Carbon fiber oriented distribution high thermal conductivity sealed paste and preparation method thereof

Abstract

The application provides a kind of carbon fiber directional distribution high-thermal-conductivity sealed paste and a preparation method thereof, and belongs to the technical field of sealed paste.The application builds efficient heat conduction network and significantly improves the thermal conductivity, mechanical properties and long-term stability of the composite material through the synergistic effect of various heat-conducting fillers:potassium titanate whiskers are modified by silica sol coating and silane coupling agent to improve interface compatibility and dispersibility, uniformly distributed in the matrix, reducing interface defects;trimethylhydroxy phosphate and epoxy reactive diluent synergistically react to prepare functional additives, enhance the interface bonding force and optimize the dispersibility of fillers;metal salt is chelated with ethylenediaminetetraacetic acid and polyethylene glycol 400 is introduced to form a flexible complex, improve the interface stability and filler dispersion efficiency;long and short carbon fibers synergistically act and directional arrangement strategy optimizes the uniformity and continuity of the heat conduction network.The synergistic effect of various fillers and modification methods significantly improves the thermal conductivity efficiency, mechanical properties and processing adaptability of the composite material.

Description

Technical Field

[0001] This invention belongs to the field of sealed paste technology, and relates to a carbon fiber oriented high thermal conductivity sealed paste and its preparation method. Background Technology

[0002] In the field of materials science today, sealing paste, as an important composite material, is widely used in industries such as construction, automotive, electronics, and aerospace due to its excellent adhesion, formability, and durability. The widespread application of sealing paste benefits from its ability to effectively fill complex structures, provide excellent sealing, and thus enhance the strength and stability of the overall structure.

[0003] The performance of hermetically sealed pastes largely depends on their constituent materials and their dispersion, especially in applications requiring high thermal conductivity. Thermal conductivity is a key factor affecting the thermal management performance of materials, particularly in electronic equipment and high-temperature environments. Good thermal conductivity can effectively reduce heat buildup, prevent equipment overheating, and thus improve its efficiency and lifespan. However, traditional hermetically sealed pastes have some shortcomings in terms of thermal conductivity and material uniformity, which limit their potential in many application areas, especially in industries with high thermal conductivity requirements.

[0004] In existing technologies, the thermal conductivity of sealed pastes typically depends on the type and amount of filler material, such as metal particles or other thermally conductive fillers. However, this approach often fails to effectively balance thermal conductivity and mechanical properties. Excessive filler material can lead to material embrittlement, reducing its mechanical strength and toughness, thus negatively impacting the overall performance of the sealed paste. Furthermore, many sealed paste formulations are prone to bubble formation or uneven distribution during curing, which not only affects the material's appearance but also obstructs heat conduction paths, reducing overall thermal conductivity efficiency. These problems cause traditional sealed pastes to perform poorly under high heat load conditions, failing to meet the demands of modern engineering and limiting their widespread use in high-tech applications. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a carbon fiber-oriented, high-thermal-conductivity closed-cell paste and its preparation method. This invention utilizes the synergistic effect of various thermally conductive fillers and modification strategies to construct a highly efficient thermally conductive network and significantly improve the thermal conductivity, mechanical properties, and long-term stability of the composite material. Potassium titanate whiskers, through silica sol coating and silane coupling agent modification, improve interfacial compatibility and dispersibility, ensuring uniform distribution within the matrix and reducing interfacial defects. Trimethylhydroxyphosphate and epoxy reactive diluent synergistically react to prepare functionalized additives, enhancing interfacial bonding and optimizing filler dispersibility. The chelation of metal salts with ethylenediaminetetraacetic acid and the introduction of polyethylene glycol 400 form flexible complexes, improving interfacial stability and filler dispersion efficiency. The synergistic effect of long and short carbon fibers and the directional arrangement strategy optimize the uniformity and continuity of the thermally conductive network. The synergistic effect of various fillers and modification methods significantly improves the thermal conductivity, mechanical properties, and processing adaptability of the composite material.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a carbon fiber oriented high thermal conductivity sealed paste, the method comprising:

[0008] S1: Disperse potassium titanate whisker powder in deionized water, add silica sol to mix and obtain a suspension, evaporate to obtain a slurry, calcine it to obtain surface-coated potassium titanate; grind to obtain surface-coated potassium titanate powder; react and treat it with a silane coupling agent to obtain modified potassium titanate whisker powder;

[0009] S2: Trimethylhydroxyphosphate is mixed with epoxy reactive diluent, and a catalyst is added to obtain reaction solution B. The reaction is stirred at a constant temperature under nitrogen protection and cooled to obtain phosphate ester functionalized crosslinking aid.

[0010] S3: Prepare a metal salt solution, adjust its pH and add ethylenediaminetetraacetic acid to obtain a chelate solution, add a polymer solution to obtain reaction solution C, adjust the pH to obtain reaction solution D, stir at constant temperature to obtain a pretreatment solution, distill under reduced pressure to obtain a concentrated solution, add polyethylene glycol 400 and continue distillation to obtain a viscous metal salt / polymer complex solution.

[0011] S4: Modified potassium titanate whisker powder is added to epoxy resin and stirred and dispersed evenly. Then, phosphate ester functionalized crosslinking agent, metal salt / polymer complex viscous liquid and curing agent are added in sequence to obtain base material. Carbon fiber is added to base material in batches and stirred evenly to obtain paste. It is spread on the table, scraped with a scraper and placed in a vacuum drying oven for degassing, preliminary curing and curing to obtain carbon fiber oriented high thermal conductivity sealed paste.

[0012] Specifically, S1: Disperse potassium titanate whisker powder in deionized water, add silica sol under stirring to obtain a suspension, disperse evenly by ultrasonication and evaporate to obtain a slurry, calcine it to obtain potassium titanate coated on the surface; grind to obtain potassium titanate powder coated on the surface, add it and silane coupling agent to ethanol / water solution to obtain reaction solution A, stir at constant temperature, filter and dry to obtain modified potassium titanate whisker powder;

[0013] S2: Trimethylhydroxyphosphate is mixed with epoxy reactive diluent, and a catalyst is added to obtain reaction solution B. The reaction is carried out under nitrogen protection with constant temperature stirring, and then cooled to obtain phosphate ester functionalized crosslinking aid.

[0014] S3: Prepare a metal salt solution, adjust its pH and add ethylenediaminetetraacetic acid and stir to obtain a chelate solution; prepare a polymer solution and mix it with the chelate solution to obtain reaction solution C, adjust the pH to obtain reaction solution D, stir at constant temperature to obtain a pretreatment solution, distill under reduced pressure to obtain a concentrated solution, add polyethylene glycol 400 and continue distillation to obtain a viscous metal salt / polymer complex solution.

[0015] S4: Modified potassium titanate whisker powder is added to epoxy resin and stirred and dispersed evenly. Then, phosphate ester functionalized crosslinking agent, metal salt / polymer complex viscous liquid and curing agent are added in sequence to obtain base material. Carbon fiber is added to base material in batches and stirred evenly to obtain paste. It is spread on the table, scraped with a scraper and placed in a vacuum drying oven for degassing, preliminary curing and curing to obtain carbon fiber oriented high thermal conductivity sealed paste.

[0016] As a preferred technical solution of the present invention, in step S1, the mass fraction of the potassium titanate whisker powder in deionized water is 10-15 wt.%, for example, it can be 10 wt.%, 10.5 wt.%, 11 wt.%, 11.5 wt.%, 12 wt.%, 12.5 wt.%, 13 wt.%, 13.5 wt.%, 14 wt.%, 14.5 wt.%, or 15 wt.%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] In some optional embodiments, the mass ratio of the potassium titanate whisker powder to the silicon oxide in the silica sol is 100:5-10, for example, it can be 100:5, 100:5.5, 100:6, 100:6.5, 100:7, 100:7.5, 100:8, 100:8.5, 100:9, 100:9.5 or 100:10, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0018] In some optional embodiments, the suspension is ultrasonically dispersed and then evaporated at 60-80°C, for example, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0019] In some optional embodiments, the calcination temperature of the slurry is 800-900°C, for example, 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C or 900°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the calcination time of the slurry is 1-2 hours, for example, it can be 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the particle size of the surface-coated potassium titanate powder is 5-10 μm, for example, it can be 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0022] In some optional embodiments, the silane coupling agent is silane coupling agent KH550, and the amount of silane coupling agent added is 1-3% of the mass of the surface-coated potassium titanate powder, for example, it can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8% or 3%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the volume ratio of ethanol to water in the ethanol / water solution is (95:5)-(90:10), for example, it can be 95:5, 94.5:5.5, 94:6, 93.5:6.5, 93:7, 92.5:7.5, 92:8, 91.5:8.5, 91:9, 90.5:9.5 or 90:10, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the mass ratio of the surface-coated potassium titanate powder to the ethanol / water solution is 1:5-10, for example, it can be 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5 or 1:10, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, the temperature of the isothermal reaction of the reaction solution A is 40-60°C, for example, it can be 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the reaction time of the reaction solution A at constant temperature is 30-60 min, for example, it can be 30 min, 33 min, 36 min, 39 min, 42 min, 45 min, 48 min, 51 min, 54 min, 57 min or 60 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0027] As a preferred technical solution of the present invention, in step S2, the epoxy reactive diluent is any one of n-butyl glycidyl ether, polypropylene glycol diglycidyl ether, and phenyl glycidyl ether.

[0028] In some optional embodiments, the molar ratio of the trimethylhydroxyphosphate to the epoxy reactive diluent is 1:0.5-1, for example, it can be 1:0.5, 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75, 1:0.8, 1:0.85, 1:0.9, 1:0.95 or 1:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the catalyst is tetrabutylammonium bromide, and the amount of catalyst fed is 0.5-1% of the mass of trimethylhydroxyphosphate, for example, it can be 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95% or 1%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the temperature of the isothermal stirring reaction of the reaction solution B is 120-150°C, for example, it can be 120°C, 122°C, 124°C, 126°C, 128°C, 130°C, 132°C, 134°C, 36°C, 138°C, 140°C, 142°C, 144°C, 146°C, 148°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the reaction solution B is stirred at a constant temperature for 1-3 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] As a preferred technical solution of the present invention, in step S3, the metal salt is either zirconium oxychloride octahydrate or zirconium nitrate.

[0033] In some optional embodiments, the mass fraction of the metal salt solution is 5-15 wt.%, for example, it can be 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, 10 wt.%, 11 wt.%, 12 wt.%, 13 wt.%, 14 wt.%, or 15 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0034] In some alternative embodiments, ethylenediaminetetraacetic acid is added after the pH of the metal salt solution is adjusted to 4-5. For example, it can be 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] In some optional embodiments, the molar ratio of ethylenediaminetetraacetic acid to the metal salt is 0.5-1:1, for example, it can be 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1 or 1:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the metal salt is added to ethylenediaminetetraacetic acid and stirred for 30-40 min to obtain a chelate solution, for example, 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min or 40 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] The polymer is any one or a combination of two of polyvinylpyrrolidone or polyvinyl alcohol;

[0038] In some alternative embodiments, the polymer solution has a mass fraction of 5-10 wt.%, for example, 5 wt.%, 5.5 wt.%, 6 wt.%, 6.5 wt.%, 7 wt.%, 7.5 wt.%, 8 wt.%, 8.5 wt.%, 9 wt.%, 9.5 wt.%, or 10 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0039] In some alternative embodiments, the mass ratio of the metal salt to the polymer is 1-2:1, for example, it can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0040] In some alternative embodiments, the pH of the reaction solution C is adjusted to 6-7 to obtain the reaction solution D, for example, it can be 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9 or 7, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0041] In some optional embodiments, the temperature of the reaction solution D being stirred at a constant temperature is 30-40°C, for example, it can be 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C or 40°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0042] In some optional embodiments, the reaction solution D is stirred at a constant temperature for 3-4 hours, for example, 3 hours, 3.1 hours, 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.6 hours, 3.7 hours, 3.8 hours, 3.9 hours or 4 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0043] In some optional embodiments, the temperature of the pretreatment liquid vacuum distillation is 50-60°C, for example, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0044] In some alternative embodiments, the volume of the polyethylene glycol 400 is 5-10% of the volume of the concentrate, for example, it can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0045] As a preferred technical solution of the present invention, in step S4, the curing agent is either methylhexahydrophthalic anhydride or triethylenetetramine.

[0046] In some optional embodiments, the mass ratio of long carbon fibers to short carbon fibers in the carbon fiber is 1-2:1, for example, it can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0047] The short carbon fibers have a length of 3-5 mm, and the long carbon fibers have a length of 10-20 mm;

[0048] In some optional embodiments, the time for degassing the paste after it is applied with a scraper and placed in a vacuum drying oven is 5-10 minutes, for example, 5 minutes, 5.5 minutes, 6 minutes, 6.5 minutes, 7 minutes, 7.5 minutes, 8 minutes, 8.5 minutes, 9 minutes, 9.5 minutes or 10 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] In some alternative embodiments, the initial curing temperature is 40-60°C, for example, 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0050] In some optional embodiments, the initial curing time is 1-2 hours, for example, it can be 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0051] In some alternative embodiments, the curing temperature is 120-150°C, for example, 120°C, 123°C, 126°C, 129°C, 132°C, 135°C, 138°C, 141°C, 144°C, 147°C or 150°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0052] In some optional embodiments, the curing time is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0053] In some alternative embodiments, the angle of the scraper is 50-60°, for example, it can be 50°, 51°, 52°, 53°, 54°, 55°, 56°, 57°, 58°, 59° or 60°, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0054] In some optional embodiments, the scraping speed is 20-30 cm / min, for example, it can be 20 cm / min, 21 cm / min, 22 cm / min, 23 cm / min, 24 cm / min, 25 cm / min, 26 cm / min, 27 cm / min, 28 cm / min, 29 cm / min or 30 cm / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0055] The mass ratio of the modified potassium titanate whisker powder, epoxy resin, phosphate ester functionalized crosslinking agent, metal salt / polymer complex viscous liquid, curing agent and carbon fiber is (15-20):(45-55):(3-8):(5-10):(8-12):(10-15).

[0056] Secondly, the present invention provides a carbon fiber oriented high thermal conductivity sealed paste prepared by the above preparation method.

[0057] This invention introduces potassium titanate whiskers as an inorganic filler to enhance thermal conductivity. Potassium titanate is a typical chain-like inorganic material, its crystal structure consisting of titanium-oxygen octahedrons linked by oxygen bridges along a specific direction to form a chain-like arrangement. This chain-like structure is further stacked into a layered morphology, giving it excellent mechanical strength and thermal stability. Potassium titanate whiskers exhibit excellent directional thermal conductivity along the crystal direction, enabling efficient heat transfer. Introducing them as a filler into composite materials can construct a highly efficient thermal conductivity network at the microscale. However, potassium titanate whiskers have some prominent problems in practical applications, limiting their potential and functionality in high thermal conductivity composite materials.

[0058] First, potassium titanate whiskers expose a large number of hydroxyl and oxygen-bridging groups on their surface. These groups are highly polar and readily interact with polar solvents, but exhibit poor interfacial compatibility when in contact with hydrophobic organic matrices such as epoxy resins. This polarity difference makes it difficult for potassium titanate whiskers to disperse uniformly in the epoxy resin matrix, easily leading to agglomeration and the formation of localized filler-rich regions. These agglomerates not only hinder the uniform construction of the thermally conductive network but also introduce defects at the interface, thereby increasing interfacial thermal resistance and significantly reducing the overall thermal conductivity of the material. Furthermore, although the polar groups on the surface of potassium titanate whiskers can interact with epoxy resin molecules to some extent through physical adsorption or hydrogen bonding, their low chemical reactivity prevents them from forming stable chemical bonds with the epoxy groups in the epoxy resin. This weak interfacial bonding makes the composite material prone to interfacial debonding during use, further limiting the material's thermal conductivity and mechanical properties.

[0059] To overcome these problems, this invention employs a dual modification strategy combining silica sol coating and silane coupling agent modification, significantly improving the interfacial compatibility and dispersion properties of potassium titanate whiskers. First, a dense silica coating layer is formed on the surface of the potassium titanate whiskers using silica sol coating technology. During hydrolysis and polycondensation reactions, the silica sol is uniformly deposited on the surface of the potassium titanate whiskers through electrostatic interaction or chemical adsorption. After calcination, this coating layer further transforms into a highly crystalline silica layer. The silica coating layer reduces the agglomeration tendency between fillers by lowering the surface energy of the whiskers. Furthermore, the high thermal stability of silica further enhances the stability and reliability of potassium titanate whiskers under high-temperature environments, ensuring the long-term use of the composite material.

[0060] Building upon silica sol coating, potassium titanate whiskers were further surface-functionalized using silane coupling agents. The siloxane groups in the silane coupling agent molecule hydrolyze to generate silanol groups, which then undergo condensation reactions with the hydroxyl groups on the coated or uncoated portions of the potassium titanate whisker surface, forming stable chemical bonds. This process not only enhances the bonding strength between the silane coupling agent and the potassium titanate whiskers but also introduces organic functional groups onto the whisker surface. These functional groups can, on the one hand, undergo ring-opening crosslinking reactions with the epoxy groups of the epoxy resin matrix, significantly improving interfacial adhesion; on the other hand, their appropriate polarity effectively coordinates the polarity differences between the filler and the matrix, further improving the filler's dispersibility and interfacial compatibility.

[0061] Potassium titanate whiskers, after dual modification, exhibit superior dispersion and interfacial bonding properties. Within the epoxy resin matrix, the modified potassium titanate whiskers distribute uniformly, reducing agglomeration and thus constructing a more continuous and stable microscopic thermal conductivity network. This network significantly improves the thermal conductivity of the composite material by reducing interfacial thermal resistance and enhancing thermal conductivity efficiency. Simultaneously, the enhanced interfacial bonding prevents problems such as interfacial debonding, improving the mechanical properties and long-term stability of the composite material.

[0062] This invention introduces the reaction of trimethylhydroxyphosphate with an epoxy reactive diluent to prepare a phosphate-based functionalized crosslinking agent. Trimethylhydroxyphosphate is a molecule with high polarity and chemical stability, containing phosphorus-oxygen double bonds and phosphorus-oxygen single bonds in its structure. These polar groups can significantly improve the wettability of material interfaces and provide key chemical sites for interfacial interactions between fillers and organic matrices. Furthermore, the high polarity of the phosphate groups can effectively improve the thermal conductivity of composite materials, enhancing interfacial heat transfer and reducing interfacial thermal resistance, thereby constructing a more efficient thermally conductive network.

[0063] The introduction of epoxy reactive diluents further facilitates the functionalization process of this system. Epoxy reactive diluent molecules contain multiple epoxy groups, which can undergo ring-opening addition reactions with the hydroxyl groups in trimethylhydroxyphosphate molecules to generate phosphate-based functionalized crosslinking aids. In this reaction, the high chemical activity of the epoxy groups not only provides multiple chemical binding sites, giving the functionalized aids higher activity, but also reduces the viscosity of the epoxy resin system through dilution. This reduction in viscosity helps the filler to disperse uniformly in the matrix, reduces filler agglomeration, and thus constructs a more uniform thermally conductive network within the material.

[0064] The prepared phosphate-based functionalized crosslinking agent played a significant role in the epoxy resin curing process. On one hand, this agent participated in the epoxy resin curing reaction, forming a dense three-dimensional crosslinked network structure through its epoxy groups. This three-dimensional crosslinked structure not only improved the mechanical properties of the material but also enhanced the thermal stability and long-term reliability of the composite material. On the other hand, the phosphate groups, due to their high polarity and chemical stability, formed strong interfacial bonds with the filler and matrix during the curing process. This strong interfacial bond reduced the generation of interfacial defects, effectively lowering the interfacial thermal resistance and enabling the filler to efficiently transfer heat. Furthermore, the high stability of the phosphate groups ensured that the composite material maintained excellent interfacial properties during long-term use or under high-temperature environments.

[0065] Through the synergistic effect of trimethylhydroxyphosphate and epoxy reactive diluent, the final functionalized crosslinking aid not only achieves uniform distribution within the matrix but also improves the interfacial bonding and thermal conductivity between the filler and the matrix. The high polarity of the phosphate groups significantly enhances the construction efficiency of the thermally conductive network, while the multifunctionality of the epoxy groups further improves the overall performance of the composite material. This synergistic effect comprehensively optimizes the composite material's thermal conductivity, mechanical properties, and interfacial stability, providing crucial technical support for the preparation of high-performance thermally conductive composite materials.

[0066] In this invention, a stable metal chelate is prepared by chelating a metal salt with ethylenediaminetetraacetic acid (EDTA). This chelate is then further combined with a polymer to form a metal salt / polymer complex, thereby optimizing the interfacial and thermal conductivity properties of the composite material. The core of this chelation process lies in the polydentate coordination characteristic of the EDTA molecule. EDTA contains four carboxyl groups and two amino groups, which can form stable chelate ring structures with metal ions through coordinate bonds. This polydentate coordination endows the metal chelate with extremely high chemical and thermal stability, while also significantly improving the dispersibility and chemical reactivity of the metal ions. Through this chelation process, the metal ions are firmly immobilized within the chelate, preventing aggregation or deposition in the matrix, thus providing a chemical basis for subsequent complexation.

[0067] In the preparation of metal salt / polymer complexes, polymer molecules are introduced. These polymers contain abundant hydroxyl or carbonyl groups, which can further interact with the metal ions in the metal chelate through hydrogen bonding or coordination, thereby forming a stable complex. Through this process, the metal chelate is uniformly dispersed in the polymer matrix, forming a metal salt / polymer complex with high chemical stability. These complexes not only possess excellent chemical and thermal stability, but their surface polar groups can also interact with the epoxy resin matrix. This interaction significantly enhances the interfacial bonding force between the filler and the matrix through hydrogen bonding or surface wetting, thereby reducing interfacial defects, lowering interfacial thermal resistance, and further optimizing the thermal conductivity of the composite material.

[0068] Metal salt / polymer complexes exhibit multiple functions in the preparation of composite materials. Their moderate viscosity and unique chemical properties are crucial for the dispersibility of fillers. Polar groups (such as hydroxyl and carbonyl groups) in the complex can form stable interfacial interactions with the surface of thermally conductive fillers through hydrogen bonding or coordination, effectively inhibiting filler particle agglomeration. This interfacial wetting effect not only improves the uniform distribution of fillers in the matrix but also lays the foundation for constructing a continuous thermal conductivity network. In this process, the viscosity of the complex needs to be moderate, providing dispersion stability for the filler without significantly increasing the flow resistance of the matrix. Especially under shear conditions, the complex further improves the dispersion efficiency of the filler in the matrix by coating the filler particles and preventing their re-agglomeration. Furthermore, the high thermal stability and excellent thermal conductivity of the metal salt in the complex play an important auxiliary role in the thermal conductivity network. The metal salt can maintain a stable structure in the high-temperature environment of the composite material while enhancing the heat transfer efficiency within the system, thereby improving the overall thermal conductivity of the material and providing reliability assurance for its high-temperature applications.

[0069] To further optimize the flexibility and dispersion properties of the metal salt / polymer complex, polyethylene glycol 400 was introduced as an auxiliary component in this invention. Polyethylene glycol 400 is a low-molecular-weight linear polyether with high polarity and flexibility, containing numerous ether bonds and hydroxyl groups. These functional groups can form stronger interfacial interactions with the polar groups on the surface of the metal salt chelate through hydrogen bonding or van der Waals forces, thereby improving the dispersibility and stability of the metal chelate in the matrix. The long molecular chain and good flexibility of polyethylene glycol 400 provide greater lubrication and flowability in the matrix, contributing to improved processing performance of the material.

[0070] Secondly, the molecular chains of polyethylene glycol 400 can act as fillers and connectors in composite materials. Its flexible segments can act as bridges between metal chelates and other thermally conductive fillers, further enhancing interfacial bonding and reducing interfacial thermal resistance. This interfacial reinforcement effect helps to construct a more continuous and efficient thermal conductivity network, thereby improving the thermal conductivity of the composite material.

[0071] Furthermore, polyethylene glycol 400 exhibits high thermal stability, maintaining the integrity of its molecular structure at high temperatures without introducing additional thermal decomposition products, thus ensuring the long-term thermal stability of the composite material. This is particularly important in the application of high-performance thermal management materials.

[0072] This invention introduces carbon fibers and directionally distributes them within a composite material to construct a multi-scale, highly efficient thermally conductive network, significantly improving the overall thermal conductivity and thermal stability of the material. Carbon fiber is a material with excellent thermal conductivity; its graphitized structure consists of carbon atoms in a two-dimensional plane distributed through sp... 2 Hybridization forms a hexagonal honeycomb arrangement, and this layered structure endows carbon fibers with extremely high thermal conductivity along the fiber axis. Simultaneously, carbon fibers also possess high thermal stability, maintaining their structural integrity and thermal conductivity even at high temperatures, a significant advantage as a thermally conductive reinforcement material. To fully utilize the thermal conductivity potential of carbon fibers, this invention employs a synergistic strategy of using long and short carbon fibers to construct both penetrating and localized thermal conduction channels at both the macroscopic and microscopic scales.

[0073] Long carbon fibers primarily serve as building blocks for continuous thermal conductive channels in composite materials. Their greater length and high thermal conductivity enable them to effectively connect different regions of the matrix, providing a continuous and preferential conduction path for heat. This significantly reduces energy loss due to interfacial thermal resistance during heat conduction, thereby improving the overall thermal conductivity of the composite material. Simultaneously, short carbon fibers act as filler units, filling voids and microscopic defects in the matrix. Short carbon fibers can form highly efficient thermally conductive networks within localized areas, compensating for thermal resistance regions that might be missed during the distribution of long carbon fibers. This multi-scale synergistic effect of short and long carbon fibers effectively optimizes the continuity and uniformity of the thermal conductive network, resulting in excellent thermal conductivity at different structural levels in the composite material.

[0074] To achieve efficient functionality of carbon fibers within the matrix, this invention utilizes external forces such as stirring and coating during the preparation process to induce directional alignment of the carbon fibers. During coating, a uniform external force is applied to control the orientation of the carbon fibers, ensuring their orderly alignment along a specified direction. This directional distribution strategy reduces cross-linking and stacking between carbon fibers, lowers scattering losses in the heat conduction path, and improves heat conduction efficiency along the fiber direction. Furthermore, the directional distribution of carbon fibers enhances the mechanical properties of the composite material. For example, carbon fibers aligned along the heat flow direction can effectively improve the tensile strength and flexural strength of the material, thereby achieving synergistic optimization of mechanical and thermal conductivity properties.

[0075] In this invention, the performance enhancement of composite materials, especially the significant improvement in thermal conductivity, is effectively achieved through the synergistic effect of various functional materials, modification methods, and structural design. This synergistic enhancement is not only reflected in the chemical compatibility and interfacial interactions of the components, but also further optimized through the complementary physical properties between materials and the construction of multi-scale networks, thus improving the overall performance of the materials.

[0076] First, there is a synergistic reinforcing effect between carbon fibers and potassium titanate whiskers. Carbon fibers, with their graphitized structure and high axial thermal conductivity, construct a continuous macroscopic thermal conductivity channel in the composite material, effectively reducing thermal resistance during long-distance heat conduction. Meanwhile, potassium titanate whiskers, through their chain-like and layered structures, form a localized thermal conductivity network at the microscopic scale. The combination of these two forms a multidimensional thermal conductivity network integrating macroscopic and microscopic scales. Specifically, the directional alignment of carbon fibers further optimizes the continuity of the macroscopic thermal conductivity path, reducing heat loss during long-distance transfer; while potassium titanate whiskers, through their uniform distribution and efficient microscopic heat transfer capabilities, compensate for potential thermal resistance regions within the carbon fiber network. This multi-scale synergistic effect of long carbon fibers and short potassium titanate whiskers significantly improves the overall thermal conductivity of the composite material.

[0077] Furthermore, the introduction of metal salt / polymer complexes generates significant interfacial synergies between carbon fibers and potassium titanate whiskers. The metal salts form complexes by coordinating with hydroxyl or carbonyl groups in the polymer, and are uniformly distributed within the matrix. The polar groups in these complexes can interact with the surface polar groups of the carbon fibers and potassium titanate whiskers through interfacial interactions, such as hydrogen bonding or coordination bonding, significantly enhancing the interfacial adhesion between the filler and the matrix. This enhanced interfacial adhesion reduces microscopic defects and thermal resistance at the interface, enabling the filler to transfer heat more efficiently. Moreover, the high thermal stability of the metal salts further enhances the reliability of the composite material under high-temperature conditions, ensuring the long-term functionality of the filler.

[0078] The chemical modification techniques in this invention also demonstrate a significant synergistic enhancement effect. For example, modifying potassium titanate whiskers through silica sol coating and silane coupling agent functionalization significantly improves their interfacial compatibility and dispersibility. The silica sol coating layer not only endows potassium titanate whiskers with higher thermal stability and thermal conductivity but also reduces the agglomeration tendency between fillers, thereby optimizing the construction of the microscopic thermal conductivity network. Simultaneously, the silane coupling agent chemically bonds the potassium titanate whiskers firmly to the matrix, further enhancing the interfacial bonding force. This synergistic effect of combining physical and chemical modification enables potassium titanate whiskers to function more efficiently in composite materials and, together with carbon fibers and metal salt / polymer complexes, constitutes a highly efficient thermal conductivity system.

[0079] External force-induced carbon fiber orientation further enhances the synergistic effect among the multi-component materials. The external force applied during stirring and coating causes the carbon fibers to orient themselves in a specified direction, thus forming a more continuous thermally conductive network together with potassium titanate whiskers and metal salt / polymer complexes. This orientation not only reduces cross-linking and stacking between fillers but also significantly improves the heat transfer efficiency along the fiber direction. This synergistic strategy combining physical force field control and chemical modification comprehensively optimizes the thermal conductivity and mechanical properties of the composite material.

[0080] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0081] This invention utilizes potassium titanate whiskers as a thermally conductive filler and improves its interfacial compatibility and dispersion performance through silica sol coating and silane coupling agent modification strategies. The chain-like structure of potassium titanate whiskers endows them with excellent directional thermal conductivity; however, their surface polar groups have poor compatibility with the epoxy resin matrix, easily leading to filler agglomeration and interfacial thermal resistance. Silica sol coating forms a dense silica layer, reducing the filler surface energy and enhancing thermal stability; the silane coupling agent further introduces organic functional groups, forming a strong interfacial bond with the matrix, improving dispersibility and reducing interfacial defects. The modified potassium titanate whiskers are uniformly distributed in the matrix, constructing a highly efficient thermal conductivity network, significantly improving the thermal conductivity, mechanical properties, and long-term stability of the composite material.

[0082] This invention utilizes the synergistic reaction of trimethylhydroxyphosphate (THP) and an epoxy reactive diluent to prepare phosphate-based functionalized additives, significantly improving the thermal conductivity and mechanical properties of composite materials. THP enhances interfacial bonding, reduces interfacial thermal resistance, and constructs a highly efficient thermally conductive network; the epoxy reactive diluent enhances chemical activity and crosslinking ability, improving filler dispersibility. During curing, the functionalized additives form a dense crosslinked network, improving the material's thermal conductivity, mechanical properties, and thermal stability, providing an effective solution for the preparation of high-performance thermally conductive composite materials.

[0083] This invention utilizes the chelation of metal salts with ethylenediaminetetraacetic acid (EDTA) to form stable metal chelates, which are then combined with polymers to prepare metal salt / polymer complexes, thereby improving the interfacial and thermal conductivity properties of composite materials. The chelation process imparts high chemical stability and dispersibility to the metal chelates, preventing metal ion aggregation, while the complexation process enhances the interfacial bonding between the filler and the matrix, reduces interfacial thermal resistance, and constructs a highly efficient thermal conductivity network. The introduction of polyethylene glycol 400 further improves the flexibility and flowability of the complexes, enhances filler dispersibility and material processability, ultimately significantly improving the thermal conductivity and overall performance of the composite material, providing technical support for the preparation of high-performance thermal management materials.

[0084] This invention utilizes the multi-scale synergistic effect and directional distribution strategy of long and short carbon fibers to construct a highly efficient thermally conductive network, significantly improving the thermal conductivity and thermal stability of composite materials. Long carbon fibers act as through-channel thermal conduction pathways, connecting different regions of the matrix and reducing interfacial thermal resistance; short carbon fibers fill microscopic defects, constructing localized thermally conductive networks and optimizing the uniformity and continuity of heat conduction. External force is applied to achieve directional alignment of the carbon fibers, reducing cross-stacking and scattering losses, enhancing thermal conductivity efficiency, and simultaneously improving the tensile strength and flexural strength of the material, thus achieving synergistic optimization of thermal conductivity and mechanical properties.

[0085] This invention achieves a significant improvement in the thermal conductivity and mechanical properties of composite materials through the synergistic effect of carbon fibers, potassium titanate whiskers, and metal salt / polymer complexes, combined with chemical modification and structural design. Carbon fibers construct a continuous macroscopic thermal conductivity channel, while potassium titanate whiskers form a microscopic thermal conductivity network; the two synergistically optimize the multi-scale thermal conductivity structure. The metal salt / polymer complex enhances interfacial bonding, reduces interfacial defects, and improves high-temperature stability. Through silica sol coating and silane coupling agent modification, the dispersibility and interfacial compatibility of potassium titanate whiskers are significantly improved, forming a highly efficient thermal conductivity system together with carbon fibers and metal complexes. Furthermore, external force-induced directional alignment of carbon fibers further enhances the continuity and conductivity of the thermal conductivity network, achieving comprehensive optimization of thermal conductivity and mechanical properties. Detailed Implementation

[0086] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0087] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0088] Example 1

[0089] This embodiment provides a carbon fiber oriented high thermal conductivity sealing paste and its preparation method. The preparation method of the carbon fiber oriented high thermal conductivity sealing paste specifically includes the following steps:

[0090] S1: Potassium titanate whisker powder was dispersed in deionized water at a mass fraction of 13 wt.%, and silica sol was added under stirring to obtain a suspension. The mass ratio of potassium titanate whisker powder to silicon oxide in silica sol was 100:7. After ultrasonic dispersion, the slurry was evaporated at 60°C to obtain a paste. The paste was then calcined at 850°C for 1 h to obtain surface-coated potassium titanate. The surface-coated potassium titanate powder with a particle size of 5 μm was obtained by grinding. The paste was then added to an ethanol / water solution with silane coupling agent KH550 to obtain reaction solution A. The solid-liquid mass ratio of surface-coated potassium titanate powder to ethanol / water solution was 1:7, the amount of silane coupling agent KH550 was 2% of the mass of surface-coated potassium titanate powder, and the volume ratio of ethanol to water in the ethanol / water solution was 92:8. The mixture was stirred at a constant temperature of 40°C for 40 min, filtered, and dried to obtain modified potassium titanate whisker powder.

[0091] S2: Trimethylhydroxyphosphate is mixed with epoxy reactive diluent n-butyl glycidyl ether, wherein the molar ratio of trimethylhydroxyphosphate to epoxy reactive diluent is 1:0.8. Tetrabutylammonium bromide catalyst is added to obtain reaction solution B, wherein the amount of catalyst added is 0.7% of the mass of trimethylhydroxyphosphate. The reaction is stirred at a constant temperature of 120°C for 2 hours under nitrogen protection, and then cooled to obtain phosphate ester-functionalized crosslinking aid.

[0092] S3: Prepare a 10 wt.% solution of zirconium oxychloride octahydrate, adjust its pH to 4.5, add ethylenediaminetetraacetic acid (EDTA) and stir for 30 min to obtain a chelate solution, wherein the molar ratio of EDTA to the metal salt is 0.7:1; prepare an 8 wt.% solution of polyvinylpyrrolidone (PVP) polymer, mix it with the chelate solution to obtain reaction solution C, wherein the mass ratio of metal salt to polymer is 1.5:1, adjust the pH to 6 to obtain reaction solution D, stir at a constant temperature of 30℃ for 3 h to obtain a pretreatment solution, distill under reduced pressure at 50℃ to obtain a concentrated solution, add polyethylene glycol 400 at a feed amount of 8% of the concentrated solution volume and continue distillation to obtain a viscous metal salt / polymer complex solution;

[0093] S4: Modified potassium titanate whisker powder is added to epoxy resin and stirred until evenly dispersed. Then, phosphate ester-based functionalized crosslinking agent, metal salt / polymer complex viscous liquid, and curing agent methyl hexahydrophthalic anhydride are added sequentially to obtain a base material. Carbon fibers are added to the base material in batches, with a mass ratio of short carbon fibers to long carbon fibers of 1.8:1. The mixture is stirred until evenly mixed to obtain a paste. The paste is spread on a work surface and coated with a scraper at an angle of 55° and a scraping speed of 25 cm / min. After coating, the paste is placed in a vacuum drying oven for 5 min to remove bubbles, and then initially cured at 40°C for 1.5 h and cured at 130°C for 2 h to obtain a carbon fiber oriented, high thermal conductivity, and sealed paste. The mass ratio of modified potassium titanate whisker powder, epoxy resin, phosphate ester-based functionalized crosslinking agent, metal salt / polymer complex viscous liquid, curing agent, and carbon fibers is 18:52:7:8:10:13.

[0094] Example 2

[0095] This embodiment provides a carbon fiber oriented high thermal conductivity sealing paste and its preparation method. The preparation method of the carbon fiber oriented high thermal conductivity sealing paste specifically includes the following steps:

[0096] S1: Potassium titanate whisker powder was dispersed in deionized water at a mass fraction of 10 wt.%, and silica sol was added under stirring to obtain a suspension. The mass ratio of potassium titanate whisker powder to silicon oxide in silica sol was 100:9. After ultrasonic dispersion, the suspension was evaporated at 70°C to obtain a slurry. The slurry was then calcined at 900°C for 1.5 h to obtain surface-coated potassium titanate. The surface-coated potassium titanate powder with a particle size of 8 μm was obtained by grinding. The powder was then added to an ethanol / water solution with silane coupling agent KH550 to obtain reaction solution A. The solid-liquid mass ratio of the surface-coated potassium titanate powder to the ethanol / water solution was 1:5, the amount of silane coupling agent KH550 was 1% of the mass of the surface-coated potassium titanate powder, and the volume ratio of ethanol to water in the ethanol / water solution was 95:5. The mixture was stirred at a constant temperature of 55°C for 50 min, filtered, and dried to obtain modified potassium titanate whisker powder.

[0097] S2: Trimethylhydroxyphosphate is mixed with epoxy reactive diluent polypropylene glycol diglycidyl ether, wherein the molar ratio of trimethylhydroxyphosphate to epoxy reactive diluent is 1:0.7. Tetrabutylammonium bromide catalyst is added to obtain reaction solution B, wherein the amount of catalyst added is 0.5% of the mass of trimethylhydroxyphosphate. The reaction is carried out under nitrogen protection at a constant temperature of 140℃ for 1 hour and then cooled to obtain phosphate ester-based functionalized crosslinking aid.

[0098] S3: Prepare a 12 wt.% zirconium nitrate solution, adjust its pH to 4.8, add ethylenediaminetetraacetic acid (EDTA) and stir for 35 min to obtain a chelate solution, wherein the molar ratio of EDTA to the metal salt is 0.8:1; prepare a 5 wt.% polyvinyl alcohol (PVA) polymer solution, mix it with the chelate solution to obtain reaction solution C, wherein the mass ratio of metal salt to polymer is 1:1, adjust the pH to 6.8 to obtain reaction solution D, stir at a constant temperature of 35℃ for 3.5 h to obtain a pretreatment solution, distill under reduced pressure at 57℃ to obtain a concentrated solution, add 7% polyethylene glycol 400 (equivalent to 7% of the volume of the concentrated solution) and continue distillation to obtain a viscous metal salt / polymer complex solution;

[0099] S4: Modified potassium titanate whisker powder is added to epoxy resin and stirred until evenly dispersed. Then, phosphate ester-based functionalized crosslinking agent, metal salt / polymer complex viscous liquid, and curing agent triethylenetetramine are added sequentially to obtain a base material. Carbon fibers are added to the base material in batches, with a mass ratio of short carbon fibers to long carbon fibers of 1.5:1. The mixture is stirred until evenly mixed to obtain a paste. The paste is spread on a work surface and coated with a scraper at an angle of 50° and a scraping speed of 30 cm / min. After coating, the paste is placed in a vacuum drying oven for 8 min to remove bubbles, initially cured at 50°C for 1 h, and then cured at 140°C for 2.5 h to obtain a carbon fiber oriented, high thermal conductivity, and sealed paste. The mass ratio of modified potassium titanate whisker powder, epoxy resin, phosphate ester-based functionalized crosslinking agent, metal salt / polymer complex viscous liquid, curing agent, and carbon fibers is 20:45:3:7:8:15.

[0100] Example 3

[0101] This embodiment provides a carbon fiber oriented high thermal conductivity sealing paste and its preparation method. The preparation method of the carbon fiber oriented high thermal conductivity sealing paste specifically includes the following steps:

[0102] S1: Potassium titanate whisker powder was dispersed in deionized water at a mass fraction of 15 wt.%, and silica sol was added under stirring to obtain a suspension. The mass ratio of potassium titanate whisker powder to silicon oxide in silica sol was 100:5. After ultrasonic dispersion, the suspension was evaporated at 75°C to obtain a slurry. The slurry was then calcined at 870°C for 1.8 h to obtain surface-coated potassium titanate. The surface-coated potassium titanate powder with a particle size of 10 μm was obtained by grinding. The powder was then added to an ethanol / water solution with silane coupling agent KH550 to obtain reaction solution A. The solid-liquid mass ratio of surface-coated potassium titanate powder to ethanol / water solution was 1:10, the amount of silane coupling agent KH550 was 2.5% of the mass of surface-coated potassium titanate powder, and the volume ratio of ethanol to water in the ethanol / water solution was 93:7. The mixture was stirred at a constant temperature of 50°C for 30 min, filtered, and dried to obtain modified potassium titanate whisker powder.

[0103] S2: Trimethylhydroxyphosphate is mixed with epoxy reactive diluent phenyl glycidyl ether, wherein the molar ratio of trimethylhydroxyphosphate to epoxy reactive diluent is 1:0.5. Tetrabutylammonium bromide catalyst is added to obtain reaction solution B, wherein the amount of catalyst added is 1% of the mass of trimethylhydroxyphosphate. The reaction is carried out under nitrogen protection at a constant temperature of 130℃ for 2.5h with stirring. After cooling, phosphate ester-functionalized crosslinking aid is obtained.

[0104] S3: Prepare a 5 wt.% zirconium nitrate solution, adjust its pH to 4, add ethylenediaminetetraacetic acid (EDTA) and stir for 38 min to obtain a chelate solution, wherein the molar ratio of EDTA to the metal salt is 0.5:1; prepare a 7 wt.% polyvinylpyrrolidone (PVP) solution, mix it with the chelate solution to obtain reaction solution C, wherein the mass ratio of metal salt to polymer is 1.8:1, adjust the pH to 6.6 to obtain reaction solution D, stir at a constant temperature of 38℃ for 3.8 h to obtain a pretreatment solution, distill under reduced pressure at 58℃ to obtain a concentrated solution, add polyethylene glycol 400 at a feed amount of 5% of the concentrated solution volume and continue distillation to obtain a viscous metal salt / polymer complex solution;

[0105] S4: Modified potassium titanate whisker powder is added to epoxy resin and stirred until evenly dispersed. Then, phosphate ester-based functionalized crosslinking agent, metal salt / polymer complex viscous liquid, and curing agent methyl hexahydrophthalic anhydride are added sequentially to obtain a base material. Carbon fibers are added to the base material in batches, with a mass ratio of short carbon fibers to long carbon fibers of 1:1. The mixture is stirred evenly to obtain a paste, which is then spread on a work surface and coated with a scraper at an angle of 59° and a scraping speed of 20 cm / min. After coating, the paste is placed in a vacuum drying oven for 7 min to remove bubbles, initially cured at 55° for 1.8 h, and then cured at 120° for 1 h to obtain a carbon fiber oriented, high thermal conductivity, and sealed paste. The mass ratio of modified potassium titanate whisker powder, epoxy resin, phosphate ester-based functionalized crosslinking agent, metal salt / polymer complex viscous liquid, curing agent, and carbon fibers is 15:50:5:5:12:10.

[0106] Example 4

[0107] This embodiment provides a carbon fiber oriented high thermal conductivity sealing paste and its preparation method. The preparation method of the carbon fiber oriented high thermal conductivity sealing paste specifically includes the following steps:

[0108] S1: Potassium titanate whisker powder was dispersed in deionized water at a mass fraction of 14 wt.%, and silica sol was added under stirring to obtain a suspension. The mass ratio of potassium titanate whisker powder to silicon oxide in silica sol was 100:10. After ultrasonic dispersion, the slurry was evaporated at 80℃ and calcined at 800℃ for 2 h to obtain surface-coated potassium titanate. The surface-coated potassium titanate powder with a particle size of 9 μm was obtained by grinding. The powder was added to an ethanol / water solution with silane coupling agent KH550 to obtain reaction solution A. The solid-liquid mass ratio of surface-coated potassium titanate powder to ethanol / water solution was 1:8, the amount of silane coupling agent KH550 was 3% of the mass of surface-coated potassium titanate powder, and the volume ratio of ethanol to water in the ethanol / water solution was 90:10. The mixture was stirred at a constant temperature of 60℃ for 60 min, filtered, and dried to obtain modified potassium titanate whisker powder.

[0109] S2: Trimethylhydroxyphosphate is mixed with epoxy reactive diluent n-butyl glycidyl ether, wherein the molar ratio of trimethylhydroxyphosphate to epoxy reactive diluent is 1:1. Tetrabutylammonium bromide catalyst is added to obtain reaction solution B, wherein the amount of catalyst added is 0.8% of the mass of trimethylhydroxyphosphate. The reaction is stirred at a constant temperature of 150°C for 3 hours under nitrogen protection, and then cooled to obtain phosphate ester-functionalized crosslinking aid.

[0110] S3: Prepare a 15 wt.% solution of zirconium oxychloride octahydrate, adjust its pH to 5, add ethylenediaminetetraacetic acid (EDTA) and stir for 40 min to obtain a chelate solution, wherein the molar ratio of EDTA to the metal salt is 1:1; prepare a 10 wt.% solution of polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PEA), mix it with the chelate solution to obtain reaction solution C, wherein the mass ratio of metal salt to polymer is 2:1, adjust the pH to 7 to obtain reaction solution D, stir at a constant temperature of 40℃ for 4 h to obtain a pretreatment solution, distill under reduced pressure at 60℃ to obtain a concentrated solution, add polyethylene glycol 400 at a feed amount of 10% of the volume of the concentrated solution and continue distillation to obtain a viscous metal salt / polymer complex solution;

[0111] S4: Modified potassium titanate whisker powder is added to epoxy resin and stirred until evenly dispersed. Then, phosphate ester-based functionalized crosslinking agent, metal salt / polymer complex viscous liquid, and curing agent triethylenetetramine are added sequentially to obtain a base material. Carbon fibers are added to the base material in batches, with a mass ratio of short carbon fibers to long carbon fibers of 2:1. The mixture is stirred evenly to obtain a paste, which is then spread on a work surface and coated with a scraper at an angle of 60° and a scraping speed of 23 cm / min. After coating, the paste is placed in a vacuum drying oven for 10 min to remove bubbles, initially cured at 60° for 2 h, and then cured at 150° for 3 h to obtain a carbon fiber oriented, high thermal conductivity, and sealed paste. The mass ratio of modified potassium titanate whisker powder, epoxy resin, phosphate ester-based functionalized crosslinking agent, metal salt / polymer complex viscous liquid, curing agent, and carbon fibers is 16:55:8:10:11:12.

[0112] Comparative Example 1

[0113] This comparative example provides a carbon fiber oriented high thermal conductivity sealed paste. The difference from Example 1 is that the treatment step of modifying potassium titanate whiskers in S1 is omitted. Other operation steps and process parameters are exactly the same as in Example 1.

[0114] Comparative Example 2

[0115] This comparative example provides a carbon fiber oriented high thermal conductivity sealed paste. The difference from Example 1 is that in S1, only the potassium titanate whiskers are coated with silicon oxide, and the silane coupling agent modification treatment is omitted. Other operation steps and process parameters are exactly the same as in Example 1.

[0116] Comparative Example 3

[0117] This comparative example provides a carbon fiber oriented high thermal conductivity closed paste. The difference from Example 1 is that no phosphate ester functionalized crosslinking agent is added, but the other operating steps and process parameters are exactly the same as in Example 1.

[0118] Comparative Example 4

[0119] This comparative example provides a carbon fiber oriented high thermal conductivity sealed paste. The difference from Example 1 is that no metal salt / polymer complex is added, but the other operating steps and process parameters are exactly the same as in Example 1.

[0120] Comparative Example 5

[0121] This comparative example provides a carbon fiber oriented high thermal conductivity sealed paste. The difference from Example 1 is that in S4, only long carbon fibers are used. Other operating steps and process parameters are exactly the same as in Example 1.

[0122] Comparative Example 6

[0123] This comparative example provides a carbon fiber oriented high thermal conductivity sealed paste. The difference from Example 1 is that in S4, only short carbon fibers are used. Other operating steps and process parameters are exactly the same as in Example 1.

[0124] The performance of the carbon fiber oriented high thermal conductivity sealed pastes of Examples 1-4 and Comparative Examples 1-6 was tested.

[0125] The thermal conductivity of the sample was tested according to ASTM E1461;

[0126] The test results are shown in Table 1.

[0127] Table 1: Test results of carbon fiber oriented high thermal conductivity sealed paste in Examples 1-4 and Comparative Examples 1-6

[0128] Thermal conductivity (W / m·K) Compressive strength (MPa) Example 1 2.5 30 Example 2 2.4 27 Example 3 2.3 29 Example 4 2.4 28 Comparative Example 1 1.5 20 Comparative Example 2 1.8 23 Comparative Example 3 1.9 24 Comparative Example 4 2.0 25 Comparative Example 5 1.8 22 Comparative Example 6 1.7 24

[0129] The test results from Example 1 and Comparative Example 1 show that when the S1 step of modifying potassium titanate whiskers is omitted, the thermal conductivity drops to 1.5 W / m·K and the compressive strength drops to 20 MPa. This is because the unmodified potassium titanate whiskers have high surface energy and are prone to agglomeration in the organic matrix, resulting in uneven filler dispersion. At the same time, due to the lack of active groups on the surface, the interfacial bonding with the epoxy resin matrix is ​​poor, the interfacial thermal resistance increases, and the thermal conduction efficiency decreases. In addition, the poor interfacial bonding leads to poor stress transmission, resulting in a decrease in the overall mechanical properties of the composite material.

[0130] The test results from Example 1 and Comparative Example 2 show that when only silica coating is applied, the thermal conductivity drops to 1.8 W / m·K and the compressive strength drops to 23 MPa. This is because although silica coating alone improves the surface activity of potassium titanate whiskers, it lacks the introduction of organic functional groups, resulting in insufficient compatibility with the epoxy resin matrix. Furthermore, the lack of silane coupling agent modification leads to insufficient interfacial chemical bonding, affecting heat transfer and stress transfer efficiency.

[0131] The test results from Example 1 and Comparative Example 3 show that without the addition of phosphate ester functionalized crosslinking agents, the thermal conductivity drops to 1.9 W / m·K and the compressive strength drops to 24 MPa. This is because the lack of chemical bonding between phosphate ester groups and the filler surface reduces the interfacial bonding strength; at the same time, the crosslinking network density decreases, resulting in insufficient heat conduction channels and reduced stress transfer efficiency.

[0132] The test results from Example 1 and Comparative Example 4 show that without the addition of metal salt / polymer complex, the thermal conductivity drops to 2.0 W / m·K, and the compressive strength drops to 25 MPa. This is because the lack of complex to regulate the rheology of the system affects the orientation of the filler; at the same time, the synergistic effect of complex on filler dispersion is lost, resulting in an incomplete filler network structure, which affects the formation of thermal conduction channels and the performance of mechanical properties.

[0133] The test results from Example 1 and Comparative Example 5 show that when only long carbon fibers are used, the thermal conductivity drops to 1.8 W / m·K and the compressive strength drops to 22 MPa. This is because long carbon fibers are prone to entanglement in the matrix, making dispersion difficult and resulting in an insufficiently dense thermally conductive network. At the same time, due to the uniform fiber length, multi-scale thermally conductive channels cannot be formed, and the stress distribution is uneven, leading to local stress concentration.

[0134] The test results from Example 1 and Comparative Example 6 show that when only short carbon fibers are used, the thermal conductivity drops to 1.7 W / m·K and the compressive strength drops to 24 MPa. This is because although short carbon fibers have good dispersion, their thermal conduction path is short, resulting in reduced thermal conductivity; at the same time, the lack of a skeleton structure built from long fibers prevents the formation of an efficient three-dimensional thermal conduction network, and the reinforcement effect is limited.

[0135] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a carbon fiber oriented, high thermal conductivity, sealed paste, characterized in that, The preparation method includes: S1: Disperse potassium titanate whisker powder in deionized water, add silica sol to mix and obtain a suspension, evaporate to obtain a slurry, calcine it to obtain surface-coated potassium titanate; grind to obtain surface-coated potassium titanate powder; react and treat it with a silane coupling agent to obtain modified potassium titanate whisker powder; S2: Trimethylhydroxyphosphate is mixed with epoxy reactive diluent, and a catalyst is added to obtain reaction solution B. The reaction is stirred at a constant temperature under nitrogen protection and cooled to obtain phosphate ester functionalized crosslinking aid. S3: Prepare zirconium salt solution, adjust its pH and add ethylenediaminetetraacetic acid to obtain chelate solution, add polymer solution to obtain reaction solution C, adjust pH to obtain reaction solution D, stir at constant temperature to obtain pretreatment solution, distill under reduced pressure to obtain concentrated solution, add polyethylene glycol 400 and continue distillation to obtain zirconium salt / polymer complex viscous solution. S4: Modified potassium titanate whisker powder is added to epoxy resin and stirred and dispersed evenly. Then, phosphate ester functionalized crosslinking agent, zirconium salt / polymer complex viscous liquid and curing agent are added in sequence to obtain base material. Carbon fiber is added to base material in batches and stirred evenly to obtain paste. It is spread on the table, scraped with a scraper and placed in a vacuum drying oven for degassing, preliminary curing and curing to obtain carbon fiber oriented high thermal conductivity sealed paste. The mass ratio of potassium titanate whisker powder to silicon oxide in silica sol is 100:5-10. The silane coupling agent is silane coupling agent KH550, and the amount of silane coupling agent added is 1-3% of the mass of the surface-coated potassium titanate powder; The zirconium salt is either zirconium oxychloride octahydrate or zirconium nitrate. The mass ratio of the modified potassium titanate whisker powder, epoxy resin, phosphate ester functionalized crosslinking agent, zirconium salt / polymer complex viscous liquid, curing agent and carbon fiber is (15-20):(45-55):(3-8):(5-10):(8-12):(10-15).

2. The method for preparing a carbon fiber oriented high thermal conductivity sealed paste according to claim 1, characterized in that, In S1: The potassium titanate whisker powder has a mass fraction of 10-15 wt.% in deionized water.

3. The method for preparing a carbon fiber oriented high thermal conductivity sealed paste according to claim 1, characterized in that, In S1: The particle size of the potassium titanate powder coated on the surface is 5-10 μm; The mass ratio of the potassium titanate powder coated on the surface to the ethanol / water solution is 1:5-10.

4. The method for preparing a carbon fiber oriented high thermal conductivity sealed paste according to claim 1, characterized in that, In S2: The epoxy reactive diluent is any one of n-butyl glycidyl ether, polypropylene glycol diglycidyl ether, and phenyl glycidyl ether. The molar ratio of the trimethylhydroxyphosphate to the epoxy reactive diluent is 1:0.5-1.

5. The method for preparing a carbon fiber oriented high thermal conductivity sealed paste according to claim 1, characterized in that, In S2: the catalyst is tetrabutylammonium bromide, and the amount of catalyst fed is 0.5-1% of the mass of trimethylhydroxyphosphate.

6. The method for preparing a carbon fiber oriented high thermal conductivity sealed paste according to claim 1, characterized in that, In S3: The zirconium salt solution has a mass fraction of 5-15 wt.%; After adjusting the pH of the zirconium salt solution to 4-5, ethylenediaminetetraacetic acid is added. The molar ratio of ethylenediaminetetraacetic acid to zirconium salt is 0.5-1:

1.

7. The method for preparing a carbon fiber oriented high thermal conductivity sealed paste according to claim 1, characterized in that, In S3: The polymer is any one or a combination of two of polyvinylpyrrolidone or polyvinyl alcohol; The polymer solution has a mass fraction of 5-10 wt.%; The mass ratio of the zirconium salt to the polymer is 1-2:1; The pH of reaction solution C is adjusted to 6-7 to obtain reaction solution D; The volume of the polyethylene glycol 400 is 5-10% of the volume of the concentrated liquid.

8. The method for preparing a carbon fiber oriented high thermal conductivity sealed paste according to claim 1, characterized in that, In S4: The curing agent is either methylhexahydrophthalic anhydride or triethylenetetramine. The mass ratio of long carbon fibers to short carbon fibers in the carbon fiber is 1-2:1; The short carbon fibers have a length of 3-5 mm, and the long carbon fibers have a length of 10-20 mm.

9. The method for preparing a carbon fiber oriented high thermal conductivity sealed paste according to claim 1, characterized in that, In S4: The initial curing temperature is 40-60℃; The initial curing time is 1-2 hours; The curing temperature is 120-150℃; The curing time is 1-3 hours.

10. A carbon fiber oriented high thermal conductivity sealed paste prepared by the preparation method according to any one of claims 1-9.