A method for in-situ synthesizing perfluoroether rubber materials by emulsion polymerization

Abstract

The present invention provides a method for in-situ synthesizing perfluoroether rubber materials by emulsion polymerization, which relates to the technical field of rubber materials and specifically includes: after carrying out emulsion polymerization of tetrafluoroethylene, perfluoroalkyl vinyl ether and a sulfurization point monomer containing bromine or iodine in an aqueous medium containing fluorinated modified carbon nanotubes, through coagulation, washing and drying, a perfluoroether rubber elastomer is obtained; after mixing the perfluoroether rubber elastomer with a vulcanizing agent and a crosslinking promoter, through compression molding and high-temperature vulcanization, the perfluoroether rubber material is obtained. In the present invention, tetrafluoroethylene, perfluoroalkyl vinyl ether and a sulfurization point monomer are used as copolymer monomers, and at the same time, fluorinated modified carbon nanotubes are introduced to participate in in-situ polymerization. The obtained perfluoroether rubber material has excellent comprehensive properties. When used for semiconductor seals, it not only meets the sealing requirements of semiconductor equipment, but also can increase the seismic resistance of the seals and reduce the adverse effects caused by external forces on the sealed parts.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber materials, and particularly relates to a method for in-situ synthesizing perfluoroether rubber materials by emulsion polymerization. Background Art

[0002] Perfluoroether rubber (FFKM) is a high-performance sealing material. Its excellent properties enable it to be deeply applied to the entire manufacturing system of semiconductor products. Perfluoroether rubber seals are one of the main consumables required for integrated circuit production. Perfluoroether rubber is mainly copolymerized from tetrafluoroethylene and perfluoroalkyl vinyl ether as the main monomers and a small amount of crosslinkable third monomer. There is no carbon-hydrogen bond in the macromolecular chain of perfluoroether rubber, and the C-C bond is basically surrounded by F atoms, making the polymer have remarkable chemical resistance, resistance to high and low temperatures, resistance to high-temperature steam, low release and precipitation properties, resistance to plasma, etc.

[0003] At present, most of the perfluoroether rubber materials used for semiconductor seals can meet the usage requirements by direct crosslinking and curing or adding a small amount of reinforcing agents. However, due to the short industrialization time of perfluoroether rubber materials, their physical properties such as tensile strength, hardness, and modulus at a specified elongation are not excellent enough, and a large amount of reinforcing agents or fillers are needed to blend and modify perfluoroether rubber. However, with the increase of reinforcing agents or fillers, the compression set of the product will be affected, resulting in large permanent deformation of the seal. When the compression set (AS568-214 O-ring, 70h@204°C) > 30%, the seal will fail and cannot achieve the due sealing effect, causing certain difficulties in formula development. Therefore, it is an urgent problem to obtain perfluoroether rubber materials for semiconductor seals with excellent performance and low cost.

[0004] Publication No. CN106751257A discloses a perfluoroether rubber material for high-temperature and high-pressure seals, a preparation method and its application. By adding a small amount of carbon nanotubes to the perfluoroether rubber polymer and reasonably optimizing the filler and vulcanization system, the hardness, modulus at a specified elongation, extrusion resistance and shear resistance of the seal are improved. However, the seal prepared from the perfluoroether rubber material described in this patent has too high hardness and is difficult to be applied to semiconductor equipment with high precision requirements. Moreover, its seismic performance is poor during actual use, and there may be a disadvantage that the stability of the semiconductor equipment decreases due to rigid collision at the seal connection. Summary of the Invention

[0005] Based on the technical problems existing in the background art, the present invention provides a method for in-situ synthesizing perfluoroether rubber materials by emulsion polymerization. Tetrafluoroethylene, perfluoroalkyl vinyl ether, and a vulcanization point monomer are used as copolymer monomers. At the same time, fluorinated modified carbon nanotubes are introduced to participate in in-situ polymerization. The obtained perfluoroether rubber materials have excellent comprehensive properties. When used in semiconductor seals, they not only meet the sealing requirements of semiconductor equipment but also can increase the seismic resistance of the seals and reduce the adverse effects caused by external forces on the sealed parts.

[0006] A method for in-situ synthesizing perfluoroether rubber materials by emulsion polymerization provided by the present invention includes the following steps:

[0007] S1. Tetrafluoroethylene, perfluoroalkyl vinyl ether, and a vulcanization point monomer containing bromine or iodine are subjected to emulsion polymerization in an aqueous medium containing fluorinated modified carbon nanotubes, and then, after coagulation, washing, and drying, a perfluoroether rubber elastomer is obtained;

[0008] S2. The perfluoroether rubber elastomer is further mixed with a vulcanizing agent and a crosslinking accelerator, and then, after molding by compression and high-temperature vulcanization, the perfluoroether rubber material is obtained;

[0009] The fluorinated modified carbon nanotubes are obtained by hydroxylating carbon nanotubes, carrying out a condensation reaction with haloalkyl acyl halide and perfluoroalkyl acyl halide, and then carrying out a copolymerization reaction with fluorinated acrylate and dialkylamino acrylate.

[0010] In the present invention, when tetrafluoroethylene, perfluoroalkyl vinyl ether, and a vulcanization point monomer are subjected to emulsion polymerization in an aqueous medium to obtain a perfluoroether rubber latex, fluorinated modified carbon nanotubes are added to participate in the polymerization to obtain a perfluoroether rubber with in-situ modification of carbon nanotubes. Thus, the mechanical properties of the perfluoroether rubber materials can be effectively improved by carbon nanotubes, and the technical defect that the compression set is relatively large and the application in seals fails caused by directly adding fillers or reinforcing agents for blending modification is avoided.

[0011] Preferably, the perfluoroalkyl vinyl ether is at least one of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, or perfluoropropyl vinyl ether; the vulcanization point monomer is at least one of 4-bromo-3,3,4,4-tetrafluorobutene, 1-bromo-2,2-difluoroethylene, perfluorobromoethyl vinyl ether, perfluoroiodoethyl vinyl ether, trifluorobromoethylene, or trifluoroiodoethylene.

[0012] Preferably, the haloalkyl acyl halide is α-bromoisobutyryl bromide or α-chloropropionyl chloride, the perfluoroalkyl acyl halide is at least one of perfluorobutyryl chloride, perfluorohexanoyl fluoride, perfluoroheptanoyl fluoride or perfluorooctanoyl chloride, the fluorinated acrylate is at least one of hexafluorobutyl methacrylate, trifluoroethyl methacrylate, dodecafluoroheptyl methacrylate, tridecafluorooctyl methacrylate, hexafluorobutyl acrylate or tridecafluorooctyl acrylate, and the dialkylamino acrylate is at least one of dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate or dimethylaminopropyl acrylate.

[0013] In the present invention, after the carbon nanotubes are hydroxylated, they are condensed with the haloalkyl acyl halide and the perfluoroalkyl acyl halide. As a result, a perfluoroalkyl group is grafted onto the surface of the carbon nanotubes, so that the surface of the carbon nanotubes has a low surface energy and high hydrophobicity, reducing the agglomeration of carbon nanotube particles. In addition, a haloalkyl group is also grafted onto the surface of the carbon nanotubes. Thereafter, when the fluorinated acrylate and the dialkylamino acrylate are added, an atom transfer radical polymerization reaction can occur, so that a fluoropolymer layer is grafted onto the surface of the carbon nanotubes. On the one hand, based on the principle of similar compatibility, this fluoropolymer layer can promote the compatibility of the carbon nanotubes with comonomers such as tetrafluoroethylene and perfluoroalkyl vinyl ether. On the other hand, the fluoropolymer layer also has a dialkylamine group, which can form a quaternization reaction with the sulfurization point monomer containing bromine or iodine. This not only ensures that the carbon nanotubes can be chemically grafted into the perfluoroether rubber molecular chain and fully play the reinforcing role, but also the generated quaternary ammonium salt can act as an emulsifier to ensure the smooth progress of the copolymerization reaction, and finally a perfluoroether rubber material with excellent comprehensive properties is obtained.

[0014] Preferably, the weight ratio of the tetrafluoroethylene, the perfluoroalkyl vinyl ether and the sulfurization point monomer containing bromine or iodine is 1:0.6-0.8:0.01-0.1;

[0015] Preferably, the weight ratio of the tetrafluoroethylene and the fluorination-modified carbon nanotubes is 1:0.01-0.2.

[0016] Preferably, the emulsion polymerization is carried out using a persulfide as a free radical initiator and an iodoalkane as a chain transfer agent;

[0017] Preferably, the persulfide is potassium persulfate or ammonium persulfate, and the iodoalkane is at least one of 1,2-diiodoethane, iodoform or iodomethane;

[0018] Preferably, the aqueous medium is at least one of water, tert-butanol, propylene glycol, dipropylene glycol, dipropylene glycol monomethyl ether or tripropylene glycol.

[0019] Preferably, the vulcanizing agent is at least one of di-tert-butyl peroxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane or bis(tert-butylperoxyisopropyl)benzene;

[0020] Preferably, the crosslinking accelerator is at least one of triallyl cyanurate, triallyl isocyanurate, tri-2-methylallyl isocyanurate, 1,3,5-acryloyl hexahydro-1,3,5-triazine, triallyl trimellitate or m-phenylenediamine bismaleimide.

[0021] Preferably, the weight ratio of the perfluoroether rubber elastomer, the vulcanizing agent and the crosslinking accelerator is 100:0.1-5:0.1-5.

[0022] Preferably, the pressure for the compression molding is 8-16 MPa, the temperature is 160-180 °C, and the time is 5-15 min;

[0023] Preferably, the temperature for the high-temperature vulcanization is 200-220 °C, and the time is 12-24 h.

[0024] The present invention also provides an in-situ emulsion polymerization method for synthesizing a perfluoroether rubber material, which is obtained by the above method.

[0025] The present invention also provides an application of the above perfluoroether rubber material in semiconductor seals.

[0026] The in-situ emulsion polymerization method for synthesizing a perfluoroether rubber material provided by the present invention directly disperses fluorinated modified carbon nanotubes into the copolymer monomers of the perfluoroether rubber for emulsion polymerization reaction, thereby obtaining a perfluoroether rubber modified by carbon nanotubes in-situ. The obtained perfluoroether rubber material has good comprehensive properties, especially good tensile strength, hardness, elongation at break, compression set, etc., and also greatly improves the plasma etching resistance of the perfluoroether rubber material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the chemical structure of the fluorinated modified carbon nanotubes described in Example 1;

[0028] Figure 2 It is a schematic diagram of the product appearance of the perfluoroether rubber elastomer described in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Hereinafter, the technical solutions of the present invention will be described in detail through specific examples. However, it should be clearly stated that these examples are for illustrative purposes only and are not construed as limiting the scope of the present invention.

[0030] Example 1

[0031] A method for in-situ synthesizing perfluoroether rubber material by emulsion polymerization, comprising the following steps:

[0032] (1) Adding carbon nanotubes (multi-walled carbon nanotubes) into nitric acid solution (65wt%) and ultrasonically dispersing evenly, then stirring and reacting at 80 °C for 4 h. After cooling to room temperature, filtering, washing, and drying to obtain hydroxylated carbon nanotubes; adding the hydroxylated carbon nanotubes into dichloromethane and ultrasonically dispersing evenly, then successively adding 4-dimethylaminopyridine and triethylamine and stirring evenly. The weight ratio of carbon nanotubes, 4-dimethylaminopyridine, and triethylamine is 1:0.1:0.8. Dropwise adding a dichloromethane solution dissolved with α-bromoisobutyryl bromide and perfluorobutyryl chloride under ice bath. The weight ratio of carbon nanotubes, α-bromoisobutyryl bromide, and perfluorobutyryl chloride is 1:0.1:0.5. After stirring and reacting for 36 h, filtering, washing, and drying to obtain brominated carbon nanotubes; adding the brominated carbon nanotubes into N,N-dimethylformamide and ultrasonically dispersing evenly, then adding cuprous bromide, pentamethyldiethylenetriamine, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-nonadecafluorooctyl methacrylate, and dimethylaminoethyl acrylate. The weight ratio of carbon nanotubes, cuprous bromide, pentamethyldiethylenetriamine, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-nonadecafluorooctyl methacrylate, and dimethylaminoethyl acrylate is 1:0.2:0.3:1.3:0.2. Under nitrogen protection, heating to 60 °C and then stirring and reacting for 48 h, filtering, washing, and drying to obtain fluorinated modified carbon nanotubes;

[0033] (2) Adding water, tert-butanol, disodium hydrogen phosphate, and the above-mentioned fluorinated modified carbon nanotubes into a reaction kettle according to a weight ratio of 100:5:0.5:0.5 and stirring and mixing evenly. After heating to 80 °C, pressing into a mixed gas composed of tetrafluoroethylene and perfluoromethyl vinyl ether with a mass ratio of 1:0.7 by a diaphragm compressor, controlling the pressure in the reaction kettle to be 3.0 MPa, adding an aqueous solution (10wt%) dissolved with ammonium persulfate under stirring conditions, and stirring and polymerizing. During the reaction process, continuously introducing a mixed gas composed of tetrafluoroethylene and perfluoromethyl vinyl ether with a mass ratio of 1:0.7 to keep the pressure constant, and adding a vulcanization point monomer (4-bromo-3,3,4,4-tetrafluorobutene) and a chain transfer agent (1,2-diiodoethane). Stirring and reacting at 80 °C until the predetermined feeding amount. The mass ratio of tetrafluoroethylene, 4-bromo-3,3,4,4-tetrafluorobutene, 1,2-diiodoethane, ammonium persulfate, and fluorinated modified carbon nanotubes is 1:0.05:0.02:0.001:0.1. After cooling to room temperature, stopping the polymerization reaction, adding the latex into an aqueous calcium chloride solution (1.5wt%) with 1.5 times its mass, and salting out to cause the latex to agglomerate and precipitate. Filtering, washing, and drying to obtain a perfluoroether rubber elastomer;

[0034] (3) Add the above perfluoroether rubber elastomer into an open mill, and then add triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane. The weight ratio of the above perfluoroether rubber elastomer, triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane is 100:3:1. After kneading evenly at 70 °C, roll it thinly into sheets, place it in a molding die for molding under pressure. The pressure is 10 MPa, the temperature is 170 °C, and the time is 10 min. After completion, take out the mold, cool it naturally and demold it, and then put it into a vacuum oven for high-temperature vulcanization. The vulcanization temperature is 210 °C and the time is 16 h, thus obtaining the perfluoroether rubber material.

[0035] Example 2

[0036] A method for in-situ synthesizing perfluoroether rubber material by emulsion polymerization, comprising the following steps:

[0037] (1) Obtain fluorinated modified carbon nanotubes by referring to the method described in Example 1;

[0038] (2) Add water, tert-butanol, disodium hydrogen phosphate and the above fluorinated modified carbon nanotubes into a reaction kettle according to a weight ratio of 100:5:0.5:0.5, stir and mix evenly. After heating to 80 °C, press into a mixed gas composed of tetrafluoroethylene and perfluoropropyl vinyl ether with a mass ratio of 1:0.6 by a diaphragm compressor. Control the pressure in the reaction kettle to be 3.0 MPa. Then add an aqueous solution (10 wt%) of ammonium persulfate under stirring conditions, and carry out stirring polymerization reaction. During the reaction process, continuously introduce a mixed gas composed of tetrafluoroethylene and perfluoropropyl vinyl ether with a mass ratio of 1:0.6 to keep the pressure constant, and add a vulcanization point monomer (1-bromo-2,2-difluoroethylene) and a chain transfer agent (1,2-diiodoethane). Stir and react at 80 °C until the predetermined feeding amount. The mass ratio of tetrafluoroethylene, 1-bromo-2,2-difluoroethylene, 1,2-diiodoethane, ammonium persulfate and fluorinated modified carbon nanotubes is 1:0.1:0.05:0.001:0.2. After cooling to room temperature, stop the polymerization reaction. Add the latex into an aqueous calcium chloride solution (1.5 wt%) with 1.5 times its mass for salting out to agglomerate and precipitate the latex, filter, wash, and dry to obtain a perfluoroether rubber elastomer;

[0039] (3) Add the above perfluoroether rubber elastomer into an open mill, and then add triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane. The weight ratio of the above perfluoroether rubber elastomer, triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane is 100:3:1. After kneading evenly at 70 °C, roll it out thinly, place it in a molding die and press-mold it. The pressure is 16 MPa, the temperature is 160 °C, and the time is 15 min. After completion, take out the die, cool it naturally and demold it, and then put it into a vacuum oven for high-temperature vulcanization. The vulcanization temperature is 220 °C and the time is 12 h to obtain the perfluoroether rubber material.

[0040] Example 3

[0041] A method for in-situ synthesizing a perfluoroether rubber material by emulsion polymerization, comprising the following steps:

[0042] (1) Obtain fluorinated modified carbon nanotubes by referring to the method described in Example 1;

[0043] (2) Add water, tert-butanol, disodium hydrogen phosphate and the above fluorinated modified carbon nanotubes into a reaction kettle according to a weight ratio of 100:5:0.5:0.5, stir and mix evenly. After heating to 80 °C, press in a mixed gas composed of tetrafluoroethylene and perfluoroethyl vinyl ether with a mass ratio of 1:0.8 by a diaphragm compressor. Control the pressure in the reaction kettle to be 3.0 MPa. Then add an aqueous solution (10 wt%) of ammonium persulfate under stirring conditions, and carry out a stirring polymerization reaction. During the reaction process, continuously introduce a mixed gas composed of tetrafluoroethylene and perfluoroethyl vinyl ether with a mass ratio of 1:0.8 to keep the pressure constant, and add a vulcanization point monomer (4-bromo-3,3,4,4-tetrafluorobutene) and a chain transfer agent (1,2-diiodoethane). Stir and react at 80 °C until the predetermined feeding amount. The mass ratio of tetrafluoroethylene, 4-bromo-3,3,4,4-tetrafluorobutene, 1,2-diiodoethane, ammonium persulfate and fluorinated modified carbon nanotubes is 1:0.01:0.01:0.001:0.01. After cooling to room temperature, stop the polymerization reaction. Add the latex into an aqueous calcium chloride solution (1.5 wt%) with 1.5 times its mass, and salting out causes the latex to agglomerate and precipitate. Filter, wash, and dry to obtain a perfluoroether rubber elastomer;

[0044] (3) Add the above perfluoroether rubber elastomer into an open mill, and then add triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane. The weight ratio of the above perfluoroether rubber elastomer, triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane is 100:3:1. After kneading evenly at 70 °C, roll it thinly into sheets, place it in a molding die for molding under pressure. The pressure is 8 MPa, the temperature is 180 °C, and the time is 5 min. After completion, take out the die, cool naturally and demold, and then put it into a vacuum oven for high-temperature vulcanization. The vulcanization temperature is 200 °C and the time is 24 h, thus obtaining the perfluoroether rubber material.

[0045] Comparative Example 1

[0046] A method for in-situ synthesizing perfluoroether rubber material by emulsion polymerization, comprising the following steps:

[0047] (1) Add water, tert-butanol and disodium hydrogen phosphate into a reaction kettle according to a weight ratio of 100:5:0.5, stir and mix evenly, heat up to 80 °C, and then press in a mixed gas composed of tetrafluoroethylene and perfluoromethyl vinyl ether with a mass ratio of 1:0.7 by a diaphragm compressor. Control the pressure in the reaction kettle to be 3.0 MPa. Under stirring conditions, add an aqueous solution (10 wt%) of ammonium persulfate, and carry out the stirring polymerization reaction. During the reaction process, continuously introduce a mixed gas composed of tetrafluoroethylene and perfluoromethyl vinyl ether with a mass ratio of 1:0.7 to keep the pressure constant, and add a vulcanization point monomer (4-bromo-3,3,4,4-tetrafluorobutene) and a chain transfer agent (1,2-diiodoethane). Stir and react at 80 °C until the predetermined feeding amount is reached. The mass ratio of tetrafluoroethylene, 4-bromo-3,3,4,4-tetrafluorobutene, 1,2-diiodoethane and ammonium persulfate is 1:0.05:0.02:0.001. After cooling to room temperature, stop the polymerization reaction. Add the latex into an aqueous calcium chloride solution (1.5 wt%) with 1.5 times its mass for salting out to agglomerate and precipitate the latex, filter, wash, and dry to obtain a perfluoroether rubber elastomer;

[0048] (2) Add the above perfluoroether rubber elastomer into an open mill, and then add multi-walled carbon nanotubes (multi-walled carbon nanotubes), triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane. The weight ratio of the above perfluoroether rubber elastomer, multi-walled carbon nanotubes, triallyl isocyanurate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane is 100:6:3:1. After kneading evenly at 70 °C, roll it thinly into sheets, place it in a molding die for molding under pressure. The pressure is 10 MPa, the temperature is 170 °C, and the time is 10 min. After completion, take out the die, cool naturally and demold, and then put it into a vacuum oven for high-temperature vulcanization. The vulcanization temperature is 210 °C and the time is 16 h, thus obtaining the perfluoroether rubber material.

[0049] Comparative Example 2

[0050] A method for in-situ synthesizing a perfluoroether rubber material by emulsion polymerization, comprising the following steps:

[0051] (1) Add carbon nanotubes (multi-walled carbon nanotubes) to nitric acid solution (65 wt%) and ultrasonically disperse evenly, then stir and react at 80 °C for 4 h. After cooling to room temperature, filter, wash, and dry to obtain hydroxylated carbon nanotubes; add the hydroxylated carbon nanotubes to dichloromethane and ultrasonically disperse evenly, then successively add 4-dimethylaminopyridine and triethylamine and stir evenly. The weight ratio of carbon nanotubes, 4-dimethylaminopyridine, and triethylamine is 1:0.1:0.8. Dropwise add a dichloromethane solution containing α-bromoisobutyryl bromide under ice bath. The weight ratio of carbon nanotubes and α-bromoisobutyryl bromide is 1:0.1. After stirring and reacting for 36 h, filter, wash, and dry to obtain brominated carbon nanotubes; add the brominated carbon nanotubes to N,N-dimethylformamide and ultrasonically disperse evenly, then add cuprous bromide, pentamethyldiethylenetriamine, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluorodecyl methacrylate, and 2-(dimethylamino)ethyl acrylate. The weight ratio of carbon nanotubes, cuprous bromide, pentamethyldiethylenetriamine, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluorodecyl methacrylate, and 2-(dimethylamino)ethyl acrylate is 1:0.2:0.3:1.3:0.2. Under nitrogen protection, heat to 60 °C and then stir and react for 48 h. Filter, wash, and dry to obtain fluorinated modified carbon nanotubes;

[0052] (2) Obtain the perfluoroether rubber elastomer by referring to the method described in Example 1;

[0053] (3) Obtain the perfluoroether rubber material by referring to the method described in Example 1.

[0054] Comparative Example 3

[0055] A method for in-situ synthesizing a perfluoroether rubber material by emulsion polymerization, comprising the following steps:

[0056] (1) Carbon nanotubes (multi-walled carbon nanotubes) were added to nitric acid solution (65 wt%) and ultrasonically dispersed evenly. Then, the mixture was stirred and reacted at 80 °C for 4 h. After cooling to room temperature, it was filtered, washed, and dried to obtain hydroxylated carbon nanotubes. The hydroxylated carbon nanotubes were added to dichloromethane and ultrasonically dispersed evenly. Then, 4-dimethylaminopyridine and triethylamine were added successively and stirred evenly. The weight ratio of carbon nanotubes, 4-dimethylaminopyridine, and triethylamine was 1:0.1:0.8. A dichloromethane solution containing α-bromoisobutyryl bromide and perfluorobutyryl chloride was added dropwise under an ice bath. The weight ratio of carbon nanotubes, α-bromoisobutyryl bromide, and perfluorobutyryl chloride was 1:0.1:0.5. After stirring and reacting for 36 h, it was filtered, washed, and dried to obtain brominated carbon nanotubes. The brominated carbon nanotubes were added to N,N-dimethylformamide and ultrasonically dispersed evenly. Then, cuprous bromide, pentamethyldiethylenetriamine, and 13-perfluorooctyl methacrylate were added. The weight ratio of multi-walled carbon nanotubes, cuprous bromide, pentamethyldiethylenetriamine, and 13-perfluorooctyl methacrylate was 1:0.2:0.3:1.3. Under nitrogen protection, the temperature was raised to 60 °C and then stirred and reacted for 48 h. After filtration, washing, and drying, fluorinated modified carbon nanotubes were obtained.

[0057] (2) The perfluoroether rubber elastomer was obtained by referring to the method described in Example 1.

[0058] (3) The perfluoroether rubber material was obtained by referring to the method described in Example 1.

[0059] The perfluoroether rubber materials obtained in the examples and comparative examples were made into standard test specimens and tested. The data results of the performance tests are shown in Table 1 below.

[0060] Shore A hardness: Tested in accordance with GB / T 531.1-2008 "Vulcanized rubber or thermoplastic rubber - Determination of indentation hardness - Part 1: Durometer method (Shore hardness)".

[0061] Tensile strength and elongation at break: Tested in accordance with GB / T 528-2009 "Vulcanized rubber or thermoplastic rubber - Determination of tensile stress-strain properties".

[0062] Compression set: Tested in accordance with ASTM D395-03 "Standard test methods for rubber property - Compression Set", specimen size: AS568-214 O-ring, test conditions: 204 °C, 70 h.

[0063] Plasma etching: At a temperature of 100 °C, time of 60 min, power of 800 w, and gas flow rate of 80 sccm, O 2 and CH 4Ion etching gas, calculate the weight change of particulate matter precipitation. The weight change is calculated according to the following formula: Weight change of particulate matter precipitation (%) = (weight before etching - weight after etching) / weight before etching × 100;

[0064] Heat-resistant air aging: Test according to GB / T3512-2014 "Thermal air aging and heat resistance test for vulcanized rubber or thermoplastic rubber". Test conditions: 300 °C, 72 h;

[0065] Table 1 Test results of perfluoroether rubber materials obtained corresponding to the examples and comparative examples

[0066]

[0067] It can be seen from the results in the above table that compared with the comparative examples, in the examples, after directly dispersing the fluorinated modified carbon nanotubes into the comonomer of perfluoroether rubber for in-situ emulsion polymerization reaction, the obtained perfluoroether rubber material not only ensures the physical and mechanical properties of hardness (Shore A) 72±3, tensile strength ≥15 MPa, and elongation at break ≥140%. On this premise, the compression set ≤25% ensures a good sealing effect. At the same time, good physical and mechanical properties can still be ensured under the condition of 300 °C heat-resistant air aging, and in O 2 and CH 4 For plasma etching, the weight change rate of the sealing ring material after particulate matter precipitation is less than 5%, which is completely applicable to semiconductor processing with more stringent environments.

[0068] Compared with Comparative Examples 2 and 3, although they also directly disperse the fluorinated modified carbon nanotubes into the comonomer of perfluoroether rubber for emulsion polymerization reaction, if the polymers of perfluoroalkyl or dialkylamino acrylate are omitted from grafting on the surface of the carbon nanotubes in the fluorinated modified carbon nanotubes, the properties of the in-situ modified perfluoroether rubber of the obtained carbon nanotubes will deteriorate.

[0069] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A method for in-situ synthesis of perfluoroether rubber material by emulsion polymerization, characterized in that: The steps include: S1, emulsion polymerizing tetrafluoroethylene, perfluoroalkyl vinyl ether and a bromine- or iodine-containing vulcanization point monomer in an aqueous medium containing fluorinated modified carbon nanotubes, followed by coagulation, washing and drying to obtain a perfluoroether rubber elastomer; S2, mixing the perfluoroether rubber elastomer with a vulcanizing agent and a cross-linking accelerator, molding the mixture through molding, and vulcanizing the mixture at high temperature to obtain the perfluoroether rubber material; The fluorinated modified carbon nanotubes are obtained by hydroxylating carbon nanotubes, performing condensation reaction with halogenated alkyl acyl halide or perfluoroalkyl acyl halide, and then performing copolymerization reaction with fluorinated acrylate or dialkylamino acrylate.

2. The method for in-situ synthesis of perfluoroether rubber material by emulsion polymerization according to claim 1, characterized in that: The perfluoroalkyl vinyl ether is at least one of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether or perfluoropropyl vinyl ether; the vulcanization site monomer is at least one of 4-bromo-3,3,4,4-tetrafluorobutene, 1-bromo-2,2-difluoroethylene, perfluorobromoethyl vinyl ether, perfluoroiodoethyl vinyl ether, trifluorobromoethylene or trifluoroiodoethylene.

3. The method for in-situ synthesis of perfluoroether rubber material by emulsion polymerization according to claim 1 or 2, characterized in that: The halogenated alkyl acyl halide is α-bromoisobutyryl bromide or α-chloropropionyl chloride, the perfluoroalkyl acyl halide is at least one of perfluorobutyryl chloride, perfluorohexanoyl fluoride, perfluoroheptanoyl fluoride or perfluorooctanoyl chloride, the fluorine-containing acrylate is at least one of hexafluorobutyl methacrylate, trifluoroethyl methacrylate, dodecafluoroheptyl methacrylate, tridecafluorooctyl methacrylate, hexafluorobutyl acrylate or tridecafluorooctyl acrylate, and the dialkylamino acrylate is at least one of dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate or dimethylaminopropyl acrylate.

4. The method for in-situ synthesis of perfluoroether rubber material by emulsion polymerization according to claim 1 or 2, characterized in that: The weight ratio of tetrafluoroethylene, perfluoroalkyl vinyl ether and bromine- or iodine-containing vulcanization site monomer is 1:0.6-0.8:0.01-0.1; The weight ratio of tetrafluoroethylene to fluorinated modified carbon nanotubes is 1:0.01-0.

2.

5. The method for in-situ synthesis of perfluoroether rubber material by emulsion polymerization according to claim 1 or 2, characterized in that: The emulsion polymerization is carried out using persulfide as a free radical initiator and iodinated alkane as a chain transfer agent; The persulfide is potassium persulfate or ammonium persulfate, and the iodinated alkane is at least one of 1,2-diiodoethane, iodoform or methyl iodide.

6. The method for in-situ synthesis of perfluoroether rubber material by emulsion polymerization according to claim 1 or 2, characterized in that: The vulcanizing agent is at least one of di-tert-butyl peroxide, tert-butyl peroxide isopropyl benzene, diisopropyl benzene peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane or di-tert-butyl peroxy isopropyl benzene; The cross-linking accelerator is at least one of triallyl cyanurate, triallyl isocyanurate, tri-2-methallyl isocyanurate, 1,3,5-acryloylhexahydro-1,3,5-triazine, triallyl trimellitate or metaphenylenediamine bismaleimide.

7. The method for in-situ synthesis of perfluoroether rubber material by emulsion polymerization according to claim 1 or 2, characterized in that: The weight ratio of the perfluoroether rubber elastomer to the vulcanizing agent and the cross-linking accelerator is 100:0.1-5:0.1-5.

8. The method for in-situ synthesis of perfluoroether rubber material by emulsion polymerization according to claim 1 or 2, characterized in that: The compression molding process has a pressure of 8-16 MPa, a temperature of 160-180° C., and a time of 5-15 min. The high temperature vulcanization temperature is 200-220° C. and the time is 12-24 hours.

9. An emulsion polymerization in-situ synthesis of perfluoroether rubber material, characterized in that: The invention is synthesized by the method described in any one of claims 1 to 8.

10. Use of the perfluoroether rubber material according to claim 9 in semiconductor seals.

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