High-insulation black organic silicon coloring agent and preparation method thereof

Abstract

The invention provides a high-insulation black organic silicon coloring agent and a preparation method thereof. The high-insulation black organic silicon coloring agent comprises the following raw materials in parts by mass: 100 parts of a silicone oil carrier; 3-5 parts of passivated carbon black; 1-3 parts of fumed silica; wherein the passivated carbon black comprises carbon black and an organic silicon layer coated on the surface of the carbon black; the organic silicon 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 an aryl silane coupling agent and a fluorine-containing silane coupling agent. According to the black coloring agent, the advantage of high blackness of carbon black is maintained, meanwhile, the electric insulation performance and dispersion stability of the black coloring agent in a silicone oil system are remarkably improved, the problems that the carbon black is high in conductivity, poor in interface compatibility and prone to agglomeration are solved, and the black coloring agent is especially suitable for being applied to organic silicon materials with the high requirement for the insulation performance.

Description

Technical Field

[0001] The present application relates to the technical field of organic silicon colorants, and in particular to a high-insulation black organic silicon colorant and a preparation method thereof. Background Art

[0002] Black colorants are widely used in silicone materials for applications such as electronic component packaging, heat-resistant coatings, and insulating sealants, imparting a dark appearance and providing visual shielding. 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 exceptionally high tinting strength, thermal stability, and cost advantages. However, carbon black is inherently highly conductive and significantly hydrophobic, making it prone to agglomeration in silicone systems, making it difficult to disperse evenly and significantly degrading the material's electrical insulation properties. This issue is particularly prominent in applications requiring high insulation properties, such as electronic sealing and insulating coatings, significantly limiting product performance.

[0004] While iron black (Fe₃O₄) has some coloring properties, it is inherently magnetic and easily absorbs impurity ions (such as iron ions or other conductive metal impurities), posing electrical performance risks in systems requiring high insulation properties. Furthermore, iron black's blackness is far lower than that of carbon black, resulting in weaker tinting strength, making it difficult to meet requirements for color depth and hiding power.

[0005] While composite oxide pigments like copper chrome black offer a certain degree of chemical stability, their tinting strength is inferior to carbon black, resulting in a grayish color. These pigments are unsuitable for high-end silicone products that require a deep black appearance. Furthermore, these composite oxide pigments face application limitations in terms of fineness, wettability, and system compatibility.

[0006] In summary, current black silicone colorants generally rely on carbon black to meet tinting strength requirements. However, carbon black's high conductivity and tendency to agglomerate severely restrict its performance in high-insulation applications. Therefore, effectively addressing the reduced insulation and uneven dispersion caused by carbon black in silicone systems while maintaining a deep black appearance has become a key issue in this field that urgently needs to be addressed. Summary of the Invention

[0007] The present application provides a high-insulation black organosilicon colorant and a preparation method thereof, aiming to solve the problem in the prior art that black colorants are easy to agglomerate and difficult to disperse in organosilicon systems, and their electrical insulation performance is significantly reduced.

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

[0009] According to the present application, the black colorant significantly improves the electrical insulation performance and dispersion stability of carbon black in the silicone oil system while maintaining the high blackness advantage of carbon black, overcoming the problems of strong conductivity, poor interface compatibility, and easy agglomeration of carbon black, and is particularly suitable for applications in silicone materials with high insulation requirements.

[0010] Specifically, the passivated carbon black forms a polysiloxane skeleton layer on the surface of the carbon black through multi-site condensation of polymethyltriethoxysilane, constructing a basic coating structure, preliminarily reducing its surface free energy and conductivity, thereby improving the dispersion stability and insulation of the passivated carbon black in the system; the inventors found that the introduction of functionalized silane coupling agents can further improve the dispersion stability and insulation of the passivated carbon black in the system, which may be because the functionalized silane coupling agents can further regulate the interface chemical properties and microstructure of the coating layer, wherein the aromatic silicon Alkane coupling agents can enhance the affinity with the carbon skeleton on the surface of carbon black through π-π interaction, and introduce rigid skeletons and non-polar fragments into the coating layer, which helps to improve the film density of the coating layer and the anchoring stability of carbon black, thereby improving the dispersibility and thermal stability of passivated carbon black; fluorine-containing silane 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 recombination risk in the silicone system. At the same time, the high insulating properties of fluorine element also help to improve the overall resistivity.

[0011] In addition, the introduction of fumed silica as inorganic nanoparticles with high surface activity can form a spatially distributed network structure in the system, distributed between the carbon black particles, forming a certain degree of physical space steric hindrance and dispersed skeleton structure, limiting the agglomeration behavior of carbon black from a microscopic level, thereby inhibiting the movement and recombination tendency of carbon black, and further improving the system stability and rheological control ability of passivated carbon black in silicone oil.

[0012] The above-mentioned structural synergistic mechanism enables the high-insulation black silicone colorant of the present application to significantly improve the dispersibility, electrical insulation and system stability without sacrificing color depth, and is suitable for the preparation of black silicone materials with high dielectric performance requirements.

[0013] In some embodiments, the silicone oil carrier includes 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 aforementioned embodiments, vinyl silicone oil not only serves as a primary carrier, providing excellent low viscosity, heat resistance, and a good dispersion environment, but the vinyl groups in its molecular structure also participate in crosslinking reactions during subsequent thermal curing or vulcanization, reacting with crosslinkers (such as hydrosilanes) in the organosilicon system through addition reactions, thereby embedding itself into the overall organosilicon network. This property not only helps enhance the structural integrity and mechanical strength of the system, but also locks in the dispersed passivated carbon black and other components during the crosslinking and curing process, reducing the risk of subsequent migration or phase separation, and helping to maintain the electrical insulation stability of the colorant during use.

[0015] As an auxiliary carrier, the polar polyether chain segments of polyether silicone oil are difficult to participate in the cross-linking reaction, but they play an important function in the dispersion stage: on the one hand, their segments can be adsorbed on the incompletely coated areas or microscopic gaps on the surface of passivated carbon black 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, their hydrophilic polyether segments can also form hydrogen bonds or electrostatic effects with the hydroxyl groups on the surface of gas-phase SiO2, thereby helping to build a weak thixotropic network structure in the system, inhibiting the sedimentation or stratification of particles, and improving storage stability and dispersion uniformity.

[0016] In addition, in the interfacial region between passivated carbon black, polyether silicone oil can reduce the interfacial tension between particles, allowing them to be distributed in a lower energy state in the system, 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 9:0.5-1.5, the polyether silicone oil's dispersing synergistic effect can be fully utilized, while ensuring the system's thermal stability and subsequent crosslinking performance, achieving a balance between dispersibility and structural stability. However, when the polyether silicone oil ratio is too high, excessive polar segments may be introduced, leading to an imbalance in the system's polarity and compromising electrical insulation. Therefore, this silicone oil compound system not only achieves synergistic effects among dispersion, thixotropy, and crosslinking, but also significantly enhances the interfacial compatibility and stability of the colorant and silicone matrix.

[0018] In some embodiments, the viscosity of the vinyl silicone oil at 25° C. is 350-10,000 cP; the model of the polyether silicone oil is KF-6017.

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

[0020] Furthermore, the polyether silicone oil, model KF-6017, features a polydimethylsiloxane backbone with polyether segments grafted onto the side chains. This oil exhibits excellent wetting and interfacial spreading properties, further reducing interfacial tension and enhancing lubricity and particle stability. The presence of the polyether segments in KF-6017 allows it to adsorb onto carbon black surfaces or filler interfaces that are not fully coated with silicone. Through flexible segment extension and steric hindrance, it mitigates the aggregation tendency caused by van der Waals attraction between particles. Furthermore, it forms an auxiliary wetting barrier on the passivated carbon black surface, enhancing its dispersibility in the silicone oil carrier.

[0021] In some embodiments, the method for preparing the passivated carbon black comprises the following steps: S1: mixing carbon black with ethanol to disperse the carbon black in the ethanol to obtain a carbon black dispersion; S2: mixing polymethyltriethoxysilane, a functionalized silane coupling agent, and an ethanol aqueous solution to partially hydrolyze the polymethyltriethoxysilane and the aromatic silane coupling agent to obtain a silane solution; S3: adding the silane solution to the carbon black dispersion to allow polymethyltriethoxysilane and aromatic silane coupling agent to undergo polycondensation and crosslinking on the surface of the carbon black to obtain passivated carbon black.

[0022] In some of the above embodiments, the preparation method of passivated carbon black significantly improves the surface wettability and effective contact area of ​​carbon black, reduces the degree of agglomeration, and ensures the uniformity of the subsequent silane reaction by dispersing carbon black in a polar solvent (such as ethanol).

[0023] In step S2, polymethyltriethoxysilane (PMTES) serves as the main cross-linking substance and can be partially hydrolyzed in an ethanol-water solution to form a multifunctional silanol intermediate with a strong cross-linking tendency; while the functionalized silane coupling agent can simultaneously hydrolyze to produce a silanol structure with specific functional groups, so that the resulting organosilicon shell layer introduces structural units such as aromatic rings and fluorine atoms during the formation process, thereby giving the shell layer stronger interface control capabilities and microscopic configuration stability.

[0024] In step S3, the silane solution is added to the carbon black dispersion, and the silane hydrolyzate undergoes a polycondensation and cross-linking reaction on the surface of the carbon black to construct an organic silicon shell layer on the surface of the carbon black particles.

[0025] The shell structure is composed of the main cross-linked network skeleton formed by PMTES and modified functional groups. It not only significantly improves the hydrophobic stability of carbon black particles and reduces their tendency to migrate and aggregate in the silicone system, but also effectively weakens the surface conductivity of carbon black, giving it excellent electrical insulation properties.

[0026] This method is simple and easy to scale up. It is suitable for constructing carbon black particles with good dispersibility and high insulation performance, providing an ideal insulating black filler for the construction of high-insulation silicone colorant systems.

[0027] In some embodiments, the method for preparing the passivated carbon black comprises the following steps: S1: ultrasonically disperse 10 parts of carbon black in 40-60 parts of ethanol to obtain a carbon black dispersion; S2: Dispersing 4 to 6 parts of polymethyltriethoxysilane and 1 to 2 parts of a functionalized silane coupling agent in 5 to 15 parts of an aqueous ethanol solution, and adjusting the pH to 4 to 5 to obtain a silane solution; S3: adding the silane solution to the carbon black dispersion, reacting at 60-80° C. for 4-6 hours to obtain passivated carbon black.

[0028] 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 area of ​​the carbon black surface, and provides reaction sites for the subsequent silane coating reaction.

[0029] In step S2, polymethyltriethoxysilane (PTMS) serves as the primary crosslinker, rapidly hydrolyzing under acidic conditions (pH 4-5) to form a trifunctional silanol intermediate. Functionalized silane coupling agents (such as silanes with aromatic or fluoroalkyl groups) also partially hydrolyze under the same conditions. This acidic pH control helps inhibit the self-condensation of the silanol prepolymer in solution, thereby enhancing its preferential condensation efficiency with the carbon black surface and forming a directional coating structure. Controlling the addition of PTMS to 40%-60% of the carbon black mass forms a more complete organosilicon coating to passivate the carbon black surface. The relatively small proportion of the functionalized silane coupling agent involved in the reaction further improves the integrity and surface energy of the organic coating, thereby further inhibiting agglomeration of the passivated carbon black and enhancing its insulating properties.

[0030] Step S3, by continuing the reaction at 60-80°C for 4-6 hours, ensures that the silane hydrolysis products fully condense and form a film on the carbon black surface, gradually forming a relatively complete and firmly adhered organosilicon coating. This coating is structurally supported by a cross-linked network formed by PMTES, while the substituents introduced by the functionalized silanes control the interface polarity and compliance of the shell, thereby achieving structural passivation and reduced conductivity on the carbon black surface.

[0031] Through the coordinated regulation of the above-mentioned reaction parameters and the addition ratio, on the one hand, 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 be effectively regulated, which helps to construct black functional particles with excellent dispersibility and outstanding insulation properties, thereby enhancing the electrical insulation performance and long-term stability of the silicone colorant system.

[0032] In some embodiments, the average degree of polymerization of the polymethyltriethoxysilane is 2 to 3.

[0033] In some embodiments, the functionalized silane coupling agent includes an aromatic silane coupling agent and a fluorine-containing silane coupling agent, and the mass ratio of the aromatic silane coupling agent to the fluorine-containing silane coupling agent is 1:0.4-0.6.

[0034] In some of the aforementioned embodiments, aromatic silane coupling agents, with their strong π-π interactions and relatively rigid structure, can introduce a stable organic skeleton structure into the coating, enhancing the anchoring ability of the shell layer to the carbon black surface and improving the compatibility of the overall system with the organosilicon matrix. Fluorosilane 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.

[0035] The combined use of aromatic silanes and fluorinated silanes in a mass ratio of 1:0.4-0.6 improves the shell's compactness and structural stability, while further enhancing the coating's insulation and interfacial energy control capabilities. This ratio balances the surface anchoring effect of the aromatic structure with the electrical insulation regulation of the fluorocarbon segments, creating a silicone coating structure with both dispersion stability and high insulation performance. This helps improve the compatibility of passivated carbon black in silicone systems and the insulation properties of the resulting colorant.

[0036] It should be noted that aromatic silane coupling agents and fluorinated silane coupling agents have well-known meanings in the art. Aromatic silane coupling agents refer to silane coupling agents containing aromatic rings, while fluorinated silane coupling agents refer to silane coupling agents containing fluoroalkyl groups. For example, trifluoropropyltriethoxysilane is used as the fluorinated silane coupling agent in one embodiment of the present application.

[0037] In some embodiments, the aromatic silane coupling agent includes 4-methoxyphenyltriethoxysilane.

[0038] In some of the aforementioned embodiments, when 4-methoxyphenyltriethoxysilane is used as an aromatic silane coupling agent, the resulting colorant exhibits superior electrical insulation and stability compared to other phenylsilane coupling agents. This may be due to the fact that the methoxy group in the 4-methoxyphenyltriethoxysilane molecule is a strong electron-donating group that significantly enhances the electron density of the benzene ring, thereby increasing the strength of its π-π stacking interaction with the carbon black surface and promoting directional adsorption and effective coverage of the coupling agent on the carbon black surface. Furthermore, the methoxy-substituted structure also modulates the polarity distribution of the silane coupling agent, resulting in better interfacial compatibility between the coating formed during the hydrolysis and polycondensation process and the less polar silicone resin system, reducing the energy difference at the interface and inhibiting the tendency for delamination or agglomeration between the coating and the substrate.

[0039] Therefore, using 4-methoxyphenyltriethoxysilane as an aromatic silane coupling agent can further improve the electrical insulation properties and stability of the colorant.

[0040] In some embodiments, the average particle size of the fumed silica is 10 to 50 nm. Based on the above embodiment, fumed silica with a particle size within this range has a large specific surface area and good surface activity, which can form a uniformly dispersed filler network in the system and effectively embed the interfacial gaps 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 forms a physical barrier to carbon black aggregation to a certain extent, helping to improve the overall dispersion uniformity and anti-migration ability of the system. At the same time, 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 silicone colorant.

[0041] In some embodiments, the specific surface area of ​​the carbon black is 100 to 300 m 2 Based on the above embodiment, a moderate specific surface area can ensure that the carbon black has good coloring ability and surface reactivity, which not only helps to achieve more complete silane polycondensation coating during the passivation process, but also strengthens the directional adsorption ability of the functionalized silane coupling agent while retaining certain surface active sites, further enhancing the overall electrical insulation and coloring ability of the material.

[0042] In a second aspect, the present application provides a method for preparing a high-insulation black organic silicone colorant, comprising: Providing raw materials for the high-insulation black organic silicone colorant according to any embodiment of the first aspect; The raw materials are mixed to obtain an insulating black organic silicon colorant.

[0043] According to the present application, the method involves mixing and dispersing passivated carbon black, fumed silica, and a compounded silicone oil in a proportional manner, resulting in a uniform distribution of the passivated carbon black within the organosilicon system. The fumed silica then fills the gaps to form a three-dimensional support structure, while the silicone oil, as a continuous phase, provides excellent wettability and dispersion stability. In this preparation method, the passivated carbon black already has a pre-formed organosilicon coating, exhibiting excellent 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 and silicone rubber, achieving co-curing of the system. The polyether silicone oil provides excellent interfacial blending capabilities, enhancing overall mixing uniformity. This preparation method is simple and can be performed in conventional mixing and dispersion equipment (such as a three-roll mill or planetary mixer), helping to improve product stability and consistency in industrial applications.

[0044] In some embodiments, the step of mixing the raw materials to obtain an insulating black organosilicon colorant comprises: Dispersing passivated carbon black in polyether silicone oil to obtain a first component; dispersing fumed silica in vinyl silicone oil to obtain a second component; The first component and the second component are then mixed to obtain an insulating black organic silicone colorant.

[0045] Based on the above-mentioned embodiments, the inventors discovered that adopting this dispersion sequence can significantly enhance the coordinated distribution behavior of the various components in the system while improving dispersion efficiency. The moderate surface polarity of the passivated carbon black makes it easier to wet and encapsulate in the polyether silicone oil. The polyether segments can also form a reversible adsorption layer on the carbon black surface (part of the passivated carbon black that may not be completely encapsulated by the silicone layer), further inhibiting particle agglomeration and improving the initial dispersion stability of the system. Furthermore, the high specific surface area and abundant surface hydroxyl groups of fumed silica form a good physical embedding and van der Waals interaction with the vinyl silicone oil, forming a relatively continuous three-dimensional skeleton network during shear dispersion.

[0046] In the final mixed composite system, the carbon black particles are evenly embedded in the support network constructed by gas-phase SiO2 with polyether silicone oil as the lubricating interface. The coexistence of vinyl silicone oil and polyether silicone oil in the system can not only ensure the moderate viscosity of the system and excellent workability, but also form a stable cross-linked structure during the subsequent silicone cross-linking and curing process, effectively preventing carbon black migration, aggregation or conductive path formation, and further improving insulation and service life.

[0047] Compared with the prior art, the present invention has the following advantages: 1. This application significantly improves the electrical insulation performance of black silicone colorants by constructing a multiphase composite system of "passivated carbon black + fumed silica + silicone oil carrier", solving the problem of dielectric breakdown or insulation failure caused by conductivity in traditional carbon black filling systems; 2. This application uses polymethyltriethoxysilane and aromatic or fluorinated silane coupling agents to synergistically coat carbon black. By regulating the polarity, flexibility, and surface energy of the coating structure, a dense and electrically controllable organic silicon passivation layer is constructed. This effectively blocks the conductive path while maintaining black coloring power. 3. The obtained organosilicon colorant can directly participate in the cross-linking reaction of vinyl organosilicon materials, significantly improving the compatibility between the colorant and the matrix and the cross-linking embedding strength, avoiding carbon black precipitation, bleeding or migration, and extending the service life of the material.

[0048] 4. The high-insulation black silicone colorant provided in this application has excellent electrical insulation, dispersion stability and tinting strength, and is particularly suitable for fields such as silicone potting glue, sealant, electrical packaging materials, etc. that have high requirements for insulation performance. DETAILED DESCRIPTION

[0049] The various embodiments or implementation schemes in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments.

[0050] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with an embodiment or example is included in at least one embodiment or example of the present application. In this specification, 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 any one or more embodiments or examples.

[0051] 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0052] In the description of this specification, unless otherwise specified, "parts" refer to "parts by mass".

[0053] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0054] Vinyl silicone oil: vinyl terminated dimethyl (siloxane and polysiloxane) with a viscosity of 1000 cP at 25°C; Polyether silicone oil: Model KF-6017; Polymethyltriethoxysilane: average degree of polymerization is 2~3; Trifluoropropyltriethoxysilane: CAS number is 86876-45-1; 4-Methoxyphenyltriethoxysilane: CAS number is 21130-91-6; Phenyltriethoxysilane: CAS number is 780-69-8; Carbon black: Specific surface area is about 230m 2 / g; Fumed silica: The average particle size is about 30 nm.

[0055] Preparation Example 1 Preparation of passivated carbon black: Add 10 parts of carbon black and 50 parts of ethanol into the reactor, and perform ultrasonic treatment (frequency 40 kHz, power 200 W) for 30 minutes to fully disperse the carbon black to obtain a carbon black dispersion. 5 parts of polymethyltriethoxysilane, 1 part of 4-methoxyphenyltriethoxysilane, and 0.5 parts of trifluoropropyltriethoxysilane were added to 10 parts of an ethanol aqueous solution having a volume fraction of 80% ethanol, stirred and mixed, and then acetic acid was added to adjust the pH to 4.5, and hydrolyzed for 30 minutes to obtain a silane solution; The above-mentioned silane hydrolyzate was slowly added dropwise to the carbon black dispersion under stirring. The reaction system was heated to 70°C and kept warm for 6 hours. After the reaction was completed, it was naturally cooled to room temperature. The product was centrifuged to obtain a black solid, which was 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.

[0056] Preparation Example 2 Preparation of passivated carbon black: Add 10 parts of carbon black and 50 parts of ethanol into the reactor, and perform ultrasonic treatment (frequency 40 kHz, power 200 W) for 30 minutes to fully disperse the carbon black to obtain a carbon black dispersion. 5 parts of polymethyltriethoxysilane and 1.5 parts of 4-methoxyphenyltriethoxysilane were added to 10 parts of an ethanol solution with a volume fraction of 80%, stirred and mixed, and then acetic acid was added to adjust the pH to 4.5, and hydrolyzed for 30 minutes to obtain a silane solution; The above-mentioned silane hydrolyzate was slowly added dropwise to the carbon black dispersion under stirring. The reaction system was heated to 70°C and kept warm for 6 hours. After the reaction was completed, it was naturally cooled to room temperature. The product was centrifuged to obtain a black solid, which was 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.

[0057] Preparation Example 3 Preparation of passivated carbon black: Add 10 parts of carbon black and 50 parts of ethanol into the reactor, and perform ultrasonic treatment (frequency 40 kHz, power 200 W) for 30 minutes to fully disperse the carbon black to obtain a carbon black dispersion. 5 parts of polymethyltriethoxysilane and 1.5 parts of trifluoropropyltriethoxysilane were added to 10 parts of an ethanol solution with a volume fraction of 80%, stirred and mixed, and then acetic acid was added to adjust the pH to 4.5, and hydrolyzed for 30 minutes to obtain a silane solution; The above-mentioned silane hydrolyzate was slowly added dropwise to the carbon black dispersion under stirring. The reaction system was heated to 70°C and kept warm for 6 hours. After the reaction was completed, it was naturally cooled to room temperature. The product was centrifuged to obtain a black solid, which was 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.

[0058] Comparative Preparation Example 1 Preparation of passivated carbon black: Add 10 parts of carbon black and 50 parts of ethanol into the reactor, and perform ultrasonic treatment (frequency 40 kHz, power 200 W) for 30 minutes to fully disperse the carbon black to obtain a carbon black dispersion. 6.5 parts of polymethyltriethoxysilane were added to 10 parts of an 80% ethanol aqueous solution, stirred and mixed, and then acetic acid was added to adjust the pH to 4.5, and hydrolyzed for 30 minutes to obtain a silane solution; The above-mentioned silane hydrolyzate was slowly added dropwise to the carbon black dispersion under stirring. The reaction system was heated to 70°C and kept warm for 6 hours. After the reaction was completed, it was naturally cooled to room temperature. The product was centrifuged to obtain a black solid, which was 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.

[0059] Example 1 Preparation of insulating black silicone colorant: Take 4 parts of the passivated carbon black A prepared in Preparation Example 1, add them to 10 parts of polyether silicone oil, and disperse them at room temperature using a high-speed shear disperser for 10 minutes to obtain a uniform dispersion of carbon black in the polyether silicone oil, which is recorded as the first component; 3 parts of fumed silica were added to 90 parts of vinyl silicone oil, mechanically stirred at room temperature for 5 minutes, and then ground three times in a three-roll mill (roller spacing was set at 20 μm, 10 μm, and 5 μm) to obtain a uniformly dispersed fumed SiO2 dispersion, which was recorded as the second component; The first component and the second component are mixed and then rotated and ground with zirconium beads in a grinding chamber of a sand mill for 30 minutes to obtain an insulating black silicone colorant.

[0060] Example 2 Preparation of insulating black silicone colorant: Take 4 parts of the passivated carbon black A prepared in Preparation Example 1, add them to 10 parts of vinyl silicone oil, and disperse them at room temperature using a high-speed shear disperser for 10 minutes to obtain a uniform dispersion of carbon black in vinyl silicone oil, which is recorded as the first component; 3 parts of fumed silica were added to 90 parts of vinyl silicone oil, mechanically stirred at room temperature for 5 minutes, and then ground three times in a three-roll mill (roller spacing was set at 20 μm, 10 μm, and 5 μm) to obtain a uniformly dispersed fumed SiO2 dispersion, which was recorded as the second component; The first component and the second component are mixed and then rotated and ground with zirconium beads in a grinding chamber of a sand mill for 30 minutes to obtain an insulating black silicone colorant.

[0061] Example 3 Preparation of insulating black silicone colorant: Take 4 parts of the passivated carbon black A prepared in Preparation Example 1, add them to 30 parts of polyether silicone oil, and disperse them at room temperature using a high-speed shear disperser for 10 minutes to obtain a uniform dispersion of carbon black in the polyether silicone oil, which is recorded as the first component; 3 parts of fumed silica were added to 70 parts of vinyl silicone oil, mechanically stirred at room temperature for 5 minutes, and then ground three times in a three-roll mill (roller spacing was set at 20 μm, 10 μm, and 5 μm) to obtain a uniformly dispersed fumed SiO2 dispersion, which was recorded as the second component; The first component and the second component are mixed and then rotated and ground with zirconium beads in a grinding chamber of a sand mill for 30 minutes to obtain an insulating black silicone colorant.

[0062] Example 4 Preparation of insulating black silicone colorant: It is substantially the same as Example 1, except that the passivated carbon black used is the passivated carbon black B obtained in Preparation Example 2.

[0063] Example 5 Preparation of insulating black silicone colorant: It is substantially the same as Example 1, except that the passivated carbon black used is the passivated carbon black C obtained in Preparation Example 3.

[0064] Example 6 Preparation of insulating black silicone colorant: Take 4 parts of the passivated carbon black A prepared in Preparation Example 1, add them to 10 parts of vinyl silicone oil, and disperse them at room temperature using a high-speed shear disperser for 10 minutes to obtain a uniform dispersion of carbon black in vinyl silicone oil, which is recorded as the first component; Take 3 parts of fumed silica and add it to 80 parts of vinyl silicone oil and 10 parts of polyether silicone oil. After mechanical stirring at room temperature for 5 minutes, transfer it to a three-roll mill and grind it three times (roller spacing is set to 20μm, 10μm, and 5μm) to obtain a uniformly dispersed fumed SiO2 dispersion, which is recorded as the second component; The first component and the second component are mixed and then rotated and ground with zirconium beads in a grinding chamber of a sand mill for 30 minutes to obtain an insulating black silicone colorant.

[0065] Comparative Example 1 Preparation of insulating black silicone colorant: It is substantially the same as Example 1, except that the passivated carbon black used is the passivated carbon black D obtained in Comparative Preparation Example 1.

[0066] Test section Electrical insulation performance test: Add 2.5 g of the high-insulation black silicone colorant to be tested to 50 g of RTV-1 silicone rubber (model: Dow Corning 732) and grind it three times using a three-roll mill to evenly disperse the colorant in the silicone.

[0067] The ground mixture was injected into a 100 mm × 100 mm × 1 mm PTFE mold and allowed to stand for 48 hours at room temperature (25 ± 2 ° C) and relative humidity > 50% for natural vulcanization. After complete curing, the mixture was demoulded to obtain a test sample.

[0068] According to GB / T1410-2006 "Determination of volume resistivity and surface resistivity of solid insulating materials", the sample was cut into the test specifications of 50mm×50mm×1mm; the upper and lower surfaces of the sample were clamped with standard copper disc electrodes; the volume resistivity ρ of the sample was tested at room temperature (25±2℃), relative humidity (50%±2%) and 500V DC voltage. V1 (Ω·cm); 3 samples were tested in each group and the average value was taken; the results are shown in Table 1.

[0069] In addition, in order to test the stability of the high-insulation black silicone colorant, the high-insulation black silicone colorant obtained in each example was placed in a 60°C constant temperature box for 15 days for accelerated aging, and then the high-insulation black silicone colorant after high-temperature storage was subjected to the above electrical insulation performance test to test the volume resistivity ρ of the corresponding sample. V2 (Ω·cm); 3 samples were tested in each group and the average value was taken; the results are shown in Table 1.

[0070] Table 1 <![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 ]]> According to Table 1, the ρ of the corresponding samples in each embodiment V1 and ρ V2 Compared with Comparative Example 1, the storage stability of the organosilicon colorant is also indirectly reflected by comparing the attenuation of the volume resistivity of the samples after storage, indicating that the high-insulation black organosilicon colorant provided by this application has the beneficial effect of significantly improving the volume resistivity and enhancing the storage stability. The possible reason for this is that in Comparative Example 1, the passivated carbon black used only a single coating agent of polymethyltriethoxysilane, without the introduction of aromatic silanes with π-π stacking ability or fluorinated silanes with interfacial energy regulation. This resulted in a loose and uneven structure of the carbon black coating layer, and the residual conductive paths between the particles could not be effectively cut off, resulting in a significantly lower resistivity than the various examples. In addition, agglomeration easily occurred during storage, further reducing the resistivity and making it difficult to meet high insulation requirements.

[0071] Examples 1-3 show that 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 in a proportional combination as the carrier, maintaining system compatibility while providing good wettability and a bridging dispersion structure, resulting in the highest initial resistivity (and lowest decay rate) of the colorant in the RTV system. In Example 2, in which no polyether silicone oil was added and only vinyl silicone oil was used as the carrier, the initial resistivity and the resistivity after storage decreased significantly, indicating that the lack of polar wetting segments reduced the dispersion stability of the colorant. In Example 3, the excessive proportion of polyether silicone oil resulted in a lower initial resistivity and a higher resistivity decay rate compared to Example 1, indicating that the introduction of too many polar segments into the system not only affects electrical insulation but also may lead to polarity imbalance, which is detrimental to maintaining electrical insulation.

[0072] Examples 1, 4, and 5 show that the type and combination of silane coupling agents in the passivated carbon black has a certain impact on the insulation performance of the system. Example 1 uses a combination of PMTES, aromatic silane, and fluorinated silane to form a dense coating with a coordinated interfacial polarity gradient, achieving the best resistivity and storage stability. Example 4 only increases the proportion of aromatic silane and does not use a fluorinated component, resulting in reduced insulation and increased surface energy of the shell layer, with initial and post-storage resistivity slightly lower than that of Example 1. Example 5 uses a fluorinated silane instead of an aromatic silane and lacks a π-π stacking auxiliary alignment layer, resulting in slightly inferior insulation and storage stability to Example 1, indicating that the three-component synergistic system is most conducive to constructing a high-efficiency electrical insulation shielding layer.

[0073] According to Examples 1 and 6, the method of introducing polyether silicone oil has a certain impact on the insulation performance enhancement effect of passivated carbon black. In Example 1, polyether silicone oil is directly used as a dispersion medium to disperse the passivated carbon black. Its polar segments can preferentially adsorb on the carbon black surface areas where the coating layer may have defects or be incompletely covered, thereby further enhancing the coating density and electrical insulation shielding effect at the microscopic level, effectively inhibiting the formation of conductive paths. In contrast, in Example 6, polyether silicone oil is added to the dispersion system of fumed silica. Due to the strong hydrogen bonding and entanglement between the polyether segments and the hydroxyl-rich surface of the fumed silica, the polyether segments are preferentially formed as the surface coating of the fumed silica, making it difficult to achieve supplementary modification of the carbon black. As a result, the overall insulation and storage stability of the colorant system are slightly lower than those of Example 1.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A high-insulation black silicone colorant, characterized in that: Including the following raw materials by weight: 100 parts silicone oil carrier; 3-5 parts passivated carbon black; 1-3 parts fumed silica; 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 grafting and polymerizing polymethyltriethoxysilane and a functionalized silane coupling agent on the surface of the carbon black; the functionalized silane coupling agent comprises at least one of an aromatic silane coupling agent and a fluorine-containing silane coupling agent.

2. The high-insulation black organic silicon colorant according to claim 1, characterized in that: The silicone oil carrier includes 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.

3. The high-insulation black organic silicon colorant according to claim 2, characterized in that: The viscosity of the vinyl silicone oil at 25° C. is 350-10,000 cP; the model of the polyether silicone oil is KF-6017.

4. The high-insulation black organic silicon colorant according to claim 1, characterized in that: The preparation method of the passivated carbon black comprises the following steps: S1: mixing carbon black with ethanol to disperse the carbon black in the ethanol to obtain a carbon black dispersion; S2: mixing polymethyltriethoxysilane, a functionalized silane coupling agent, and an ethanol aqueous solution to partially hydrolyze the polymethyltriethoxysilane and the aromatic silane coupling agent to obtain a silane solution; S3: adding the silane solution to the carbon black dispersion to allow polymethyltriethoxysilane and aromatic silane coupling agent to undergo polycondensation and crosslinking on the surface of the carbon black to obtain passivated carbon black.

5. The high-insulation black organic silicon colorant according to claim 4, characterized in that: The preparation method of the passivated carbon black comprises the following steps: S1: ultrasonically disperse 10 parts of carbon black in 40-60 parts of ethanol to obtain a carbon black dispersion; S2: Dispersing 4 to 6 parts of polymethyltriethoxysilane and 1 to 2 parts of a functionalized silane coupling agent in 5 to 15 parts of an aqueous ethanol solution, and adjusting the pH to 4 to 5 to obtain a silane solution; S3: adding the silane solution to the carbon black dispersion, reacting at 60-80° C. for 4-6 hours to obtain passivated carbon black.

6. The high-insulation black organic silicon colorant according to claim 4, characterized in that: The functionalized silane coupling agent includes an aromatic silane coupling agent and a fluorine-containing silane coupling agent, and the mass ratio of the aromatic silane coupling agent to the fluorine-containing silane coupling agent is 1:0.4-0.

6.

7. The high-insulation black organic silicon colorant according to claim 6, characterized in that: The aromatic silane coupling agent includes 4-methoxyphenyltriethoxysilane.

8. The high-insulation black organic silicone colorant according to any one of claims 1 to 7, 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 to 50 nm; 2) The specific surface area of ​​the carbon black is 100~300m 2 / g.

9. A method for preparing a high-insulation black organic silicone colorant, characterized in that: include: Providing raw materials for the high-insulation black organic silicone colorant according to any one of claims 1 to 8; The raw materials are mixed to obtain an insulating black organic silicon colorant.

10. The method according to claim 9, characterized in that The insulating black organic silicon colorant obtained by mixing the raw materials comprises: Dispersing passivated carbon black in polyether silicone oil to obtain a first component; dispersing fumed silica in vinyl silicone oil to obtain a second component; The first component and the second component are then mixed to obtain an insulating black organic silicone colorant.