into fine particles due to excessive shear. A stirring time of 10-12 min ensures that the coagulation reaction is fully completed, allowing the polymer to precipitate completely in the form of flocs. The agglomerates are washed 4-5 times with deionized water. The purpose of multiple washings is to thoroughly remove impurities such as surfactants, salts, and unreacted additives remaining in the pores and on the surface of the agglomerates.

[0059] Specifically, the washed agglomerates undergo gradient drying: first, drying at 40℃ for 3.5-4 hours; then at 60℃ for 7.5-8 hours; and finally at 70℃ for 7.5-8 hours. The first stage, low-temperature drying at 40℃, aims to slowly remove free water from the rubber compound's surface, preventing excessively high temperatures from causing rapid vaporization and forming a hard shell that hinders the escape of internal moisture. The second stage, medium-temperature drying at 60℃, allows the surface of the rubber compound to be largely dry, and the increased temperature provides sufficient kinetic energy for the adsorbed water to migrate to the surface and evaporate, achieving uniform dehydration. The third stage, high-temperature drying at 70℃, is used to deeply remove residual moisture from the rubber compound, ensuring the raw rubber's moisture content meets usage requirements. If a single high-temperature rapid drying method is used, the rubber compound surface is prone to rapid crusting, preventing the timely escape of vaporized internal moisture, leading to blistering or surface cracking. Conversely, if the drying temperature is too low or the drying time is insufficient, residual moisture in the raw rubber may cause problems during subsequent processing or use. By using the above-mentioned gradient heating drying method, uniform dehydration of the rubber compound can be achieved from the surface to the interior, resulting in modified fluororubber raw rubber with an intact appearance and no bubbling or adhesion.

[0060] To make the technical solution of the present invention clearer and more repeatable, the following detailed description is provided in conjunction with embodiments and comparative examples.

[0061] Example 1: The raw fluororubber formulation is as follows: 50 mol vinylidene fluoride, 25 mol hexafluoropropylene, 23 mol perfluorohexyl vinyl ether, and 2 mol 2-bromo-1,1,2,3,3,3-hexafluoropropylene.

[0062] In this Example 1, the preparation process of fluororubber is as follows: A monomer preemulsion was prepared by stirring a mixture of monomers, 6% perfluoropolyether ammonium carboxylate, and 35% deionized water at 500 rpm for 35 min. A mixture of 65% deionized water, 0.15% compounded pH adjuster, 0.2% perfluorodiiodoethane, and 0.06% initiator was stirred at 400 rpm for 25 min, and the pH was adjusted to 7.5. The polymerization reactor was heated to 45°C, and the preemulsion was pumped in to a reactor pressure of 2.0 MPa. The temperature was increased to 50°C at a rate of 1°C / h, and the reaction was carried out at a constant pressure of 2.0 MPa, maintaining a stirring rate of 250 rpm until the emulsion solid content reached 35%. The monomers were recovered, and the mixture was coagulated by stirring at 150 rpm for 12 min with a 10% magnesium nitrate aqueous solution. The coagulated material was washed five times with deionized water and dried in gradients at 40°C for 4 h, 60°C for 8 h, and 70°C for 8 h to obtain fluororubber raw rubber. In Example 1, the fluororubber vulcanization process is as follows: 100 parts of fluororubber raw rubber, 1.5 parts of peroxide vulcanizing agent, 2.5 parts of TAIC, vulcanization at 170°C for 15 min, and vulcanization at 230°C for 12 h. Example 2: The raw fluororubber formulation is as follows: 50 mol vinylidene fluoride, 25 mol hexafluoropropylene, 10 mol perfluorohexyl vinyl ether, 13 mol perfluorooctyl vinyl ether, and 2 mol perfluoro(2-iodoethyl) vinyl ether. In this Example 2, the fluororubber preparation process is the same as in Example 1. The fluororubber vulcanization process is also the same as in Example 1.

[0063] In Comparative Example 1, the fluororubber raw material formulation was: 68 mol of vinylidene fluoride, 30 mol of hexafluoropropylene, and 2 mol of 2-bromo-1,1,2,3,3,3-hexafluoropropylene. In Comparative Example 1, the fluororubber preparation process was the same as in Example 1. Comparative Example 2: The fluororubber raw rubber formulation is the same as that in Example 1; in this Comparative Example 2, the fluororubber preparation process is without pre-emulsification, without temperature gradient, with a polymerization temperature of 40~60℃, without constant pressure addition, and is directly fed into the polymerization at a stirring rate of 300r / min, and the rest is the same as in Example 1. Comparative Example 3: The fluororubber raw rubber formulation is the same as that in Example 1; in this Comparative Example 3, the fluororubber preparation process is gradient heating to 60°C isothermal polymerization, and other processes are the same as in Example 1; Experimental results

[0064] It should be understood that in Examples 1-2 of this invention, due to the introduction of long-chain perfluoroether monomers, the Tg is reduced by 10-13°C compared to the traditional fluororubber formulation in Comparative Example 1, the high-temperature compression set is reduced to below 15%, and the plasma resistance is significantly improved. Example 2 uses a compound modification of perfluorohexyl vinyl ether / perfluorooctyl vinyl ether, and the performance is optimal, indicating that the synergistic effect of long-chain perfluoroether monomers can further improve the wide-temperature elasticity and plasma resistance of fluororubber. Comparative Example 2 proves that even if the formulation is the same as that of this invention, problems such as uneven copolymerization, large performance fluctuations, and poor high-temperature sealing performance still occur without controlled polymerization process, indicating the inventiveness of the controlled copolymerization reaction process of this invention. Comparative Example 3 proves that even if the formulation and gradient heating process of this invention are used, if the polymerization endpoint temperature exceeds the reasonable range of 50-55°C, it will still lead to a decrease in copolymerization stability and a significant deterioration in low-temperature elasticity and high-temperature sealing performance, further verifying the necessity of the polymerization temperature range setting of this invention.

[0065] The second embodiment of the present invention also provides a modified fluororubber, wherein the components of the raw materials for preparing the modified fluororubber, in molar ratio, include: 40-60 vinylidene fluoride, 15-30 hexafluoropropylene, 5-20 long-chain modified flexible monomer, 0.5-20 fluorine content adjusting monomer, and 0.1-2 vulcanization point monomer.

[0066] It should be understood that this implementation, by precisely defining the molar ratio of each monomer, solves the technical problem of existing fluororubbers, which, due to unreasonable molecular chain structure design, struggle to simultaneously achieve wide-temperature elasticity and high-temperature compression set resistance. It achieves synergistic optimization of molecular chain rigidity, flexibility, and cross-linked network structure. The formulation scheme allows each monomer to work synergistically during polymerization, ensuring both the processability and mechanical rigidity of the fluororubber. Furthermore, the internal plasticizing effect of the long-chain perfluoroether significantly improves the flexibility of the molecular chain. Simultaneously, the uniformly distributed vulcanization sites provide a structural basis for the formation of a stable cross-linked network during subsequent vulcanization, thus providing a modified fluororubber with a low glass transition temperature and low high-temperature compression set.

[0067] For example, the raw materials for preparing modified fluororubber consist of 45 mol vinylidene fluoride, 20 mol hexafluoropropylene, 10 mol long-chain modified flexible monomer, 1 mol fluorine content adjusting monomer, and 1 mol vulcanization point monomer.

[0068] Please combine Figure 1 and Figure 2 The third embodiment of the present invention provides a semiconductor sealing assembly, wherein at least a portion of the semiconductor sealing assembly is made of the aforementioned modified fluororubber.

[0069] It should be understood that this example solves the technical problem that existing sealing materials cannot maintain stable sealing performance for a long time under multiple harsh conditions such as wide temperature range cycling, exposure to highly corrosive media and high cleanliness requirements involved in semiconductor manufacturing processes by applying modified fluororubber with a specific monomer composition ratio to semiconductor sealing components.

[0070] Specifically, in semiconductor manufacturing processes, sealing components are frequently exposed to highly corrosive gases such as hydrogen fluoride, nitrogen trifluoride, and chlorine trifluoride, as well as plasma environments. The process temperature range is wide, and extremely high requirements are placed on the sealing materials for low particle release and temperature cycling sealing stability. Existing semiconductor fluororubber seals are mostly prepared using binary copolymers of vinylidene fluoride / hexafluoropropylene or ternary copolymers of vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene. These materials suffer from high steric hindrance of the -CF3 side groups in their molecular chains, resulting in insufficient chain segment flexibility and a high glass transition temperature. This leads to decreased elasticity retention at low temperatures and significant compression set at high temperatures, affecting the long-term reliability of the seal. This example applies modified fluororubber with a specific monomer composition ratio to semiconductor sealing components, enabling the seals to possess both good low-temperature elasticity and high-temperature compression set resistance over a wide temperature range. Simultaneously, they exhibit excellent resistance to highly corrosive media and low particle release characteristics, meeting the comprehensive performance requirements of semiconductor manufacturing processes for sealing materials under extreme conditions.

[0071] The above provides a detailed description of a modified fluororubber and its preparation method, as well as a semiconductor sealing component, disclosed in the embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention. Any modifications, equivalent substitutions, and improvements made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing modified fluororubber, characterized in that: The preparation method of the modified fluororubber includes the following steps: The raw materials are provided as vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomers and sulfurization point monomers, and the raw materials are mixed to obtain mixed monomers; Solvents and fluorinated surfactants are provided. After mixing the mixed monomers, solvents and fluorinated surfactants, a first stirring treatment is performed to obtain a monomer preemulsion. An additive is provided, and the monomer preemulsion, additive and solvent are mixed and then subjected to a second stirring treatment to obtain the product to be treated; The product to be processed is placed at a first temperature and heated to a second temperature to react and obtain the reaction product; A magnesium nitrate aqueous solution is provided. After recovering the unreacted mixed monomers from the reaction product, the magnesium nitrate aqueous solution is added back in, and the mixture is stirred a third time before drying to obtain modified fluororubber.

2. The method for preparing modified fluororubber as described in claim 1, characterized in that: Mixing raw materials to obtain mixed monomers includes: The molar ratio of vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomer and sulfur point monomer provided is (40-60):(15-30):(5-20):(0.1-2).

3. The method for preparing modified fluororubber as described in claim 2, characterized in that: The process of mixing raw materials to obtain a mixed monomer also includes: providing tetrafluoroethylene, using vinylidene fluoride, hexafluoropropylene, long-chain modified flexible monomer, sulfidation point and tetrafluoroethylene as raw materials, mixing the raw materials to obtain a mixed monomer, and adding tetrafluoroethylene to the mixed raw materials.

4. The method for preparing modified fluororubber as described in claim 2, characterized in that: The long-chain modified flexible monomer is any one or a combination of two of perfluorohexyl vinyl ether and perfluorooctyl vinyl ether; the sulfidation point monomer is a bromine- or iodine-functionalized fluorinated olefin, wherein the sulfidation point monomer is any one or a combination of two of 2-bromo-1,1,2,3,3,3-hexafluoropropene and perfluoro(2-iodoethyl) vinyl ether.

5. The method for preparing modified fluororubber as described in claim 1, characterized in that: The process of mixing the monomer, solvent, and fluorinated surfactant and then performing a first stirring treatment to obtain the monomer preemulsion includes: Deionized water is used as the first solvent, and perfluoropolyether ammonium carboxylate is used as the fluorinated surfactant. The mixed monomers, deionized water and perfluoropolyether ammonium carboxylate are stirred at a speed of 400 r / min-600 r / min for 30-40 min to obtain a monomer pre-emulsion. The mass ratio of the mixed monomers, perfluoropolyether ammonium carboxylate and deionized water is 1:(5%-8%):(30%-40%).

6. The method for preparing modified fluororubber as described in claim 1, characterized in that: The second stirring process yields the following products to be processed: Additives include fluorinated surfactants, pH adjusters, perfluorodiiodoethane, and initiators; Deionized water is provided as the second solvent. The monomer preemulsion, additives and solvents are mixed and stirred at 300r / min-500r / min for 20-30min. The pH is then adjusted to 7.0-8.5 to obtain the product to be treated. The total mass of deionized water in the first and second solvents is w. The mass of the fluorinated surfactant in the additives is (0.1%-1.0%)w, the mass of the pH adjuster is (0.1%-0.2%)w, the mass of perfluorodiiodoethane is (0.05%-0.3%)w, and the mass of the initiator is (0.02%-0.1%)w.

7. The method for preparing modified fluororubber according to claim 1, characterized in that: The product to be processed is placed at a first temperature and heated to a second temperature to react and obtain reaction products, including: We provide polymerization reactor equipment to heat the reactor to 44-45℃ and maintain a reactor pressure of 1.5-2.5MPa. The product to be processed is placed in a polymerization reactor and heated to 50-55℃ at a heating rate of 1℃ / h. The copolymerization reaction is carried out under constant pressure. During the copolymerization reaction, the stirring rate is maintained at 200-300r / min until the solid content of the emulsion is 30%-40%, at which point the copolymerization reaction is terminated.

8. The method for preparing modified fluororubber as described in claim 1, characterized in that: The unreacted mixed monomers from the recovered reaction product were then added to a magnesium nitrate aqueous solution, stirred a third time, and dried to obtain modified fluororubber, comprising: Unreacted monomer mixtures are volatilized into recovered gas. After recovering the gas, magnesium nitrate aqueous solution is added to the reaction product and stirred at 140-150 r / min for 10-12 min to obtain a condensate. Deionized water is provided, and the condensate is washed 4-5 times with deionized water. The washed condensate is then subjected to gradient drying to obtain fluororubber.

9. A modified fluororubber, characterized in that: The modified fluororubber comprises, in molar amounts: 40-60 parts vinylidene fluoride, 15-30 parts hexafluoropropylene, 5-20 parts long-chain modified flexible monomer, and 0.1-2 parts vulcanization point monomer.

10. A semiconductor sealing assembly, characterized in that: At least a portion of the semiconductor sealing assembly is made of the modified fluororubber as described in claim 9.

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