A sericite modified silicone rubber material and a preparation method thereof
By modifying sericite and employing in-situ ring-opening polymerization and gradient temperature-controlled vulcanization processes, an interpenetrating network structure was constructed, solving the problem of poor compatibility between sericite and the organosilicon matrix, and achieving a synergistic improvement in the high strength, oil resistance, and heat resistance of silicone rubber materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHUZHOU WANQIAO SERICITE CO LTD
- Filing Date
- 2025-12-23
- Publication Date
- 2026-06-23
AI Technical Summary
Traditional silicone rubber materials have shortcomings in enhancing filler dispersibility and oil and heat resistance. In particular, the poor compatibility between sericite and organosilicon matrix leads to a decline in mechanical properties and phase separation, making it impossible to achieve synergistic performance improvement.
Fluorinated long-chain silanes and vinyl silanes were used to modify sericite. Polysiloxane segments were generated on the surface of sericite through in-situ ring-opening polymerization. These segments were then blended with fluorosilicone raw rubber, methylphenyl vinyl silicone rubber and MQ silicone resin to construct an interpenetrating network structure. Combined with a gradient temperature-controlled vulcanization process, uniform dispersion and synergistic reinforcement of sericite in a silicone rubber matrix were achieved.
It significantly improves the overall structural uniformity and mechanical properties of the material, enhances its resistance to solvent penetration, oil, and heat, and solves the shortcomings of traditional silicone rubber materials in terms of enhancing filler dispersion and oil and heat resistance.
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Figure CN121592185B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of silicone rubber materials technology, specifically to a sericite-modified silicone rubber material and its preparation method. Background Technology
[0002] Due to its unique silicon-oxygen bond backbone structure, silicone rubber possesses excellent resistance to high and low temperatures, electrical insulation, and weather resistance, making it widely used in aerospace, automotive manufacturing, and electronic packaging. However, with the ever-increasing performance requirements of modern industry for specialty rubber materials, traditional silicone rubber faces two major technical bottlenecks in practical applications:
[0003] Firstly, the intermolecular forces in pure silicone rubber are weak, requiring reinforcing fillers to improve its strength. Sericite, as a natural layered silicate mineral, possesses excellent insulation and barrier properties, making it an ideal filler. However, sericite's surface is rich in hydrophilic hydroxyl groups, resulting in extremely poor compatibility with the hydrophobic organosilicon matrix. Direct filling easily leads to agglomeration, not only failing to provide reinforcement but also becoming stress concentration points, causing a decline in the material's mechanical properties. Therefore, how to disperse sericite within the silicone rubber matrix and establish a stable interfacial bond is a problem that urgently needs to be solved.
[0004] Secondly, ordinary methyl vinyl silicone rubber has poor oil resistance and easily swells in fuel oil or lubricating oil; while fluorosilicone raw rubber is oil-resistant, it is expensive and its heat resistance is not as good as phenyl silicone rubber; methyl phenyl silicone rubber has good heat resistance, but its oil resistance is average. In actual preparation, when fluorosilicone raw rubber, methyl phenyl silicone rubber and general silicone rubber are blended, phase separation easily occurs due to the huge difference in surface energy, resulting in an uneven microstructure of the vulcanized silicone rubber, and the properties cannot be superimposed or even cancel each other out.
[0005] Therefore, developing a silicone rubber material that can synergistically improve oil resistance, heat resistance, and mechanical properties is particularly important. To this end, a sericite-modified silicone rubber material and its preparation method are proposed. Summary of the Invention
[0006] The purpose of this invention is to provide a sericite-modified silicone rubber material and its preparation method.
[0007] To achieve the above objectives, the present invention provides the following technical solution:
[0008] Unless otherwise specified, all parts in this invention are by weight.
[0009] This invention provides a method for preparing sericite-modified silicone rubber material, the method being as follows: Dimethylcyclosiloxane, octamethylcyclotetrasiloxane, modified sericite, and a vinyl end-capping agent are subjected to a ring-opening polymerization reaction to obtain a polysiloxane hybrid base rubber; 100 parts of the polysiloxane hybrid base rubber are placed in a kneader as the matrix polymer, and 30-45 parts of fluorosilicone raw rubber, 15-25 parts of methylphenyl vinyl silicone rubber, and 5-15 parts of MQ silicone resin are added sequentially, controlling the kneader temperature at 130-150℃ and the stirring speed at 40 r / s. After kneading for 2 hours, a silicone rubber compound is obtained. During this process, the fluorinated groups on the surface of the modified sericite are compatible with the fluorosilicone raw rubber, the vinyl groups co-crosslink with the base rubber and MQ resin, and the methylphenyl vinyl silicone rubber provides the heat-resistant phase. After the silicone rubber compound cools to room temperature, 3 parts of hydrogen-containing silicone oil (as a crosslinking regulator) and 2 parts of vulcanizing agent 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane are added to the open mill and passed through it 5 times to obtain the mixed silicone rubber. The mixed silicone rubber is placed in a mold for vulcanization to obtain the sericite modified silicone rubber material.
[0010] Fluorosilicone raw rubber, methyl phenyl vinyl silicone rubber, and MQ silicone resin were all purchased from Anhui Aiyota Silicone Oil Co., Ltd.; the fluorosilicone raw rubber had a molecular weight of 600,000, a vinyl content of 0.3 mol%, and a volatile content of less than 1.0%; the methyl phenyl vinyl silicone rubber was IOTA 3120, with a molecular weight of 600,000, a phenyl content of 20 mol%-25 mol%, and a vinyl content of 0.13 mol%-0.15 mol%; the MQ silicone resin was IOTA AM, with an M:Q molar ratio of 0.7:1 and a vinyl content of 2.0 mol%.
[0011] The preferred method for preparing the polysiloxane hybrid base adhesive is as follows: In a reactor equipped with a stirrer, condenser, and thermometer, 100 parts of dimethylcyclosiloxane and 50 parts of octamethylcyclotetrasiloxane, 20 parts of modified sericite, and 0.5 parts of vinyl end-capping agent 1,3-divinyltetramethyldisiloxane are added. The mixture is dispersed for 30 min at a high-shear disperser at 3000 rpm to ensure that the sericite is uniformly suspended in the monomer. Nitrogen gas is introduced to replace the air, and the temperature is raised to 110°C. 0.1 parts of the catalyst tetramethylammonium hydroxide are added, and the mixture is dehydrated for 30 min under a vacuum of -0.09 MPa. The temperature is raised to 120°C to carry out a ring-opening polymerization reaction, with the stirring speed controlled at 60 rpm, and the reaction is carried out for 5-8 h. After the reaction is completed, the temperature is raised to 170°C and held for 45 min to destroy the catalyst. Then, the mixture is evacuated under a vacuum of -0.098 MPa for 2 h to remove low molecular weight substances and catalyst decomposition products. After cooling, the polysiloxane hybrid base adhesive is obtained.
[0012] Preferred method for preparing modified sericite is as follows: 1250-mesh sericite powder is placed in a high-temperature furnace and calcined at 600°C for 2 hours to obtain activated sericite; the activated sericite is added to a high-speed mixer, along with 200 parts of 95wt% ethanol aqueous solution, heated to 70°C, stirred at 1500 rpm, and 5 parts of modifier are added, with the stirring speed increased to 2500 rpm for 4 hours; after the reaction is complete, the mixture is filtered, washed, and vacuum dried at 120°C for 6 hours to obtain modified sericite.
[0013] Preferably, the modifier is composed of perfluorooctyltriethoxysilane and vinyltrimethoxysilane; the mass ratio of the two is 1.5-4:1.
[0014] Preferably, the hydrogen-containing silicone oil is a mixture of end-hydrogen-containing silicone oil with a hydrogen content of 0.1%-0.3% and side-hydrogen-containing silicone oil with a hydrogen content of 1.0%-1.5% at a mass ratio of 1:1; the end-hydrogen-containing silicone oil is hydrogen-capped end-hydrogen polydimethylsiloxane (CAS: 70900-21-9), and the side-hydrogen-containing silicone oil is polymethylhydrosiloxane (CAS: 63148-57-2).
[0015] Preferably, the vulcanization molding includes a first-stage vulcanization and a second-stage vulcanization; the first-stage vulcanization temperature is 170℃, the pressure is 10MPa, and the time is 10min; the second-stage vulcanization is to treat in an oven at 220-250℃ for 4h.
[0016] Another aspect of the present invention provides a sericite-modified silicone rubber material, which is prepared by any of the above preparation methods; the raw materials for preparing the sericite-modified silicone rubber material include polysiloxane hybrid base rubber, fluorosilicone raw rubber, methylphenyl vinyl silicone rubber, MQ silicone resin, hydrogen-containing silicone oil and vulcanizing agent.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0018] 1. This invention modifies the surface properties of inorganic fillers by using fluorinated long-chain silanes and vinyl silanes to perform bifunctional composite modification on sericite. The introduction of fluorinated groups endows the sericite surface with unique fluorinophilic properties, enabling it to act as a physical anchor for the directional adsorption of fluorosilicone raw rubber phases; while the vinyl groups can chemically crosslink with the matrix silicone rubber and methylphenyl vinyl silicone rubber. This design makes the modified sericite a "composting bridge" connecting the fluorosilicone raw rubber phase and the general silicone rubber phase, effectively overcoming the defects of weak interfacial bonding between inorganic fillers and organic matrices and the easy macroscopic phase separation between rubber components of different polarities, thus significantly improving the overall structural uniformity of the material.
[0019] 2. This invention abandons the traditional physical blending filling process and adopts monomer in-situ ring-opening polymerization coating technology. During the polymerization of dimethylcyclosiloxane and octamethylcyclotetrasiloxane to form a polymer, polysiloxane segments grow directly on the surface of modified sericite. This process avoids the problems of filler dispersion and secondary agglomeration in high viscosity systems, and realizes single-layer or few-layer peeling dispersion of sericite in silicone rubber matrix. Due to the high orientation and dense arrangement of sericite layers, the penetration path of solvent molecules is significantly extended, thus endowing the material with excellent solvent penetration resistance.
[0020] 3. This invention utilizes the rigid spherical structure of MQ silicone resin and the two-dimensional layered structure of sericite to construct a synergistic reinforcement system within vulcanized silicone rubber. MQ silicone resin, acting as a rigid crosslinking center, significantly enhances the tensile strength of the material; while the layered sericite, through its high aspect ratio, bears and disperses stress in the matrix, effectively preventing crack propagation. The synergistic effect of these two components eliminates the drawback of excessively high modulus leading to brittleness caused by single filler reinforcement, resulting in silicone rubber that maintains high mechanical strength while also possessing excellent elongation at break and tear resistance.
[0021] 4. This invention combines the oil resistance of fluorosilicone raw rubber and the heat resistance of methylphenyl vinyl silicone rubber through multiphase blending and the construction of an interpenetrating network. Fluorine chains on the modified sericite surface adsorb fluorosilicone raw rubber, while siloxane chains adsorb phenylsilane and the base rubber, forming an interpenetrating network structure during the mixing process: fluorosilicone segments are enriched at the micro-phase interface, effectively preventing fuel swelling; while methylphenyl segments and the main-chain siloxane constitute a high-temperature resistant skeleton, achieving a balance between heat resistance and oil resistance.
[0022] 5. This invention introduces hydrogen-containing silicone oil as a chain extender and, in conjunction with a gradient temperature-controlled vulcanization process, effectively regulates the vulcanization reaction kinetics. The chain-extending effect of the hydrogen-containing silicone oil imparts higher flexibility to the molecular chains, while the gradient temperature vulcanization strategy allows the material to first form a uniform main network at a low temperature, and then complete deep cross-linking and phenyl curing at a high temperature. This process effectively releases the curing internal stress caused by the introduction of a large amount of inorganic filler (sericite) and the difference in the multiphase thermal expansion coefficients, significantly reducing the generation of microcracks inside the material. Attached Figure Description
[0023] Figure 1 The graph shows the tensile strength retention rate test results in the heat aging performance tests of Examples 1-4 and Comparative Examples 6 and 9-12 of the present invention. Detailed Implementation
[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] Please see Figure 1 This invention provides a sericite-modified silicone rubber material and its preparation method, the technical solution of which is as follows:
[0026] Example 1
[0027] 1250-mesh sericite powder was placed in a high-temperature furnace and calcined at 600°C for 2 hours to obtain activated sericite. The activated sericite was then added to a high-speed mixer along with 200 parts of 95wt% ethanol aqueous solution. The mixture was heated to 70°C, stirred at 1500 rpm, and 5 parts of a modifier were added. The stirring speed was increased to 2500 rpm, and the reaction was carried out for 4 hours. After the reaction, the mixture was filtered, washed, and vacuum dried at 120°C for 6 hours to obtain modified sericite. In a reaction vessel equipped with a stirrer, condenser, and thermometer, 100 parts of dimethylcyclosiloxane and 50 parts of octamethylcyclotetrasiloxane, 20 parts of modified sericite, and 0.5 parts of the vinyl end-capping agent 1,3-diethylene were added. Tetramethyldisiloxane was dispersed in a high-shear disperser at 3000 rpm for 30 min; nitrogen was introduced to replace the air, the temperature was raised to 110 °C, 0.1 parts of the catalyst tetramethylammonium hydroxide were added, and the mixture was dehydrated under a vacuum of -0.09 MPa for 30 min; the temperature was raised to 120 °C for ring-opening polymerization, the stirring speed was controlled at 60 rpm, and the reaction was carried out for 5 h; after the reaction was completed, the temperature was raised to 170 °C and held for 45 min to destroy the catalyst, and then the mixture was evacuated under a vacuum of -0.098 MPa for 2 h. After cooling, a polysiloxane hybrid base gel was obtained; the modifier was composed of perfluorooctyltriethoxysilane and vinyltrimethoxysilane in a mass ratio of 1.5:1.
[0028] 100 parts of polysiloxane hybrid base rubber were placed in a kneader as the matrix polymer, and 30 parts of fluorosilicone raw rubber, 15 parts of methylphenyl vinyl silicone rubber and 5 parts of MQ silicone resin were added sequentially. The kneader temperature was controlled at 130℃ and the stirring speed at 40 rpm. Kneading was carried out for 2 hours to obtain silicone rubber compound. After the silicone rubber compound cooled to room temperature, 3 parts of hydrogen-containing silicone oil and 2 parts of vulcanizing agent 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane were added to a two-roll mill and passed through it 5 times to obtain mixed silicone rubber. The mixed silicone rubber was placed in a mold and vulcanized for 10 minutes at 170℃ and 10 MPa. Then, it was treated in an oven at 220℃ for 4 hours for a second vulcanization to obtain sericite modified silicone rubber material. The hydrogen-containing silicone oil was a mixture of end-hydrogen-containing silicone oil with a hydrogen content of 0.1% and side-hydrogen-containing silicone oil with a hydrogen content of 1.0% at a mass ratio of 1:1.
[0029] Example 2
[0030] Referring to the preparation method and parameters of Example 1, the difference is that when preparing modified sericite, the modifier is composed of perfluorooctyltriethoxysilane and vinyltrimethoxysilane in a mass ratio of 2.5:1; when preparing polysiloxane hybrid rubber, the ring-opening polymerization reaction time is 6 hours; when preparing sericite modified silicone rubber material, the amount of fluorosilicone raw rubber is 35 parts, the amount of methylphenyl vinyl silicone rubber is 18 parts, the amount of MQ silicone resin is 7 parts, the kneader temperature is 135°C, the two-stage vulcanization temperature is 230°C, and the hydrogen-containing silicone oil is a mixture of end-hydrogen-containing silicone oil with a hydrogen content of 0.3% and side-hydrogen-containing silicone oil with a hydrogen content of 1.0% in a mass ratio of 1:1.
[0031] Example 3
[0032] Referring to the preparation method and parameters of Example 1, the difference is that when preparing modified sericite, the modifier is composed of perfluorooctyltriethoxysilane and vinyltrimethoxysilane in a mass ratio of 3:1; when preparing polysiloxane hybrid rubber, the ring-opening polymerization reaction time is 7 hours; when preparing sericite modified silicone rubber material, the amount of fluorosilicone raw rubber is 40 parts, the amount of methylphenyl vinyl silicone rubber is 22 parts, the amount of MQ silicone resin is 11 parts, the kneader temperature is 140°C, the two-stage vulcanization temperature is 240°C, and the hydrogen-containing silicone oil is a mixture of end-hydrogen-containing silicone oil with a hydrogen content of 0.2% and side-hydrogen-containing silicone oil with a hydrogen content of 1.2% in a mass ratio of 1:1.
[0033] Example 4
[0034] Referring to the preparation method and parameters of Example 1, the difference is that when preparing modified sericite, the modifier is composed of perfluorooctyltriethoxysilane and vinyltrimethoxysilane in a mass ratio of 4:1; when preparing polysiloxane hybrid rubber, the ring-opening polymerization reaction time is 8 hours; when preparing sericite modified silicone rubber material, the amount of fluorosilicone raw rubber is 45 parts, the amount of methylphenyl vinyl silicone rubber is 25 parts, the amount of MQ silicone resin is 15 parts, the kneader temperature is 150°C, the two-stage vulcanization temperature is 250°C, and the hydrogen-containing silicone oil is a mixture of end-hydrogen-containing silicone oil with a hydrogen content of 0.3%-1.5% and side-hydrogen-containing silicone oil with a hydrogen content of 1.0%-1.5% in a mass ratio of 1:1.
[0035] Comparative Example 1
[0036] The preparation method and parameters were the same as in Example 1, except that the sericite was not modified.
[0037] Comparative Example 2
[0038] The preparation method and parameters are the same as in Example 1, except that the sericite is modified only with vinylsilane and no fluorinated silane is used.
[0039] Comparative Example 3
[0040] The preparation method and parameters of Example 1 are the same, except that in-situ polymerization is not performed. Instead, the modified sericite is directly physically mixed with dimethylcyclosiloxane and octamethylcyclotetrasiloxane in a kneader.
[0041] Comparative Example 4
[0042] The preparation method and parameters of Example 1 are the same, except that the modified sericite is directly mixed with other components in a kneader.
[0043] Comparative Example 5
[0044] The preparation method and parameters of Example 1 are the same, except that octamethylcyclotetrasiloxane was not added when preparing the hybrid base gel.
[0045] Comparative Example 6
[0046] The preparation method and parameters of Example 1 are the same, except that methylphenyl vinyl silicone rubber is not added.
[0047] Comparative Example 7
[0048] The preparation method and parameters are the same as in Example 1, except that no fluorosilicone raw rubber is added.
[0049] Comparative Example 8
[0050] The preparation method and parameters were the same as in Example 1, except that MQ resin was not added.
[0051] Comparative Example 9
[0052] The preparation method and parameters are the same as in Example 1, except that the hydrogen-containing silicone oil is only a side-hydrogen-containing silicone oil.
[0053] Comparative Example 10
[0054] The preparation method and parameters are the same as in Example 1, except that the hydrogen-containing silicone oil is only an end-hydrogen-containing silicone oil.
[0055] Comparative Example 11
[0056] The preparation method and parameters are the same as in Example 1, except that no hydrogen-containing silicone oil is added.
[0057] Comparative Example 12
[0058] The preparation method and parameters are the same as in Example 1, except that two-stage vulcanization is not performed.
[0059] Experimental Example 1: Mechanical Property Testing
[0060] Tensile strength and elongation at break: according to GB / T 528-2009, tensile speed 500 mm / min;
[0061] Tear strength: According to GB / T 529-2008, a right-angled specimen is used;
[0062] Hardness: According to GB / T 531.1-2008, a Shore A hardness tester was used;
[0063] The results are shown in Table 1.
[0064] Table 1 Mechanical property tests of Examples 1-4 and Comparative Examples 1-5 and 8-10
[0065]
[0066] As shown in Table 1, in Examples 1-4, the in-situ polymerization and three-dimensional network construction significantly improved the overall mechanical properties of the materials. First, the in-situ ring-opening polymerization process induced the direct growth of polysiloxane molecular chains on the surface of vinyl-modified sericite, forming a strong chemical bond structure. This interfacial bonding force is far stronger than physical adsorption, effectively transferring stress and preventing interfacial debonding during stretching. Second, the introduction of rigid spherical MQ silicone resin and layered sericite constructed a "point-surface" synergistic reinforcement system, significantly improving tear resistance. Finally, by compounding high / low hydrogen-containing silicone oils, the crosslinking density and molecular chain flexibility were precisely controlled, ensuring high modulus and hardness while imparting excellent elongation at break, resolving the contradiction between high strength and high toughness. The resulting modified silicone rubber had a tensile strength of 10.0-11.2 MPa, an elongation at break of 450%-520%, a tear strength of 32-38 kN / m, and a Shore A hardness of 57-68. In Comparative Example 1, the sericite was not modified. The unmodified sericite surface is rich in hydrophilic hydroxyl groups, resulting in extremely poor compatibility with the hydrophobic organosilicon matrix. Within the matrix, the sericite severely agglomerates, failing to transfer stress and instead becoming stress concentration points, leading to brittle fracture even under low stress. In Comparative Example 2, the sericite was modified only with vinyl silane. Although vinyl groups achieved chemical bonding between the filler and the base adhesive, the lack of fluorine-containing groups resulted in weak interfacial bonding between the sericite and the fluorosilicone raw adhesive phase. During stretching, microscopic debonding easily occurred at the interface between the fluorosilicone phase and the filler, limiting further improvement in overall strength. In Comparative Examples 3 and 4, in-situ polymerization technology was not used. The filler struggled to open the interlayer structure, resulting in uneven dispersion. Furthermore, the polymer chains and filler were primarily physically adsorbed rather than chemically bonded, leading to low interfacial stress transfer efficiency and a double decrease in toughness and strength. In Comparative Example 5, the absence of octamethylcyclotetrasiloxane during the preparation of the hybrid base adhesive resulted in an excessively narrow molecular weight distribution or increased chain segment rigidity, leading to a "hard and brittle" material that sacrificed flexibility. MQ silicone resin, a rigid spherical molecule, serves as a "physical / chemical crosslinking center," providing high modulus and tear resistance. In Comparative Example 8, the absence of MQ resin resulted in material reinforcement solely by sericite, lacking a three-dimensional framework, leading to a significant decrease in tear resistance and a soft, collapsed material. In Comparative Example 9, the hydrogen-containing silicone oil was only side-containing, providing too many crosslinking points and restricting molecular chain movement. Although the strength was acceptable, the material was highly susceptible to brittle fracture during deformation, lacking elasticity. In Comparative Example 10, the hydrogen-containing silicone oil was only end-containing, resulting in insufficient crosslinking density and a loose network structure. Although the material was stretched to a considerable length, it could not withstand high loads and exhibited poor deformation recovery after stress.
[0067] Experiment Example 2: Oil Resistance Test
[0068] According to the standard GB / T 1690-2010, the oil resistance performance was tested by immersion at 150℃ for 72 hours using the IRM 903 standard, and the volume change rate was calculated; the results are shown in Table 2.
[0069] Table 2 Oil resistance test results of Examples 1-4, Comparative Examples 1-4, and Comparative Example 7
[0070]
[0071] As shown in Table 2, in Examples 1-4, the bottleneck of poor oil resistance of ordinary silicone rubber was overcome through a dual mechanism of chemical compatibilization and physical barrier. At the chemical level, the perfluorooctyl long chains grafted onto the surface of sericite endow it with significant fluorinophilicity, making it act as a compatibilizer. This induces the fluorosilicone raw rubber to accumulate on the filler surface and form a continuous microscopic oil-resistant network, effectively inhibiting the chemical swelling of fuel molecules. At the physical level, the sericite, after in-situ exfoliation, forms a single-layer or few-layer highly dense arrangement in the matrix, constructing a significant "maze effect," extending the diffusion path of solvent molecules. The modified silicone rubber obtained showed a volume increase rate of 2.2%-4.0% in the oil resistance test. In Comparative Example 1, without modification of the sericite, the sericite and the organosilicon matrix were extremely incompatible, leading to severe agglomeration. The interface became a solvent penetration channel, resulting in poor oil resistance. In Comparative Example 2, sericite underwent vinyl modification but lacked fluorine-containing groups, resulting in poor compatibility with fluorosilicone raw rubber, leading to microphase separation and decreased oil resistance. In Comparative Examples 3 and 4, the filler was not coated by polymer linkages, resulting in uneven dispersion and weak interfacial bonding, allowing solvent molecules to easily penetrate along the interface. In Comparative Example 7, no fluorosilicone raw rubber was added; fluorine atoms are the core of oil resistance, and their absence renders it ordinary silicone rubber, thus reducing oil resistance.
[0072] Experiment Example 3: Heat Aging Resistance Test
[0073] According to GB / T 3512-2014 standard, hot air aging was carried out at 280℃ for 48 hours, the tensile strength retention rate was tested, and the appearance after aging was observed; the results are shown in Table 3 and... Figure 1 As shown.
[0074] Table 3. Heat aging resistance test results of Examples 1-4 and Comparative Examples 6 and 9-12
[0075]
[0076] From Table 3 and Figure 1As can be seen, in Examples 1-4, this application utilizes a heat-resistant skeleton construction and gradient temperature control process to ensure that the material does not become embrittled at high temperatures. On the one hand, methylphenyl vinyl silicone rubber is introduced, utilizing the large-volume phenyl side groups to disrupt the helical regularity of the molecular chain, inhibiting high-temperature depolymerization, and acting as an oxidative sacrificial center to protect the main chain Si-O-Si skeleton, preventing material softening. On the other hand, a gradient vulcanization process is adopted, which not only removes acidic residues and low-molecular-weight volatiles that accelerate aging and prevents high-temperature blistering, but more importantly, it releases the curing internal stress caused by the difference in the thermal expansion coefficients of the fillers, and promotes the deep cross-linking of phenyl groups affected by steric hindrance. The modified silicone rubber obtained retains 90%-95% of its tensile strength after hot air aging at 280°C for 48 hours, and has a smooth appearance. In Comparative Example 6, methylphenyl vinyl silicone rubber was not added. The phenyl group is a large side group, mainly providing high-temperature resistance and radiation resistance. Without it, the material's heat resistance drops sharply. In Comparative Example 9, the hydrogen-containing silicone oil was only side-containing, resulting in excessively dense crosslinking points and short molecular chains, leading to brittle material. In Comparative Example 10, the hydrogen-containing silicone oil was only end-containing, resulting in insufficient crosslinking density, a loose network, and low material strength. In Comparative Example 11, no hydrogen-containing silicone oil was added, lacking a chain extension step, resulting in an uneven crosslinking network, high internal stress, and a tendency for microcracks to appear after aging. In Comparative Example 12, no two-stage vulcanization was performed, leading to significant steric hindrance of the phenyl groups, preventing complete phenyl crosslinking during one-stage vulcanization, and leaving residual low-molecular-weight substances, resulting in poor high-temperature aging performance and even stickiness.
[0077] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a sericite-modified silicone rubber material, characterized in that: The preparation method is as follows: 1250-mesh sericite powder was placed in a high-temperature furnace and calcined at 600°C for 2 hours to obtain activated sericite. The activated sericite was then added to a high-speed mixer, along with 200 parts of 95wt% ethanol aqueous solution. The mixture was heated to 70°C, stirred at 1500 rpm, and 5 parts of a modifier were added. The stirring speed was increased to 2500 rpm, and the mixture was reacted for 4 hours. After the reaction, the mixture was filtered, washed, and vacuum dried at 120°C for 6 hours to obtain modified sericite. The modifier consisted of perfluorooctyltriethoxysilane and vinyltrimethoxysilane in a mass ratio of 1.5-4:
1. 100 parts of dimethylcyclosiloxane and 50 parts of octamethylcyclotetrasiloxane were added to a reactor, along with 20 parts of the modified sericite and 0.5 parts of the vinyl end-capping agent 1,3-divinyltetramethyldisiloxane. The mixture was dispersed in a high-shear disperser at 3000 rpm for 30 min. Nitrogen gas was introduced to replace the air, and the temperature was raised to 110 °C. 0.1 parts of the catalyst tetramethylammonium hydroxide were added, and the mixture was dehydrated under a vacuum of -0.09 MPa for 30 min. The temperature was raised to 120 °C for ring-opening polymerization, with the stirring speed controlled at 60 rpm, and the reaction was carried out for 5-8 h. After the reaction was completed, the temperature was raised to 170 °C and held for 45 min. Then, the mixture was evacuated under a vacuum of -0.098 MPa for 2 h. After cooling, the polysiloxane hybrid base rubber was obtained. 100 parts of the aforementioned polysiloxane hybrid base rubber were placed in a kneader as the matrix polymer, and 30-45 parts of fluorosilicone raw rubber, 15-25 parts of methylphenyl vinyl silicone rubber, and 5-15 parts of MQ silicone resin were added sequentially. The kneader temperature was controlled at 130-150℃, the stirring speed at 40 rpm, and the mixture was kneaded for 2 hours to obtain a silicone rubber compound. After the silicone rubber compound cooled to room temperature, 3 parts of hydrogen-containing silicone oil and 2 parts of vulcanizing agent 2,5-dimethyl- 2,5-Di(tert-butylperoxy)hexane is passed through a thin tube 5 times to obtain a compounded silicone rubber; the compounded silicone rubber is placed in a mold and vulcanized to obtain the sericite-modified silicone rubber material; the hydrogen-containing silicone oil is a mixture of end-hydrogen-containing silicone oil with a hydrogen content of 0.1%-0.3% and side-hydrogen-containing silicone oil with a hydrogen content of 1.0%-1.5% at a mass ratio of 1:1; the vulcanization includes a first-stage vulcanization and a second-stage vulcanization; the second-stage vulcanization is performed in an oven at 220-250℃ for 4 hours.
2. A sericite-modified silicone rubber material, characterized in that: The sericite-modified silicone rubber material is prepared by the preparation method described in claim 1; the raw materials for preparing the sericite-modified silicone rubber material include polysiloxane hybrid base rubber, fluorosilicone raw rubber, methylphenyl vinyl silicone rubber, MQ silicone resin, hydrogen-containing silicone oil and vulcanizing agent.