A high-insulation black organosilicon colorant and its preparation method

Abstract

This application provides a high-insulation black organosilicon colorant and its preparation method. The high-insulation black organosilicon colorant comprises the following raw materials in parts by weight: 100 parts silicone oil carrier; 3-5 parts passivated carbon black; 1-3 parts fumed silica; wherein the passivated carbon black comprises carbon black and an organosilicon layer coated on the surface of the carbon black; the organosilicon layer is obtained by graft polymerization of polymethyltriethoxysilane and functionalized silane coupling agent on the surface of carbon black; the functionalized silane coupling agent comprises at least one of aromatic silane coupling agent and fluorinated silane coupling agent. The black colorant, while maintaining the high blackness advantage of carbon black, significantly improves its electrical insulation performance and dispersion stability in the silicone oil system, overcoming the problems of high conductivity, poor interfacial compatibility, and easy agglomeration of carbon black, and is particularly suitable for organosilicon material applications with high insulation requirements.

Description

Technical Field

[0001] This application relates to the field of organosilicon colorant technology, specifically to a highly insulating black organosilicon colorant and its preparation method. Background Technology

[0002] Black colorants are widely used in silicone materials for applications such as electronic component packaging, heat-resistant coatings, and insulating sealants, serving to impart a dark appearance and provide visual masking. In current industrial applications, black colorants primarily include inorganic pigments such as carbon black, iron black, and copper chromium black.

[0003] Carbon black is the most widely used black pigment due to its extremely high tinting strength, thermal stability, and cost advantage. However, carbon black itself has high electrical conductivity and significant hydrophobicity, making it prone to agglomeration in organosilicon systems, difficult to disperse uniformly, and severely reducing the electrical insulation properties of the material. This problem is particularly prominent in applications requiring high insulation, such as electronic seals and insulating coatings, significantly limiting product performance.

[0004] While iron black (Fe3O4) possesses some coloring ability, it is inherently magnetic and readily adsorbs impurity ions (such as iron ions or other conductive metallic impurities), posing potential electrical performance risks in systems requiring high insulation. Furthermore, iron black's blackness is far lower than that of carbon black, and its coloring strength is weak, making it difficult to meet requirements for color depth and hiding power.

[0005] While composite oxide pigments such as copper chromium black possess a certain degree of chemical stability, their tinting strength is still inferior to that of carbon black, and their color tends to be grayish, making them unsuitable for high-end silicone products that require a deep black appearance. Furthermore, these composite oxide pigments also have limitations in terms of fineness, wettability, and system compatibility.

[0006] In summary, current black silicone colorants generally rely on carbon black to meet coloring strength requirements, but the high conductivity and agglomeration tendency of carbon black severely limit its application performance in high-insulation scenarios. Therefore, how to effectively solve the problems of reduced insulation and uneven dispersion caused by carbon black in silicone systems while maintaining a deep black appearance has become a key issue that urgently needs to be addressed in this field. Summary of the Invention

[0007] This application provides a high-insulation black organosilicon colorant and its preparation method, aiming to solve the problems of easy aggregation, difficulty in dispersion, and significant reduction in electrical insulation performance of black colorants in organosilicon systems in the prior art.

[0008] In a first aspect, this application provides a high-insulation black organosilicon colorant, comprising the following raw materials in parts by weight: 100 parts silicone oil carrier; 3-5 parts passivated carbon black; 1-3 parts fumed silica; wherein the passivated carbon black comprises carbon black and an organosilicon layer coated on the surface of the carbon black; the organosilicon layer is obtained by graft polymerization of polymethyltriethoxysilane and a functionalized silane coupling agent on the surface of the carbon black; the functionalized silane coupling agent comprises at least one of aromatic silane coupling agent and fluorinated silane coupling agent.

[0009] According to this application, the black colorant, while maintaining the high blackness advantage of carbon black, significantly improves its electrical insulation performance and dispersion stability in silicone oil systems, overcoming the problems of strong conductivity, poor interfacial compatibility, and easy agglomeration of carbon black, and is especially suitable for organosilicon material applications with high insulation requirements.

[0010] Specifically, the passivated carbon black, through multi-site condensation of polymethyltriethoxysilane, forms a polysiloxane backbone layer on the carbon black surface, constructing a basic coating structure. This initially reduces its surface free energy and conductivity, thereby improving the dispersion stability and insulation properties of the passivated carbon black in the system. The inventors discovered that the introduction of functionalized silane coupling agents can further improve the dispersion stability and insulation properties of the passivated carbon black in the system. This may be because functionalized silane coupling agents can further regulate the interfacial chemical properties and microstructure of the coating layer, among which aromatic silicon... Alkane coupling agents can enhance the affinity with the carbon skeleton on the carbon black surface through π-π interactions, introducing rigid skeletons and non-polar segments into the coating layer. This helps to improve the film density and anchoring stability of the coating layer, thereby improving the dispersibility and thermal stability of passivated carbon black. Fluorosilane coupling agents can introduce fluorocarbon structures with lower surface energy into the coating layer, further blocking the contact between carbon black and external polar components, and reducing its migration and re-aggregation risk in organosilicon systems. At the same time, the high insulation properties of fluorine also contribute to the improvement of overall resistivity.

[0011] In addition, the introduction of fumed silica, as an inorganic nanoparticle with high surface activity, can form a spatially distributed network structure in the system, distributed among carbon black particles, forming a certain degree of physical spatial steric hindrance and dispersion framework structure, which restricts the agglomeration behavior of carbon black at the micro level, thereby inhibiting the movement and re-agglomeration tendency of carbon black, and further improving the system stability and rheological control capability of passivated carbon black in silicone oil.

[0012] The aforementioned structural synergistic mechanism enables the high-insulation black organosilicon colorant of this application to significantly improve dispersibility, electrical insulation and system stability without sacrificing color depth, making it suitable for preparing black organosilicon materials with high dielectric properties.

[0013] In some embodiments, the silicone oil carrier comprises vinyl silicone oil and polyether silicone oil, wherein the mass ratio of the vinyl silicone oil to the polyether silicone oil is 9:0.5~1.5.

[0014] In some of the above embodiments, vinyl silicone oil not only provides excellent low viscosity, heat resistance, and dispersion environment as the main carrier, but the vinyl groups in its molecular structure can also participate in crosslinking reactions during subsequent thermosetting or vulcanization, undergoing addition reactions with crosslinking agents (such as hydrosilanes) in the organosilicon system, thereby embedding themselves into the overall organosilicon network structure. This characteristic not only helps to improve the structural integrity and mechanical strength of the system, but also locks the dispersed passivated carbon black and other components during the crosslinking and curing process, reducing the risk of later migration or phase separation, and helping to maintain the electrical insulation stability of the colorant during use.

[0015] Polyether silicone oil, as an auxiliary carrier, has polar polyether segments that are difficult to participate in crosslinking reactions, but it plays an important role in the dispersion stage: on the one hand, its segments can be adsorbed onto the incompletely coated areas or micro-crevices of the passivated carbon black surface through van der Waals forces and polar forces, further wetting the remaining exposed surface and inhibiting the risk of local agglomeration; on the other hand, its hydrophilic polyether segments can also form hydrogen bonds or electrostatic interactions with the hydroxyl groups on the surface of gaseous SiO2, thereby assisting in the construction of a weak thixotropic network structure in the system, inhibiting particle sedimentation or stratification, and improving storage stability and dispersion uniformity.

[0016] Furthermore, in the interfacial region between passivated carbon black particles, polyether silicone oil can reduce the interfacial tension between particles, allowing them to be distributed in the system at a lower energy state, which helps to improve the processability and interfacial adaptability of the final colorant system.

[0017] When the mass ratio of vinyl silicone oil to polyether silicone oil is controlled within the range of 9:0.5 to 1.5, the dispersive synergistic effect of polyether silicone oil can be fully utilized to achieve a balance between dispersibility and structural stability while ensuring the thermal stability and subsequent crosslinking properties of the system. However, if the proportion of polyether silicone oil is too high, it may introduce too many polar segments, leading to a polarity imbalance in the system, which is not conducive to maintaining electrical insulation. Therefore, this silicone oil compound system not only achieves synergy among dispersion, thixotropy, and crosslinking, but also significantly enhances the interfacial compatibility and stability between the colorant and the organosilicon matrix.

[0018] In some embodiments, the vinyl silicone oil has a viscosity of 350~10000 cP at 25°C; the polyether silicone oil is designated as KF-6017.

[0019] In some of the above embodiments, the control of the viscosity of vinyl silicone oil has a significant impact on the dispersion stability and application adaptability of the organosilicon colorant system. Specifically, although lower viscosity vinyl silicone oil has good fluidity, it is not conducive to the steric hindrance stability after particle dispersion; while excessively high viscosity will reduce the fluidity of the colorant pre-dispersion and easily form initial agglomerates. Controlling the viscosity of vinyl silicone oil within the range of 350~10000 cP can provide good dispersibility while ensuring that the system has good application fluidity and thixotropic response, which is a basic condition for achieving efficient dispersion and long-term stability of carbon black. As an example, in one embodiment of this application, a vinyl-terminated dimethyl (siloxane and polysiloxane) with a viscosity of 1000 cP at 25°C is used as the vinyl silicone oil.

[0020] Furthermore, the polyether silicone oil is model KF-6017, whose main chain structure is polydimethylsiloxane with polyether segments branched on the sides. It possesses excellent wetting and interfacial spreading properties, further reducing interfacial tension and enhancing the system's lubricity and particle stability. The presence of polyether segments in KF-6017 allows it to adsorb onto partially incompletely silicone-coated carbon black surfaces or filler interfaces. Through flexible segment extension and steric hindrance, it alleviates the aggregation tendency caused by van der Waals attraction between particles, while simultaneously forming an auxiliary wetting barrier on the passivated carbon black surface, improving its dispersibility in the silicone oil carrier.

[0021] In some embodiments, the method for preparing the passivated carbon black includes the following steps:

[0022] S1: Mix carbon black with ethanol to disperse the carbon black in the ethanol to obtain a carbon black dispersion;

[0023] S2: Mix polymethyltriethoxysilane, functionalized silane coupling agent and ethanol aqueous solution to partially hydrolyze polymethyltriethoxysilane and aromatic silane coupling agent to obtain silane solution;

[0024] S3: The silane solution is added to the carbon black dispersion to cause polymethyltriethoxysilane and aromatic silane coupling agent to condense and crosslink on the carbon black surface to obtain passivated carbon black.

[0025] In some of the above embodiments, the method for preparing passivated carbon black significantly improves the surface wettability and effective contact area of ​​carbon black by dispersing carbon black in a polar solvent (such as ethanol), reduces the degree of agglomeration, and ensures the uniformity of subsequent silane reactions.

[0026] In step S2, polymethyltriethoxysilane (PMTES) serves as the main crosslinking agent, which can be partially hydrolyzed in an aqueous ethanol solution to form a multifunctional silanol intermediate with a strong crosslinking tendency. Meanwhile, the functionalized silane coupling agent can be hydrolyzed to generate silanol structures with specific functional groups, thereby introducing structural units such as aromatic rings and fluorine atoms into the resulting organosilicon shell during its formation process, thus endowing the shell with stronger interfacial control capabilities and microstructure stability.

[0027] In step S3, by adding the above silane solution to the carbon black dispersion, the silane hydrolysate undergoes a polycondensation and crosslinking reaction on the carbon black surface, thereby constructing an organosilicon shell on the surface of the carbon black particles.

[0028] The shell structure is composed of a main cross-linked network framework formed by PMTES and modified functional groups, which not only significantly improves the hydrophobic stability of carbon black particles and reduces their tendency to migrate and aggregate in the organosilicon system, but also effectively weakens the surface conductivity of carbon black, giving it excellent electrical insulation properties.

[0029] This method is simple, easy to scale up, and suitable for constructing carbon black particles with good dispersibility and high insulation properties, providing an ideal insulating black filler for the construction of high-insulation organosilicon colorant systems.

[0030] In some embodiments, the method for preparing the passivated carbon black includes the following steps:

[0031] S1: Disperse 10 parts of carbon black in 40-60 parts of ethanol by ultrasonication to obtain a carbon black dispersion;

[0032] S2: Disperse 4-6 parts of polymethyltriethoxysilane and 1-2 parts of functionalized silane coupling agent in 5-15 parts of aqueous ethanol solution, adjust the pH to 4-5, and obtain a silane solution;

[0033] S3: Add the silane solution to the carbon black dispersion and react at 60~80℃ for 4~6h to obtain passivated carbon black.

[0034] In some of the above embodiments, step S1 significantly improves the dispersion stability of carbon black in ethanol by ultrasonic dispersion, effectively breaks up agglomerates, maximizes the exposed surface area of ​​carbon black, and provides reaction sites for the subsequent silane coating reaction.

[0035] In step S2, polymethyltriethoxysilane, acting as the main crosslinking agent, rapidly hydrolyzes into a trifunctional silanol intermediate under acidic conditions (pH 4-5). Functionalized silane coupling agents (such as silanes with aromatic or fluoroalkyl structures) also undergo partial hydrolysis under the same conditions. This acidic pH regulation helps suppress the self-condensation of the silanol prepolymer in solution, thereby increasing its preferential condensation efficiency with the carbon black surface and forming a directional coating structure. The addition amount of polymethyltriethoxysilane is controlled at 40%-60% of the carbon black mass, which forms a more complete organosilicon coating layer to passivate the carbon black surface. The functionalized silane coupling agent participates in the reaction at a relatively small proportion, helping to further improve the integrity and surface energy of the organic coating layer, thereby further inhibiting the agglomeration of the passivated carbon black and improving its insulation properties.

[0036] Step S3 involves a continuous reaction at 60-80°C for 4-6 hours to ensure that the silane hydrolysis products fully condense into a film on the carbon black surface, gradually forming a relatively complete and firmly adhered organosilicon coating layer. Structurally, this coating layer is supported by a cross-linked network formed by PMTES, while the substituents introduced by the functionalized silane regulate the interfacial polarity and flexibility of the shell layer, achieving structural passivation and reduced conductivity of the carbon black surface.

[0037] By synergistically controlling the reaction parameters and addition ratios mentioned above, the integrity and stability of the coating layer can be ensured, and secondary agglomeration of carbon black in the system can be avoided. On the other hand, the electrical properties of carbon black can also be effectively adjusted, which helps to construct black functional particles with excellent dispersibility and outstanding insulation, thereby enhancing the electrical insulation performance and long-term stability of the organosilicon colorant system.

[0038] In some embodiments, the polymethyltriethoxysilane has an average degree of polymerization of 2 to 3.

[0039] In some embodiments, the functionalized silane coupling agent includes an aromatic silane coupling agent and a fluorinated silane coupling agent, wherein the mass ratio of the aromatic silane coupling agent to the fluorinated silane coupling agent is 1:0.4~0.6.

[0040] In some of the above embodiments, aromatic silane coupling agents possess strong π-π interaction capabilities and a certain degree of rigidity, enabling the introduction of stable organic framework structures into the coating layer. This enhances the anchoring ability of the shell layer to the carbon black surface and improves the overall system's compatibility with the organosilicon matrix. Fluorinated silane coupling agents, on the other hand, can introduce low-polarity, low-surface-energy fluorocarbon segments onto the carbon black surface, effectively weakening the free electron conduction channels on the carbon black surface and further suppressing its conductivity at the molecular level. The introduction of aromatic rings and fluorine also synergistically enhances the group shielding effect, improving the shell density.

[0041] Using aromatic silanes and fluorinated silanes in a mass ratio of 1:0.4~0.6 can improve the density and structural stability of the coating layer, while further enhancing its insulation and interfacial energy regulation capabilities. This ratio balances the surface anchoring effect of the aromatic structure with the electrical insulation regulation function of the fluorocarbon segments, constructing an organosilicon coating structure that possesses both dispersion stability and high insulation performance. This helps improve the compatibility of passivated carbon black in organosilicon systems and the insulation performance of the final colorant.

[0042] It should be noted that aromatic silane coupling agents and fluorinated silane coupling agents have meanings known in the art. Aromatic silane coupling agents refer to a class of silane coupling agents containing an aromatic ring, while fluorinated silane coupling agents refer to a class of silane coupling agents containing a fluorinated alkyl group. As an example, in one embodiment of this application, trifluoropropyltriethoxysilane is used as a fluorinated silane coupling agent.

[0043] In some embodiments, the aromatic silane coupling agent comprises 4-methoxyphenyltriethoxysilane.

[0044] In some of the above embodiments, when 4-methoxyphenyltriethoxysilane is used as an aromatic silane coupling agent, the resulting colorant exhibits better electrical insulation properties and stability than when other phenylsilane coupling agents are used. This may be because the methoxy group in the 4-methoxyphenyltriethoxysilane molecule is a strong electron-donating group, which can significantly enhance the electron density of the benzene ring, thereby increasing the strength of its π–π stacking interaction with the carbon black surface and promoting the directional adsorption and effective coverage of the coupling agent on the carbon black surface. Simultaneously, this methoxy substitution structure also regulates the polarity distribution of the silane coupling agent, resulting in better interfacial compatibility between the coating layer formed during hydrolysis and polycondensation and the less polar organosilicon resin system, reducing energy differences at the phase interface and suppressing the tendency for interfacial delamination or aggregation between the coating layer and the matrix.

[0045] Therefore, using 4-methoxyphenyltriethoxysilane as an aromatic silane coupling agent can further improve the electrical insulation properties and stability of the colorant.

[0046] In some embodiments, the average particle size of the fumed silica is 10-50 nm. Based on the above embodiments, fumed silica with a particle size within this range has a large specific surface area and good surface activity, enabling it to form a uniformly dispersed filler network in the system and effectively embed into the interfacial voids between the silicone oil matrix and the passivated carbon black. Its micro-nano particle structure not only improves the distribution stability of the filler but also, to a certain extent, forms a physical barrier against carbon black aggregation, helping to improve the overall system's dispersion uniformity and anti-migration ability. Simultaneously, its surface hydroxyl groups can form weak hydrogen bonds or associations with the silanol structures in the silicone oil system, helping to enhance the stability of the filler in the system, thereby improving the electrical insulation properties and stability of the organosilicon colorant.

[0047] In some embodiments, the specific surface area of ​​the carbon black is 100~300m². 2 / g. Based on the above embodiments, the moderate specific surface area ensures that the carbon black has good coloring ability and surface reactivity, which not only helps to achieve more complete silane polycondensation coating during passivation, but also enhances the directional adsorption ability of functionalized silane coupling agents while retaining a certain number of surface active sites, further enhancing the overall electrical insulation and coloring ability of the material.

[0048] Secondly, this application provides a method for preparing a highly insulating black organosilicon colorant, comprising:

[0049] Provide raw materials for the highly insulating black silicone colorant according to any embodiment of the first aspect;

[0050] The raw materials are mixed to obtain an insulating black organosilicon colorant.

[0051] According to this application, the method involves mixing and dispersing passivated carbon black, fumed silica, and compounded silicone oil in a specific ratio. This results in the passivated carbon black being uniformly distributed within the organosilicon system, with fumed silica filling the space to form a three-dimensional support structure. The silicone oil, as a continuous phase, provides excellent wettability and dispersion stability. In this preparation method, the passivated carbon black has a pre-formed organosilicon coating layer, exhibiting good interfacial inertness and structural stability. The vinyl silicone oil in the compounded silicone oil can further participate in the subsequent crosslinking reaction of substrates such as silicone rubber and silicone rubber, achieving co-curing of the system. The polyether silicone oil provides good interfacial harmonization capabilities, improving overall mixing uniformity. This preparation method is simple and can be completed in conventional mixing and dispersing equipment (such as a three-roll mill or planetary mixer), contributing to improved product stability and consistency in industrial applications.

[0052] In some embodiments, the process of mixing the raw materials to obtain an insulating black silicone colorant includes:

[0053] The first component is obtained by dispersing passivated carbon black in polyether silicone oil;

[0054] The second component was obtained by dispersing fumed silica in vinyl silicone oil;

[0055] The first component and the second component are then mixed to obtain an insulating black organosilicon colorant.

[0056] Based on the above embodiments, the inventors discovered that this dispersion sequence can significantly enhance the synergistic distribution behavior of each component in the system while improving dispersion efficiency. Passivated carbon black has a moderate surface polarity, making it easier to wet and encapsulate in polyether silicone oil. The polyether segments can also form a reversible adsorption layer on the carbon black surface (where some parts of the passivated carbon black may not be completely coated by the organosilicon layer), further inhibiting particle agglomeration and improving the initial dispersion stability of the system. Meanwhile, fumed silica has a high specific surface area and abundant surface hydroxyl groups, forming good physical embedding and van der Waals interactions with vinyl silicone oil, enabling the construction of a relatively continuous three-dimensional framework network during shear dispersion.

[0057] In the final composite system, carbon black particles are uniformly embedded in the support network constructed by gaseous SiO2 with polyether silicone oil as the lubricating interface. The coexistence of vinyl silicone oil and polyether silicone oil in the system can ensure that the system has moderate viscosity and excellent workability, and can also form a stable cross-linked structure during the subsequent organosilicon cross-linking and curing process. This effectively prevents carbon black migration, aggregation or the formation of conductive paths, and further improves insulation and service life.

[0058] Compared with the prior art, the beneficial effects of this application are at least as follows:

[0059] 1. This application significantly improves the electrical insulation performance of black organosilicon colorants by constructing a multiphase composite system of "passivated carbon black + fumed silica + silicone oil carrier", and solves the problem of dielectric breakdown or insulation failure caused by conductivity in traditional carbon black filling systems.

[0060] 2. This application uses polymethyltriethoxysilane and aromatic or fluorinated silane coupling agents to synergistically coat carbon black. By controlling the polarity, flexibility and surface energy in the coating structure, a dense organosilicon passivation layer with controllable electrical properties is constructed, which can effectively block the conductive path while ensuring the black coloring power.

[0061] 3. The obtained organosilicon colorant can directly participate in the crosslinking reaction of vinyl organosilicon materials, significantly improving the compatibility and crosslinking embedding strength of the colorant and the matrix, avoiding carbon black precipitation, bleeding or migration, and extending the service life of the material.

[0062] 4. The high-insulation black silicone colorant provided in this application has excellent electrical insulation, dispersion stability and coloring power, and is especially suitable for silicone potting compounds, sealants and electrical encapsulation materials with high insulation performance requirements. Detailed Implementation

[0063] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0064] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0065] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0066] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0067] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0068] Vinyl silicone oil: vinyl-terminated dimethyl (siloxane and polysiloxane) with a viscosity of 1000 cP at 25°C;

[0069] Polyether silicone oil: Model KF-6017;

[0070] Polymethyltriethoxysilane: average degree of polymerization is 2~3;

[0071] Trifluoropropyltriethoxysilane: CAS number 86876-45-1;

[0072] 4-Methoxyphenyltriethoxysilane: CAS number 21130-91-6;

[0073] Phenylacetyltriethoxysilane: CAS number 780-69-8;

[0074] Carbon black: specific surface area is approximately 230 m² 2 / g;

[0075] Fumed silica: average particle size is approximately 30 nm.

[0076] Preparation Example 1

[0077] Preparation of passivated carbon black:

[0078] Add 10 parts carbon black and 50 parts ethanol to the reactor, and sonicate (frequency 40kHz, power 200W) for 30 minutes to fully disperse the carbon black and obtain a carbon black dispersion.

[0079] Take 5 parts of polymethyltriethoxysilane, 1 part of 4-methoxyphenyltriethoxysilane and 0.5 parts of trifluoropropyltriethoxysilane and add them to 10 parts of ethanol aqueous solution with a volume fraction of 80%. After stirring and mixing, add acetic acid to adjust the pH to 4.5 and hydrolyze for 30 min to obtain silane solution.

[0080] The above silane hydrolysate was slowly added dropwise to the carbon black dispersion under stirring. The reaction system was heated to 70°C and kept at that temperature for 6 hours. After the reaction was completed, it was naturally cooled to room temperature. The product was centrifuged to obtain a black solid, washed three times with ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain passivated carbon black A with surface passivation treatment.

[0081] Preparation Example 2

[0082] Preparation of passivated carbon black:

[0083] Add 10 parts carbon black and 50 parts ethanol to the reactor, and sonicate (frequency 40kHz, power 200W) for 30 minutes to fully disperse the carbon black and obtain a carbon black dispersion.

[0084] Take another 5 parts of polymethyltriethoxysilane and 1.5 parts of 4-methoxyphenyltriethoxysilane and add them to 10 parts of ethanol aqueous solution with a volume fraction of 80%. After stirring and mixing, add acetic acid to adjust the pH to 4.5 and hydrolyze for 30 min to obtain silane solution.

[0085] The above silane hydrolysate was slowly added dropwise to the carbon black dispersion under stirring. The reaction system was heated to 70°C and kept at that temperature for 6 hours. After the reaction was completed, it was naturally cooled to room temperature. The product was centrifuged to obtain a black solid, washed three times with ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain passivated carbon black B with surface passivation treatment.

[0086] Preparation Example 3

[0087] Preparation of passivated carbon black:

[0088] Add 10 parts carbon black and 50 parts ethanol to the reactor, and sonicate (frequency 40kHz, power 200W) for 30 minutes to fully disperse the carbon black and obtain a carbon black dispersion.

[0089] Take another 5 parts of polymethyltriethoxysilane and 1.5 parts of trifluoropropyltriethoxysilane and add them to 10 parts of ethanol aqueous solution with a volume fraction of 80%. After stirring and mixing, add acetic acid to adjust the pH to 4.5 and hydrolyze for 30 min to obtain silane solution.

[0090] The above silane hydrolysate was slowly added dropwise to the carbon black dispersion under stirring. The reaction system was heated to 70°C and kept at that temperature for 6 hours. After the reaction was completed, it was naturally cooled to room temperature. The product was centrifuged to obtain a black solid, washed three times with ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain passivated carbon black C with surface passivation treatment.

[0091] Comparative Preparation Example 1

[0092] Preparation of passivated carbon black:

[0093] Add 10 parts carbon black and 50 parts ethanol to the reactor, and sonicate (frequency 40kHz, power 200W) for 30 minutes to fully disperse the carbon black and obtain a carbon black dispersion.

[0094] Take another 6.5 parts of polymethyltriethoxysilane and add it to 10 parts of ethanol aqueous solution with a volume fraction of 80%. After stirring and mixing, add acetic acid to adjust the pH to 4.5 and hydrolyze for 30 min to obtain silane solution.

[0095] The above silane hydrolysate was slowly added dropwise to the carbon black dispersion under stirring. The reaction system was heated to 70°C and kept at that temperature for 6 hours. After the reaction was completed, it was naturally cooled to room temperature. The product was centrifuged to obtain a black solid, washed three times with ethanol, and then dried in a vacuum drying oven at 60°C for 12 hours to obtain passivated carbon black D with surface passivation treatment.

[0096] Example 1

[0097] Preparation of insulating black silicone colorant:

[0098] Take 4 parts of the passivated carbon black A prepared in Example 1 and add it to 10 parts of polyether silicone oil. Disperse it for 10 min at room temperature using a high-speed shear disperser to obtain a uniform dispersion of carbon black in polyether silicone oil, which is denoted as the first component.

[0099] Take 3 parts of fumed silica and add it to 90 parts of vinyl silicone oil. After mechanical stirring for 5 minutes at room temperature, transfer it to a three-roll mill and grind it 3 times (roller gap set to 20μm, 10μm, and 5μm) to obtain a uniformly dispersed fumed SiO2 dispersion, which is referred to as the second component.

[0100] After mixing the first and second components, the mixture is ground by rotating zirconium beads in the grinding chamber of a sand mill for 30 minutes to obtain an insulating black organosilicon colorant.

[0101] Example 2

[0102] Preparation of insulating black silicone colorant:

[0103] Take 4 parts of the passivated carbon black A prepared in Example 1 and add it to 10 parts of vinyl silicone oil. Disperse it for 10 min at room temperature using a high-speed shear disperser to obtain a uniform dispersion of carbon black in vinyl silicone oil, which is denoted as the first component.

[0104] Take 3 parts of fumed silica and add it to 90 parts of vinyl silicone oil. After mechanical stirring for 5 minutes at room temperature, transfer it to a three-roll mill and grind it 3 times (roller gap set to 20μm, 10μm, and 5μm) to obtain a uniformly dispersed fumed SiO2 dispersion, which is referred to as the second component.

[0105] After mixing the first and second components, the mixture is ground by rotating zirconium beads in the grinding chamber of a sand mill for 30 minutes to obtain an insulating black organosilicon colorant.

[0106] Example 3

[0107] Preparation of insulating black silicone colorant:

[0108] Take 4 parts of the passivated carbon black A prepared in Example 1 and add it to 30 parts of polyether silicone oil. Disperse it for 10 min at room temperature using a high-speed shear disperser to obtain a uniform dispersion of carbon black in polyether silicone oil, which is denoted as the first component.

[0109] Take 3 parts of fumed silica and add it to 70 parts of vinyl silicone oil. After mechanical stirring for 5 minutes at room temperature, transfer it to a three-roll mill and grind it 3 times (roller gap set to 20μm, 10μm, and 5μm) to obtain a uniformly dispersed fumed SiO2 dispersion, which is referred to as the second component.

[0110] After mixing the first and second components, the mixture is ground by rotating zirconium beads in the grinding chamber of a sand mill for 30 minutes to obtain an insulating black organosilicon colorant.

[0111] Example 4

[0112] Preparation of insulating black silicone colorant:

[0113] Similar to Example 1, except that the passivating carbon black used is the passivating carbon black B obtained in Preparation Example 2.

[0114] Example 5

[0115] Preparation of insulating black silicone colorant:

[0116] Similar to Example 1, except that the passivating carbon black used is the passivating carbon black C obtained in Preparation Example 3.

[0117] Example 6

[0118] Preparation of insulating black silicone colorant:

[0119] Take 4 parts of the passivated carbon black A prepared in Example 1 and add it to 10 parts of vinyl silicone oil. Disperse it for 10 min at room temperature using a high-speed shear disperser to obtain a uniform dispersion of carbon black in vinyl silicone oil, which is denoted as the first component.

[0120] Take 3 parts of fumed silica and add it to 80 parts of vinyl silicone oil and 10 parts of polyether silicone oil. After mechanically stirring for 5 minutes at room temperature, transfer it to a three-roll mill and grind it 3 times (roller gap set to 20μm, 10μm and 5μm) to obtain a uniformly dispersed fumed SiO2 dispersion, which is referred to as the second component.

[0121] After mixing the first and second components, the mixture is ground by rotating zirconium beads in the grinding chamber of a sand mill for 30 minutes to obtain an insulating black organosilicon colorant.

[0122] Comparative Example 1

[0123] Preparation of insulating black silicone colorant:

[0124] Similar to Example 1, except that the passivating carbon black used was the passivating carbon black D obtained in Comparative Preparation Example 1.

[0125] Test section

[0126] Electrical insulation performance test:

[0127] Add 2.5g of the high-insulation black silicone colorant to be tested to 50g of RTV-1 silicone rubber (Dow Corning 732), and grind it repeatedly three times using a three-roll mill to ensure that the colorant is evenly dispersed in the silicone.

[0128] The ground mixture was injected into a 100mm×100mm×1mm PTFE mold and allowed to stand for 48 hours at room temperature (25±2℃) and relative humidity >50% for natural curing. After complete curing, the mold was removed to obtain the test sample.

[0129] Referring to GB / T1410-2006 "Determination of Volume Resistivity and Surface Resistivity of Solid Insulating Materials", the sample was cut into test dimensions of 50mm×50mm×1mm; standard copper disc electrodes were used to clamp the upper and lower surfaces of the sample; the volume resistivity ρ of the sample was tested at room temperature (25±2℃), relative humidity (50%±2%), and a DC voltage of 500V. V1 (Ω·cm); 3 samples were tested in each group, and the average value was taken; the results are shown in Table 1.

[0130] In addition, to test the stability of the high-insulation black silicone colorant, the high-insulation black silicone colorants obtained in each embodiment were stored in a 60°C constant temperature chamber for 15 days for accelerated aging. Then, the high-insulation black silicone colorants stored at high temperature were subjected to the aforementioned electrical insulation performance test, and the volume resistivity ρ of the corresponding samples was measured. V2 (Ω·cm); 3 samples were tested in each group, and the average value was taken; the results are shown in Table 1.

[0131] Table 1

[0132] <![CDATA[ρ V1 (Ω·cm)]]> <![CDATA[ρ V2 (Ω·cm)]]> Example 1 <![CDATA[6.8×10 14 ]]> <![CDATA[6.7×10 14 ]]> Example 2 <![CDATA[5.5×10 14 ]]> <![CDATA[5.0×10 14 ]]> Example 3 <![CDATA[5.7×10 14 ]]> <![CDATA[4.9×10 14 ]]> Example 4 <![CDATA[6.0×10 14 ]]> <![CDATA[5.6×10 14 ]]> Example 5 <![CDATA[5.1×10 14 ]]> <![CDATA[4.6×10 14 ]]> Example 6 <![CDATA[6.5×10 14 ]]> <![CDATA[6.2×10 14 ]]> Comparative Example 1 <![CDATA[3.2×10 12 ]]> <![CDATA[1.5×10 12 ]]>

[0133] According to Table 1, the ρ of the corresponding samples in each embodiment V1 and ρ V2 Compared to Comparative Example 1, this is better. By comparing the decrease in volume resistivity of the samples after storage, the storage stability of the organosilicon colorant can also be indirectly reflected, indicating that the high-insulation black organosilicon colorant provided in this application has the beneficial effect of significantly improving volume resistivity and enhancing storage stability. The possible reason is that in Comparative Example 1, the passivated carbon black used only uses polymethyltriethoxysilane as a single coating agent, without introducing aromatic silanes with π–π stacking ability or fluorinated silanes with interfacial energy regulation. This results in a loose and uneven carbon black coating layer structure, and the residual conductive paths between particles cannot be effectively cut off, thus causing its resistivity to be significantly lower than that of the embodiments. Moreover, it is prone to agglomeration during storage, and the resistivity decreases further, making it difficult to meet the high insulation requirements.

[0134] As shown in Examples 1-3, the amount of polyether silicone oil added to the carrier has a certain impact on the dispersion stability of passivated carbon black and the insulation performance of the system. In Example 1, polyether silicone oil and vinyl silicone oil were used together as a carrier in a certain proportion. While maintaining the compatibility of the system, it provided good wetting properties and a bridging dispersion structure, resulting in the colorant exhibiting the highest initial resistivity (and the lowest decay rate) in the RTV system. In Example 2, no polyether silicone oil was added, and only vinyl silicone oil was used as a carrier. The initial resistivity and the resistivity after storage decreased significantly, indicating that the dispersion stability of the colorant decreased when polar wetting segments were lacking. In Example 3, the proportion of polyether silicone oil was too high, resulting in a lower initial resistivity than in Example 1 and a higher resistivity decay rate. This indicates that introducing too many polar segments into the system not only affects the electrical insulation but may also lead to a polarity imbalance in the system, which is not conducive to maintaining electrical insulation.

[0135] As shown in Examples 1, 4, and 5, the combination of silane coupling agents in passivated carbon black has a certain impact on the insulation performance of the system. Example 1 uses a compound of PMTES, aromatic silane, and fluorinated silane to form a dense coating layer with a coordinated interfacial polarity gradient, exhibiting the best resistivity and storage stability. Example 4 only increases the proportion of aromatic silane without using the fluorinated component, resulting in a decrease in the insulation of the shell and an increase in surface energy, with the initial resistivity and post-storage resistivity being slightly lower than that of Example 1. In Example 5, fluorinated silane is used instead of aromatic silane, lacking a π–π stacking auxiliary orientation layer, resulting in slightly inferior insulation and storage stability compared to Example 1. This indicates that the three-component synergistic system is most conducive to constructing a highly efficient electrical insulating shielding layer.

[0136] As shown in Examples 1 and 6, the method of introducing polyether silicone oil has a certain impact on the insulation performance enhancement of passivated carbon black. In Example 1, polyether silicone oil is used directly as a dispersion medium to disperse passivated carbon black. Its polar segments can preferentially adsorb on the carbon black surface areas where the coating layer may have defects or not be fully covered, thereby further enhancing the coating density and electrical insulation shielding effect at the microscopic level and effectively suppressing the formation of conductive paths. However, in Example 6, polyether silicone oil is added to the dispersion system of fumed silica. Due to the strong hydrogen bonding and entanglement between polyether silicone oil and the hydroxyl-rich surface of fumed silica, the polyether segments preferentially form the surface coating layer of fumed silica, making it difficult to supplement the modification of carbon black. As a result, the overall insulation and storage stability of the colorant system are slightly lower than those in Example 1.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A highly insulating black organosilicon colorant, characterized in that, The raw materials include the following parts by weight: 100 parts silicone oil carrier; 3-5 parts passivating carbon black; 1-3 parts fumed silica; The method for preparing the passivated carbon black includes the following steps: S1: Disperse 10 parts of carbon black in 40-60 parts of ethanol by ultrasonication to obtain a carbon black dispersion; S2: Disperse 4-6 parts of polymethyltriethoxysilane and 1-2 parts of functionalized silane coupling agent in 5-15 parts of ethanol aqueous solution, adjust the pH to 4-5, and obtain a silane solution; wherein, the functionalized silane coupling agent includes aromatic silane coupling agent and fluorinated silane coupling agent, and the mass ratio of aromatic silane coupling agent to fluorinated silane coupling agent is 1:0.4-0.6; the aromatic silane coupling agent includes 4-methoxyphenyltriethoxysilane; S3: Add the silane solution to the carbon black dispersion and react at 60~80℃ for 4~6h to obtain passivated carbon black; The silicone oil carrier comprises vinyl silicone oil and polyether silicone oil, wherein the mass ratio of the vinyl silicone oil to the polyether silicone oil is 9:0.5~1.

5.

2. The high-insulation black organosilicon colorant according to claim 1, characterized in that, The vinyl silicone oil has a viscosity of 350~10000 cP at 25°C; the polyether silicone oil is model KF-6017.

3. The high-insulation black organosilicon colorant according to claim 1 or 2, characterized in that, The raw materials meet at least one of the following conditions: 1) The average particle size of the fumed silica is 10~50 nm; 2) The specific surface area of ​​the carbon black is 100~300m². 2 / g.

4. A method for preparing a highly insulating black organosilicon colorant, characterized in that, include: Provide the raw materials for the high-insulation black organosilicon colorant according to any one of claims 1 to 3; The raw materials are mixed to obtain an insulating black organosilicon colorant.

5. The method according to claim 4, characterized in that, The insulating black organosilicon colorant obtained by mixing the raw materials includes: The first component is obtained by dispersing passivated carbon black in polyether silicone oil; The second component was obtained by dispersing fumed silica in vinyl silicone oil; The first component and the second component are then mixed to obtain an insulating black organosilicon colorant.