Rubber compound for aviation sealing element and preparation method of rubber compound

Abstract

The invention discloses a rubber compound for aviation sealing elements and a preparation method thereof, and relates to the technical field of rubber compounds. The rubber compound for the aviation sealing element comprises the following raw material components in parts by weight: 30-50 parts of methyl vinyl phenyl silicone rubber; 50 to 70 parts of perfluoroether rubber; 20-30 parts of a compatible reinforcing agent; 10-20 parts of modified hydrogenated nitrile rubber; 4 to 6 parts of fluorinated graphene; 2-5 parts of a vulcanizing agent; and 2-5 parts of an anti-aging agent. The compatibility enhancer, the modified hydrogenated nitrile rubber and the fluorinated graphene are used for enhancing and improving the rubber compound, so that the comprehensive performance of the prepared rubber compound is more excellent, and the requirements of aviation sealing elements are met.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber compounds, and particularly to a rubber compound for aviation seals and a preparation method thereof. Background Art

[0002] Aviation seals are the core components that ensure the safe operation of power systems, fuel systems, and hydraulic systems in aerospace equipment. They usually need to adapt to complex and harsh conditions such as extreme low temperatures and high temperatures. Therefore, there are high requirements for the materials of aerospace seals.

[0003] Generally speaking, in order to obtain aviation seals with more excellent performance, the rubbers used are mostly high-performance rubber compounds obtained by mixing multiple rubbers. Commonly, it is the mixing of silicone rubber and fluororubber. Silicone rubber has the advantages of good processability and heat resistance, but its strength, weather resistance, etc. are relatively poor; fluororubber has relatively poor heat resistance and processability compared with silicone rubber, but it performs excellently in terms of strength, weather resistance, etc. Therefore, mixing silicone rubber and fluororubber can obtain a rubber compound with excellent comprehensive performance. However, there are differences in the compatibility between silicone rubber and fluororubber. If the two are directly mixed, the performance of the produced rubber compound will surely be unqualified. Therefore, it is necessary to improve the compatibility between silicone rubber and fluororubber, and then make full use of the complementary advantages and disadvantages of the two to obtain a rubber compound with excellent comprehensive performance.

[0004] Based on this, the present invention provides a rubber compound for aviation seals and a preparation method thereof, which is of great significance. Summary of the Invention

[0005] The purpose of the present invention is to provide a rubber compound for aviation seals and a preparation method thereof to solve the problems raised in the above background art.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A rubber compound for aviation seals, comprising the following raw material components in parts by weight:

[0008] 30 - 50 parts of methyl vinyl phenyl silicone rubber;

[0009] 50 - 70 parts of perfluoroether rubber;

[0010] 20 - 30 parts of compatibility enhancer;

[0011] 10 - 20 parts of modified hydrogenated nitrile rubber;

[0012] 4 - 6 parts of fluorinated graphene;

[0013] 2 - 5 parts of vulcanizing agent;

[0014] 2 - 5 parts of anti-aging agent.

[0015] Furthermore, in the methyl vinyl phenyl silicone rubber, the content of phenyl is 15-20 mol%.

[0016] The reason for using methyl vinyl phenyl silicone rubber in the present invention is that it can introduce both vinyl and phenyl. Among them, vinyl can improve the mechanical properties and weather resistance of the mixed rubber in the subsequent vulcanization process; phenyl can endow the mixed rubber with certain radiation resistance and weather resistance. However, considering that if the phenyl content in the methyl vinyl phenyl silicone rubber is too high, it will increase the overall rigidity of the mixed rubber, thereby increasing the mixing processing difficulty, and also reduce the plasticity of the mixed rubber, which is not conducive to processing and manufacturing seals. Therefore, the phenyl content in the methyl vinyl phenyl silicone rubber should be controlled at 15-20 mol%.

[0017] Furthermore, the preparation method of the compatibilizing enhancer is as follows: (1) Add fluorosilane coupling agent, deionized water, and absolute ethanol to the reaction vessel at a mass ratio of 1:1:4, and add acetic acid to adjust the pH of the solution to 4-6, and stir and mix for 10-60 min to obtain a silane hydrolysis solution; (2) Add the nano-filler to the silane hydrolysis solution, stir and mix at 50-60 °C for 1-6 h, and after filtration, washing, and drying, obtain the compatibilizing enhancer.

[0018] Furthermore, the mass ratio of the fluorosilane coupling agent to the nano-filler is (0.01-0.1):1.

[0019] Furthermore, the fluorosilane coupling agent includes, but is not limited to, one or a combination of more than one of (3,3,3-trifluoropropyl)trimethoxysilane, (3,3,3-trifluoropropyl)triethoxysilane, (3,3,3-trifluoropropyl)methyldimethoxysilane, (3,3,3-trifluoropropyl)methyldiethoxysilane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)-cyclotrisiloxane, and perfluorodecyltrimethoxysilane.

[0020] Furthermore, the nano-filler is obtained by mixing and compounding graphene and carbon black at a mass ratio of (0.5-1):3.

[0021] Furthermore, the graphene is graphene oxide, and its average particle size is 10-100 nm.

[0022] Furthermore, the carbon black is obtained by mixing and compounding hard carbon black and soft carbon black at a mass ratio of 1:(0.5-1); among them, the average particle size of the hard carbon black is 10-30 nm, and the average particle size of the soft carbon black is 30-100 nm.

[0023] In the present invention, a fluorosilane coupling agent is used to perform coupling modification on nano-fillers (graphene oxide, carbon black). By grafting fluorine-containing chain ends on the surface of the nano-fillers, a compatibilizing and reinforcing agent is obtained. Generally, the carbon black commonly used for rubber modification is hard carbon black. Considering that the seal needs to have a certain elasticity to avoid deformation under long-term working conditions, which may lead to a deterioration in the sealing effect of the seal, in the present invention, a compounding method of soft carbon black and hard carbon black is adopted to enhance and modify the rubber compound.

[0024] Further, the preparation method of the modified hydrogenated nitrile rubber is as follows: (1) Under nitrogen protection, hydrogenated nitrile rubber, hydroxyvinyl silicone oil, and fluorinated acrylate are added to toluene and stirred and mixed evenly to obtain a reaction solution to be reacted with a concentration of 18-22 wt%. Then, benzoyl peroxide is added to the reaction solution to be reacted, and the mixture is stirred and reacted at 60-80 °C for 1-6 h. After reduced pressure distillation and purification, a hydrogenated nitrile rubber-hydroxyvinyl silicone oil-fluorinated acrylate polymer is obtained; (2) The hydrogenated nitrile rubber-hydroxyvinyl silicone oil-fluorinated acrylate polymer is added to toluene and stirred and mixed evenly to obtain a hydrogenation solution to be hydrogenated with a concentration of 8-10 wt%. Then, the hydrogenation solution to be hydrogenated and the palladium / carbon catalyst are added to a hydrogenation autoclave, and hydrogenation treatment is carried out at a vacuum degree of 0.1-1 MPa and 80-120 °C for 1-6 h. After reduced pressure distillation and purification, the modified hydrogenated nitrile rubber is obtained.

[0025] Further, the mass ratio of the hydrogenated nitrile rubber, hydroxyvinyl silicone oil, and fluorinated acrylate is 10:(1-2):(1-2).

[0026] Further, the addition amount of benzoyl peroxide is 0.5-1.5% of the total mass of the reactants.

[0027] Further, the content of palladium in the palladium / carbon catalyst is 5 wt%, and its addition amount is 0.05-0.15% of the mass of the hydrogenated nitrile rubber-hydroxyvinyl silicone oil-fluorinated acrylate polymer.

[0028] Further, the hydrogenation degree of the hydrogenated nitrile rubber is 50-70%, and the content of acrylonitrile is 36±1.5 mol%.

[0029] Further, the fluorinated acrylate includes, but is not limited to, one or a combination of more of trifluoroethyl acrylate, trifluoroethyl methacrylate, hexafluorobutyl acrylate, hexafluorobutyl methacrylate, hexafluoropentyl acrylate, hexafluoropentyl methacrylate, tridecafluorooctyl acrylate, tridecafluorooctyl methacrylate, 1H,1H,2H,2H-tridecafluorooctyl acrylate, and 1H,1H,2H,2H-tridecafluorooctyl methacrylate.

[0030] Further, the model of the hydroxyvinyl silicone oil is OF6052; the content of its hydroxyl group is 3.9 - 4.1 mol%, and the content of vinyl group is 2.3 - 3 mol%.

[0031] Furthermore, the average particle size of the fluorinated graphene is 10 - 100 nm.

[0032] Furthermore, the vulcanizing agent is obtained by mixing dicumyl peroxide and triallyl isocyanurate in a mass ratio of 1:1.

[0033] Furthermore, the anti-aging agent is a diphenylamine-based anti-aging agent.

[0034] Furthermore, the preparation method of the aeronautical sealant compound includes the following steps:

[0035] Step 1: Add methyl vinyl phenyl silicone rubber, perfluoroether rubber, compatibilizing and reinforcing agent, modified hydrogenated nitrile rubber, fluorinated graphene, and anti-aging agent into a kneader, stir and mix for 10 - 30 min, then under a vacuum degree of 0.01 - 0.05 MPa, heat up to 150 - 170 °C and carry out closed mixing for 1 - 6 h, discharge the material, and cool it to below 80 °C to obtain the compound to be vulcanized;

[0036] Step 2: Add the compound to be vulcanized and the vulcanizing agent into an open mill, carry out vulcanization treatment at 160 - 190 °C for 10 - 30 min, discharge the material, and cool it to obtain the aeronautical sealant compound.

[0037] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0038] (1) In the present invention, silicone rubber (methyl vinyl phenyl silicone rubber) and fluororubber (perfluoroether rubber) are used as the main raw materials. The reason for mixing silicone rubber and fluororubber is that: the heat resistance and flexibility of silicone rubber are extremely excellent, but its strength, tear resistance, weather resistance and other properties are poor; while the heat resistance and flexibility of fluororubber are poor, but its strength, tear resistance, weather resistance and other properties are significantly better than those of silicone rubber. Therefore, mixing the two can greatly utilize the complementary advantages and disadvantages of each other, and then obtain a compound with excellent comprehensive properties.

[0039] (2) The compatibilizing and reinforcing agent prepared in the present invention can effectively enhance the dispersion of nano-fillers in the rubber compound and avoid their agglomeration, thus playing the following positive strengthening effects: ① The compatibilizing and reinforcing agent can stably exist at the phase interface of fluororubber and silicone rubber, and has a certain effect of promoting the compatibility between the two; ② The nano-fillers can form a dense filler network, thereby enhancing the tensile strength, tear strength, wear resistance, heat resistance, etc. of the rubber compound; ③ The nano-fillers have a certain ability to absorb ultraviolet rays, which can weaken the influence of ultraviolet rays on the rupture of the molecular chains of the rubber compound, and thus improve the weather resistance and anti-aging properties of the rubber compound; ④ Graphene oxide can play a barrier role, enhancing the airtightness and gas permeability resistance of the rubber compound and enhancing the sealing effect of the prepared seal; ⑤ Graphene oxide can cooperate with hard carbon black to improve the antistatic performance of the rubber compound; ⑥ Soft carbon black can improve the processability and elasticity of the rubber compound, enhancing the flexibility and fatigue resistance of the rubber compound.

[0040] (3) In the present invention, the particle size of the nano-fillers is further controlled. The average particle size of graphene oxide is controlled at 10 - 100 nm and the average particle size of hard carbon black is controlled at 10 - 30 nm. The reasons are as follows: ① At this particle size, it has a larger specific surface area and is easier to form a bond with the rubber molecular chains. It can not only enhance the modification effect but also reduce the material consumption and save costs; ② At this particle size, it is also easier to disperse it by mechanical means, greatly avoiding the occurrence of agglomeration; ③ At this particle size, it can better play the role of void filling and enhance the modification effect. The average particle size of soft carbon black is controlled at 30 - 100 nm. The reason is that too small a particle size will increase its reinforcing performance while weakening its ability to improve processability and elasticity, and too large a particle size will weaken the rubber binding ability, resulting in a sharp decline in the quality of the rubber compound. Overall, it enables the nano-fillers to have the maximum dispersion, and thus can better modify the rubber compound.

[0041] (4) The modified hydrogenated nitrile rubber prepared in the present invention has fluorine-containing chain ends, silicone oil segments, and hydroxyl groups, which can cooperate with the compatibilizing and reinforcing agent to promote compatibility, thereby improving the comprehensive performance of the rubber compound.

[0042] (5) In the present invention, fluorinated graphene is further added as a lubricant. The reason is that in addition to acting as a lubricant, fluorinated graphene can cooperate with the compatibilizing and reinforcing agent to improve the heat resistance and wear resistance of the rubber compound. At the same time, like graphene oxide in the aforementioned compatibilizing and reinforcing agent, fluorinated graphene can also play a barrier role for gases and liquids, and has a certain degree of improvement on the sealing performance of the seal prepared in the subsequent processing.

[0043] In summary, in the present invention, the methyl vinyl phenyl silicone rubber and the perfluoroether rubber are enhanced and improved by a compatibilizing enhancer, a modified hydrogenated nitrile rubber, and fluorinated graphene, so that the prepared rubber compound has the following properties: it has a wider temperature range adaptability; it has good mechanical properties such as toughness, wear resistance, and tear resistance; it has a certain antistatic property; it has good processability; it has excellent comprehensive properties such as good barrier effect. When it is processed into an aviation seal, it has excellent adaptability and can maintain a good sealing effect for a long time. Detailed Embodiments

[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] It should be noted that the following parts are by weight. There are no special restrictions on the purchase manufacturers of all the raw materials involved in the present invention. Exemplarily, they include:

[0046] In the following embodiments, the methyl vinyl phenyl silicone rubber, with the model of IOTA-120, the phenyl content of 18 mol%, and the average molecular weight of 450,000, is purchased from Anhui Aiyota Silicone Oil Co., Ltd.;

[0047] The perfluoroether rubber, with the model of FOR 7380, is purchased from Dongguan Langfeng Plastic Raw Materials Co., Ltd.;

[0048] (3,3,3-Trifluoropropyl)trimethoxysilane, with a purity of 99.99%, and hydroxy vinyl silicone oil, with the model of OF6052, the hydroxy content of 4.0 mol%, and the vinyl content of 2.6 mol%, are both purchased from Sibo Organosilicon Co., Ltd.;

[0049] Graphene oxide, monolayer, the sheet diameter < 40 μm, and the thickness < 1 nm, is purchased from Angxing New Carbon Materials Changzhou Co., Ltd.;

[0050] Hard carbon black, with the model of N220, the average particle size of 10 - 30 nm, and soft carbon black, with the model of N550, the average particle size of 30 - 100 nm, are both purchased from Shanghai Weixun New Materials Co., Ltd.;

[0051] Hydrogenated nitrile rubber, with a hydrogenation degree of 60 ± 2% and an acrylonitrile content of 36 ± 1.5 mol%, is purchased from Fosman Technology (Beijing) Co., Ltd.;

[0052] Graphene fluoride, with a purity of 99%, CAS number 51311-17-2, item number 6632212, purchased from Wuhan Shuer Biotechnology Co., Ltd.;

[0053] Trifluoroethyl acrylate, with a purity of 99%, dicumyl peroxide, with a purity of 99%, triallyl isocyanurate, with a purity of 99%, octylated diphenylamine, with a purity of 99%, methyltrimethoxysilane, with a purity of 99%, all purchased from Hubei Yongkuo Technology Co., Ltd.

[0054] Preliminary preparation:

[0055] ① Grind and sieve graphene oxide and graphene fluoride respectively to make their average particle size 10 - 100 nm.

[0056] ② Compound vulcanizing agent: Mix dicumyl peroxide and triallyl isocyanurate in a mass ratio of 1:1 to obtain a vulcanizing agent.

[0057] Example 1: A preparation method of a rubber compound for aviation seals:

[0058] 1. Prepare a compatible reinforcing agent: (1) Add (3,3,3-trifluoropropyl)trimethoxysilane, deionized water, and absolute ethanol into a reaction vessel in a mass ratio of 1:1:4, and add acetic acid to adjust the pH of the solution to 5, stir and mix for 30 min to obtain a silane hydrolysis solution; (2) Mix and compound hard carbon black and soft carbon black in a mass ratio of 1:0.75 to obtain carbon black; mix and compound graphene oxide and carbon black in a mass ratio of 0.75:3 to obtain a nano filler; add the nano filler into the silane hydrolysis solution, stir and mix at 55 °C for 3 h, and after filtration, washing, and drying, obtain a compatible reinforcing agent; among them, the mass ratio of (3,3,3-trifluoropropyl)trimethoxysilane to the nano filler is 0.05:1;

[0059] 2. Preparation of modified hydrogenated nitrile rubber: (1) Under nitrogen protection, hydrogenated nitrile rubber, hydroxy vinyl silicone oil, and trifluoroethyl acrylate were added to toluene in a mass ratio of 10:1.5:1.5, stirred and mixed evenly to obtain a reaction solution to be reacted with a concentration of 20 wt%. Then, benzoyl peroxide was added to the reaction solution to be reacted, and the mixture was stirred and reacted at 70 °C for 4 h. After reduced pressure distillation and purification, a hydrogenated nitrile rubber-hydroxy vinyl silicone oil-trifluoroethyl acrylate polymer was obtained. Among them, the addition amount of benzoyl peroxide was 1% of the total mass of the reactants. (2) The hydrogenated nitrile rubber-hydroxy vinyl silicone oil-trifluoroethyl acrylate polymer was added to toluene, stirred and mixed evenly to obtain a hydrogenation solution to be hydrogenated with a concentration of 9 wt%. Then, the hydrogenation solution to be hydrogenated and the palladium / carbon catalyst were added to a hydrogenation autoclave, and hydrogenation treatment was carried out at a vacuum degree of 0.1 MPa and 100 °C for 3 h. After reduced pressure distillation and purification, modified hydrogenated nitrile rubber was obtained. Among them, the addition amount of the palladium / carbon catalyst was 0.1% of the mass of the hydrogenated nitrile rubber-hydroxy vinyl silicone oil-trifluoroethyl acrylate polymer;

[0060] 3. Preparation of the rubber compound for aircraft seals: (1) Methyl vinyl phenyl silicone rubber, perfluoroether rubber, compatibilizing enhancer, modified hydrogenated nitrile rubber, fluorinated graphene, and octylated diphenylamine were added to a kneader, stirred and mixed for 20 min, and then heated to 160 °C and kneaded for 4 h under a vacuum degree of 0.01 MPa. After discharging, it was cooled to below 80 °C to obtain a rubber compound to be vulcanized. (2) The rubber compound to be vulcanized and a vulcanizing agent were added to an open mill, and vulcanization treatment was carried out at 175 °C for 20 min. After discharging and cooling, a rubber compound for aircraft seals was obtained. Among them, the rubber compound for aircraft seals includes the following raw material components in parts by weight: 40 parts of methyl vinyl phenyl silicone rubber; 60 parts of perfluoroether rubber; 25 parts of compatibilizing enhancer; 15 parts of modified hydrogenated nitrile rubber; 5 parts of fluorinated graphene; 4 parts of vulcanizing agent; 4 parts of anti-aging agent.

[0061] Example 2: A method for preparing a rubber compound for aircraft seals:

[0062] 1. Preparation of the compatibilizing enhancer: (1) (3,3,3-Trifluoropropyl)trimethoxysilane, deionized water, and absolute ethanol were added to a reaction vessel in a mass ratio of 1:1:4, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred and mixed for 30 min to obtain a silane hydrolysis solution. (2) Hard carbon black and soft carbon black were mixed and compounded in a mass ratio of 1:0.5 to obtain carbon black. Graphene oxide and carbon black were mixed and compounded in a mass ratio of 0.5:3 to obtain a nano filler. The nano filler was added to the silane hydrolysis solution, stirred and mixed at 50 °C for 1 h, and after filtration, washing, and drying, a compatibilizing enhancer was obtained. Among them, the mass ratio of (3,3,3-trifluoropropyl)trimethoxysilane to the nano filler was 0.01:1;

[0063] 2. Preparation of modified hydrogenated nitrile rubber: (1) Under nitrogen protection, hydrogenated nitrile rubber, hydroxyvinyl silicone oil, and trifluoroethyl acrylate were added to toluene in a mass ratio of 10:1:1, and stirred and mixed evenly to obtain a reaction solution to be reacted with a concentration of 20 wt%. Then, benzoyl peroxide was added to the reaction solution to be reacted, and the mixture was stirred and reacted at 60 °C for 1 h. After vacuum distillation and purification, a hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer was obtained. Among them, the addition amount of benzoyl peroxide was 0.5% of the total mass of the reactants. (2) The hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer was added to toluene, stirred and mixed evenly to obtain a hydrogenation solution to be hydrogenated with a concentration of 9 wt%. Then, the hydrogenation solution to be hydrogenated and the Pd / C catalyst were added to a hydrogenation autoclave, and hydrogenation treatment was carried out at a vacuum degree of 1 MPa and 80 °C for 1 h. After vacuum distillation and purification, modified hydrogenated nitrile rubber was obtained. Among them, the addition amount of the Pd / C catalyst was 0.05% of the mass of the hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer;

[0064] 3. Preparation of the mixing rubber for aviation seals: (1) Methyl vinyl phenyl silicone rubber, perfluoroether rubber, compatibilizing reinforcing agent, modified hydrogenated nitrile rubber, fluorinated graphene, and octylated diphenylamine were added to a kneader, stirred and mixed for 10 min, and then heated to 150 °C and kneaded for 1 h under a vacuum degree of 0.05 MPa. The material was discharged and cooled to below 80 °C to obtain a mixing rubber to be vulcanized. (2) The mixing rubber to be vulcanized and a vulcanizing agent were added to an open mill, and vulcanization treatment was carried out at 160 °C for 10 min. The material was discharged and cooled to obtain the mixing rubber for aviation seals. Among them, the mixing rubber for aviation seals includes the following raw material components in parts by weight: 40 parts of methyl vinyl phenyl silicone rubber; 60 parts of perfluoroether rubber; 25 parts of compatibilizing reinforcing agent; 15 parts of modified hydrogenated nitrile rubber; 5 parts of fluorinated graphene; 4 parts of vulcanizing agent; 4 parts of anti-aging agent.

[0065] Example 3: A preparation method of the mixing rubber for aviation seals:

[0066] 1. Preparation of the compatibilizing reinforcing agent: (1) (3,3,3-Trifluoropropyl)trimethoxysilane, deionized water, and absolute ethanol were added to a reaction vessel in a mass ratio of 1:1:4, and acetic acid was added to adjust the pH of the solution to 5, and the mixture was stirred and mixed for 30 min to obtain a silane hydrolysis solution. (2) Hard carbon black and soft carbon black were mixed and compounded in a mass ratio of 1:1 to obtain carbon black. Graphene oxide and carbon black were mixed and compounded in a mass ratio of 1:3 to obtain a nano filler. The nano filler was added to the silane hydrolysis solution, and the mixture was stirred and mixed at 60 °C for 6 h. After filtration, washing, and drying, a compatibilizing reinforcing agent was obtained. Among them, the mass ratio of (3,3,3-trifluoropropyl)trimethoxysilane to the nano filler was 0.1:1;

[0067] 2. Preparation of modified hydrogenated nitrile rubber: (1) Under nitrogen protection, hydrogenated nitrile rubber, hydroxyvinyl silicone oil, and trifluoroethyl acrylate were added to toluene in a mass ratio of 10:2:2, stirred and mixed evenly to obtain a reaction solution to be reacted with a concentration of 20 wt%. Then, benzoyl peroxide was added to the reaction solution to be reacted, and the mixture was stirred and reacted at 80 °C for 6 h. After vacuum distillation and purification, a hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer was obtained. Among them, the addition amount of benzoyl peroxide was 1.5% of the total mass of the reactants; (2) The hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer was added to toluene, stirred and mixed evenly to obtain a hydrogenation solution to be hydrogenated with a concentration of 9 wt%. Then, the hydrogenation solution to be hydrogenated and the palladium / carbon catalyst were added to a hydrogenation autoclave, and hydrogenation treatment was carried out at a vacuum degree of 0.1 MPa and 120 °C for 6 h. After vacuum distillation and purification, modified hydrogenated nitrile rubber was obtained. Among them, the addition amount of the palladium / carbon catalyst was 0.15% of the mass of the hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer;

[0068] 3. Preparation of the mixed rubber for aviation seals: (1) Methyl vinyl phenyl silicone rubber, perfluoroether rubber, compatibilizing reinforcing agent, modified hydrogenated nitrile rubber, fluorinated graphene, and octylated diphenylamine were added to a kneader, stirred and mixed for 30 min, and then the temperature was raised to 170 °C and kneaded for 6 h under a vacuum degree of 0.01 MPa. The material was discharged and cooled to below 80 °C to obtain a mixed rubber to be vulcanized; (2) The mixed rubber to be vulcanized and a vulcanizing agent were added to an open mill, and vulcanization treatment was carried out at 190 °C for 30 min. The material was discharged and cooled to obtain the mixed rubber for aviation seals. Among them, the mixed rubber for aviation seals includes the following raw material components in parts by weight: 40 parts of methyl vinyl phenyl silicone rubber; 60 parts of perfluoroether rubber; 25 parts of compatibilizing reinforcing agent; 15 parts of modified hydrogenated nitrile rubber; 5 parts of fluorinated graphene; 4 parts of vulcanizing agent; 4 parts of anti-aging agent.

[0069] The following is based on Example 3 for a control experiment, and Comparative Examples 1 to 4 are set as follows:

[0070] Comparative Example 1: Comparative Example 1 was based on Example 3 and was adjusted as follows: The nano-fillers were not modified with a fluorosilane coupling agent, and other processes remained unchanged. Specifically:

[0071] A method for preparing a mixed rubber for aviation seals:

[0072] 1. Preparation of a compatibilizing and reinforcing agent: (1) Methyltrimethoxysilane, deionized water, and absolute ethanol were added to a reaction vessel in a mass ratio of 1:1:4, and acetic acid was added to adjust the pH of the solution to 5. The mixture was stirred for 30 min to obtain a silane hydrolysis solution; (2) Hard carbon black and soft carbon black were mixed and compounded in a mass ratio of 1:1 to obtain carbon black; Graphene oxide and carbon black were mixed and compounded in a mass ratio of 1:3 to obtain a nano filler; The nano filler was added to the silane hydrolysis solution, and the mixture was stirred at 60 °C for 6 h, followed by filtration, washing, and drying to obtain a compatibilizing and reinforcing agent; Among them, the mass ratio of methyltrimethoxysilane to the nano filler was 0.1:1;

[0073] 2. Preparation of modified hydrogenated nitrile rubber: (1) Under nitrogen protection, hydrogenated nitrile rubber, hydroxyvinyl silicone oil, and trifluoroethyl acrylate were added to toluene in a mass ratio of 10:2:2, and the mixture was stirred until homogeneous to obtain a reaction solution with a concentration of 20 wt%; Then, benzoyl peroxide was added to the reaction solution, and the mixture was stirred at 80 °C for 6 h, followed by vacuum distillation and purification to obtain a hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer; Among them, the addition amount of benzoyl peroxide was 1.5% of the total mass of the reactants; (2) The hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer was added to toluene, and the mixture was stirred until homogeneous to obtain a hydrogenation solution with a concentration of 9 wt%; Then, the hydrogenation solution and a Pd / C catalyst were added to a hydrogenation autoclave, and hydrogenation treatment was carried out at a vacuum of 0.1 MPa and 120 °C for 6 h, followed by vacuum distillation and purification to obtain modified hydrogenated nitrile rubber; Among them, the addition amount of the Pd / C catalyst was 0.15% of the mass of the hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer;

[0074] 3. Preparation of a masterbatch for aviation seals: (1) Methylvinylphenyl silicone rubber, perfluoroether rubber, a compatibilizing and reinforcing agent, modified hydrogenated nitrile rubber, fluorinated graphene, and octylated diphenylamine were added to a kneader, and the mixture was stirred for 30 min. Then, under a vacuum of 0.01 MPa, the temperature was raised to 170 °C and kneaded for 6 h. The material was discharged and cooled to below 80 °C to obtain a masterbatch to be vulcanized; (2) The masterbatch to be vulcanized and a vulcanizing agent were added to an open mill, and vulcanization treatment was carried out at 190 °C for 30 min. The material was discharged and cooled to obtain a masterbatch for aviation seals; Among them, the masterbatch for aviation seals includes the following raw material components in parts by weight: 40 parts of methylvinylphenyl silicone rubber; 60 parts of perfluoroether rubber; 25 parts of a compatibilizing and reinforcing agent; 15 parts of modified hydrogenated nitrile rubber; 5 parts of fluorinated graphene; 4 parts of a vulcanizing agent; 4 parts of an anti-aging agent.

[0075] Comparative Example 2: Comparative Example 2 was based on Example 3 and was adjusted as follows: Only hard carbon black was used in the nano filler, and other processes remained unchanged. Specifically:

[0076] Preparation method of a mixing rubber for an aviation sealant:

[0077] 1. Preparation of a compatible reinforcing agent: (1) Add (3,3,3-trifluoropropyl)trimethoxysilane, deionized water, and absolute ethanol into a reaction vessel at a mass ratio of 1:1:4, and add acetic acid to adjust the pH of the solution to 5. Stir and mix for 30 min to obtain a silane hydrolysis solution; (2) Add hard carbon black into the silane hydrolysis solution, stir and mix at 60°C for 6 h, filter, wash, and dry to obtain a compatible reinforcing agent; among them, the mass ratio of (3,3,3-trifluoropropyl)trimethoxysilane to hard carbon black is 0.1:1;

[0078] 2. Preparation of a modified hydrogenated nitrile rubber: (1) Under nitrogen protection, add hydrogenated nitrile rubber, hydroxyvinyl silicone oil, and trifluoroethyl acrylate into toluene at a mass ratio of 10:2:2, stir and mix evenly to obtain a reaction solution with a concentration of 20 wt%; then add benzoyl peroxide into the reaction solution, stir and react at 80°C for 6 h, and perform vacuum distillation and purification to obtain a hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer; among them, the addition amount of benzoyl peroxide is 1.5% of the total mass of the reactants; (2) Add the hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer into toluene, stir and mix evenly to obtain a hydrogenation solution with a concentration of 9 wt%; then add the hydrogenation solution and palladium / carbon catalyst into a hydrogenation kettle, perform hydrogenation treatment at a vacuum degree of 0.1 MPa and 120°C for 6 h, and perform vacuum distillation and purification to obtain a modified hydrogenated nitrile rubber; among them, the addition amount of the palladium / carbon catalyst is 0.15% of the mass of the hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer;

[0079] 3. Preparation of a mixing rubber for an aviation sealant: (1) Add methyl vinyl phenyl silicone rubber, perfluoroether rubber, compatible reinforcing agent, modified hydrogenated nitrile rubber, fluorinated graphene, and octylated diphenylamine into a kneader, stir and mix for 30 min, and then heat up to 170°C and knead for 6 h under a vacuum degree of 0.01 MPa, discharge, and cool to below 80°C to obtain a vulcanization-ready mixing rubber; (2) Add the vulcanization-ready mixing rubber and a vulcanizing agent into an open mill, perform vulcanization treatment at 190°C for 30 min, discharge, and cool to obtain a mixing rubber for an aviation sealant; among them, the mixing rubber for an aviation sealant includes the following raw material components in parts by weight: 40 parts of methyl vinyl phenyl silicone rubber; 60 parts of perfluoroether rubber; 25 parts of compatible reinforcing agent; 15 parts of modified hydrogenated nitrile rubber; 5 parts of fluorinated graphene; 4 parts of vulcanizing agent; 4 parts of anti-aging agent.

[0080] Comparative Example 3: Comparative Example 3 is based on Example 3 and is adjusted as follows: The hydrogenated nitrile rubber is not modified, and other processes remain unchanged. Specifically:

[0081] Preparation method of a kneaded rubber for an aviation sealant:

[0082] 1. Preparation of a compatible reinforcing agent: (1) Add (3,3,3-trifluoropropyl)trimethoxysilane, deionized water, and absolute ethanol into a reaction vessel at a mass ratio of 1:1:4, and add acetic acid to adjust the pH of the solution to 5. Stir and mix for 30 min to obtain a silane hydrolysis solution; (2) Mix and compound hard carbon black and soft carbon black at a mass ratio of 1:1 to obtain carbon black; mix and compound graphene oxide and carbon black at a mass ratio of 1:3 to obtain a nano filler; add the nano filler to the silane hydrolysis solution, stir and mix at 60 °C for 6 h, filter, wash, and dry to obtain a compatible reinforcing agent; among them, the mass ratio of (3,3,3-trifluoropropyl)trimethoxysilane to the nano filler is 0.1:1;

[0083] 2. Preparation of a kneaded rubber for an aviation sealant: (1) Add methyl vinyl phenyl silicone rubber, perfluoroether rubber, compatible reinforcing agent, hydrogenated nitrile rubber, fluorinated graphene, and octylated diphenylamine into a kneader, stir and mix for 30 min, then under a vacuum of 0.01 MPa, heat up to 170 °C and carry out closed mixing for 6 h, discharge, and cool to below 80 °C to obtain a vulcanization-ready kneaded rubber; (2) Add the vulcanization-ready kneaded rubber and a vulcanizing agent into an open mill, carry out vulcanization treatment at 190 °C for 30 min, discharge, and cool to obtain a kneaded rubber for an aviation sealant; among them, the kneaded rubber for an aviation sealant includes the following raw material components in parts by weight: 40 parts of methyl vinyl phenyl silicone rubber; 60 parts of perfluoroether rubber; 25 parts of compatible reinforcing agent; 15 parts of hydrogenated nitrile rubber; 5 parts of fluorinated graphene; 4 parts of vulcanizing agent; 4 parts of anti-aging agent.

[0084] Comparative example 4: Comparative example 4 is based on Example 3 and is adjusted as follows: without adding fluorinated graphene, and other processes remain unchanged. Specifically:

[0085] Preparation method of a kneaded rubber for an aviation sealant:

[0086] 1. Preparation of a compatible reinforcing agent: (1) Add (3,3,3-trifluoropropyl)trimethoxysilane, deionized water, and absolute ethanol into a reaction vessel at a mass ratio of 1:1:4, and add acetic acid to adjust the pH of the solution to 5. Stir and mix for 30 min to obtain a silane hydrolysis solution; (2) Mix and compound hard carbon black and soft carbon black at a mass ratio of 1:1 to obtain carbon black; mix and compound graphene oxide and carbon black at a mass ratio of 1:3 to obtain a nano filler; add the nano filler to the silane hydrolysis solution, stir and mix at 60 °C for 6 h, filter, wash, and dry to obtain a compatible reinforcing agent; among them, the mass ratio of (3,3,3-trifluoropropyl)trimethoxysilane to the nano filler is 0.1:1;

[0087] 2. Preparation of modified hydrogenated nitrile rubber: (1) Under nitrogen protection, hydrogenated nitrile rubber, hydroxyvinyl silicone oil, and trifluoroethyl acrylate were added to toluene in a mass ratio of 10:2:2, stirred and mixed evenly to obtain a reaction solution to be reacted with a concentration of 20 wt%. Then, benzoyl peroxide was added to the reaction solution to be reacted, and the mixture was stirred and reacted at 80 °C for 6 h. After vacuum distillation and purification, a hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer was obtained. Among them, the addition amount of benzoyl peroxide was 1.5% of the total mass of the reactants. (2) The hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer was added to toluene, stirred and mixed evenly to obtain a hydrogenation solution to be hydrogenated with a concentration of 9 wt%. Then, the hydrogenation solution to be hydrogenated and a palladium / carbon catalyst were added to a hydrogenation autoclave, and hydrogenation treatment was carried out at a vacuum degree of 0.1 MPa and 120 °C for 6 h. After vacuum distillation and purification, modified hydrogenated nitrile rubber was obtained. Among them, the addition amount of the palladium / carbon catalyst was 0.15% of the mass of the hydrogenated nitrile rubber-hydroxyvinyl silicone oil-trifluoroethyl acrylate polymer;

[0088] 3. Preparation of the mixing rubber for aircraft seals: (1) Methyl vinyl phenyl silicone rubber, perfluoroether rubber, a compatible reinforcing agent, modified hydrogenated nitrile rubber, and octylated diphenylamine were added to a kneader, stirred and mixed for 30 min, and then heated to 170 °C and kneaded for 6 h under a vacuum degree of 0.01 MPa. The material was discharged and cooled to below 80 °C to obtain a mixing rubber to be vulcanized. (2) The mixing rubber to be vulcanized and a vulcanizing agent were added to an open mill, and vulcanization treatment was carried out at 190 °C for 30 min. The material was discharged and cooled to obtain the mixing rubber for aircraft seals. Among them, the mixing rubber for aircraft seals includes the following raw material components in parts by weight: 40 parts of methyl vinyl phenyl silicone rubber; 60 parts of perfluoroether rubber; 25 parts of a compatible reinforcing agent; 15 parts of modified hydrogenated nitrile rubber; 4 parts of a vulcanizing agent; 4 parts of an anti-aging agent.

[0089] Performance test: The mixing rubbers for aircraft seals prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to heat resistance test, tear strength test, and abrasion resistance test, as follows:

[0090] (1) According to the standard of GB / T 7759.1-2015, the mixing rubbers for aircraft seals corresponding to each example were processed into cylindrical specimens with a diameter of 29 mm and a height of 12.5 mm. Then, the cylindrical specimens were placed at 200 °C for 24 h, and then compressed by a compression device with a compression ratio of 25%. The compression set rate was tested to evaluate its high-temperature resistance performance;

[0091] (2) According to the standard of GB / T 1682-2014, the mixing rubbers for aircraft seals corresponding to each example were processed into specimens with a length of 25 mm, a width of 6 mm, and a thickness of 2 mm, and their low-temperature brittleness was tested to evaluate their low-temperature resistance performance;

[0092] (3) According to the standard of GB / T 529-2008, the aviation seals corresponding to each example were processed into trouser-shaped specimens with the mixed rubber, and a tensile testing machine was used to test them at a tensile speed of 100 mm / min to measure their tear resistance at room temperature.

[0093] (4) According to the standard of GB / T 1689-2014, the wear resistance of the aviation seals corresponding to each example was tested with the mixed rubber.

[0094] The results of the above test items are shown in Table 1 below:

[0095] Table 1

[0096]

[0097] Result analysis: By comparing the data results of Examples 1 to 3 in Table 1 above, it can be seen that Example 3 of the present invention is the optimal example; by comparing the data of Example 3 and Comparative Examples 1 to 4, it can be seen that after the present invention uses a fluorosilane coupling agent ((3,3,3-trifluoropropyl)trimethoxysilane) to modify the nano-fillers (graphene oxide, hard carbon black, soft carbon black), the heat resistance, tear resistance, and wear resistance of the mixed rubber are greatly enhanced, indicating that the compatibilizing enhancer prepared by the present invention has an obvious effect of promoting the compatibility and enhancement of methyl vinyl phenyl silicone rubber and perfluoroether rubber; by comparing the data of Example 3 and Comparative Example 3, it can be seen that the modification treatment of hydrogenated nitrile rubber in the present invention is extremely important, which can greatly affect the compatibility of methyl vinyl phenyl silicone rubber and perfluoroether rubber and has a great impact on the performance of the mixed rubber; by comparing the data of Example 3 and Comparative Example 4, it can be seen that incorporating fluorinated graphene into the mixed rubber in the present invention is also an important measure for enhancing and modifying the mixed rubber.

[0098] In summary, through the synergistic effect of the compatibilizing enhancer, modified hydrogenated nitrile rubber, and fluorinated graphene in the present invention, a high-performance mixed rubber is comprehensively prepared, which has excellent properties such as heat resistance, tear resistance, and wear resistance, and can meet the requirements of aviation seals.

[0099] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rubber compound for aviation seals, characterized in that: The raw material components include the following parts by weight: 30-50 parts of methyl vinyl phenyl silicone rubber; Perfluoroether rubber 50-70 parts; 20-30 parts of compatibility enhancer; 10-20 parts of modified hydrogenated nitrile rubber; 4-6 parts of fluorinated graphene; 2 to 5 parts of vulcanizing agent; 2 to 5 parts of anti-aging agent.

2. The rubber compound for aviation seal according to claim 1, characterized in that: In the methyl vinyl phenyl silicone rubber, the content of phenyl is 15-20 mol%.

3. The rubber compound for aviation seal according to claim 1, characterized in that: The preparation method of the compatibility enhancer is: (1) adding a fluorinated silane coupling agent, deionized water, and anhydrous ethanol in a mass ratio of 1:1:4 into a reaction container, adding acetic acid to adjust the pH of the solution to 4 to 6, and stirring and mixing for 10 to 60 minutes to obtain a silane hydrolyzate; (2) adding the nanofiller to the silane hydrolyzate, stirring and mixing at 50-60° C. for 1-6 hours, filtering, washing, and drying to obtain a compatibility enhancer; Wherein, the mass ratio of the fluorinated silane coupling agent to the nanofiller is (0.01-0.1):

1.

4. The rubber compound for aviation seals according to claim 3, characterized in that: The fluorine-containing silane coupling agent includes one or more combinations of (3,3,3-trifluoropropyl)trimethoxysilane, (3,3,3-trifluoropropyl)triethoxysilane, (3,3,3-trifluoropropyl)methyldimethoxysilane, (3,3,3-trifluoropropyl)methyldiethoxysilane, 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)-cyclotrisiloxane, and perfluorodecyltrimethoxysilane; The nanofiller is obtained by mixing graphene and carbon black in a mass ratio of (0.5-1):3; Among them, the graphene is graphene oxide, and its average particle size is 10-100nm; the carbon black is obtained by mixing and compounding hard carbon black and soft carbon black in a mass ratio of 1:(0.5-1), the average particle size of the hard carbon black is 10-30nm, and the average particle size of the soft carbon black is 30-100nm.

5. The rubber compound for aviation seal according to claim 1, characterized in that: The preparation method of the modified hydrogenated nitrile rubber is: (1) Under nitrogen protection, hydrogenated nitrile rubber, hydroxy vinyl silicone oil, and fluorinated acrylate are added to toluene, stirred and mixed to obtain a reaction liquid with a concentration of 18 to 22 wt %; dibenzoyl peroxide is added to the reaction liquid, stirred and reacted at 60 to 80° C. for 1 to 6 hours, and purified by vacuum distillation to obtain a hydrogenated nitrile rubber-hydroxy vinyl silicone oil-fluorinated acrylate polymer; (2) adding hydrogenated nitrile rubber-hydroxy vinyl silicone oil-fluorinated acrylate polymer to toluene, stirring and mixing uniformly to obtain a liquid to be hydrogenated with a concentration of 8 to 10 wt %; then adding the liquid to be hydrogenated and a palladium / carbon catalyst to a hydrogenation kettle, hydrogenating for 1 to 6 h at a vacuum degree of 0.1 to 1 MPa and 80 to 120° C., and distilling and purifying under reduced pressure to obtain a modified hydrogenated nitrile rubber; The mass ratio of hydrogenated nitrile rubber, hydroxy vinyl silicone oil and fluorinated acrylate is 10:(1-2):(1-2); The amount of dibenzoyl peroxide added is 0.5-1.5% of the total mass of the reactants; The content of palladium in the palladium / carbon catalyst is 5wt%, and the added amount thereof is 0.05-0.15% of the mass of the hydrogenated nitrile rubber-hydroxy vinyl silicone oil-fluorine-containing acrylate polymer.

6. The rubber compound for aviation seals according to claim 5, characterized in that: The hydrogenation degree of the hydrogenated nitrile rubber is 50-70%, and the content of acrylonitrile is 36±1.5 mol%; The fluorine-containing acrylate includes a combination of one or more of trifluoroethyl acrylate, trifluoroethyl methacrylate, hexafluorobutyl acrylate, hexafluorobutyl methacrylate, hexafluoropentyl acrylate, hexafluoropentyl methacrylate, tridecafluorooctyl acrylate, tridecafluorooctyl methacrylate, 1H,1H,2H,2H-tridecafluorooctyl acrylate, and 1H,1H,2H,2H-tridecafluorooctyl methacrylate; In the hydroxy vinyl silicone oil, the content of hydroxyl groups is 3.9-4.1 mol %, and the content of vinyl groups is 2.3-3 mol %.

7. The rubber compound for aviation seals according to claim 1, characterized in that: The average particle size of the fluorinated graphene is 10 to 100 nm.

8. The rubber compound for aviation seals according to claim 1, characterized in that: The vulcanizing agent is prepared by mixing dicumyl peroxide and triallyl isocyanurate in a mass ratio of 1:

1.

9. The rubber compound for aviation seals according to claim 1, characterized in that: The anti-aging agent is a diphenylamine antioxidant.

10. A method for preparing a rubber compound for aviation seals according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Add methyl vinyl phenyl silicone rubber, perfluoroether rubber, compatibility enhancer, modified hydrogenated nitrile rubber, fluorinated graphene, and anti-aging agent into a kneader, stir and mix for 10 to 30 minutes, then heat to 150 to 170° C. and knead for 1 to 6 hours at a vacuum degree of 0.01 to 0.05 MPa, discharge, and cool to below 80° C. to obtain a mixed rubber to be vulcanized; Step 2: Add the rubber compound to be vulcanized and the vulcanizing agent into an open mixer, vulcanize at 160-190° C. for 10-30 min, discharge the material, cool it, and obtain the rubber compound for aviation seals.

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