Silicone rubber with thermal stability and preparation method thereof

Abstract

The invention relates to the field of silicone rubber preparation, and particularly discloses silicone rubber with thermal stability and a preparation method thereof. The invention discloses silicone rubber with thermal stability. The silicone rubber is prepared from the following raw materials in parts by weight: 100 parts of a silicone rubber matrix, 2-6 parts of hydroxyl silicone oil, 1-2.5 parts of a vulcanizing agent, 20-50 parts of white carbon black, 1-5 parts of a coupling agent, 5-10 parts of a thermal stabilizer, 10-40 parts of a flame retardant and 4-10 parts of a toughening enhancer, the heat stabilizer is prepared from active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO2 and kaolin-loaded Fe2O3 according to the mass ratio of 3 to (0.5 to 0.7) to (1.5 to 2.1); the toughening and reinforcing agent comprises carboxylated PVDF (Polyvinylidene Fluoride) nanofibers and a modified metal organic framework material in a mass ratio of 1: (0.1-0.3). The silicone rubber has the advantages of being good in mechanical performance and high in high-temperature-resistant stability.

Description

Technical Field

[0001] The present application relates to the technical field of silicone rubber preparation, and more specifically, to a silicone rubber with thermal stability and a preparation method thereof. Background Art

[0002] Silicone rubber is a special synthetic rubber. Different from the CC bond of ordinary rubber, the main chain of silicone rubber is an inorganic structure of Si-O. It is a semi-inorganic, saturated, heterochain, non-polar elastomer. A type of elastomer with an organic side group, it has excellent high and low temperature resistance, weather aging resistance, electrical insulation and physiological inertness. It is widely used in the fields of electronics, aerospace, machinery manufacturing, medical and health care, and is also widely used in daily life. The operating temperature range of ordinary silicone rubber is -50℃-200℃. Under high temperature conditions, silicone rubber is easily decomposed into free oxygen radicals when heated, which attack the main chain of silicone rubber molecules, causing the decomposition of the rubber molecular structure, resulting in high temperature aging of silicone rubber and loss of use value. With the continuous development of science and technology, the application field of silicone rubber is becoming wider and wider, and higher requirements are also put forward for the high temperature resistance and aging resistance of silicone rubber. Traditional silicone rubber can no longer meet the requirements of use under higher temperature conditions. It will quickly become brittle under conditions exceeding 250℃, and its physical properties will drop sharply.

[0003] The thermal degradation of silicone rubber is mainly caused by two reactions: main chain degradation and side group oxidation. Metal oxides such as cerium oxide and iron oxide can prevent the chain growth of silicone rubber thermal oxidation free radicals through electron transfer reactions. Therefore, they are often used as heat-resistant additives for silicone rubber. For example, the invention patent with publication number CN113278290A discloses a high-temperature resistant silicone rubber and its preparation method. Polydimethylsiloxane, cerium oxide, lanthanum oxide, nano-aluminum oxide and iron oxide are used as heat-resistant agents to reduce the possibility of silicone rubber undergoing a main chain degradation reaction, and synergistically improve the high-temperature resistance of silicone rubber. However, metal oxides can only keep silicone rubber stable at around 300°C and are difficult to withstand higher temperatures. In addition, metal oxides have poor compatibility with silicone rubber matrix and are easy to affect the mechanical properties of silicone rubber. Summary of the invention

[0004] In order to improve the high temperature stability and mechanical properties of silicone rubber, the present application provides a silicone rubber with thermal stability and a preparation method thereof.

[0005] In a first aspect, the present application provides a silicone rubber with thermal stability, using the following technical solution:

[0006] A silicone rubber with thermal stability, comprising the following raw materials in parts by weight:

[0007] 100 parts of silicone rubber matrix, 2-6 parts of hydroxy silicone oil, 1-2.5 parts of vulcanizing agent, 20-50 parts of white carbon black, 1-5 parts of coupling agent, 5-10 parts of heat stabilizer, 10-40 parts of flame retardant, 4-10 parts of toughening and reinforcing agent;

[0008] The silicone rubber matrix comprises methyl vinyl silicone rubber and fluorosilicone rubber in a mass ratio of 6-7:2.5-3;

[0009] The thermal stabilizer comprises active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO 2 and kaolin loaded Fe 2 O 3 ;

[0010] The toughening and reinforcing agent comprises carboxylated PVDF nanofibers and modified metal organic framework materials in a mass ratio of 1:0.1-0.3.

[0011] By adopting the above technical scheme, with fluorosilicone rubber and methyl vinyl silicone rubber as the main matrix, fluorosilicone rubber has good chemical stability, a wide temperature resistance range, and better radiation aging resistance than methyl vinyl silicone rubber. In addition, the molecular structure of fluorosilicone rubber contains fluorine atoms, which helps to improve the rigidity and hardness of its molecular chain, thereby improving the tear resistance and tensile strength of the blending system.

[0012] Carboxylated PVDF nanofibers are used as toughening and reinforcing agents. The introduction of carboxylation can graft active functional groups onto PVDF nanofibers, which can react chemically with the silicone rubber matrix to form chemical bonds or hydrogen bonds and other interactions. In addition, the introduction of carboxyl groups on the surface of PVDF nanofibers can also improve the surface chemical properties of PVDF nanofibers, making it easier for them to interact with the silicone rubber matrix, improve their compatibility and dispersibility with the silicone rubber matrix, and reduce agglomeration. In addition, the interface interaction between the carboxyl groups and the silicone rubber matrix in the carboxylated PVDF nanofibers is strong, and they are well dispersed in the silicone rubber, so that the carboxylated PVDF nanofibers can give full play to their free radical capture ability. The active hydrogen atoms in the carboxyl groups can react with free radicals to form alkyl free radical intermediates, effectively blocking free radical reactions, thereby inhibiting the oxidative cross-linking reaction of silicone rubber and reducing the degree of thermal oxidation of silicone rubber.

[0013] Cage-shaped oligomeric silsesquioxane (POSS) is a molecular-level organic / inorganic hybrid material with a hexahedral inorganic framework core of a Si-O-Si nanostructure surrounded by organic groups. It has a nanometer size effect and good thermal stability. The nanometer size and uniform particle size of POSS make it easier to achieve molecular-level dispersion in the silicone rubber matrix, thereby reducing the agglomeration of cerium oxide, improving the dispersibility of cerium oxide, and reducing the effect of thermal stabilizers on the mechanical properties of silicone rubber materials. In addition, the introduction of POSS significantly improves the thermal stability and mechanical strength of silicone rubber while weakening the effect of the addition of metal oxides on silicone rubber.

[0014] Kaolin loaded with Fe 2 O 3 Kaolin is a layered material with a large specific surface area and a certain adsorption capacity. It can significantly improve the mechanical strength, wear resistance and chemical stability of silicone rubber. Its layered structure and good fluidity make it easy to disperse in rubber materials to form a uniform dispersion system. The Fe 2 O 3 The particles form steric hindrance, which reduces the Fe 2 O 3 The agglomeration phenomenon between particles is reduced, thereby reducing the effect of metal oxide addition on the mechanical strength of silicone rubber. In addition, the addition of kaolin can also improve the thermal aging ability of silicone rubber to a certain extent.

[0015] The metal compound Fe 2 O 3 With CeO 2 Fe 3+ and Ce 4+ It can undergo redox reaction with these free radicals and produce inactive R + , and low-valent metal ions Fe 2+ and Ce 3+ In this process, a single electron is transferred, and the low-valent metal ion Fe 2+ and Ce 3+ It can also react with oxygen to be oxidized to a high-valent Fe 3+ and Ce 4+ This reaction goes back and forth, inhibiting the side-group oxidation cross-linking reaction of silicone rubber, and ultimately improving the heat resistance of silicone rubber. 2 O 3 Or CeO 2 The heat resistance of silicone rubber is greatly improved.

[0016] Optionally, the modified metal organic framework material is prepared by the following method:

[0017] The metal organic framework material is added into deionized water after being acidified, and ultrasonically homogenized to obtain a dispersion;

[0018] Mix tin chloride pentahydrate and antimony trichloride and add them to a hydrochloric acid solution, drop the dispersion into it, and simultaneously drop ammonia water into it. After the drop is complete, continue stirring for 1-2 hours, filter, wash, dry, and calcine to obtain a coating;

[0019] The coated material is added into an ethanolamine solution, filtered, washed and dried after ultrasonic treatment to obtain a modified metal organic framework material.

[0020] Metal-organic framework materials have antioxidant properties, can capture free radicals and inhibit the occurrence of oxidation reactions. Therefore, after being compounded with silicone rubber, they can slow down the oxidative aging of silicone rubber. In addition, metal-organic frameworks have high thermal stability and can maintain structural stability under high temperature environments, thereby reducing thermal aging. ATO is coated on the metal-organic framework by in-situ chemical precipitation, containing Sn 4+ and Sb 3+ The hydrochloric acid mixed solution is slowly dripped into the dispersion. With the addition of hydrochloric acid solution, the pH increases to 4+ and Sb 3+ Hydrolysis begins to occur to generate positively charged hydrolysis product Sn(OH) 4-n n+ and SbO + After acidification, the surface of the metal organic framework material has a negative charge, so the hydrolysis product can be adsorbed to the surface through electrostatic adsorption, and the precipitated precipitate forms a coating layer on the surface of the metal organic framework. Then, the coating is modified with ethanolamine. Ethanolamine will be adsorbed on the surface of the coating due to the coordination effect between amine substances and metal ions, that is, a N-Sb (Sn) bond with strong adsorption bond energy will be formed between ethanolamine and the ATO surface. The metal organic framework material with ATO coated on the surface has strong dispersibility because the alkyl chain segment of ethanolamine provides spatial repulsion between particles, and can be dispersed more evenly in silicone rubber. ATO with high thermal stability is coated on the metal organic framework material. After being added to silicone rubber, it can maintain the stability of the molecular chain in a high temperature environment and reduce the occurrence of degradation reactions. In addition, ATO also has certain antioxidant properties, which can slow down the oxidation reaction rate of silicone rubber at high temperatures, thereby extending its service life.

[0021] Optionally, kaolin loaded with Fe 2 O 3 The amount of cage-shaped oligomeric silsesquioxane grafted CeO 2 3 times the dosage.

[0022] By adopting the above technical solution, Fe 2 O 3 With 3 times CeO2 Adding it into silicone rubber in appropriate amounts can more effectively improve the heat resistance and anti-aging effects of silicone rubber.

[0023] Optionally, the method for preparing the carboxylated PVDF nanofibers comprises the following steps:

[0024] PVDF and ethylene maleic anhydride copolymer are mixed, added to a solvent prepared by mixing DMA and acetone in a volume ratio of 3:2, copper oxide is added, the temperature is raised to 50-60° C., and stirred for 10-12 hours to obtain a spinning solution, wherein the amounts of copper oxide and ethylene maleic anhydride copolymer are 5-9wt% and 15-20wt% of the mass of PVDF, respectively;

[0025] The spinning solution is subjected to electrostatic spinning to obtain a nanofiber membrane, which is vacuum dried at 50-60° C., then immersed in a sulfuric acid solution, washed, and vacuum dried to obtain carboxylated PVDF nanofibers.

[0026] By adopting the above technical scheme, PVDF is polyvinylidene fluoride, which has excellent weather corrosion resistance and good wear resistance, flexibility and impact strength. It is mixed with ethylene maleic anhydride copolymer and copper oxide as a spinning solution, and soaked in acid solution after spinning, so that the anhydride bonds in the film are all hydrolyzed into carboxyl groups, and carboxyl-rich PVDF nanofibers are obtained. Copper oxide also has an improving effect on the thermal stability of silicone rubber. Therefore, the carboxyl groups in the prepared carboxylated PVDF nanofibers make the PVDF nanofibers evenly dispersed in the silicone rubber, resulting in a strong interfacial interaction, which plays a role in increasing the initial tensile strength and breaking strength of the silicone rubber, while blocking free radicals and inhibiting oxidative cross-linking reactions. Copper oxide further improves the thermal oxidation resistance of silicone rubber to a certain extent and improves the thermal stability.

[0027] Optionally, carbon nanotubes are further added to the spinning solution, and the amount of carbon nanotubes and PVDF is 0.01-0.1:1.

[0028] By adopting the above technical scheme, the carbon nanotubes have excellent high temperature resistance and thermal conductivity. After being blended with the spinning solution, the carbon nanotubes are acidified with sulfuric acid and have carboxyl groups on the surface, thereby enhancing the interaction with the silicone rubber matrix and improving the thermal stability. The copper oxide in the spinning solution can play a certain barrier role, separating the carbon nanotubes from each other, increasing the distance between the carbon nanotubes, and weakening the van der Waals force and π-π interaction between the carbon nanotubes. Therefore, the mutual attraction between the carbon nanotubes in the spinning solution is reduced, and the dispersion in the spinning solution is good. Due to the addition of the carbon nanotubes, the particle size of the copper oxide particles is reduced, the dispersion is improved, the specific surface area is increased, and the interaction with the silicone rubber is enhanced. Therefore, the two cooperate with each other to further improve the thermal oxidation stability of the silicone rubber. Moreover, the addition of the carbon nanotubes can increase the action area of ​​the PVDF nanofibers and the silicone rubber matrix, and enhance the interfacial bonding force between the carboxylated PVDF nanofibers and the silicone rubber matrix.

[0029] Optionally, the cage-shaped oligomeric silsesquioxane is grafted with CeO 2 The method is as follows:

[0030] CeO 2 Add to acetic acid solution, stir at 50-70℃ for 3-4h, filter and dry to obtain acidified CeO 2 ;

[0031] Acidified CeO 2 Add to tetrahydrofuran, add N,N-carbonyldiimidazole, heat to 60-70°C, stir for 3-5h, then add amino cage-shaped oligomeric silsesquioxane, pass nitrogen, react at 60-70°C for 10-12h, filter, and vacuum dry at 60-70°C.

[0032] By adopting the above technical solution, CeO 2 Reaction with acetic acid to make acetic acid and CeO 2 Surface reaction, carboxyl groups are grafted onto cerium oxide particles, and then N,N-carbonyldiimidazole is added to graft imidazole groups onto carboxyl groups, and then amino-modified cage-shaped oligomeric silsesquioxanes are reacted with imidazole groups to obtain the final cage-shaped oligomeric silsesquioxane grafted CeO 2 , and the POSS surface is connected with a large number of polar groups, which effectively promotes the 2 POSS has good miscibility in silicone rubber, and its core is a three-dimensional cage-type inorganic framework with excellent thermal stability. At high temperatures, the alkyl chains on POSS are mainly decomposed, while the Si-O-Si bond of its inorganic core will break at higher temperatures. The decomposition of the organic part of POSS itself will consume some heat, slowing down the decomposition rate. During the degradation process, it decomposes into SiO 2It can form a deposition and form a protective layer on the surface of cerium oxide, which can slow down heat transfer to a certain extent, inhibit the volatilization of combustible gases, and block the mixing of combustible gases and oxygen. POSS gradually migrates to the surface of cerium oxide to form a barrier layer with high thermal stability, thereby improving the thermal oxygen stability of the particles.

[0033] Optionally, the kaolin loaded with Fe 2 O 3 Made by the following method:

[0034] Add kaolin to anhydrous ethanol, stir evenly, add silane coupling agent KH560, continue stirring for 40-60 minutes, dry to obtain modified kaolin, the mass ratio of silane coupling agent to kaolin is 8-10:1;

[0035] The volume ratio of CF is 25:1. 4 and N 2 As a mixed gas, kaolin is subjected to plasma fluoridation treatment for 15-20 minutes to obtain fluoridated kaolin;

[0036] The fluorinated kaolin is immersed in a 10% ferric nitrate solution, allowed to stand for 10-12 hours, then heated to 60-65°C, allowed to stand for 5-6 hours, the pH value is adjusted to produce precipitation, then filtered and washed to neutrality, dried, and heated to 400-450°C under nitrogen protection, and kept at a constant temperature for 1-1.5 hours.

[0037] By adopting the above technical scheme, kaolin is firstly modified by using silane coupling agent KH560 to improve the interface force between kaolin and silicone rubber, improve mechanical strength, enhance thermal stability, and then CF 4 and N 2 The mixed gas is used for plasma fluorination treatment, CF 4 As a plasma discharge gas, nitrogen has relatively stable chemical properties. As a protective gas, it provides an excited state for the reaction and hits the surface of kaolin to open chemical bonds. During the plasma discharge process, high-energy particles accumulate on the surface of the medium and react with CF 4 Molecules collide, and the collision causes CF 4 The molecules are ionized to form fluorine-containing free radicals, which then react with the groups pre-grafted on the surface of kaolin. The fluorine element is effectively introduced into the surface of kaolin, thereby effectively inhibiting the agglomeration of kaolin in the matrix and achieving its uniform dispersion in the matrix. After fluorination treatment, the average particle size of kaolin is reduced and the surface roughness is increased, so that it is more evenly dispersed in the silicone rubber matrix and the bonding strength with silicone rubber is increased; then the fluorinated kaolin is impregnated with ferric nitrate solution, and the ferric nitrate is formed into Fe by adjusting the pH value and high temperature treatment. 2 O 3 , while Fe2 O 3 Fe 3+ It can undergo redox reaction with free radicals generated by oxidative crosslinking and degradation of silicone rubber at high temperature, and produce inactive R + , and low-valent metal ions Fe 2+ , low-valent metal ion Fe 2+ It can also react with oxygen to be oxidized to a high-valent Fe 3+ , continuously inhibiting the side group oxidation cross-linking reaction of silicone rubber and improving heat resistance.

[0038] Optionally, the specific method of the plasma fluorination treatment is: loading the modified kaolin into a reactor, evacuating the vacuum to 2.8×10 -3 Pa, then charged into CF 4 and N 2 The mixed gas was used to raise the internal pressure to 10 kPa and then evacuated to 2.8 × 10 - 3 Pa, finally charged into CF 4 and N 2 of mixed gas until the internal pressure stabilizes at 13.5kPa, the applied voltage is 24kv and the frequency is 9kHz.

[0039] By adopting the above technical solution, the above parameters can effectively activate the surface groups of kaolin, promote the formation of new chemical bonds and the grafting reaction of functional groups, have high electrochemical activity, and have the advantages of high efficiency, safety and stability.

[0040] Optionally, the vulcanizing agent is any one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,4-dichlorobenzoyl peroxide or tert-butyl perbenzoate;

[0041] The flame retardant is selected from at least one of ammonium polyphosphate, magnesium hydroxide and aluminum hydroxide;

[0042] The coupling agent is selected from at least one of A151 coupling agent, A171 coupling agent, KH550 coupling agent and KH560 coupling agent.

[0043] In a second aspect, the present application provides a method for preparing silicone rubber with thermal stability, using the following technical solution:

[0044] A method for preparing silicone rubber with thermal stability comprises the following steps:

[0045] The silicone rubber matrix, white carbon black and hydroxy silicone oil are mixed at 80-100°C for 20-30 minutes, a coupling agent, a toughening agent, a heat stabilizer and a flame retardant are added, and the mixture is mixed at 80-100°C for 1-1.5 hours, and then vacuumed for 30-40 minutes with a vacuum degree of -0.07 MPa to obtain a rubber compound;

[0046] Mix the rubber material with the vulcanizing agent, mix at 120-130°C for 1-2 hours, and thin out the sheet to form a mixed rubber;

[0047] The mixed rubber is vulcanized at 160-170°C and 25-30MPa for 10-20 minutes, then vulcanized at 180-190°C for 2-4 hours, and cooled to room temperature to prepare a silicone rubber with thermal stability.

[0048] By adopting the above technical scheme, the silicone rubber matrix is ​​first mixed with white carbon black and the like to increase the mixing uniformity of the raw materials, and then mixed with a coupling agent and the like. The coupling agent can increase the compatibility of the silicone rubber matrix with the toughening agent and the heat stabilizer. Finally, it is mixed with a vulcanizing agent and subjected to secondary vulcanization to obtain a silicone rubber material with excellent thermal stability.

[0049] In summary, this application has the following beneficial effects:

[0050] 1. Since the present application adopts methyl vinyl silicone rubber and fluorosilicone rubber as the silicone rubber matrix, the fluorosilicone rubber has a wide temperature resistance range and contains fluorine atoms, which can improve the tear resistance and tensile resistance of the finished silicone rubber material; in addition, carboxylated PVDF nanofibers and modified metal organic framework materials are used as toughening and reinforcing agents, and the introduced carboxyl groups can react chemically with the silicone rubber matrix, and improve its dispersibility and compatibility in the silicone rubber matrix, reduce agglomeration, and enhance the mechanical strength of the silicone rubber material. ATO is loaded on the metal organic framework material, and the thermal stability is further improved; the thermal stabilizer is an active spherical silica sol, a cage-shaped oligomeric silsesquioxane grafted CeO 2 and kaolin loaded Fe 2 O 3 Cage-shaped oligomeric silsesquioxane can improve the dispersibility of cerium oxide, reduce agglomeration, and improve the mechanical strength of silicone rubber, while the loading of kaolin can also reduce the agglomeration of ferric oxide and increase its dispersibility. Cerium oxide and ferric oxide can cooperate to inhibit the oxidative cross-linking degradation reaction of silicone rubber and enhance its thermal stability.

[0051] 2. In the present application, it is preferred to use a mixture of PVDF and ethylene maleic anhydride copolymer, copper oxide and carbon nanotubes, etc., which are acidified after electrospinning to obtain carboxylated PVDF nanofibers. Copper oxide and carbon nanotubes can cooperate with each other, reduce agglomeration between each other, and are evenly dispersed in the PVDF nanofibers. When the carbon nanotubes are acidified, carboxyl groups can also be introduced on their surfaces, thereby increasing the interaction between the PVDF nanofibers and the silicone rubber and improving the thermal stability.

[0052] 3. In this application, kaolin is preferably treated with silane coupling agent KH560, and then CF 4 and N 2 The mixed gas is subjected to plasma fluorination treatment to graft CF on its surface. 2 , in order to reduce the particle size of kaolin, increase its surface roughness, improve the dispersion of particles in silicone rubber materials, increase the interfacial compatibility between the two, and at the same time increase the loading capacity of ferric oxide. DETAILED DESCRIPTION

[0053] The following examples further illustrate the present application in detail.

[0054] Preparation Examples 1-4 of Carboxylated PVDF Nanofibers

[0055] In Preparation Example 1, the Mw of PVDF is 500000, the Mw of ethylene maleic anhydride copolymer is 50000, and the carbon nanotubes are selected from Xianfeng Nano, with the product number 100252 and the serial number XFM13.

[0056] Preparation Example 1: 20 g of PVDF and ethylene maleic anhydride copolymer were mixed and added to a solvent prepared by mixing DMA and acetone in a volume ratio of 3:2, copper oxide and carbon nanotubes were added, the temperature was raised to 50°C, and stirred for 12 hours to obtain a spinning solution, wherein the amounts of copper oxide and ethylene maleic anhydride copolymer were 9 wt% and 20 wt% of the mass of PVDF, respectively, and the mass ratio of carbon nanotubes to PVDF was 0.1:1;

[0057] The spinning solution was electrospun to obtain a nanofiber membrane, which was vacuum dried at 50°C, then immersed in a 0.1 mol / l sulfuric acid solution, washed, and vacuum dried to obtain carboxylated PVDF nanofibers. The spinning voltage was 15 kV, the solution flow rate was 0.5 mL / h, and the receiving distance was 15 cm.

[0058] Preparation Example 2: 20 g of PVDF and ethylene maleic anhydride copolymer were mixed and added to a solvent prepared by mixing DMA and acetone in a volume ratio of 3:2, copper oxide and carbon nanotubes were added, the temperature was raised to 60°C, and stirred for 10 hours to obtain a spinning solution, wherein the amounts of copper oxide and ethylene maleic anhydride copolymer were 5 wt% and 15 wt% of the mass of PVDF, respectively, and the mass ratio of carbon nanotubes to PVDF was 0.01:1;

[0059] The spinning solution was electrospun to obtain a nanofiber membrane, which was vacuum dried at 60°C, then immersed in a 0.1 mol / l sulfuric acid solution, washed, and vacuum dried to obtain carboxylated PVDF nanofibers. The spinning voltage was 15 kV, the solution flow rate was 0.5 mL / h, and the receiving distance was 15 cm.

[0060] Preparation Example 3: The difference from Preparation Example 1 is that an equal amount of copper oxide is used to replace carbon nanotubes.

[0061] Preparation Example 4: The difference from Preparation Example 1 is that an equal amount of carbon nanotubes is used to replace copper oxide.

[0062] Preparation Example 5: The difference from Preparation Example 1 is that no carbon nanotubes and copper oxide are added.

[0063] Cage-shaped oligomeric silsesquioxane grafted CeO 2 Preparation Example 6-9

[0064] Preparation Example 6: 10 g CeO 2 Add to 0.1 mol / l acetic acid solution, stir at 50 °C for 4 h, filter, and dry at 60 °C to obtain acidified CeO 2 ;

[0065] Acidified CeO 2 Add to 250 ml of tetrahydrofuran, add 10 g of N,N-carbonyldiimidazole, heat to 60°C, stir for 5 hours, then add 10 g of amino cage-shaped oligomeric silsesquioxane, pass nitrogen, react at 60°C for 12 hours, filter, and vacuum dry at 60°C for 72 hours.

[0066] Preparation Example 7: 10 g CeO 2 Add to 0.1 mol / l acetic acid solution, stir at 70°C for 3 h, filter, and dry at 60°C to obtain acidified CeO 2 ;

[0067] Acidified CeO 2Add to 300 ml of tetrahydrofuran, add 10 g of N, N-carbonyldiimidazole, heat to 70°C, stir for 3 h, then add 10 g of amino cage-shaped oligomeric silsesquioxane, pass nitrogen, react at 70°C for 10 h, filter, and vacuum dry at 70°C for 72 h.

[0068] Preparation Example 8: The difference from Preparation Example 6 is that N,N-carbonyldiimidazole is not added. The specific method is as follows: 10g CeO 2 Add to 0.1 mol / l acetic acid solution, stir at 50 °C for 4 h, filter, and dry at 60 °C to obtain acidified CeO 2 ;

[0069] Acidified CeO 2 Add to 250 ml of tetrahydrofuran, heat to 60°C, stir for 5 hours, then add 10 g of amino cage-shaped oligomeric silsesquioxane, introduce nitrogen, react at 60°C for 12 hours, filter, and vacuum dry at 60°C for 72 hours.

[0070] Preparation Example 9: The difference from Preparation Example 6 is that CeO 2 Acidification was performed by adding 10 g CeO 2 Add to 250 ml of tetrahydrofuran, add 10 g of N,N-carbonyldiimidazole, heat to 60°C, stir for 5 hours, then add 10 g of amino cage-shaped oligomeric silsesquioxane, pass nitrogen, react at 60°C for 12 hours, filter, and vacuum dry at 60°C for 72 hours.

[0071] Kaolin loaded with Fe 2 O 3 Preparation Examples 10-13

[0072] Preparation Example 10: 10 g of kaolin was added to 100 g of anhydrous ethanol, and the mixture was stirred at 4500 r / min for 20 min, and then a silane coupling agent KH560 was added. The mixture was heated to 70° C., stirred for 40 min, and dried at 80° C. for 48 h to obtain modified kaolin. The mass ratio of the silane coupling agent to the kaolin was 10:1.

[0073] The modified kaolin was loaded into the reactor and vacuumed to 2.8 × 10 -3 Pa, and then filled with CF with a volume ratio of 25:1 4 and N 2 The mixed gas was used to raise the internal pressure to 10 kPa and then evacuated to 2.8 × 10 -3 Pa, and finally filled with CF with a volume ratio of 25:1 4 and N 2The mixed gas was added until the internal pressure was stabilized at 13.5 kPa, the applied voltage was 24 kV, the frequency was 9 kHz, and the kaolin was subjected to plasma fluoridation treatment for 20 minutes to obtain fluoridated kaolin;

[0074] The fluorinated kaolin was immersed in a 10% ferric nitrate solution, allowed to stand for 12 hours, then heated to 60°C, allowed to stand for 6 hours, 1 mol / l ammonia water was added to adjust the pH value to 7, then filtered, rinsed to neutrality, dried at 110°C for 12 hours, heated to 400°C under nitrogen protection, and kept at this temperature for 1 hour.

[0075] Preparation Example 11: 10 g of kaolin was added to 100 g of anhydrous ethanol, and the mixture was stirred at 4500 r / min for 20 min, and then a silane coupling agent KH560 was added. The mixture was heated to 70° C., stirred for 60 min, and dried at 80° C. for 48 h to obtain modified kaolin. The mass ratio of the silane coupling agent to the kaolin was 8:1.

[0076] The modified kaolin was loaded into the reactor and vacuumed to 2.8 × 10 -3 Pa, and then filled with CF with a volume ratio of 25:1 4 and N 2 The mixed gas was used to raise the internal pressure to 10 kPa and then evacuated to 2.8 × 10 -3 Pa, and finally filled with CF with a volume ratio of 25:1 4 and N 2 The mixed gas was added until the internal pressure was stabilized at 13.5 kPa, the applied voltage was 24 kV, the frequency was 9 kHz, and the kaolin was subjected to plasma fluoridation treatment for 15 minutes to obtain fluoridated kaolin;

[0077] The fluorinated kaolin was immersed in a 10% ferric nitrate solution, allowed to stand for 10 hours, then heated to 65°C, allowed to stand for 5 hours, 1 mol / l ammonia water was added to adjust the pH value to 7, then filtered, rinsed to neutrality, dried at 110°C for 12 hours, heated to 450°C under nitrogen protection, and kept at a constant temperature for 1.5 hours.

[0078] Preparation Example 12: The difference from Preparation Example 10 is that the kaolin is not modified by using silane coupling agent KH560, and the kaolin is directly subjected to plasma fluorination treatment. The remaining operations are the same as those of Preparation Example 10.

[0079] Preparation Example 13: The difference from Preparation Example 10 is that the modified kaolin is not subjected to plasma fluorination treatment, and the modified kaolin treated with silane coupling agent KH550 is directly immersed in the ferric nitrate solution.

[0080] Preparation Example 14 of Modified Metal-Organic Framework Material: 10 g of metal-organic framework material was soaked in 5 wt% acetic acid solution, and then filtered, washed to neutrality, dried at 60° C., and added to 90 g of deionized water, and ultrasonically homogenized to obtain a dispersion;

[0081] Tin chloride pentahydrate and antimony trichloride were mixed in a molar ratio of tin to antimony of 6:1, and then added to a 1.5 mol / l hydrochloric acid solution, and the dispersion was dropped into the mixture, and ammonia water was added at the same time. After the addition was completed, stirring was continued for 2 hours, and the mixture was filtered, washed, dried, and calcined to obtain a coating;

[0082] 1 g of the coating was added into an ethanolamine solution formed by 2 ml of ethanolamine and 500 g of deionized water, and after ultrasonication for 30 minutes, the solution was filtered, washed, and dried at 80° C. to obtain a modified metal organic framework material.

[0083] Example

[0084] Example 1: A thermally stable silica sol, the raw material dosage is as shown in Table 1, wherein the silicone rubber matrix comprises methyl vinyl silicone rubber and fluorosilicone rubber in a mass ratio of 7:3, the methyl vinyl silicone rubber is selected from Ningbo Ruichen High-tech New Materials, model 110 raw rubber, the fluorosilicone rubber is selected from Dow Corning, model LS5-2040, the hydroxy silicone oil is selected from Guangzhou Canxiang Chemical, product number Dow Corning PMX-0156, the vulcanizing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, The white carbon black is selected from Jiangsu Tianxing New Materials, the product number is TSP-L12, the coupling agent is KH550 coupling agent, the flame retardant is aluminum hydroxide, the toughening and reinforcing agent includes carboxylated PVDF nanofibers and modified metal organic framework materials in a mass ratio of 1:0.3, the carboxylated PVDF nanofibers are prepared by Preparation Example 1, the modified metal organic framework materials are prepared by Preparation Example 14, and the thermal stabilizer includes active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO in a mass ratio of 3:0.5:1.5. 2 and kaolin loaded Fe 2 O 3 The preparation method of active spherical silica sol is as follows: add silica sol to acetone, heat to 60°C, add divinyltetramethyldisilazane, stir and mix evenly, and then stand for 24 hours to make divinyltetramethyldisilazane react with hydroxyl groups on the surface of silica sol, replace hydroxyl groups with vinyl groups, and prepare active spherical silica sol, wherein the silica sol is selected from Shandong Better New Materials, model SS3015, particle size of 10-15nm, silicon dioxide content of 30±1%; cage-shaped oligomeric silsesquioxane grafted CeO 2 Prepared from Preparation Example 6, kaolin loaded with Fe 2 O 3 Prepared by Preparation Example 10.

[0085] The method for preparing the above-mentioned silicone rubber with thermal stability comprises the following steps:

[0086] The silicone rubber matrix, white carbon black and hydroxy silicone oil were mixed at 100°C for 20 minutes, a coupling agent, a toughening agent, a heat stabilizer and a flame retardant were added, mixed at 100°C for 1 hour, and then vacuumed for 30 minutes with a vacuum degree of -0.07 MPa to obtain a rubber compound;

[0087] The rubber material and the vulcanizing agent are mixed, kneaded at 120°C for 2 hours, and thinly sliced ​​to form a mixed rubber;

[0088] The mixed rubber was vulcanized at 160°C and 25MPa for 20 minutes, then vulcanized at 180°C for 4 hours, and cooled to room temperature to prepare a silicone rubber with thermal stability.

[0089] Table 1 Amount of heat-stable silicone rubber raw materials used in Examples 1-4

[0090] Raw material / kg Example 1 Example 2 Example 3 Example 4 Silicone rubber substrate 100 100 100 100 Hydroxy silicone oil 4 6 5 2 Vulcanizing agent 2 2.5 1.5 1 White Carbon Black 35 50 40 20 Coupling agent 3.5 5 2 1 Heat Stabilizer 8 10 6 5 Flame retardants 30 40 20 10 Toughening and strengthening agent 8 10 6 4

[0091] Example 2: A thermally stable silica sol, the raw material dosage is shown in Table 1, wherein the silicone rubber matrix includes methyl vinyl silicone rubber and fluorosilicone rubber in a mass ratio of 6:2.5, the methyl vinyl silicone rubber is selected from Ningbo Ruichen High-tech New Materials, model 110 raw rubber, the fluorosilicone rubber is selected from Dow Corning, model LS5-2040, the hydroxy silicone oil is selected from Guangzhou Canxiang Chemical, product number Dow Corning PMX-0156, and the vulcanizing agent is 2,4-dichlorobenzoyl peroxide The white carbon black is selected from Jiangsu Tianxing New Materials, and the product number is TSP-L12. The coupling agent is KH560 coupling agent. The flame retardant is magnesium hydroxide. The toughening and reinforcing agent includes carboxylated PVDF nanofibers and modified metal organic framework materials. The carboxylated PVDF nanofibers are prepared by Preparation Example 2, and the modified metal organic framework materials are prepared by Preparation Example 14. The thermal stabilizer includes active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO with a mass ratio of 3:0.7:2.1. 2 and kaolin loaded Fe 2 O 3 The preparation method of active spherical silica sol is as follows: add silica sol to acetone, heat to 60°C, add divinyltetramethyldisilazane, stir and mix evenly, and then stand for 24 hours to make divinyltetramethyldisilazane react with hydroxyl groups on the surface of silica sol, replace hydroxyl groups with vinyl groups, and prepare active spherical silica sol, wherein the silica sol is selected from Shandong Better New Materials, model SS3015, particle size of 10-15nm, silicon dioxide content of 30±1%; cage-shaped oligomeric silsesquioxane grafted CeO 2 Prepared from Preparation Example 7, kaolin loaded with Fe 2 O 3 Prepared by Preparation Example 11.

[0092] The method for preparing the above-mentioned silicone rubber with thermal stability comprises the following steps:

[0093] The silicone rubber matrix, white carbon black and hydroxy silicone oil were mixed at 80°C for 30 minutes, a coupling agent, a toughening agent, a heat stabilizer and a flame retardant were added, mixed at 80°C for 1 hour, and then vacuumed for 40 minutes with a vacuum degree of -0.07 MPa to obtain a rubber compound;

[0094] The rubber material and the vulcanizing agent are mixed, kneaded at 130°C for 1 hour, and thinly sliced ​​to form a mixed rubber;

[0095] The mixed rubber was vulcanized at 170°C and 30MPa for 10 minutes, then vulcanized at 190°C for 2 hours, and cooled to room temperature to prepare a silicone rubber with thermal stability.

[0096] Example 3: A thermally stable silica sol, the raw material dosage is as shown in Table 1, wherein the silicone rubber matrix comprises methyl vinyl silicone rubber and fluorosilicone rubber in a mass ratio of 7:2.5, the methyl vinyl silicone rubber is selected from Ningbo Ruichen High-tech New Materials, model 110 raw rubber, the fluorosilicone rubber is selected from Dow Corning, model LS5-2040, the hydroxy silicone oil is selected from Guangzhou Canxiang Chemical, product number Dow Corning PMX-0156, the vulcanizing agent is tert-butyl perbenzoate, and the white carbon black is selected from The product number is TSP-L12 from Jiangsu Tianxing New Materials, the coupling agent is A171 coupling agent, the flame retardant is ammonium polyphosphate, the toughening and reinforcing agent includes carboxylated PVDF nanofibers and modified metal organic framework materials in a ratio of 1:0.2, the carboxylated PVDF nanofibers are prepared by Preparation Example 1, the modified metal organic framework materials are prepared by Preparation Example 14, and the thermal stabilizer includes active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO in a mass ratio of 3:0.6:1.8. 2 and kaolin loaded Fe 2 O 3 The preparation method of active spherical silica sol is as follows: add silica sol to acetone, heat to 60°C, add divinyltetramethyldisilazane, stir and mix evenly, and then stand for 24 hours to make divinyltetramethyldisilazane react with hydroxyl groups on the surface of silica sol, replace hydroxyl groups with vinyl groups, and prepare active spherical silica sol, wherein the silica sol is selected from Shandong Better New Materials, model SS3015, particle size of 10-15nm, silicon dioxide content of 30±1%; cage-shaped oligomeric silsesquioxane grafted CeO 2 Prepared from Preparation Example 6, kaolin loaded with Fe 2 O 3 Prepared by Preparation Example 11.

[0097] The method for preparing the above-mentioned silicone rubber with thermal stability comprises the following steps:

[0098] The silicone rubber matrix, white carbon black and hydroxy silicone oil were mixed at 90°C for 25 minutes, a coupling agent, a toughening agent, a heat stabilizer and a flame retardant were added, mixed at 100°C for 1 hour, and then vacuumed for 35 minutes with a vacuum degree of -0.07 MPa to obtain a rubber compound;

[0099] The rubber material and the vulcanizing agent are mixed, kneaded at 125°C for 1.5 hours, and thinly sliced ​​to form a mixed rubber;

[0100] The mixed rubber was vulcanized at 165°C and 30 MPa for 15 minutes, then vulcanized at 185°C for 3 hours, and cooled to room temperature to prepare a silicone rubber with thermal stability.

[0101] Example 4: A silicone rubber with thermal stability, which is different from Example 1 in that the amounts of raw materials used are as shown in Table 1.

[0102] Example 5: A silicone rubber with thermal stability, which is different from Example 1 in that the thermal stabilizer comprises active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO in a mass ratio of 3:0.5:2. 2 and kaolin loaded Fe 2 O 3 .

[0103] Example 6: A silicone rubber with thermal stability, which is different from Example 1 in that the carboxylated PVDF nanofibers are made from Preparation Example 3.

[0104] Example 7: A silicone rubber with thermal stability, which is different from Example 1 in that the carboxylated PVDF nanofibers are made from Preparation Example 4.

[0105] Example 8: A silicone rubber with thermal stability, which is different from Example 1 in that the carboxylated PVDF nanofibers are made from Preparation Example 5.

[0106] Example 9: A thermally stable silicone rubber, which is different from Example 1 in that a cage-shaped oligomeric silsesquioxane is grafted with CeO 2 Prepared by Preparation Example 8.

[0107] Example 10: A thermally stable silicone rubber, which is different from Example 1 in that a cage-shaped oligomeric silsesquioxane is grafted with CeO 2 Prepared by Preparation Example 9.

[0108] Example 11: A thermally stable silicone rubber, which differs from Example 1 in that kaolin loaded Fe 2 O 3 Prepared by Preparation Example 12.

[0109] Example 12: A thermally stable silicone rubber, which differs from Example 1 in that kaolin loaded Fe 2 O 3 Prepared by Preparation Example 13.

[0110] Comparative Example

[0111] Comparative Example 1: A silicone rubber with thermal stability, which is different from Example 1 in that the thermal stabilizer includes active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO in a mass ratio of 3:0.5:1. 2 and kaolin loaded Fe 2 O 3 .

[0112] Comparative Example 2: A silicone rubber with thermal stability, which is different from Example 1 in that the thermal stabilizer comprises active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO in a mass ratio of 3:0.5:3. 2 and kaolin loaded Fe 2 O 3 .

[0113] Comparative Example 3: A silicone rubber with thermal stability, which differs from Example 1 in that no toughening and reinforcing agent is added.

[0114] Comparative Example 4: A silicone rubber with thermal stability, which is different from Example 1 in that the thermal stabilizer is nano-alumina.

[0115] Comparative Example 5: A silicone rubber with thermal stability, which is different from Example 1 in that the thermal stabilizer includes active spherical silica sol, CeO 2 and kaolin loaded Fe 2 O 3 .

[0116] Comparative Example 6: A silicone rubber with thermal stability, which is different from Example 1 in that the thermal stabilizer comprises active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO in a mass ratio of 3:0.5:1.5. 2 and Fe 2 O 3 .

[0117] Comparative Example 7: A silicone rubber with thermal stability, which is different from Example 1 in that a cage-shaped oligomeric silsesquioxane is used as a thermal stabilizer to graft CeO 2 Equal amount of kaolin replacement loading Fe 2 O 3 , that is, the thermal stabilizer includes active spherical silica sol and cage-shaped oligomeric silsesquioxane grafted CeO in a mass ratio of 3:2 2 .

[0118] Comparative Example 8: A silicone rubber with thermal stability, which differs from Example 1 in that kaolin is used as a thermal stabilizer to load Fe 2 O 3 Equal amount of substitution of cage-shaped oligomeric silsesquioxane to graft CeO 2 , that is, the heat stabilizer includes active spherical silica sol and kaolin loaded Fe in a mass ratio of 3:2 2 O 3 .

[0119] Comparative Example 9: A silicone rubber with thermal stability, which is different from Example 1 in that the thermal stabilizer comprises active spherical silica sol, CeO 2 and Fe 2 O 3 .

[0120] Comparative Example 10: A silicone rubber with thermal stability, which differs from Example 1 in that an equal amount of carboxylated PVDF nanofibers is used in the toughening and toughening agent to replace the modified metal organic framework material.

[0121] Performance testing

[0122] Silicone rubber materials were prepared according to the methods in the examples and comparative examples, and performance tests were performed according to the following methods. The test results are recorded in Table 2.

[0123] 1. Tensile strength and elongation at break: Tested in accordance with GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", with a tensile rate of 500 mm / min.

[0124] 2. Tear strength: Test in accordance with GB / T529-2008 "Determination of tear strength of vulcanized rubber or thermoplastic rubber (trouser-type, right-angled and crescent-shaped specimens)" at a rate of 500 mm / min.

[0125] 3. Thermal oxidation resistance: Place the silicone rubber sample in an electric blast drying oven and age it at 300°C for 12 hours to obtain the sample after thermal oxidation aging. Test its tensile strength again and calculate the decrease rate (%) of tensile strength according to the following formula: (initial tensile strength - tensile strength after aging) / initial tensile strength × 100.

[0126] Table 2 Test results of thermally stable silicone rubber properties

[0127]

[0128]

[0129] Combining the raw material ratios and selections in Examples 1-4, and the test data in Table 2, it can be seen that the silicone rubber materials prepared in Examples 1-4 have high initial tensile strength and elongation at break, high mechanical strength, and after thermal oxidation at 300°C for 12 hours, the tensile strength decrease rate is maintained within 10%, having strong resistance to thermal oxidation and strong thermal stability.

[0130] Example 5 Compared with Example 1, kaolin loaded Fe 2 O 3 The dosage is cage-shaped oligomeric silsesquioxane grafted CeO 2 The amount of kaolin was 4 times that of FeO2, and the initial tensile strength, elongation at break and tear strength of the silicone rubber material prepared in Example 5 decreased slightly, and the tensile strength decreased significantly after aging, exceeding 10%, indicating that the kaolin loaded Fe 2 O 3 The dosage is cage-shaped oligomeric silsesquioxane grafted CeO 2 3 times more effective in anti-aging protection.

[0131] Compared with Example 1, Example 6 uses the carboxylated PVDF nanofibers prepared in Preparation Example 3. Compared with Preparation Example 1, an equal amount of copper oxide is used to replace the carbon nanotubes. The mechanical strength of the silicone rubber material prepared in Example 6 is reduced, and its anti-aging ability is reduced, and its thermal stability is deteriorated.

[0132] In Example 7, the carboxylated PVDF nanofibers prepared in Preparation Example 4 were used. In Preparation Example 4, an equal amount of carbon nanotubes were used to replace copper oxide. It can be seen that the thermal aging resistance thereof decreased and the thermal stability became worse.

[0133] In Example 8, the carboxylated PVDF nanofibers prepared in Preparation Example 5 were used, and no carbon nanotubes and copper oxide were added in Preparation Example 5. Compared with Example 1, the thermal aging ability of the silicone rubber prepared in Example 8 was significantly reduced.

[0134] In Example 9, the cage-shaped oligomeric silsesquioxane prepared in Preparation Example 8 was used to graft CeO 2 Compared with Example 6 in Example 1, no N,N-carbonyldiimidazole was added, so the amino-modified cage-shaped oligomeric silsesquioxane could not be grafted onto the acidified CeO 2 Therefore, its heat aging resistance decreases and its thermal stability weakens.

[0135] In Example 10, the cage-shaped oligomeric silsesquioxane prepared in Preparation Example 9 was used to graft CeO 2 Compared with Preparation Example 6, no 2 After acidification, it can be seen that the mechanical strength and other properties of the silicone rubber material prepared are quite different from those in Example 1, but are similar to the properties of the silicone rubber prepared in Example 9 without adding N,N-carbonyldiimidazole.

[0136] Example 11 Compared with Example 1, the kaolin prepared in Preparation Example 12 was used to load Fe 2 O 3 Compared with Preparation Example 10 in Example 1, Preparation Example 12 did not use silane coupling agent KH550 to pretreat kaolin, and in Example 12, kaolin prepared in Preparation Example 13 was used to load Fe 2 O 3 , the modified kaolin was not subjected to plasma fluorination treatment. Table 2 shows that the heat aging resistance of the silicone rubber materials prepared in Examples 11 and 12 is significantly reduced.

[0137] In Comparative Example 1 and Comparative Example 2, the kaolin loading Fe was reduced and increased respectively. 2 O 3 The data in Table 2 show that compared with Example 1 and Example 5, the mechanical strength of the silicone rubber materials prepared in Comparative Examples 1 and 2 is significantly reduced, and after thermal aging, the tensile strength decreases significantly.

[0138] Compared with Example 1, Comparative Example 3 does not add a toughening agent. It can be seen that the tensile and tear strengths of the silicone rubber material prepared in Comparative Example 3 are reduced, and after thermal oxidation, the tensile strength decreases significantly, and the thermal stability is weakened.

[0139] In Comparative Example 4, nano-alumina was used as a heat stabilizer. Compared with Example 1, the thermal oxidation resistance of the silicone rubber material prepared thereby decreased significantly, and the improvement effect on the initial tensile strength, elongation at break and tear strength of the silicone rubber was poor.

[0140] In Comparative Example 5, cerium oxide was used to replace cage-shaped oligomeric silsesquioxane to graft CeO 2 In Comparative Example 6, Fe 2 O 3 Replace kaolin to load Fe 2 O 3 The initial tensile and tear resistance of the silicone rubber materials prepared in Comparative Examples 5 and 6 are weakened, and the heat aging resistance is weakened.

[0141] In Comparative Example 7, active spherical silica sol and cage-shaped oligomeric silsesquioxane grafted CeO with a mass ratio of 3:2 were used. 2 As a thermal stabilizer, active spherical silica sol and kaolin loaded Fe in a mass ratio of 3:2 were used in Comparative Example 8. 2 O 3 The data in Table 2 show that the anti-aging ability of silicone rubber prepared in Comparative Examples 7 and 8 is reduced, indicating that the cage-shaped oligomeric silsesquioxane grafted CeO 2 and kaolin loaded Fe 2 O 3The combined effect is beneficial to the improvement of anti-aging performance; in Comparative Example 9, only active spherical silica sol, CeO 2 and Fe 2 O 3 As a heat stabilizer, it can be seen that its thermal stability decreases most significantly.

[0142] In Comparative Example 10, only carboxylated PVDF nanofibers are used as toughening and reinforcing agents. It can be seen that after thermal aging, the tensile strength and the reduction rate of the silicone rubber decrease significantly.

[0143] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A silicone rubber having thermal stability, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of silicone rubber matrix, 2-6 parts of hydroxy silicone oil, 1-2.5 parts of vulcanizing agent, 20-50 parts of white carbon black, 1-5 parts of coupling agent, 5-10 parts of heat stabilizer, 10-40 parts of flame retardant, 4-10 parts of toughening and reinforcing agent; The silicone rubber matrix comprises methyl vinyl silicone rubber and fluorosilicone rubber in a mass ratio of 6-7:2.5-3; The heat stabilizer comprises active spherical silica sol, cage-shaped oligomeric silsesquioxane grafted CeO2 and kaolin-loaded Fe2O3 in a mass ratio of 3:0.5-0.7:1.5-2.1; The toughening and reinforcing agent comprises carboxylated PVDF nanofibers and modified metal organic framework materials in a mass ratio of 1:0.1-0.

3.

2. The heat-stable silicone rubber according to claim 1, characterized in that: The method for preparing the carboxylated PVDF nanofiber comprises the following steps: PVDF and ethylene maleic anhydride copolymer are mixed, added to a solvent prepared by mixing DMA and acetone in a volume ratio of 3:2, copper oxide is added, the temperature is raised to 50-60° C., and stirred for 10-12 hours to obtain a spinning solution, wherein the amounts of copper oxide and ethylene maleic anhydride copolymer are 5-9wt% and 15-20wt% of the mass of PVDF, respectively; The spinning solution is subjected to electrostatic spinning to obtain a nanofiber membrane, which is vacuum dried at 50-60° C., then immersed in a sulfuric acid solution, washed, and vacuum dried to obtain a carboxylated PVDF nanofiber.

3. The heat-stable silicone rubber according to claim 2, characterized in that: Carbon nanotubes are also added to the spinning solution, and the amount of the carbon nanotubes and PVDF is 0.01-0.1:

1.

4. The heat-stable silicone rubber according to claim 1, characterized in that: The preparation method of the cage-shaped oligomeric silsesquioxane grafted CeO2 is as follows: Add CeO2 to acetic acid solution, stir at 50-70°C for 3-4h, filter, and dry to obtain acidified CeO2; Add acidified CeO2 to tetrahydrofuran, add N,N-carbonyldiimidazole, heat to 60-70°C, stir for 3-5h, then add amino cage-shaped oligomeric silsesquioxane, pass nitrogen, react at 60-70°C for 10-12h, filter, and vacuum dry at 60-70°C.

5. The heat-stable silicone rubber according to claim 1, characterized in that: The kaolin-loaded Fe2O3 is prepared by the following method: Add kaolin to anhydrous ethanol, stir evenly, add silane coupling agent KH560, continue stirring for 40-60 minutes, dry to obtain modified kaolin, the mass ratio of silane coupling agent to kaolin is 8-10:1; Using CF4 and N2 with a volume ratio of 25:1 as a mixed gas, the kaolin is subjected to plasma fluoridation treatment for 15-20 minutes to obtain fluoridated kaolin; The fluorinated kaolin is immersed in a 10% ferric nitrate solution, allowed to stand for 10-12 hours, then heated to 60-65°C, allowed to stand for 5-6 hours, the pH value is adjusted to produce precipitation, then filtered and washed to neutrality, dried, and heated to 400-450°C under nitrogen protection, and kept at a constant temperature for 1-1.5 hours.

6. The heat-stable silicone rubber according to claim 5, characterized in that: The specific method of plasma fluorination treatment is: put the modified kaolin into the reactor, evacuate to 2.8×10 -3 Pa, then fill with a mixture of CF4 and N2 to raise the internal pressure to 10 kPa, and evacuate again to 2.8 × 10 -3 Pa, and finally filled with a mixture of CF4 and N2 until the internal gas pressure stabilized at 13.5kPa, the applied voltage was 24kv, and the frequency was 9kHz.

7. The heat-stable silicone rubber according to claim 1, characterized in that: The vulcanizing agent is any one of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,4-dichlorobenzoyl peroxide or tert-butyl perbenzoate; The flame retardant is selected from at least one of ammonium polyphosphate, magnesium hydroxide and aluminum hydroxide; The coupling agent is selected from at least one of A151 coupling agent, A171 coupling agent, KH550 coupling agent and KH560 coupling agent.

8. The method for preparing the heat-stable silicone rubber according to any one of claims 1 to 7, characterized in that: The following steps are involved: The silicone rubber matrix, white carbon black and hydroxy silicone oil are mixed at 80-100°C for 20-30 minutes, a coupling agent, a toughening agent, a heat stabilizer and a flame retardant are added, and the mixture is mixed at 80-100°C for 1-1.5 hours, and then vacuumed for 30-40 minutes with a vacuum degree of -0.07 MPa to obtain a rubber compound; Mix the rubber material with the vulcanizing agent, mix at 120-130°C for 1-2 hours, and thin out the sheet to form a mixed rubber; The mixed rubber is vulcanized at 160-170°C and 25-30MPa for 10-20 minutes, then vulcanized at 180-190°C for 2-4 hours, and cooled to room temperature to prepare a silicone rubber with thermal stability.

Images