Nano aluminum oxide-n-amyl alcohol synergistic heat conduction type low-conductivity cooling liquid

Abstract

The invention discloses nanometer aluminum oxide-n-amyl alcohol synergistic heat conduction type low-conductivity cooling liquid, relates to the technical field of cooling liquid, and is particularly suitable for heat dissipation scenes of electronic equipment and power batteries. The preparation method comprises a core functional component, a basic cooling system, an auxiliary functional component and a modified solvent. The preparation process sequentially comprises the steps of raw material and equipment pretreatment, nanometer aluminum oxide modification, n-amyl alcohol purification, synergistic pre-dispersion liquid preparation, system mixing regulation and after-treatment packaging. Wherein after being grafted and modified by a silane coupling agent, the nanometer aluminum oxide and purified n-amyl alcohol form a particle-alcohol molecule hydrogen bond heat conduction network through ultrasonic dispersion; the basic liquid and the synergistic pre-dispersion liquid are mixed in a gradient manner, and are matched with staged pH regulation and whole-course protective gas application, so that component agglomeration, hydrolysis or oxidation is avoided. According to the scheme, dynamic balance of heat conduction performance and insulation performance is achieved, the long-acting stability of the cooling liquid is improved, meanwhile, the system flowability is guaranteed, and the circulating cooling requirement is met.

Description

Technical Field

[0001] This invention relates to the field of coolant technology, and more particularly to a nano-alumina-n-pentanol synergistic thermally conductive low-conductivity coolant. Background Technology

[0002] With the increasing demand for heat dissipation in electronic devices, power batteries, and other fields, nanoparticle-reinforced coolants have attracted widespread attention due to their excellent thermal conductivity. Existing technologies often employ inorganic nanomaterials such as nano-alumina as thermal conductivity-enhancing components, combined with an ethylene glycol-water system as the basic cooling medium. Surface modification with silane coupling agents is used to improve dispersibility, while auxiliary components such as ammonium dihydrogen phosphate, triethanolamine, and benzotriazole are introduced to achieve functions such as corrosion inhibition and pH adjustment. The preparation process typically includes core steps such as nanoparticle pretreatment, raw material purification, dispersion and mixing, filtration, and encapsulation, aiming to improve the thermal conductivity and operational stability of the coolant.

[0003] However, existing technologies still have many problems that urgently need to be solved: First, nanoparticles are prone to agglomeration in coolants due to van der Waals forces. Simply relying on coupling agent modification or a single dispersion process is insufficient to form a stable thermally conductive network, resulting in limited improvement in thermal conductivity. At the same time, agglomerated particles can easily damage the insulation of the system, causing an increase in electrical conductivity, making it difficult to achieve a dynamic balance between thermal conductivity and insulation performance. Second, the means of ensuring system stability are relatively simple, mostly relying on a single corrosion inhibitor or pH adjuster, lacking comprehensive control over hydrolysis, metal corrosion, and failure of synergistic units. This leads to significant performance degradation of the coolant during long-term cyclic use and insufficient long-term stability. Third, insufficient attention is paid to the control of raw material purity and the removal of system impurities. Impurities in raw materials and contaminants introduced during the preparation process can easily damage the synergistic effect of core functional components, affecting thermal conductivity and insulation performance, and shortening the product shelf life. Fourth, the design of mixing processes lacks specificity, often using simple mixing modes, which can easily lead to the destruction of the thermally conductive network or an increase in system viscosity, making it difficult to balance thermal conductivity and flow performance, and limiting the ability to adapt to different application scenarios. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a nano-alumina-n-pentanol synergistic thermally conductive low-conductivity coolant to solve one or more problems in the prior art.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A nano-alumina-n-pentanol synergistic thermally conductive low-conductivity coolant comprises a core functional component, a basic cooling system, auxiliary functional components, and a modified solvent, wherein each component is expressed in parts by mass.

[0006] The core functional components include nano-alumina and n-pentanol, with the mass fraction of n-pentanol being 1.2 to 2.5 times that of nano-alumina. The nano-alumina has a particle size of 10 to 30 nm, a purity of ≥99.9%, and a μ phase content of ≥95%, while the n-pentanol has a purity of ≥99.5%.

[0007] The basic cooling system comprises ethylene glycol and deionized water. The auxiliary functional components include a silane coupling agent, ammonium dihydrogen phosphate, and triethanolamine, wherein the silane coupling agent is KH550.

[0008] The modified solvent is anhydrous ethanol.

[0009] This coolant is prepared through the following steps: (1) Pretreatment of nano-alumina: The nano-alumina was spread out and dried under vacuum. After cooling, it was sealed under nitrogen protection. The dried nano-alumina was added to anhydrous ethanol and stirred. Then, silane coupling agent KH550 was added, and the mixture was heated and stirred to react. After separation, washing, and drying, modified nano-alumina was obtained.

[0010] (2) Purification of n-pentanol: n-pentanol is purified by molecular distillation, and the first 5% of the fraction is discarded before collecting the remaining fraction.

[0011] (3) Preparation of synergistic pre-dispersion liquid: The purified n-pentanol was added to a closed reaction vessel, nitrogen gas was introduced for protection, and then modified nano-alumina was added. The mixture was then subjected to closed ultrasonic dispersion under stirring.

[0012] (4) Preparation of base solution: Mix ethylene glycol and deionized water and stir, then add triethanolamine to adjust the pH value to obtain ethylene glycol-water base solution.

[0013] (5) System mixing and functional regulation: Heat the base solution, add the synergistic pre-dispersed solution dropwise while stirring, continue stirring after the addition is complete, add ammonium dihydrogen phosphate in batches to adjust the pH value of the system, and finally add the remaining auxiliary functional components. After stirring evenly, let it cool naturally.

[0014] (6) Post-processing and packaging: After filtering the above mixture, it is packaged with nitrogen gas for protection.

[0015] Further, the silane coupling agent KH550 is 0.5-1.5 parts, ammonium dihydrogen phosphate is 0.5-2.0 parts, and triethanolamine is 0.2-0.5 parts. The modified solvent, anhydrous ethanol, is 10-15 parts by mass.

[0016] Furthermore, the mass fraction of the basic cooling system is: 50-85 parts ethylene glycol, with the remainder being deionized water.

[0017] Furthermore, the auxiliary functional components also include polyethylene glycol 400 and benzotriazole, wherein the mass fraction of polyethylene glycol 400 is 0.1 to 3.0 parts and the purity is ≥99.0%, and the mass fraction of benzotriazole is 0.1 to 0.3 parts and the purity is ≥99.0%.

[0018] Further, in step (1), the heating rate of vacuum drying is 5℃ / min, the drying temperature is 90±2℃, the vacuum degree is -0.095~-0.098MPa, and the holding time is 3±0.5h. The temperature for heating and stirring reaction is 65±2℃, and the reaction time is 1.5±0.2h. The separation method is centrifugation, with a centrifugation speed of 4000rpm and a time of 15min. Washing is performed 3 times with anhydrous ethanol. The drying temperature is 80±5℃, the vacuum degree is -0.09MPa, and the drying time is 2±0.5h.

[0019] Furthermore, in step (2), the evaporation temperature of molecular distillation purification is 80±2℃, the condensation temperature is 15±2℃, and the vacuum degree is -0.098~-0.1MPa.

[0020] Further, in step (3), the nitrogen gas introduction rate is 100~150mL / min, the modified nano-alumina addition rate is 1~2 parts / min, and the stirring speed is 300±20r / min. The closed ultrasonic dispersion power is 400±20W, the frequency is 20kHz, and the time is 45±5min. During the ultrasonic process, the reaction temperature is controlled at 28±1℃ by the jacket water temperature. If the pressure drop of the reactor is >0.01MPa, purified n-pentanol is added.

[0021] Further, in step (4), the stirring speed of the mixture of ethylene glycol and deionized water is 400±20 r / min and the stirring time is 15±2 min. Triethanolamine is added dropwise to adjust the pH value to 6.5~7.5. After stirring, the viscosity fluctuation of the base liquid is detected to be ≤5 mPa·s.

[0022] Further, in step (5), the base solution is heated to 30±2℃, the dropping rate of the synergistic pre-dispersed solution is 2~3mL / min, and the stirring speed after the dropping is completed is 500±20r / min, and the stirring time is 20±3min. The pH of the system is adjusted to 6.8±0.2 with ammonium dihydrogen phosphate, and ammonium dihydrogen phosphate is added in 3 portions, with an interval of 5min between each addition. After adding the remaining auxiliary functional components, the stirring speed is 600±20r / min, and the stirring time is 12±2min. The system is then allowed to cool naturally to 25±2℃.

[0023] Furthermore, in step (6), a polyethersulfone filter membrane is used for filtration, with a filtration accuracy of 0.22 μm and a filtration pressure of 0.1~0.15 MPa. The nitrogen protection pressure is 0.02~0.03 MPa, and the packaging uses a light-proof storage container with a storage temperature of 5~30℃.

[0024] Compared with the prior art, the beneficial technical effects of the present invention are as follows: (i) By combining nano-alumina, n-pentanol and silane coupling agent KH550, and using a combination of nano-alumina pretreatment and closed ultrasonic dispersion processes, a stable "particle-alcohol molecule" hydrogen bond thermal conductive network is constructed. This is different from the existing technologies that use single nanoparticle dispersion, simple compounding of multiple components or no synergistic mechanism. It achieves a dynamic balance between thermal conductivity and insulation performance, and fundamentally solves the technical contradiction of easy agglomeration and increased conductivity after adding thermally conductive particles to traditional nano-cooling liquids.

[0025] (ii) By combining a phased pH adjustment mechanism (triethanolamine to adjust the pH of the base solution and ammonium dihydrogen phosphate to stabilize the pH of the system) with nitrogen protection (sealing after pretreatment, protection during pre-dispersion, and nitrogen purging during encapsulation), and with the corrosion inhibition effect of benzotriazole, this method differs from existing technologies that rely on a single stabilization method or lack long-term stability design. It achieves long-term maintenance of the core thermal conductivity and insulation performance, avoids system hydrolysis, metal corrosion, and failure of synergistic units, and allows the coolant to maintain a stable effect during long-term cyclic use.

[0026] (III) The purity control combination of purification by molecular distillation of n-pentanol, diluent by deionized water, and filtration by polyethersulfone filter membrane after preparation, combined with light-proof sealing and packaging process, is different from the existing technology which has insufficient control over the purity of raw materials and impurities in the system. It effectively avoids the damage of impurities to hydrogen bond network and insulation performance, ensures that the core technology effect is not interfered with by external factors, and extends the shelf life of the product, making the solution more in line with the needs of actual application scenarios.

[0027] (iv) By using a gradient mixing process of the basic cooling system (ethylene glycol and deionized water) and the synergistic pre-dispersion liquid, combined with the steric hindrance of polyethylene glycol 400 to assist in stabilization, this technology, unlike the lack of system adaptation design in existing technologies, achieves a balance between thermal conductivity and fluidity. This ensures the integrity of the synergistic thermal network and avoids the increase in system viscosity from affecting the circulating cooling effect, allowing the coolant to adapt to the circulating cooling needs of different scenarios such as electronic devices and power batteries. Attached Figure Description

[0028] Figure 1 This is a flowchart of the coolant preparation method in this invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and exemplary descriptions. It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0030] Application Overview This invention relates to a nano-alumina-n-pentanol synergistic thermally conductive low-conductivity coolant, aiming to address the technical pain points of existing nanoparticle-reinforced coolants. Its core features, which distinguish it from existing technologies, are as follows: This invention defines the synergistic combination of core functional components, basic cooling system, auxiliary functional components, and modified solvents. It constructs a core synergistic unit by using nano-alumina and n-pentanol in a specific mass ratio, and combines it with silane coupling agent KH550 to achieve surface modification of nano-alumina, forming a stable "particle-alcohol molecule" hydrogen bond thermally conductive network. At the same time, it designs a complete preparation process including nano-alumina pretreatment, n-pentanol molecular distillation purification, sealed nitrogen-protected ultrasonic dispersion, staged pH adjustment, gradient mixing, and filtration nitrogen-filled encapsulation, forming a comprehensive solution for thermal conductivity-insulation balance, long-term stability, purity control, and flowability-thermal conductivity efficiency adaptation.

[0031] Compared with existing technologies, this invention abandons the design concept of relying solely on dispersants or simple mixing processes. By organically integrating component combinations and process steps, it fundamentally solves the problems in existing technologies such as easy agglomeration of nanoparticles, difficulty in balancing thermal conductivity and insulation, performance degradation after long-term use, interference of impurities with core functions, and poor adaptability between flowability and thermal conductivity. It provides a cooling medium with high thermal conductivity, low electrical conductivity, long-term stability, and good flowability for electronic devices, power batteries, and other fields.

[0032] Comprehensive explanation This invention details the composition and preparation process of a nano-alumina-n-pentanol synergistic thermally conductive low-conductivity coolant. Those skilled in the art can reproduce this technical solution without ambiguity based on the following content.

[0033] I. Raw material components This coolant, by weight, comprises core functional components, a basic cooling system, auxiliary functional components, and modified solvents. The specifications and proportions of each component are as follows: The core functional components include nano-alumina and n-pentanol. The nano-alumina has a particle size of 10-30 nm, a purity of ≥99.9%, a μ-phase content of ≥95%, and exhibits no agglomeration or clumping. The n-pentanol is an anhydrous product with a purity of ≥99.5%, a moisture content of ≤0.05%, a distillation range of 137-139℃, and a refractive index of 1.410-1.412 (25℃). The mass ratio of nano-alumina to n-pentanol is 1.2-2.5:1, meaning that the mass fraction of n-pentanol is 1.2-2.5 times the mass fraction of nano-alumina. This ratio is the core foundation for forming a stable and synergistic heat conduction network.

[0034] The basic cooling system includes ethylene glycol and deionized water. The ethylene glycol is an industrial-grade product with a purity ≥99.5%, pH value 6.5~7.5, freezing point ≤-40℃, and density 1.113~1.115 g / cm³. 3 (25℃), the mass fraction is 50~85 parts; the resistivity of deionized water is ≥18.2MΩ·cm (25℃), the total organic carbon (TOC) is ≤10ppb, and there are no metal ions (verified by ICP-MS detection). The mass fraction is the balance, used to adjust the viscosity of the system to 20~30mPa·s (25℃) and improve the fluidity.

[0035] The auxiliary functional components include silane coupling agent KH550, ammonium dihydrogen phosphate, triethanolamine, polyethylene glycol 400, and benzotriazole. Specifically, the silane coupling agent KH550 has a purity ≥98.0%, an active ingredient ≥95%, a boiling point of 217℃, and a mass fraction of 0.5–1.5 parts; ammonium dihydrogen phosphate is analytical grade, with a purity ≥99.0%, a pH buffer range of 4.5–6.0, and a water solubility ≥28 g / 100 mL (25℃), and a mass fraction of 0.5–2.0 parts; triethanolamine has a purity ≥99.0% and a pH value of 10.5–11. 5. Boiling point 360℃, mass fraction 0.2~0.5 parts; Polyethylene glycol 400 purity ≥99.0%, molecular weight 380~420, viscosity 40~50mPa·s (25℃), moisture ≤0.2%, mass fraction 0.1~3.0 parts; Benzotriazole purity ≥99.0%, melting point 98~100℃, water solubility ≤5g / L (25℃), mass fraction 0.1~0.3 parts.

[0036] The modifying solvent is anhydrous ethanol with a purity ≥99.5%, moisture content ≤0.05%, and no impurities. The mass fraction is 10~15 parts, and it is used in the surface modification process of nano-alumina.

[0037] II. Preparation Process (a) Preliminary preparations Preparation must be carried out in a Class 10,000 cleanroom, with the room temperature controlled at 25±2℃, relative humidity at 40%~60%, and ventilation rate at 0.5~1m / s, to prevent the evaporation of volatile solvents such as n-pentanol and anhydrous ethanol from causing an imbalance in the component ratio and the introduction of environmental impurities.

[0038] All equipment used must be calibrated to the required accuracy in advance, including vacuum drying ovens, sealed probe ultrasonic dispersers, mechanical stirrers, pH meters, molecular distillation apparatus, centrifugal separation equipment, and filtration devices, to ensure precise control of each process parameter.

[0039] Before use, raw materials must undergo pretreatment and inspection: nano alumina must be passed through a 300-mesh sieve to remove agglomerates; n-pentanol, ethylene glycol, and anhydrous ethanol must be tested for purity by gas chromatography to ensure they meet specifications before being put into use.

[0040] (II) Pretreatment of nano-alumina First, a drying pretreatment is performed: Weigh out the specified mass fraction of nano-alumina and spread it evenly on the quartz tray of the vacuum drying oven, with a thickness ≤5mm to ensure uniform drying. Start the vacuum drying oven and heat to 90±2℃ at a rate of 5℃ / min, maintaining a vacuum of -0.095~-0.098MPa for 3±0.5h. After drying, allow it to cool naturally and seal it under nitrogen protection for later use to prevent moisture absorption and surface hydroxyl oxidation.

[0041] Surface modification was then performed: dried nano-alumina was added to a predetermined amount of anhydrous ethanol, and stirred for 5 minutes to initially disperse the nano-alumina. Then, a predetermined amount of silane coupling agent KH550 was added, and the mixture was heated to 65±2℃ and stirred continuously for 1.5±0.2 hours to allow the amino groups of KH550 to react with the hydroxyl groups on the surface of the nano-alumina, achieving amino grafting modification. After the reaction was complete, the mixture was transferred to a centrifuge and centrifuged at 4000 rpm for 15 minutes. The precipitate was collected and washed three times with anhydrous ethanol to remove unreacted KH550 and impurities. Finally, the precipitate was placed in a vacuum drying oven and dried at 80±5℃ and a vacuum of -0.09 MPa for 2±0.5 hours to obtain modified nano-alumina.

[0042] (III) Purification of n-pentanol Weigh out a predetermined amount of n-pentanol (calculated as 1.2 to 2.5 times the mass of nano-alumina) and purify it using a molecular distillation apparatus. Set the evaporation temperature of the molecular distillation apparatus to 80±2℃, the condensation temperature to 15±2℃, and the vacuum degree to -0.098 to -0.1MPa. Discard the first 5% of the distillate during distillation and collect the remaining fraction as the purified n-pentanol. After purification, the n-pentanol should be tested to ensure a purity ≥99.5% and an electrical conductivity ≤1×10⁻⁶. -8S / m ensures that the requirements for subsequent synergistic effects are met.

[0043] (iv) Preparation of synergistic predispersant All the purified n-pentanol was added to a sealed ultrasonic reactor. Nitrogen gas was introduced into the reactor at a rate of 100-150 mL / min for protection, to remove air from the reactor and prevent oxidation of n-pentanol and deactivation of the modified groups on the surface of the nano-alumina. Modified nano-alumina was added to the reactor at a set rate (1-2 parts / min), and the stirrer was started simultaneously at a speed of 300±20 r / min to initially disperse the modified nano-alumina in the n-pentanol.

[0044] The ultrasonic disperser was started, with the ultrasonic power set to 400±20W, frequency 20kHz, and ultrasonic time 45±5min. During ultrasonication, the temperature inside the reactor was controlled at 28±1℃ using the jacket water temperature control to prevent excessive temperature from causing volatilization of n-pentanol and disruption of hydrogen bonds. The pressure was monitored in real-time using a reactor pressure sensor during ultrasonication. If the pressure drop exceeded 0.01MPa, purified n-pentanol was added promptly to maintain a stable component ratio. After ultrasonication, a nano-alumina-n-pentanol synergistic pre-dispersion was obtained. This dispersion was tested using a laser particle size analyzer to ensure that the particle size of the nano-alumina was ≤50nm, and infrared spectroscopy confirmed a 20%~30% increase in hydroxyl peak intensity, indicating the formation of a hydrogen bond network.

[0045] (v) Preparation of base solution Weigh out the specified mass fraction of ethylene glycol and add it to a double-walled glass reactor. Start the stirrer and stir at a speed of 400±20 r / min. Slowly add the remaining deionized water to the reactor and continue stirring for 15±2 min to ensure thorough mixing of the ethylene glycol and deionized water. After stirring, measure the pH value of the mixture with a pH meter and adjust the pH value to 6.5~7.5 by adding triethanolamine dropwise to obtain the ethylene glycol-water base solution. After adjustment, check that the viscosity fluctuation of the base solution is ≤5 mPa·s to ensure the homogeneity of the base solution.

[0046] (vi) System mixing and functional regulation Heat the ethylene glycol-water base solution to 30±2℃, maintain the stirrer speed at 500±20r / min, and add the synergistic pre-dispersion solution dropwise to the base solution at a rate of 2~3mL / min. After the addition is complete, continue stirring for 20±3min to allow the synergistic pre-dispersion solution to fully mix with the base solution.

[0047] Subsequently, ammonium dihydrogen phosphate was added in three portions, with a 5-minute interval between each addition, while continuous stirring was maintained. The buffering effect of ammonium dihydrogen phosphate stabilized the pH of the system to 6.8±0.2, preventing hydrolysis of the nano-alumina. Finally, polyethylene glycol 400 and benzotriazole were added in the specified proportions, and the stirrer speed was increased to 600±20 r / min, with continuous stirring for 12±2 min to ensure uniform mixing of all components. The mixture was then allowed to cool naturally to 25±2℃.

[0048] (vii) Post-processing and packaging The cooled mixture was pressure filtered through a polyethersulfone membrane at a precision of 0.22 μm and a pressure controlled between 0.1 and 0.15 MPa to remove any trace impurities and incompletely dispersed particles. After filtration, the coolant was transferred to a light-protected storage container, which was then filled with nitrogen gas at a pressure of 0.02–0.03 MPa to purge air from the container before sealing. The sealed coolant must be stored at 5–30°C in a light-protected environment and has a shelf life of ≥12 months.

[0049] III. Explanation of Core Invention Points The core of this solution lies in the organic integration of component combination and process design to construct a stable "particle-alcohol molecule" hydrogen bond thermally conductive network, while simultaneously achieving synergistic optimization of thermal conductivity, insulation, long-term stability and flowability. Among them, after surface modification with KH550, the amino groups grafted onto the surface of nano-alumina form strong hydrogen bonds with the hydroxyl groups of n-pentanol. Combined with a precise mass ratio of 1.2~2.5:1 and a closed nitrogen-protected ultrasonic process, the problem of easy agglomeration of nanoparticles is fundamentally solved. The formed hydrogen bond network not only improves the thermal conductivity, but also ensures the low electrical conductivity of the system due to the insulating properties of n-pentanol. The combination of staged pH adjustment (triethanolamine to adjust the pH of the base solution and ammonium dihydrogen phosphate to stabilize the pH of the system) with full-process nitrogen protection and benzotriazole corrosion inhibition effectively avoids component hydrolysis, metal corrosion and failure of synergistic units, ensuring long-term stability. The molecular distillation purification of n-pentanol, the high purity requirements of deionized water and the filtration process prevent impurities from damaging the hydrogen bond network and insulation performance. The gradient mixing of ethylene glycol-water base solution and synergistic pre-dispersion solution and the steric hindrance effect of polyethylene glycol 400 balance the integrity of the thermal conductivity network and the fluidity of the system, ensuring that the coolant is suitable for the needs of circulating cooling scenarios.

[0050] To verify the impact of key process parameters and component ratios in this scheme on the final coolant performance and to clarify the practical technical significance of each core parameter limit, a comparative experiment was designed. The thermal conductivity, insulation performance, and long-term stability of the coolant under different parameter combinations were analyzed using the controlled variable method. The experimental data were all obtained based on objective standard tests to ensure the reliability and comparability of the results.

[0051] Test Standards and Methods 1. Thermal conductivity test Detailed method: Sample preparation: Take 50 mL of the filtered coolant and put it into a cylindrical test container (diameter ≥ 50 mm, height ≥ 100 mm), ensuring that there are no air bubbles in the sample; Probe installation: Insert the hot wire probe vertically into the center of the sample, with the top of the probe ≥20mm from the sample liquid surface, the bottom of the probe ≥20mm from the bottom of the container, and the distance between the probe and the container wall ≥2 times the probe length; Parameter settings: Set the heating power of the hot wire to 0.5W / cm and the test time to 60s; Data recording: Record the temperature change curve over time after the hot wire is energized, and calculate the thermal conductivity λ (λ=Q / (4πΔT / Ln(t2 / t1)) by the slope of the curve, where Q is the heating power and ΔT is the temperature change from t1 to t2). Repeated testing: Each sample was tested three times, and the average value was taken as the final result.

[0052] 2. Conductivity test Detailed method: Instrument calibration: The conductivity meter was calibrated using a 0.01 mol / L KCl standard solution (conductivity of 1413 μS / cm at 25℃); Sample preparation: Take 20 mL of the filtered coolant and heat it in a constant temperature bath to 25℃±0.5℃; Test reading: Insert the calibrated electrode into the sample, stir evenly, let stand for 30 seconds, and read the conductivity value; Repeated testing: Each sample was tested three times, and the average value was taken as the final result.

[0053] 3. Thermal conductivity retention test after aging Detailed method: Sample packaging: Take 100mL of the filtered coolant and put it into a sealed glass container (with a rubber stopper to ensure no leakage). Accelerated aging: Place the container in a constant temperature chamber, set the temperature to 80℃±2℃, and keep it at the constant temperature for 72 hours; Recovery test: Remove the container and allow it to cool naturally to 25℃±0.5℃. Measure the thermal conductivity after aging according to the above thermal conductivity test method. Retention rate calculation: Thermal conductivity retention rate after aging = (thermal conductivity after aging / initial thermal conductivity) × 100%.

[0054] Detailed Explanation of Weighted Scoring Mechanism Using existing technology average levels and target values ​​as benchmarks: Benchmark setting: Take the average performance of the standard groups (groups 1-5) as the benchmark value: Thermal conductivity benchmark: 0.55 W / (m·K) (average thermal conductivity of existing technology) Conductivity benchmark: 0.8 μS / cm (industry target value for low conductivity coolants) Benchmark value for thermal conductivity retention after aging: 80% (average aging retention rate of existing technology) Score calculation formula: Thermal conductivity score = (Measured thermal conductivity / Reference thermal conductivity) × 100 × 0.4 Conductivity score = (Reference conductivity / Measured conductivity) × 100 × 0.3 Aging retention rate score = (Measured retention rate / Baseline retention rate) × 100 × 0.3 Overall score = thermal conductivity score + electrical conductivity score + aging retention score.

[0055] Exemplary Description To ensure the clear operability and reproducibility of the following embodiments, the ten sets of embodiments directly adopted the core variable data of the ten experimental groups in the experiment. At the same time, combined with the complete preparation process of the present invention, each process parameter and raw material dosage were determined to specific values, so that each embodiment can be operated independently and obtain the corresponding product performance.

[0056] Example 1 Preparation method Preparation: The preparation was carried out in a Class 10,000 cleanroom with the temperature controlled at 25°C and the relative humidity at 45%. The vacuum drying oven, the sealed probe ultrasonic disperser, the mechanical stirrer (accuracy ±5r / min), the pH meter (accuracy ±0.01), and the molecular distillation apparatus were calibrated in advance to ensure the accuracy of the equipment parameters. Raw materials were checked before use: the nano alumina passed through a 300-mesh sieve (no agglomeration), and the purity of n-pentanol, ethylene glycol, and anhydrous ethanol was tested by gas chromatography and found to meet the requirements.

[0057] Nano alumina pretreatment: Weigh 10 parts of nano alumina (particle size 20nm, purity 99.9%, μ phase content 95%) and spread them evenly on the quartz tray of the vacuum drying oven (thickness 3mm); start the vacuum drying oven and heat to 91℃ at a heating rate of 5℃ / min, maintain vacuum degree -0.096MPa, and keep at this temperature for 3.2h; after cooling to 25℃, seal and store for later use under nitrogen protection. The dried nano-alumina was then added to 12 parts of anhydrous ethanol (99.5% purity, 0.04% moisture), and the mixture was stirred at 300 rpm for 5 min using a mechanical stirrer. 0.5 parts of silane coupling agent KH550 (98.0% purity) were added, and the mixture was heated to 64℃ and stirred at 350 rpm for 1.4 h. After the reaction was complete, the mixture was transferred to a centrifuge and centrifuged at 4000 rpm for 15 min to collect the precipitate. The precipitate was washed three times with anhydrous ethanol (8 parts each time) to remove unreacted KH550. The washed precipitate was then placed in a vacuum drying oven and dried at 82℃ and a vacuum of -0.09 MPa for 2.3 h to obtain modified nano-alumina.

[0058] Purification of n-pentanol: Weigh 12 portions of n-pentanol (purity 99.5%, water content 0.05%) and put them into a molecular distillation apparatus; set the evaporation temperature of the molecular distillation apparatus to 81℃, the condensation temperature to 14℃, and the vacuum degree to -0.099MPa; discard the first 5% of the distillate during the distillation process and collect the remaining distillate as the purified n-pentanol.

[0059] Preparation of synergistic predispersant: 12 parts of purified n-pentanol were added to a sealed ultrasonic reactor. Nitrogen gas was introduced into the reactor at a rate of 110 mL / min to remove air from the reactor. The modified nano-alumina was added to the reactor at a rate of 1.2 parts / min, and the stirrer was started at 300 r / min. After all the modified nano-alumina was added, the ultrasonic disperser was started, and the ultrasonic power was set to 410 W, the frequency to 20 kHz, and the ultrasonic time to 40 min. During the ultrasonic process, the temperature inside the reactor was controlled at 28 °C by the jacket water temperature, and the pressure inside the reactor was monitored in real time (stable at 0.098 MPa, no need to add n-pentanol) to obtain the synergistic predispersant.

[0060] Preparation of the base solution: Weigh 60 parts of ethylene glycol (purity 99.5%, pH 6.8) and add it to a double-walled glass reactor. Start the stirrer and stir at 400 r / min. Slowly add 15 parts of deionized water (resistivity 18.2 MΩ·cm) to the reactor and continue stirring for 14 min. Use a pH meter to detect the pH value of the mixture and adjust the pH value to 6.6 by adding triethanolamine (purity 99.0%) dropwise to obtain the ethylene glycol-water base solution.

[0061] System mixing and functional regulation: The ethylene glycol-water base solution was heated to 29°C, and the stirrer speed was maintained at 500 r / min. The above-mentioned synergistic pre-dispersion solution was added dropwise to the base solution at a rate of 2.2 mL / min. After the addition was completed, stirring was continued for 19 min. 1.0 part of ammonium dihydrogen phosphate (purity 99.0%) was added in 3 portions, with an interval of 5 min between each addition (each addition was 0.3 part, 0.3 part, and 0.4 part, respectively), and stirring was continued during the addition. The pH value of the system was monitored by a pH meter and finally stabilized at 6.7. 1.2 parts of polyethylene glycol 400 (purity 99.0%) and 0.2 parts of benzotriazole (purity 99.0%) were added, and the stirrer speed was increased to 600 r / min. Stirring was continued for 11 min. After stirring was completed, the system was allowed to cool naturally to 25°C.

[0062] Post-processing and packaging: The cooled mixture is filtered under pressure through a polyethersulfone filter membrane (filtration accuracy 0.22μm) at a pressure of 0.13MPa. After filtration, the coolant is transferred to a light-proof storage container, nitrogen gas is introduced into the container (nitrogen pressure 0.024MPa), the air inside the container is removed, and then the container is sealed. The sealed coolant is stored in a light-proof environment at 22℃.

[0063] Performance Results The obtained nano-alumina-n-pentanol synergistic thermally conductive low-conductivity coolant has a thermal conductivity of 0.61 W / m·K and an electrical conductivity of 0.82 μS / cm. After being aged at 80℃ for 72 h, the thermal conductivity retention rate is 89.10%.

[0064] Example 2 The differences between this embodiment and Example 1 are as follows: Variable A (mass ratio of nano-alumina to n-pentanol) is 1:1.5 (10 parts nano-alumina and 15 parts n-pentanol are weighed), Variable B (dosage of silane coupling agent KH550) is 0.8 parts, and Variable C (ultrasonic time of synergistic pre-dispersion liquid) is 43 min; the remaining raw material dosages, process parameters and preparation steps are the same as in Example 1.

[0065] Performance Results The obtained coolant has a thermal conductivity of 0.63 W / m·K, an electrical conductivity of 0.78 μS / cm, and a thermal conductivity retention rate of 91.20% after aging. Example 3

[0066] The differences between this embodiment and Example 1 are as follows: Variable A (mass ratio of nano-alumina to n-pentanol) is 1:2.0 (10 parts nano-alumina and 20 parts n-pentanol are weighed), Variable B (dosage of silane coupling agent KH550) is 1.0 part, and Variable C (ultrasonic time of synergistic pre-dispersion liquid) is 45 min; the remaining raw material dosages, process parameters and preparation steps are the same as in Example 1.

[0067] Performance Results The resulting coolant has a thermal conductivity of 0.66 W / m·K, an electrical conductivity of 0.73 μS / cm, and retains 93.50% of its thermal conductivity after aging.

[0068] Example 4 The differences between this embodiment and Example 1 are as follows: Variable A (mass ratio of nano-alumina to n-pentanol) is 1:2.3 (10 parts nano-alumina and 23 parts n-pentanol are weighed), Variable B (dosage of silane coupling agent KH550) is 1.3 parts, and Variable C (ultrasonic time of synergistic pre-dispersion liquid) is 48 min; the remaining raw material dosages, process parameters and preparation steps are the same as in Example 1.

[0069] Performance Results The obtained coolant has a thermal conductivity of 0.65 W / m·K, an electrical conductivity of 0.75 μS / cm, and a thermal conductivity retention rate of 92.80% after aging.

[0070] Example 5 The differences between this embodiment and Example 1 are as follows: Variable A (mass ratio of nano-alumina to n-pentanol) is 1:2.5 (10 parts nano-alumina and 25 parts n-pentanol are weighed), Variable B (dosage of silane coupling agent KH550) is 1.5 parts, and Variable C (ultrasonic time of synergistic pre-dispersion liquid) is 50 min; the remaining raw material dosages, process parameters and preparation steps are the same as in Example 1.

[0071] Performance Results The obtained coolant has a thermal conductivity of 0.64 W / m·K, an electrical conductivity of 0.77 μS / cm, and a thermal conductivity retention rate of 91.90% after aging.

[0072] Example 6 The differences between this embodiment and Example 1 are as follows: Variable A (mass ratio of nano-alumina to n-pentanol) is 1:1.0 (10 parts nano-alumina and 10 parts n-pentanol are weighed, which is below the limit range), Variable B (dosage of silane coupling agent KH550) is 1.0 part, and Variable C (ultrasonic time of synergistic pre-dispersion liquid) is 45 min; the remaining raw material dosages, process parameters and preparation steps are the same as in Example 1.

[0073] Performance Results The obtained coolant has a thermal conductivity of 0.58 W / m·K, an electrical conductivity of 0.90 μS / cm, and retains 86.30% of its thermal conductivity after aging.

[0074] Example 7 The differences between this embodiment and Example 1 are as follows: Variable A (mass ratio of nano-alumina to n-pentanol) is 1:2.0 (10 parts nano-alumina and 20 parts n-pentanol are weighed), Variable B (dosage of silane coupling agent KH550) is 0.3 parts (below the limit range), and Variable C (ultrasonic time of synergistic pre-dispersion liquid) is 45 min; the remaining raw material dosages, process parameters and preparation steps are the same as in Example 1.

[0075] Performance Results The resulting coolant has a thermal conductivity of 0.59 W / m·K, an electrical conductivity of 0.88 μS / cm, and retains 85.70% of its thermal conductivity after aging.

[0076] Example 8 The differences between this embodiment and Example 1 are as follows: Variable A (mass ratio of nano-alumina to n-pentanol) is 1:2.0 (10 parts nano-alumina and 20 parts n-pentanol are weighed), Variable B (dosage of silane coupling agent KH550) is 1.0 part, and Variable C (ultrasonic time of synergistic pre-dispersion liquid) is 35 min (below the limit range); the remaining raw material dosages, process parameters and preparation steps are the same as in Example 1.

[0077] Performance Results The obtained coolant has a thermal conductivity of 0.57 W / m·K, an electrical conductivity of 0.92 μS / cm, and a thermal conductivity retention rate of 84.90% after aging.

[0078] Example 9 The differences between this embodiment and Example 1 are as follows: Variable A (mass ratio of nano-alumina to n-pentanol) is 1:3.0 (10 parts nano-alumina and 30 parts n-pentanol are weighed, which is higher than the limit range), Variable B (dosage of silane coupling agent KH550) is 1.0 part, and Variable C (ultrasonic time of synergistic pre-dispersion liquid) is 45 min; the remaining raw material dosages, process parameters and preparation steps are the same as in Example 1.

[0079] Performance Results The obtained coolant has a thermal conductivity of 0.60 W / m·K, an electrical conductivity of 0.85 μS / cm, and retains 87.20% of its thermal conductivity after aging.

[0080] Example 10 (Blank control group, using existing technology) Preparation method Preparatory work: Same as the cleanroom environment and equipment calibration requirements in Example 1; Raw material inspection: Nano alumina passes through a 300-mesh sieve, and ethylene glycol meets the purity requirements after purity testing.

[0081] Preparation of the base solution: Weigh 60 parts of ethylene glycol (purity 99.5%) and add it to a double-walled glass reactor. Start the stirrer and stir at 400 r / min. Slowly add 20 parts of deionized water (resistivity 18.2 MΩ·cm) to the reactor and continue stirring for 15 min. Add triethanolamine dropwise to adjust the pH of the mixture to 6.8 to obtain the ethylene glycol-water base solution.

[0082] Nano-alumina dispersion: Weigh 10 parts of nano-alumina (particle size 20nm, purity 99.9%) and add it directly to the above ethylene glycol-water base solution. Start the stirrer and stir at 450r / min for 30min. Add 1.0 part of ammonium dihydrogen phosphate and continue stirring at 400r / min for 15min to make the mixture uniform.

[0083] Post-processing and packaging: The mixture is filtered through a 0.45μm filter membrane (filtration pressure 0.12MPa); after filtration, it is placed into a regular transparent glass container and sealed directly; and stored at 25℃.

[0084] Performance Results The obtained coolant has a thermal conductivity of 0.52 W / m·K and a conductivity significantly higher than that of the products in Examples 1 to 9. After being aged at 80°C for 72 hours, the thermal conductivity decreases significantly. It does not meet the requirements for low conductivity and long-term stability in application, and its overall performance is far lower than that of the product prepared by the technical solution of this invention.

[0085] The following is a table recording the experimental results (Table 1). Table 1 Experimental group number <![CDATA[Variable A (Al2O3: n-pentanol)]]> Variable B (number of KH550 copies) Variable C (ultrasound time in min) Thermal conductivity (W / m·K) Conductivity (μS / cm) Thermal conductivity retention rate after aging (%) 1 1:1.2 0.5 40 0.61 0.82 89.10 2 1:1.5 0.8 43 0.63 0.78 91.20 3 1:2.0 1.0 45 0.66 0.73 93.50 4 1:2.3 1.3 48 0.65 0.75 92.80 5 1:2.5 1.5 50 0.64 0.77 91.90 6 1:1.0 (lower than 1.2) 1.0 45 0.58 0.90 86.30 7 1:2.0 0.3 (below 0.5) 45 0.59 0.88 85.70 8 1:2.0 1.0 35 (below 40) 0.57 0.92 84.90 9 1:3.0 (higher than 2.5) 1.0 45 0.60 0.85 87.20 10 Existing technology (without n-pentanol) - - 0.52 1.21 75.60 To further clarify the influence of each variable on the performance of the coolant and its underlying mechanism, the following analysis, based on the core performance test results, will dissect the core reasons behind the performance trends from the perspective of molecular interactions, revealing the logical relationship between the combination of variables and the thermal conductivity, insulation, and long-term stability of the coolant.

[0086] Judging from the performance of the conventional group, its overall performance in terms of thermal conductivity, insulation and long-term stability is at a high level, and it shows a trend of "first rising and then falling". The middle group has the best performance in all core aspects. This phenomenon is due to the fact that each variable forms an optimal molecular interaction network within a limited range. When variable A (mass ratio of nano-alumina to n-pentanol) is within a defined range, the hydroxyl groups of n-pentanol can fully form hydrogen bonds with the hydroxyl groups on the surface of nano-alumina, and the n-pentanol molecules can uniformly coat the nano-alumina particles. This avoids the breakage of the thermal conductivity path caused by particle agglomeration and maintains the low electrical conductivity of the system through the insulating properties of n-pentanol. The defined range of variable B (KH550 content) precisely meets the surface modification requirements of nano-alumina—the amino groups of KH550 can undergo grafting reactions with the hydroxyl groups on the surface of nano-alumina, reducing the van der Waals forces between particles. At the same time, its organic segments can interact with n-pentanol molecules, further enhancing the stability of the hydrogen bond network. The defined range of variable C (ultrasonic time) ensures that the agglomerated nano-alumina particles are fully dispersed, so that the hydrogen bond network is uniformly distributed in the system, avoiding local particle accumulation or network gaps. When the synergy of the three factors is within a limited range, the intermolecular interaction is most complete, and the resulting thermally conductive network is complete and stable. Therefore, the conventional group exhibits better overall performance, and the intermediate group has the highest score because the synergy between the ratio of the three factors and the interaction time is optimal, and there are no defects caused by excess or deficiency in the molecular network.

[0087] The control group, due to a single variable exceeding the specified range, exhibited inferior core performance compared to the conventional group, essentially due to significant defects in the molecular interaction network. Specifically, when variable A was below the lower limit, insufficient n-pentanol content prevented complete encapsulation of the nano-alumina particles, leading to agglomeration of exposed particles, resulting in hydrogen bond network breakage, reduced thermal conductivity paths, and increased conductivity caused by surface charge on exposed particles. When variable A was above the upper limit, excessive n-pentanol diluted the effective concentration of nano-alumina, reducing the number of thermal conductivity paths, and excess n-pentanol molecules could form localized enrichment zones in the system, disrupting the uniformity of the hydrogen bond network. When variable B was below the lower limit, insufficient KH550 modification resulted in inadequate grafting of hydroxyl groups on the nano-alumina surface, increased agglomeration tendency between particles, and difficulty in stable hydrogen bond network formation. Furthermore, unmodified particles were prone to hydrolysis during aging, accelerating the decline in thermal conductivity. When variable C was below the lower limit, insufficient ultrasonic time resulted in inadequate dispersion of agglomerated particles, uneven distribution of the hydrogen bond network, and localized thermal conductivity blind spots. Additionally, undispersed agglomerates were prone to further aggregation after aging, exacerbating performance degradation. The molecular-level defects caused by these variables exceeding their limits ultimately manifest as a decrease in the performance of the control group.

[0088] The blank control group, lacking the introduction of n-pentanol and the modification by KH550, as well as a suitable ultrasonic process, exhibited significantly inferior performance compared to the conventional group. From a molecular perspective, without n-pentanol, nano-alumina cannot form a stable hydrogen-bonded network. The particles are directly exposed to the ethylene glycol-water system, making them prone to severe aggregation due to van der Waals forces and hydroxyl interactions. This results in a scarcity of thermal pathways and a substantial decrease in thermal conductivity. Simultaneously, the surface charge of unmodified nano-alumina readily combines with ions in the system, increasing electrical conductivity. Furthermore, without the protective effect of KH550, the particles are susceptible to hydrolysis and oxidation during storage or aging, further compromising system stability. Therefore, its overall performance cannot compare to the conventional group, fully demonstrating the crucial significance of variable combination and process design in constructing the molecular interaction network in this scheme.

[0089] Specific work process Please refer to Figure 1 The equipment required for preparation is calibrated to ensure the accuracy of process parameter control. At the same time, the raw materials are inspected. Nano-alumina is sieved to remove agglomerates, and the purity of n-pentanol, ethylene glycol, modified solvents, etc. is tested to remove unqualified raw materials.

[0090] Nano-alumina was spread out and vacuum dried to remove adsorbed moisture from the particle surface. After drying, it was sealed and stored under a protective gas atmosphere. Then, the dried nano-alumina was added to a modified solvent and stirred to initially disperse the particles. A silane coupling agent was then added, and the mixture was heated and stirred continuously. The functional groups of the silane coupling agent underwent a grafting reaction with the hydroxyl groups on the surface of the nano-alumina to form a modified layer, thereby reducing the tendency of particle agglomeration. After the reaction was completed, the mixture was centrifuged to separate the particles, and the precipitate was collected. The precipitate was washed multiple times with the modified solvent to remove unreacted silane coupling agent and impurities. Finally, the washed precipitate was vacuum dried to obtain surface-modified nano-alumina.

[0091] Molecular distillation was used to purify n-pentanol. By controlling the distillation temperature and vacuum, low-boiling-point impurities and high-boiling-point residues in n-pentanol were separated and removed. After discarding the initial fraction, the target fraction was collected to obtain high-purity n-pentanol.

[0092] Purified n-pentanol was added to a sealed reactor, and a protective gas was introduced into the reactor to remove air and prevent oxidation of n-pentanol and failure of the nano-alumina modified layer. Modified nano-alumina was added in proportion, and stirring was started to initially disperse the particles in n-pentanol. Then, an ultrasonic device was started for closed ultrasonic dispersion. The residual particle agglomerates were broken by ultrasonic vibration, so that the modified nano-alumina was uniformly dispersed. At the same time, the reactor temperature was controlled to prevent the volatilization of n-pentanol. During this process, the hydroxyl groups of n-pentanol formed hydrogen bonds with the functional groups of the modified layer on the surface of nano-alumina, constructing a stable "particle-alcohol molecule" synergistic system, and obtaining a synergistic pre-dispersion liquid.

[0093] Ethylene glycol and deionized water are mixed and stirred to fully integrate them and form a basic system. Then, a pH adjuster is added dropwise while stirring to adjust the pH value of the basic system to a suitable range, thus obtaining the base solution.

[0094] Heat the base solution to the set temperature, and slowly add the co-dispersed pre-dispersant dropwise while maintaining stirring, so that the co-dispersed pre-dispersant and base solution gradually blend together. After the dropwise addition is complete, continue stirring for a period of time, and then add ammonium dihydrogen phosphate in batches. The buffering effect of ammonium dihydrogen phosphate is used to stabilize the pH value of the system in a more precise range to prevent the hydrolysis of nano-alumina. Finally, add polyethylene glycol and benzotriazole, increase the stirring rate to mix all components evenly, and allow the mixture to cool naturally to room temperature after mixing.

[0095] The cooled mixture is filtered under pressure through a filter membrane to remove any trace impurities and incompletely dispersed fine particles that may be present in the system. After filtration, the coolant is transferred to a light-proof storage container, and a protective gas is introduced into the container to remove air. The container is then sealed, and the sealed coolant is stored in a light-proof environment at a suitable temperature.

[0096] In the preparation of the blank control group, unmodified nano-alumina was directly added to a mixture of ethylene glycol and deionized water. After stirring and dispersing, ammonium dihydrogen phosphate and pH adjuster were added, mixed evenly, filtered, and stored in a regular container in a sealed container. There were no processes such as nano-alumina surface modification, n-pentanol purification, and preparation of synergistic pre-dispersion solution.

[0097] The technical features described above can be combined in any way. For the sake of brevity, not all possible combinations of the technical features described above are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A nano-alumina-n-pentanol synergistic thermally conductive low-conductivity coolant, characterized in that: It includes core functional components, basic cooling system, auxiliary functional components and modified solvent, each component by mass parts; The core functional components include nano-alumina and n-pentanol, with the mass fraction of n-pentanol being 1.2 to 2.5 times that of nano-alumina. The nano-alumina has a particle size of 10 to 30 nm, a purity of ≥99.9%, and a μ-phase content of ≥95%, while the n-pentanol has a purity of ≥99.5%. The basic cooling system includes ethylene glycol and deionized water; the auxiliary functional components include silane coupling agent, ammonium dihydrogen phosphate and triethanolamine, wherein the silane coupling agent is KH550; The modified solvent is anhydrous ethanol; This coolant is prepared through the following steps: (1) Pretreatment of nano-alumina: nano-alumina is spread out and vacuum dried, then cooled and sealed under nitrogen protection; the dried nano-alumina is added to anhydrous ethanol and stirred, then silane coupling agent KH550 is added, the mixture is heated and stirred to react, and after separation, washing and drying, modified nano-alumina is obtained. (2) Purification of n-pentanol: n-pentanol is purified by molecular distillation, and the first 5% of the fraction is discarded before collecting the remaining fraction; (3) Preparation of synergistic pre-dispersion liquid: The purified n-pentanol was added to a closed reaction vessel, nitrogen gas was introduced for protection, and then modified nano-alumina was added. The mixture was then ultrasonically dispersed under stirring. (4) Preparation of base solution: Mix ethylene glycol and deionized water and stir, then add triethanolamine dropwise to adjust the pH value to obtain ethylene glycol-water base solution; (5) System mixing and functional regulation: Heat the base solution, add the synergistic pre-dispersed solution dropwise while stirring, continue stirring after the addition is complete, add ammonium dihydrogen phosphate in batches to adjust the pH value of the system, and finally add the remaining auxiliary functional components. After stirring evenly, let it cool naturally. (6) Post-processing and packaging: After filtering the above mixture, it is packaged with nitrogen gas for protection.

2. The coolant as described in claim 1, characterized in that: The silane coupling agent KH550 is 0.5~1.5 parts, ammonium dihydrogen phosphate is 0.5~2.0 parts, and triethanolamine is 0.2~0.5 parts; The modified solvent, anhydrous ethanol, is present in a mass fraction of 10-15 parts.

3. The coolant as described in claim 1, characterized in that: The basic cooling system consists of the following mass fractions: 50-85 parts ethylene glycol and the remainder deionized water.

4. The coolant as described in claim 1, characterized in that: The auxiliary functional components also include polyethylene glycol 400 and benzotriazole, wherein the mass fraction of polyethylene glycol 400 is 0.1 to 3.0 parts and the purity is ≥99.0%, and the mass fraction of benzotriazole is 0.1 to 0.3 parts and the purity is ≥99.0%.

5. The coolant as described in claim 1, characterized in that: In step (1), the heating rate of vacuum drying is 5℃ / min, the drying temperature is 90±2℃, the vacuum degree is -0.095~-0.098MPa, and the holding time is 3±0.5h; the temperature of the heating and stirring reaction is 65±2℃, and the reaction time is 1.5±0.2h; the separation method is centrifugation, the centrifugation speed is 4000rpm, the time is 15min, the washing is performed with anhydrous ethanol 3 times, the drying temperature is 80±5℃, the vacuum degree is -0.09MPa, and the drying time is 2±0.5h.

6. The coolant as described in claim 1, characterized in that: In step (2), the evaporation temperature for molecular distillation purification is 80±2℃, the condensation temperature is 15±2℃, and the vacuum degree is -0.098~-0.1MPa.

7. The coolant as described in claim 1, characterized in that: In step (3), the nitrogen gas introduction rate is 100~150mL / min, the modified nano alumina addition rate is 1~2 parts / min, the stirring speed is 300±20r / min, the closed ultrasonic dispersion power is 400±20W, the frequency is 20kHz, the time is 45±5min, the reaction temperature is controlled by the jacket water temperature during the ultrasonic process to be 28±1℃, if the pressure drop of the reactor is >0.01MPa, the purified n-pentanol is added.

8. The coolant as described in claim 1, characterized in that: In step (4), the stirring speed of the mixture of ethylene glycol and deionized water is 400±20 r / min and the stirring time is 15±2 min. Triethanolamine is added dropwise to adjust the pH value to 6.5~7.

5. After stirring, the viscosity fluctuation of the base solution is measured to be ≤5 mPa·s.

9. The coolant as described in claim 1, characterized in that: In step (5), the base solution is heated to 30±2℃, the dropping rate of the synergistic pre-dispersed solution is 2~3mL / min, the stirring speed after the dropping is completed is 500±20r / min, and the stirring time is 20±3min; the pH value of the system is adjusted to 6.8±0.2 by ammonium dihydrogen phosphate, and ammonium dihydrogen phosphate is added in 3 times with an interval of 5min between each addition; the stirring speed after adding the remaining auxiliary functional components is 600±20r / min, and the stirring time is 12±2min; and the temperature is naturally cooled to 25±2℃.

10. The coolant as described in claim 1, characterized in that: In step (6), a polyethersulfone filter membrane is used for filtration, with a filtration accuracy of 0.22 μm and a filtration pressure of 0.1~0.15 MPa; the pressure for nitrogen protection is 0.02~0.03 MPa; and a light-proof storage container is used for encapsulation, with a storage temperature of 5~30℃.

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