A plasma-resistant perfluoroether rubber and its preparation method

Abstract

The present invention discloses a method for preparing a plasma-resistant perfluoroether rubber, comprising the following steps: S1. ball-milling boron nitride nanosheets and silica sol, drying, adding a polyvinyl alcohol aqueous solution, mixing, granulating, and calcining to obtain an intermediate 1; mixing the intermediate 1 with a silane coupling agent solution, performing a grafting reaction, solid-liquid separation, and drying to obtain three-dimensional boron nitride nanosheet particles; S2. mixing tetrafluoroethylene, a perfluoroalkyl vinyl ether, a vulcanization site monomer, an initiator, a chain transfer agent, three-dimensional boron nitride nanosheet particles, an emulsifier, a pH adjuster, and water, performing an in-situ emulsion polymerization reaction to obtain a perfluoroether emulsion, followed by coagulation, washing, and drying to obtain a perfluoroether raw rubber; and kneading the perfluoroether raw rubber, octavinylsilsesquioxane, and a vulcanizing agent, and performing staged vulcanization to obtain a plasma-resistant perfluoroether rubber. The present invention also discloses a plasma-resistant perfluoroether rubber. The present invention has excellent high-temperature resistance and plasma resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of perfluoroether rubber, in particular to a plasma-resistant perfluoroether rubber and a preparation method thereof. Background Art

[0002] Perfluoroether rubber (PFER) is typically polymerized from a variety of monomers, including tetrafluoroethylene, a third-vulcanization monomer, and perfluoroalkyl(oxy)vinyl ether. It exhibits excellent chemical and heat resistance and is often used as a seal in semiconductor products. However, since semiconductor manufacturing processes often require high temperatures and plasma treatment, existing PFERs lack sufficient resistance to high-temperature plasma. This treatment often leads to cracks in seals, which can develop into through-cracks during subsequent use due to compression or stretching, leading to seal failure. Therefore, there is a need to improve the high-temperature and plasma resistance of PFER. Summary of the Invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes a plasma-resistant perfluoroether rubber and a preparation method thereof. The present invention cooperates with boron nitride nanosheet particles with a three-dimensional structure and octavinylsilsesquioxane to make a three-dimensional thermal conductive structure uniformly distributed in the perfluoroether rubber, which can greatly improve the high temperature resistance and plasma resistance of the perfluoroether rubber.

[0004] The present invention provides a method for preparing plasma-resistant perfluoroether rubber, comprising the following steps:

[0005] S1, mixing boron nitride nanosheets and silica sol by ball milling, drying, adding polyvinyl alcohol aqueous solution, mixing, granulating, and calcining to obtain intermediate 1; mixing intermediate 1 with silane coupling agent solution, performing grafting reaction, solid-liquid separation, and drying to obtain three-dimensional boron nitride nanosheet particles;

[0006] S2. Tetrafluoroethylene, perfluoroalkyl vinyl ether, vulcanization point monomer, initiator, chain transfer agent, three-dimensional boron nitride nanosheet particles, emulsifier, pH regulator and water are mixed, and an in-situ emulsion polymerization reaction is carried out to obtain a perfluoroether emulsion, which is then coagulated, washed and dried to obtain a perfluoroether raw rubber; the perfluoroether raw rubber, octavinylsilsesquioxane and a vulcanizing agent are mixed, and the mixture is vulcanized in sections to obtain a plasma-resistant perfluoroether rubber.

[0007] In the above S2, the specific preparation steps of the perfluoroether emulsion can be: first, three-dimensional boron nitride nanosheet particles, an emulsifier, a pH regulator, and water are mixed, and after removing the air, tetrafluoroethylene and perfluoroalkyl vinyl ether are introduced, an initiator is added to react, and then a vulcanization point monomer and a chain transfer agent are added to continue the reaction. Tetrafluoroethylene and perfluoroalkyl vinyl ether are continuously introduced during the entire reaction process until the reaction is completed.

[0008] Preferably, in S1, the weight ratio of the boron nitride nanosheets to the silica sol is 1:0.2-0.3; the weight ratio of the boron nitride nanosheets to the polyvinyl alcohol is 1:0.4-0.5.

[0009] In the above S1, the content of SiO2 in the silica sol is 15-20wt%.

[0010] In the above S1, the mass fraction of the polyvinyl alcohol aqueous solution is 6-8wt%.

[0011] In the above S1, the particle size of the intermediate 1 is 100-200 μm.

[0012] Preferably, in S1, the calcination temperature is 750-850°C, and the calcination time is 3-4 hours.

[0013] Preferably, in S1, the silane coupling agent is a mixture of tridecafluorooctyltriethoxysilane and a silane coupling agent containing a carbon-carbon double bond.

[0014] The weight ratio of the tridecafluorooctyltriethoxysilane to the silane coupling agent containing a carbon-carbon double bond is 1:0.8-1.

[0015] The silane coupling agent containing a carbon-carbon double bond may be vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, or the like.

[0016] Preferably, in S1, the solvent of the silane coupling agent solution is an ethanol aqueous solution with a volume fraction of 20-30%.

[0017] In the above S1, the mass fraction of the silane coupling agent solution is 2-3 wt %.

[0018] Preferably, in S1, the grafting reaction temperature is 70-80°C and the time is 2-3 hours.

[0019] Preferably, in S2, the perfluoroalkyl vinyl ether is at least one of perfluoromethyl vinyl ether and perfluoroethyl vinyl ether; and the sulfide monomer is at least one of 4-bromo-3,3,4,4-tetrafluorobutene and 1-bromo-2,2-difluoroethylene.

[0020] Preferably, in S2, the weight ratio of tetrafluoroethylene to perfluoroalkyl vinyl ether is 6-6.5:3.5-4; the weight ratio of tetrafluoroethylene to sulfurization site monomer is 6-6.5:0.2-0.3; and the weight ratio of tetrafluoroethylene to three-dimensional boron nitride nanosheet particles is 6-6.5:0.6-0.8.

[0021] In the above S2, the chain transfer agent is at least one of 1,4-diiodoperfluorobutane and 1,6-diiodoperfluorohexane; the initiator is at least one of potassium persulfate and ammonium persulfate; the emulsifier is a combination of perfluoropolyether peroxide and sodium octylsulfonate; and the pH adjuster is at least one of dipotassium hydrogen phosphate and disodium hydrogen phosphate.

[0022] In the above S2, the weight ratio of tetrafluoroethylene, chain transfer agent and initiator is 6-6.5:0.08-0.12:0.004-0.006.

[0023] In the above S2, the weight ratio of the three-dimensional boron nitride nanosheet particles, the emulsifier, the pH adjuster, and water is 0.6-0.8:0.02-0.04:0.05-0.07:20.

[0024] In the above S2, the temperature of the in-situ emulsion polymerization reaction is 70-80°C.

[0025] Preferably, in S2, the weight ratio of perfluoroether rubber, octavinylsilsesquioxane and vulcanizing agent is 100:5-6:5-6.

[0026] In the above S2, the vulcanizing agent is a mixture of bis-25 vulcanizing agent and triallyl isocyanurate.

[0027] The weight ratio of the bis-25 vulcanizing agent to triallyl isocyanurate is 1:1.

[0028] The above water is all deionized water.

[0029] The present invention also provides a plasma-resistant perfluoroether rubber, which is prepared according to the preparation method of the plasma-resistant perfluoroether rubber.

[0030] The present invention ball-mills boron nitride nanosheets and silica sol to uniformly distribute nano-silicon dioxide on the surface and between layers of the boron nitride nanosheets; then mixes and granulates with polyvinyl alcohol, and calcines to decompose the polyvinyl alcohol to obtain an intermediate 1, so that the boron nitride nanosheets in the intermediate 1 form a porous three-dimensional structure, and nano-silicon dioxide is uniformly distributed on the surface and between layers of the boron nitride nanosheets; hydroxyl groups on the surface of the nano-silicon dioxide are grafted with tridecafluorooctyltriethoxysilane and a silane coupling agent containing a carbon-carbon double bond, so that fluoroalkyl groups and carbon-carbon double bonds are grafted onto the boron nitride nanosheet particles with the porous three-dimensional structure.

[0031] The fluoroalkyl group in the three-dimensional boron nitride nanosheet particles can be mixed with tetrafluoroethylene, perfluoroalkyl vinyl ether, and vulcanization point monomers, and the grafted carbon-carbon double bonds can participate in the in-situ emulsion polymerization reaction, so that the porous three-dimensional structure of boron nitride nanosheet particles is evenly distributed in the perfluoroether main chain, and the perfluoroether raw rubber can be filled in the porous three-dimensional structure, so that the perfluoroether raw rubber has a continuous three-dimensional thermal conductive network; then it cooperates with octavinyl silsesquioxane, which itself has a three-dimensional network, and its carbon-carbon double bonds can form a cross-linked network during vulcanization, thereby increasing the density of the three-dimensional thermal conductive network in the rubber, further improving the thermal conductivity, and making the perfluoroether rubber have good high-temperature resistance; its evenly distributed three-dimensional network can also improve the barrier properties of the rubber, improve its plasma resistance; and can improve the mechanical properties of the perfluoroether rubber. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a photograph of the plasma-resistant perfluoroether rubber prepared in Example 3 after plasma etching. DETAILED DESCRIPTION

[0033] Hereinafter, the technical solutions of the present invention will be described in detail through specific embodiments. However, it should be clearly stated that these embodiments are provided for illustration only and are not to be construed as limiting the scope of the present invention.

[0034] Example 1

[0035] A method for preparing plasma-resistant perfluoroether rubber comprises the following steps:

[0036] S1. Add boron nitride nanosheets and silica sol (the content of SiO2 in the silica sol is 15wt%) in a weight ratio of 1:0.3 into a ball mill, ball mill for 2h to mix, take out and dry at 100℃, then add to a 6wt% polyvinyl alcohol aqueous solution, mix and granulate so that the weight ratio of boron nitride nanosheets to polyvinyl alcohol is 1:0.4, heat to 850℃ and calcine for 3h to obtain intermediate 1 with a particle size of 100μm; add intermediate 1 to a 2wt% silane coupling agent solution (the solvent is a 30% volume fraction ethanol aqueous solution, and the silane coupling agent is a mixture of tridecafluorooctyltriethoxysilane and vinyltrimethoxysilane in a weight ratio of 1:0.8) and mix, heat to 80℃ and stir for 2h to carry out grafting reaction, filter and dry to obtain three-dimensional boron nitride nanosheet particles;

[0037] S2. Three-dimensional boron nitride nanosheet particles, emulsifier (equal weights of perfluoropolyether peroxide and sodium octylsulfonate), disodium hydrogen phosphate, and water were mixed in a weight ratio of 0.8:0.04:0.05:20, nitrogen was introduced to remove air, a mixture of tetrafluoroethylene and perfluoromethyl vinyl ether was compressed into the mixture using a diaphragm compressor, the pressure was controlled at 2.5 MPa, potassium persulfate was added, and an in-situ polymerization reaction was carried out at 80°C. During the reaction, the mixture of tetrafluoroethylene and perfluoromethyl vinyl ether was continuously introduced to maintain a constant pressure, and 4- Bromo-3,3,4,4-tetrafluorobutene and 1,4-diiodoperfluorobutane are reacted at 80° C. until a predetermined amount of material is added, cooled to room temperature, and the reaction is stopped to obtain a perfluoroether emulsion, wherein the weight ratio of tetrafluoroethylene, perfluoromethyl vinyl ether, 4-bromo-3,3,4,4-tetrafluorobutene, three-dimensional boron nitride nanosheet particles, 1,4-diiodoperfluorobutane, and potassium persulfate in the perfluoroether is 6:4:0.3:0.8:0.12:0.004; then salting out and coagulation are performed, filtering, washing, and drying are performed to obtain a perfluoroether raw rubber.

[0038] Perfluoroether rubber, octavinylsilsesquioxane, and a vulcanizing agent (the vulcanizing agent is equal weight of bis-25 vulcanizing agent and triallyl isocyanurate) are mixed in a weight ratio of 100:5:6, and vulcanized at 170°C for 8 minutes in a first stage and then at 220°C for 20 hours in a second stage to obtain a plasma-resistant perfluoroether rubber.

[0039] Example 2

[0040] A method for preparing plasma-resistant perfluoroether rubber comprises the following steps:

[0041] S1. Add boron nitride nanosheets and silica sol (the content of SiO2 in the silica sol is 20wt%) in a weight ratio of 1:0.2 into a ball mill, ball mill for 2 hours to mix, take out and dry at 100°C, then add to an 8wt% polyvinyl alcohol aqueous solution, mix and granulate so that the weight ratio of boron nitride nanosheets to polyvinyl alcohol is 1:0.5, heat to 750°C and calcine for 4 hours to obtain an intermediate 1 with a particle size of 200μm; add intermediate 1 to a 3wt% silane coupling agent solution (the solvent is a 20% volume fraction ethanol aqueous solution, and the silane coupling agent is a mixture of tridecafluorooctyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane in a weight ratio of 1:1) and mix, heat to 70°C and stir for 3 hours to carry out grafting reaction, filter and dry to obtain three-dimensional boron nitride nanosheet particles;

[0042] S2, three-dimensional boron nitride nanosheet particles, emulsifier (equal weights of perfluoropolyether peroxide and sodium octylsulfonate), disodium hydrogen phosphate, and water are mixed in a weight ratio of 0.6:0.02:0.07:20, nitrogen is introduced to remove air, a mixture of tetrafluoroethylene and perfluoromethyl vinyl ether is compressed into the mixture using a diaphragm compressor, the pressure is controlled at 2.5 MPa, potassium persulfate is added, and an in-situ polymerization reaction is carried out at 70°C. During the reaction, a mixture of tetrafluoroethylene and perfluoromethyl vinyl ether is continuously introduced to maintain a constant pressure, and a mixture of 1-bromo-2,2-difluoroethylene and 1,6-diiodoperfluorohexane are reacted at 70° C. until a predetermined amount of material is added, and then cooled to room temperature and the reaction is stopped to obtain a perfluoroether emulsion, wherein the weight ratio of tetrafluoroethylene, perfluoromethyl vinyl ether, 1-bromo-2,2-difluoroethylene, three-dimensional boron nitride nanosheet particles, 1,6-diiodoperfluorohexane, and potassium persulfate in the perfluoroether is 6.5:3.5:0.2:0.6:0.08:0.006; then salting out and coagulation are carried out, filtering, washing, and drying are carried out to obtain a perfluoroether raw rubber;

[0043] Perfluoroether rubber, octavinylsilsesquioxane, and a vulcanizing agent (the vulcanizing agent is equal weight of bis-25 vulcanizing agent and triallyl isocyanurate) are mixed in a weight ratio of 100:6:5, and vulcanized at 170°C for 8 minutes in a first stage and then at 220°C for 20 hours in a second stage to obtain a plasma-resistant perfluoroether rubber.

[0044] Example 3

[0045] A method for preparing plasma-resistant perfluoroether rubber comprises the following steps:

[0046] S1. Add boron nitride nanosheets and silica sol (the content of SiO2 in the silica sol is 20wt%) in a weight ratio of 1:0.25 into a ball mill, ball mill for 2 hours to mix, take out and dry at 100°C, then add to a 7wt% polyvinyl alcohol aqueous solution, mix and granulate so that the weight ratio of boron nitride nanosheets to polyvinyl alcohol is 1:0.45, heat to 800°C and calcine for 3.5 hours to obtain an intermediate 1 with a particle size of 150 μm; add the intermediate 1 to a 2.5wt% silane coupling agent solution (the solvent is a 25% volume fraction ethanol aqueous solution, and the silane coupling agent is a mixture of tridecafluorooctyltriethoxysilane and vinyltriethoxysilane in a weight ratio of 1:0.9) and mix, heat to 75°C and stir for 2.5 hours to carry out grafting reaction, filter and dry to obtain three-dimensional boron nitride nanosheet particles;

[0047] S2. Three-dimensional boron nitride nanosheet particles, emulsifier (equal weights of perfluoropolyether peroxide and sodium octylsulfonate), disodium hydrogen phosphate, and water were mixed in a weight ratio of 0.7:0.03:0.06:20, nitrogen was introduced to remove air, a mixture of tetrafluoroethylene and perfluoromethyl vinyl ether was compressed into the mixture using a diaphragm compressor, the pressure was controlled at 2.5 MPa, potassium persulfate was added, and an in-situ polymerization reaction was carried out at 75°C. During the reaction, the mixture of tetrafluoroethylene and perfluoromethyl vinyl ether was continuously introduced to maintain a constant pressure, and 4-bromo- 3,3,4,4-tetrafluorobutene and 1,6-diiodoperfluorohexane are reacted at 75° C. until a predetermined amount of material is added, and then cooled to room temperature and the reaction is stopped to obtain a perfluoroether emulsion, wherein the weight ratio of tetrafluoroethylene, perfluoromethyl vinyl ether, 4-bromo-3,3,4,4-tetrafluorobutene, three-dimensional boron nitride nanosheet particles, 1,6-diiodoperfluorohexane, and potassium persulfate in the perfluoroether is 6.2:3.8:0.25:0.7:0.1:0.005; then salting out and coagulation are carried out, filtering, washing, and drying are carried out to obtain a perfluoroether raw rubber;

[0048] Perfluoroether rubber, octavinylsilsesquioxane, and a vulcanizing agent (the vulcanizing agent is equal weight of bis-25 vulcanizing agent and triallyl isocyanurate) are mixed in a weight ratio of 100:5.5:5.5, and vulcanized at 170°C for 8 minutes in a first stage and then at 220°C for 20 hours in a second stage to obtain a plasma-resistant perfluoroether rubber.

[0049] Comparative Example 1

[0050] A method for preparing plasma-resistant perfluoroether rubber comprises the following steps:

[0051] The three-dimensional boron nitride nanosheet particles were not added, and the other steps were the same as in Example 3.

[0052] Comparative Example 2

[0053] A method for preparing plasma-resistant perfluoroether rubber comprises the following steps:

[0054] Prepare three-dimensional boron nitride nanosheet particles according to the method of S1 in Example 3;

[0055] Then, when preparing perfluoroether rubber according to the method of Example 3, no three-dimensional boron nitride nanosheet particles were added;

[0056] The obtained perfluoroether rubber, three-dimensional boron nitride nanosheet particles, octavinylsilsesquioxane, and a vulcanizing agent (the vulcanizing agent is equal weight of bis-25 vulcanizing agent and triallyl isocyanurate) are then mixed in a weight ratio of 100:7:5.5:5.5, and vulcanized at 170°C for 8 minutes in a first stage and then at 220°C for 20 hours in a second stage to obtain a plasma-resistant perfluoroether rubber.

[0057] Comparative Example 3

[0058] A method for preparing plasma-resistant perfluoroether rubber comprises the following steps:

[0059] The hydroxylated boron nitride nanosheets were added to a 2.5 wt% silane coupling agent solution (the solvent was a 25% volume fraction ethanol aqueous solution, and the silane coupling agent was a mixture of tridecafluorooctyltriethoxysilane and vinyltriethoxysilane in a weight ratio of 1:0.9), mixed, heated to 75°C and stirred for 2.5 hours to carry out a grafting reaction, filtered, and dried to obtain modified boron nitride nanosheets;

[0060] Modified boron nitride nanosheets were used instead of three-dimensional boron nitride nanosheet particles, and plasma-resistant perfluoroether rubber was prepared according to the method of S2 in Example 3.

[0061] Comparative Example 4

[0062] A method for preparing plasma-resistant perfluoroether rubber comprises the following steps:

[0063] The same procedures as in Example 3 were followed except that octavinylsilsesquioxane was not added.

[0064] The plasma-resistant perfluoroether rubbers prepared in Examples 1-3 and Comparative Examples 1-4 were tested for their properties, and the results are shown in Table 1.

[0065] Plasma resistance test: The rubber was placed on the reaction table of a plasma etcher with a heating plate temperature of 250°C, an RPS of 6000W, NF3 gas at a flow rate of 3000sccm, and etched for 48 hours; then the weight loss rate, cracks, and compression set of the rubber were tested. It can be seen from Table 1 that the perfluoroether rubber of the present invention has good high temperature resistance, plasma etching resistance and good mechanical properties.

[0066] Typical pictures such as Figure 1 shown. Figure 1 This is a photo of the plasma-resistant perfluoroether rubber prepared in Example 3 after plasma etching.

[0067] Depend on Figure 1 It can be seen that after the plasma-resistant perfluoroether rubber prepared in the present invention is etched by plasma, no cracks are generated on the surface, and the plasma-resistant performance is good.

[0068] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing plasma-resistant perfluoroether rubber, characterized in that: The steps include: S1, mixing boron nitride nanosheets and silica sol by ball milling, drying, adding polyvinyl alcohol aqueous solution, mixing, granulating, and calcining to obtain intermediate 1; mixing intermediate 1 with silane coupling agent solution, performing grafting reaction, solid-liquid separation, and drying to obtain three-dimensional boron nitride nanosheet particles; S2, tetrafluoroethylene, perfluoroalkyl vinyl ether, vulcanization site monomer, initiator, chain transfer agent, three-dimensional boron nitride nanosheet particles, emulsifier, pH regulator, and water are mixed and subjected to in-situ emulsion polymerization to obtain a perfluoroether emulsion, which is then coagulated, washed, and dried to obtain a perfluoroether rubber; the perfluoroether rubber, octavinylsilsesquioxane, and a vulcanizing agent are mixed and subjected to staged vulcanization to obtain a plasma-resistant perfluoroether rubber; In S1, the weight ratio of boron nitride nanosheets to silica sol is 1:0.2-0.3; the weight ratio of boron nitride nanosheets to polyvinyl alcohol is 1:0.4-0.5; In S1, the silane coupling agent is a mixture of tridecafluorooctyltriethoxysilane and a silane coupling agent containing a carbon-carbon double bond; In S1, the content of SiO2 in the silica sol is 15-20wt%; in S1, the particle size of the intermediate 1 is 100-200μm; In S2, the perfluoroalkyl vinyl ether is at least one of perfluoromethyl vinyl ether and perfluoroethyl vinyl ether; the curing site monomer is at least one of 4-bromo-3,3,4,4-tetrafluorobutene and 1-bromo-2,2-difluoroethylene; In S2, the weight ratio of tetrafluoroethylene to perfluoroalkyl vinyl ether is 6-6.5:3.5-4; the weight ratio of tetrafluoroethylene to vulcanization site monomer is 6-6.5:0.2-0.3; the weight ratio of tetrafluoroethylene to three-dimensional boron nitride nanosheet particles is 6-6.5:0.6-0.8; In S2, the weight ratio of perfluoroether rubber, octavinylsilsesquioxane and vulcanizing agent is 100:5-6:5-6.

2. The method for preparing the plasma-resistant perfluoroether rubber according to claim 1, wherein: In S1, the calcination temperature is 750-850°C and the time is 3-4 hours.

3. The method for preparing the plasma-resistant perfluoroether rubber according to claim 1, wherein: In S1, the solvent of the silane coupling agent solution is an ethanol aqueous solution with a volume fraction of 20-30%.

4. The method for preparing the plasma-resistant perfluoroether rubber according to claim 1, wherein: In S1, the grafting reaction temperature is 70-80°C and the time is 2-3 hours.

5. A plasma-resistant perfluoroether rubber, characterized in that: The method for preparing the plasma-resistant perfluoroether rubber is according to any one of claims 1 to 4.

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