High-stability plant-based coolant and preparation method thereof

Abstract

The application discloses a kind of high stability plant-based coolant and preparation method thereof, belong to liquid cooling heat dissipation technical field.The coolant includes plant-based base oil and specific proportion of epoxy soybean oil modifier.The introduction of the modifier produces synergistic effect with plant-based base oil and antioxidant, so that the coolant has excellent oxidative stability while maintaining high flash point and excellent biodegradability.The preparation method includes modifier pretreatment, mixing, refining and additive compounding and other steps, simple process, suitable for large-scale production.The application effectively solves the technical problem that traditional plant-based coolant is easy to oxidize, and is suitable for immersion liquid cooling system in the fields of data center, energy storage battery, etc.

Description

Technical Field

[0001] This invention relates to the field of liquid cooling technology, and in particular to a highly stable plant-based coolant and its preparation method. Background Technology

[0002] With the rapid development of high-power-density electronic devices and energy storage systems, immersion liquid cooling technology has become a research hotspot due to its efficient and uniform heat dissipation capabilities. The core medium of this technology, the coolant, must possess high insulation, excellent thermal conductivity, material compatibility, high safety, and environmental friendliness. Plant-based coolants, represented by soybean oil and rapeseed oil, have attracted attention due to their advantages such as high flash point, biodegradability, and renewable raw materials. However, the unsaturated double bonds in their molecules are easily oxidized under thermal and oxygen conditions, leading to increased acid value, increased viscosity, and the formation of sludge, which seriously affects long-term stability and equipment safety.

[0003] To improve the performance of vegetable oils, existing technologies mostly employ compounding methods, but these all have significant drawbacks: compounding with synthetic esters increases costs and offers limited antioxidant benefits; mixing with mineral oils / synthetic hydrocarbons significantly lowers the flash point, causing the loss of the core advantages of plant-based cooling; and mixing with fluorinated liquids results in high costs, poor environmental performance, and difficulty in recycling fluorides, contradicting the environmentally friendly principles of plant-based cooling. None of these methods can effectively address the critical issue of easy oxidation and deterioration of plant-based coolants while preserving their core advantages.

[0004] Therefore, how to address the critical drawback of easy oxidation and deterioration in plant-based coolants while retaining their core advantages of high flash point, biodegradability, and low cost has become a pressing technical challenge in this field. Epoxidized soybean oil is a common environmentally friendly plasticizer and stabilizer, possessing characteristics of high flash point, non-toxicity, and biodegradability. However, its application as a functional modifier, through specific component design and refining processes, to improve the oxidative stability of plant-based submerged coolants has not yet been reported. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing technologies and provide a highly stable plant-based coolant and its preparation method. While maintaining the high flash point, high biodegradability, and low cost of plant oils, this coolant significantly improves the oxidative stability of the system and reduces the acid value of the system after aging by introducing a specific proportion of epoxidized soybean oil, thus obtaining a submersible coolant with excellent overall performance, high safety, and environmental friendliness.

[0006] The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a plant-based coolant comprising a plant-based base oil and an epoxidized soybean oil modifier.

[0007] Based on the above technical solutions, preferably, the plant-based coolant, by weight, comprises: 20-95 parts of plant-based base oil and 5-80 parts of epoxidized soybean oil modifier.

[0008] More preferably, the epoxy value of the epoxidized soybean oil modifier is 1% to 7%. Epoxidized soybean oil has a high surface tension, which helps to form a more stable liquid-gas interface on the liquid surface, effectively blocking the penetration of air and water molecules. At the same time, the epoxy groups in its molecules have high chemical reactivity and can act as "capture agents" to react with organic acidic substances (such as free fatty acids) produced during oil oxidation, thereby delaying the rancidity process of vegetable oil.

[0009] More preferably, the epoxy value of the epoxidized soybean oil modifier is 3% to 6%.

[0010] More preferably, the epoxidized soybean oil modifier is obtained by the following steps: adding an acidic aqueous solution to epoxidized soybean oil for reaction, washing with water until neutral, and then adding an alkaline aqueous solution for reaction to obtain the epoxidized soybean oil modifier.

[0011] More preferably, the acidic aqueous solution is a phosphoric acid or citric acid aqueous solution with a concentration of 1-8 g / L, the amount of acidic aqueous solution is 5%-40% of the mass of epoxidized soybean oil, the reaction temperature is 40-60℃, the reaction time is 0.5-2 hours, after which deionized water is added to wash until neutral, and the oil phase is collected; the alkaline aqueous solution is a sodium hydroxide or potassium hydroxide aqueous solution with a concentration of 1-10 g / L, the mass ratio of alkaline aqueous solution to oil phase is 1:1, and the reaction is carried out at a temperature of 40-60℃ for 0.5-2 hours, about 10 wt% saturated brine is added and stirred for 20-50 minutes, and finally the mixture is centrifuged while hot, and the upper oil phase, which is the epoxidized soybean oil modifier, is retained.

[0012] More preferably, the epoxidized soybean oil modifier has an acid value ≤ 0.2 mg KOH / g and a media loss factor ≤ 1.0.

[0013] More preferably, the epoxidized soybean oil modifier has an acid value ≤0.06 mg KOH / g and a media loss factor ≤0.05.

[0014] More preferably, the plant-based base oil is refined vegetable oil and / or hydrogenated vegetable oil, with an acid value ≤0.06mg KOH / g and a media loss factor ≤0.05.

[0015] More preferably, the plant-based coolant further comprises, by weight, the following components: antioxidant: 0.1-2 parts; pour point depressant: 0.1-2 parts; metal deactivator: 0.001-0.05 parts and defoamer: 0.001-0.05 parts.

[0016] More preferably, the antioxidant is at least one of hindered phenolic antioxidants and aromatic amine antioxidants, such as 2,6-di-tert-butyl-p-cresol or alkylated diphenylamine. Vegetable oils generate free radicals when exposed to light, heat, and oxygen during use; the role of antioxidants is to eliminate these free radicals and extend the service life of the base oil.

[0017] More preferably, the pour point depressant is at least one selected from polyacrylate pour point depressants, polyalphaolefin pour point depressants, and alkylnaphthalene pour point depressants. The function of the pour point depressant is to lower the pour point of the coolant and ensure performance at low temperatures.

[0018] More preferably, the metal deactivator is benzotriazole and its derivatives or thiadiazole and its derivatives; such substances can form a dense inert protective film on the surface of metals such as copper, effectively shielding the catalytic activity of metal ions on oxidation reactions and inhibiting corrosion reactions on the metal surface.

[0019] More preferably, the defoamer is a polysiloxane or acrylate defoamer, which reduces local surface tension or disrupts the elasticity of the bubble film, causing the bubbles to break down and be eliminated quickly, thereby improving the antifoaming performance of the coolant and ensuring the stability of the system operation.

[0020] Secondly, the present invention provides a method for preparing the above-mentioned coolant, comprising the following steps: S1. Mix and stir the plant-based base oil with the epoxidized soybean oil modifier to obtain a mixed oil solution; S2. Add the adsorbent to the mixed oil obtained in step S1 while stirring, stir, filter, and obtain refined base oil. S3. Add antioxidants, pour point depressants, metal deactivators and defoamers to the refined base oil obtained in step S2, and stir until all additives are completely dissolved and uniformly dispersed; filter to obtain the plant-based coolant.

[0021] Based on the above technical solutions, preferably, in step S2, the adsorbent is at least one of activated clay, alkaline alumina and diatomaceous earth; the amount of adsorbent used is 0.5% to 2% of the mass of the base oil.

[0022] In a further preferred embodiment, in step S3, the stirring temperature is 60~80℃, the stirring time is 1~2 hours, and then the temperature is lowered to 40℃ before filtration to obtain the plant-based cooling liquid.

[0023] The present invention has the following advantages over the prior art: (1) The epoxy groups in epoxidized soybean oil act as "acid scavengers," working synergistically with the free radical termination mechanism of antioxidants to fundamentally inhibit the rancidity of vegetable oils. Data from the examples show that the acid value of the coolant after accelerated aging (as low as 0.06 mg KOH / g) is far lower than that of the control sample without modifiers (0.45 mg KOH / g), representing an increase of over 85%, thus addressing the core pain point of short lifespan in plant-based coolants.

[0024] (2) The modifier is completely compatible with vegetable oil and has an extremely high flash point (>300℃), which keeps the flash point / ignition point of the coolant stable above 310℃. It retains the inherent safety characteristics of the plant-based "flame-retardant" properties 100%, and the biodegradability rate in 28 days is >93%, so the environmental advantages are not affected in any way.

[0025] (3) The introduction of epoxidized soybean oil moderately increases the surface tension of the system, which helps to form a more stable liquid-gas interface. This provides a potential advantage for the application of coolant in non-completely sealed environments. The process of this invention is simple and the cost is controllable, providing a reliable path with great commercial value for solving the application bottleneck of plant-based coolant. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] Table 1: Material Source Description Table

[0028] In all examples, 1 part = 10 g.

[0029] Example 1: S1. Take 50 parts of epoxidized soybean oil (epoxidation value 3.5%) and heat to 50℃; add 5 parts of citric acid aqueous solution with a concentration of 4 g / L, and react at 50℃ for 1 hour; after the reaction, wash with deionized water until neutral, and collect the oil phase. Add 50 parts of sodium hydroxide aqueous solution with a concentration of 5 g / L to the oil phase and react at 50℃ for 1 hour. Add about 10 wt% saturated brine (relative to the mass of the oil phase), stir for 30 minutes, centrifuge while hot, and retain the upper oil phase to obtain the pretreated epoxidized soybean oil modifier. Mix 47 parts of refined soybean oil with the above-obtained epoxidized soybean oil modifier at 70℃ and stir at 300 rpm for 0.5 hours to obtain a homogeneous mixed oil.

[0030] S2. Add 1.2 parts of activated clay to the mixed oil under stirring; keep warm and stir for 2 hours, then filter to obtain refined base oil.

[0031] S3. Maintain the refined base oil at 70°C, and sequentially add 1.0 part of 2,6-di-tert-butyl-p-cresol, 0.2 parts of alkylated diphenylamine, 1.75 parts of polymethacrylate pour point depressant, 0.045 parts of benzotriazole (BTA), and 0.005 parts of polysiloxane defoamer; continue stirring for 1 hour until all additives are completely dissolved and uniformly dispersed. Cool to below 40°C, filter, and obtain the plant-based coolant product of Example 1.

[0032] Example 2: S1. Take 5 parts of epoxidized soybean oil (epoxidation value 3.5%) and heat to 40℃; add 2 parts of 1 g / L phosphoric acid aqueous solution and react at 40℃ for 0.5 hours; after the reaction, wash with deionized water until neutral and collect the oil phase. Add 5 parts of 1 g / L sodium hydroxide aqueous solution to the oil phase and react at 40℃ for 0.5 hours. Add about 10 wt% saturated brine (relative to the mass of the oil phase), stir for 20 minutes, centrifuge while hot, and retain the upper oil phase to obtain the pretreated epoxidized soybean oil modifier. Mix 95 parts of refined soybean oil with the above-obtained epoxidized soybean oil modifier at 60℃ and stir at 200 rpm for 0.5 hours to obtain a homogeneous mixed oil.

[0033] S2. Add 2 parts of alkaline alumina to the mixed oil under stirring; keep warm and stir for 1 hour, then filter to obtain refined base oil.

[0034] S3. Maintain the refined base oil at 60°C, and sequentially add 0.1 parts of 2,6-di-tert-butyl-p-cresol, 0.1 parts of polymethacrylate pour point depressant, 0.001 parts of benzotriazole (BTA), and 0.001 parts of polysiloxane defoamer; continue stirring for 1 hour until all additives are completely dissolved and uniformly dispersed. Cool to below 40°C, filter, and obtain the plant-based coolant product of Example 2.

[0035] Example 3: S1. Take 80 parts of epoxidized soybean oil (epoxidation value 3.5%) and heat to 60℃; add 4 parts of citric acid aqueous solution with a concentration of 8 g / L, and react at 60℃ for 1 hour; after the reaction, wash with deionized water until neutral, and collect the oil phase. Add 80 parts of sodium hydroxide aqueous solution with a concentration of 10 g / L to the oil phase and react at 60℃ for 2 hours. Add about 10 wt% saturated brine (relative to the mass of the oil phase), stir for 50 minutes, centrifuge while hot, and retain the upper oil phase to obtain the pretreated epoxidized soybean oil modifier. Mix 20 parts of refined soybean oil with the above-obtained epoxidized soybean oil modifier at 80℃ and stir at 500 rpm for 1 hour to obtain a homogeneous mixed oil.

[0036] S2. Add 0.5 parts of activated clay to the mixed oil under stirring; keep warm and stir for 3 hours, then filter to obtain refined base oil.

[0037] S3. Maintain the refined base oil at 80°C, and sequentially add 2 parts of 2,6-di-tert-butyl-p-cresol, 2 parts of polymethacrylate pour point depressant, 0.05 parts of benzotriazole (BTA), and 0.05 parts of polysiloxane defoamer; continue stirring for 2 hours until all additives are completely dissolved and uniformly dispersed. Cool to below 40°C, filter, and obtain the plant-based coolant product of Example 3.

[0038] Examples 4-7: Unlike Example 1, 50 portions of epoxidized soybean oil were taken with epoxy values ​​of 1%, 3%, 6% and 7%, respectively. The remaining steps were the same as in Example 1, and will not be repeated here.

[0039] Comparative Example 8: Unlike Example 1, epoxidized soybean oil is not used. The remaining steps are the same as in Example 1, and will not be repeated here.

[0040] Comparative Examples 9-10: Unlike Example 1, 50 parts mineral oil and 50 parts synthetic ester were used instead of epoxidized soybean oil, respectively. The remaining steps were the same as in Example 1 and will not be repeated here.

[0041] Comparative Examples 11-12: Unlike Example 1, 50 parts of epoxidized soybean oil were taken with epoxy values ​​of 0.5% and 8%, respectively. The remaining steps were the same as in Example 1, and will not be repeated here.

[0042] Comparative Example 13: Unlike Example 1, 50 parts of epoxidized soybean oil were used but not modified. The remaining steps were the same as in Example 1 and will not be repeated here.

[0043] Key performance tests were conducted on the coolant samples obtained in Examples 1-7 and Comparative Examples 8-10. All tests were performed in accordance with national or industry standards, as detailed below: Oxidation stability test: conducted according to the method described in Appendix B of the power industry standard DL / T 1811; Acid value: determined according to the petrochemical industry standard NB / SH / T 0811; Dielectric loss factor (tanδ): determined according to the national standard GB / T 5654 at 90°C; Flash point: tested according to the national standard GB / T 3536 using the Cleveland open cup method; Pour point: tested according to the national standard GB / T 3535; Surface tension: determined according to the national standard GB / T22237 at 25°C; Biodegradability (28 days): determined according to the national standard GB / T 21856-2008.

[0044] Table 2: Coolant Performance Test Results

[0045] Acid value can be used to assess the degree of aging of oil products or to determine whether the chemical composition of oil products has changed. The higher the acid value, the higher the degree of aging of the oil products.

[0046] After oxidation, the acid values ​​of Examples 1-3 were significantly lower than those of Comparative Examples 8-10, indicating a milder degree of oxidation, fewer acidic products, and a significantly longer service life. In particular, Example 3 (with the highest content of epoxidized soybean oil) showed an acid value only 1 / 7 to 1 / 8 that of Comparative Example 1 (pure vegetable oil), demonstrating the remarkable effect of epoxidized soybean oil in improving the oxidative stability of vegetable oils. In Comparative Example 9, although the added mineral oil had higher surface tension, its thermal stability was poor, and it lacked a synergistic antioxidant effect; therefore, its post-oxidation acid value was only slightly stronger than that of Comparative Example 8. In Comparative Example 10, the synthetic ester showed better thermal stability, with a post-oxidation acid value stronger than Comparative Examples 8-9, but still weaker than that of Examples 1-3. This is mainly because the synthetic ester lacks a synergistic antioxidant effect, and its price is significantly higher than that of epoxidized soybean oil, making it less cost-effective and less competitive as a commercial product.

[0047] Dielectric loss refers to the dielectric loss angle tangent, which is an important indicator of the insulation quality of coolant. The lower the dielectric loss angle, the smaller the dielectric loss and the better the insulation. After oxidation, the dielectric loss of Examples 1-3 is 8-10 lower than that of Comparative Examples, indicating that the oxidation degree of the system is light, less polar substances are generated, and the impact on the insulation performance of the coolant is small, resulting in a significantly longer service life.

[0048] Safety performance (flash point): The flash points of Examples 1-3 all remained above 310°C, meeting the standard for flame-retardant liquids, similar to Comparative Example 8 (pure vegetable oil), and far exceeding those of Comparative Example 9 and Comparative Example 10 (whose flash point dropped significantly to 150°C after the addition of mineral oil). This fully meets the core objective of this invention, "not lowering the flash point," and preserves the high safety of vegetable oil.

[0049] Low-temperature fluidity (pour point): The addition of epoxidized soybean oil did not significantly increase the pour point, and it still meets the requirements of most application scenarios (-18℃).

[0050] Surface tension: The surface tension of the examples was higher than that of Comparative Example 8, confirming that the introduction of epoxidized soybean oil increased the surface tension of the system. This may be beneficial for forming a more stable interface, blocking air and water vapor, and solving the problem that plant-based coolants are not suitable for working in open systems.

[0051] Environmental friendliness: Examples and Comparative Example 8 both maintained excellent biodegradability (>93%), while Comparative Examples 9-10 had poor biodegradability due to the presence of mineral oil and synthetic esters with low biodegradability.

[0052] In summary, by introducing a specific proportion of epoxidized soybean oil as a modifier, this invention successfully solves the technical bottleneck of easy oxidation of plant-based coolants without sacrificing their core advantages of high flash point and high biodegradability, and provides a new solution for high-performance, long-life, high-safety and environmentally friendly immersion coolants.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A plant-based coolant, characterized in that, Including plant-based base oils and epoxidized soybean oil modifiers.

2. The plant-based coolant as described in claim 1, characterized in that, By weight, vegetable-based base oil: 20-95 parts; epoxidized soybean oil modifier: 5-80 parts.

3. The plant-based coolant as described in claim 1, characterized in that, The epoxy value of the epoxidized soybean oil modifier is 1% to 7%.

4. The plant-based coolant as described in claim 1, characterized in that, The epoxidized soybean oil modifier is obtained through the following steps: adding an acidic aqueous solution to epoxidized soybean oil and reacting, washing with water until neutral, and then adding an alkaline aqueous solution to react, thereby obtaining the epoxidized soybean oil modifier.

5. The plant-based coolant as described in claim 4, characterized in that, The acidic aqueous solution is a phosphoric acid or citric acid aqueous solution with a concentration of 1~8 g / L, and the amount of acidic aqueous solution used is 5%~40% of the mass of epoxidized soybean oil; the alkaline aqueous solution is a sodium hydroxide or potassium hydroxide aqueous solution with a concentration of 1~10 g / L, and the mass ratio of alkaline aqueous solution to oil phase is 1:

1.

6. The plant-based coolant as described in claim 1, characterized in that, The epoxidized soybean oil modifier has an acid value ≤0.2 mg KOH / g and a media loss factor ≤1.

0.

7. The plant-based coolant as described in claim 1, characterized in that, The plant-based base oil is refined vegetable oil and / or hydrogenated vegetable oil, with an acid value ≤0.06 mg KOH / g and a media loss factor ≤0.

05.

8. The plant-based coolant as described in claim 2, characterized in that, By weight, it also includes the following components: Antioxidant: 0.1~2 parts; pour point depressant: 0.1~2 parts; metal deactivator: 0.001~0.05 parts and defoamer: 0.001~0.05 parts.

9. A method for preparing a plant-based coolant as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Mix and stir the plant-based base oil with the epoxidized soybean oil modifier to obtain a mixed oil solution; S2. Add the adsorbent to the mixed oil obtained in step S1 while stirring, stir, filter, and obtain refined base oil. S3. Add antioxidants, pour point depressants, metal deactivators and defoamers to the refined base oil obtained in step S2, and stir until all additives are completely dissolved and uniformly dispersed; filter to obtain the plant-based coolant.

10. The preparation method according to claim 9, characterized in that, In step S2, the adsorbent is at least one of activated clay, alkaline alumina, and diatomaceous earth; the amount of adsorbent used is 0.5% to 2% of the mass of the base oil.

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