A coolant and a method for preparing the same

Abstract

This invention discloses a coolant and its preparation method. The coolant, by mass percentage, comprises the following raw materials: 45-50% ethylene glycol, 0.18-0.36% mandelate-based corrosion inhibitor, 0.1-0.3% organic base corrosion inhibitor, 0.04-0.15% free radical scavenger, 0.0001-0.001% polyether defoamer, with the balance being water. The organic base corrosion inhibitor includes imidazole corrosion inhibitors and alkanolamines. The coolant provided by this invention achieves high reserve alkalinity, strong high-temperature acid resistance, and excellent corrosion inhibition effect.

Description

Technical Field

[0001] This invention relates to coolants, and more particularly to a coolant and its preparation method. Background Technology

[0002] Engine coolant, as the core functional medium of internal combustion engines and various high-temperature cooling systems, primarily undertakes four core functions: antifreeze, anti-boiling, heat transfer, and corrosion protection. Its performance and stability directly determine the service life, operational safety, and energy efficiency of the engine and cooling system. With the automotive industry's development towards high power, high speed, and lightweight designs, and the widespread application of coolant in new energy vehicle motors and electronic controls, data center liquid cooling, and industrial high-temperature equipment, the working environment of cooling systems is becoming increasingly harsh. Operating under conditions of high temperature (100-180℃), high pressure, and repeated hot and cold cycles, coolants face serious acidification and aging problems, while also placing higher demands on reserve alkalinity, multi-metal corrosion inhibition performance, and system stability.

[0003] Currently, coolants on the market are mainly divided into three categories: silicate type, all-organic acid type (OAT), and mixed organic acid type (HOAT). Among them, traditional silicate type coolants, although possessing certain corrosion inhibition properties and reserve alkalinity, are prone to hydrolysis and polymerization reactions during long-term use at high temperatures, forming gel-like precipitates that clog cooling pipes and radiators, leading to reduced heat dissipation efficiency and even engine overheating failure. While OAT coolants solve the problem of silicate gel precipitation, they are prone to organic acid oxidation and decomposition under high-temperature conditions, causing coolant acidification and loss of corrosion inhibition properties, which in turn leads to corrosion and pitting of various metals such as aluminum, copper, and cast iron, shortening the service life of the cooling system.

[0004] Furthermore, existing coolants have significant deficiencies in their high-temperature anti-acidification design. Most formulations do not employ an effective high-temperature antioxidant synergistic system. Under prolonged high-temperature environments, the organic components in the coolant are prone to oxidative degradation, producing acidic substances. This leads to a continuous decrease in the system's pH value and rapid depletion of reserve alkalinity. This not only results in the loss of passivation protection for metal surfaces but also accelerates the corrosion failure of the cooling system. Simultaneously, some coolants add phosphorus compounds, nitrites, and other substances to increase reserve alkalinity. These substances are not only environmentally unfriendly and prone to causing water pollution, but may also react with other components in the cooling system to form harmful precipitates, further affecting the coolant's performance and safety. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a coolant with high alkalinity, strong resistance to acidification at high temperatures, and excellent corrosion inhibition effect; another purpose of this invention is to provide a method for preparing the above-mentioned coolant.

[0006] Technical solution: The coolant of the present invention comprises, by mass percentage, the following raw materials: 45-50% ethylene glycol, 0.18-0.36% mandelate corrosion inhibitor, 0.1-0.3% organic base corrosion inhibitor, 0.04-0.15% free radical scavenger, 0.0001-0.001% polyether defoamer, with the balance being water.

[0007] Preferably, the mandelic acid ester corrosion inhibitor is one or more of n-octyl mandelate, isobutyl mandelate, isooctyl mandelate, and ethyl mandelate.

[0008] The organic base corrosion inhibitors include imidazole corrosion inhibitors and alkanolamines; the imidazole corrosion inhibitors are one or more of imidazole, 2-methylimidazolium, 4-methylimidazolium, 2-hydroxyimidazolium, and 2-ethylimidazolium; the alkanolamines are one or more of triethanolamine, diethanolamine, and ethanolamine.

[0009] The free radical scavenger is one or more of 2,6-di-tert-butyl-p-cresol, 4-methyl-6-tert-butylphenol, and p-methylbenzoic acid.

[0010] The mass ratio of the mandelate corrosion inhibitor, the organic base corrosion inhibitor, and the free radical scavenger is 36:(22-27):(9-14), and more preferably 3:2:1.

[0011] The polyether defoamer is a copolymer of ethylene oxide and propylene oxide (GPE) type polyether with a molecular weight of 3000.

[0012] The method for preparing the coolant according to the present invention includes the following steps: (1) Mix ethylene glycol and water to obtain the first mixture; (2) After mixing water and alcohol amine, add mandelic acid ester corrosion inhibitor to prepare composite package; (3) Add the composite packet and imidazole corrosion inhibitor to the first mixture in sequence to obtain the second mixture; (4) Add a free radical scavenger to the second mixture to obtain a third mixture; (5) Add polyether defoamer to the third mixture to obtain coolant.

[0013] The coolant is prepared at room temperature, and the mass ratio of water to alcohol amine in step (2) is (6-7):1.

[0014] Invention Principle: This invention introduces mandelate-based corrosion inhibitors, organic bases (imidazolium-based corrosion inhibitors and alkanolamines), and free radical scavengers simultaneously. These multiple substances not only exert their individual effects but also produce a synergistic effect, effectively improving the reserve alkalinity and high-temperature acid resistance of the coolant. This allows the coolant to maintain stable corrosion inhibition performance, sufficient alkali reserve, and excellent acid resistance even under high-temperature and repeated hot-cold cycle conditions. It overcomes the limitation of rapid performance degradation at high temperatures in existing systems and specifically addresses the pain point of existing coolants where organic components are easily oxidized and decomposed at high temperatures, generating acidic substances.

[0015] Among them, free radical scavengers help enhance the long-term high-temperature acid resistance of coolants: free radical scavengers can exist stably at high temperatures of 120-180℃, capturing free radicals generated by the oxidation of organic acids and bases in the system, terminating the oxidation chain reaction, and reducing the generation of acidic substances from the source. At the same time, organic bases (imidazolium and alkanolamines) can improve the solubility and stability of free radical scavengers and assist antioxidants in their function. Mandelic acid esters neutralize a small amount of already generated acidic substances, reducing the loss of free radical scavengers. The three work synergistically to form a closed-loop acid resistance system that "inhibits acid generation, rapidly neutralizes, and stabilizes alkalinity," solving the technical problems of weak high-temperature acid resistance and short service life of existing coolants.

[0016] Specifically, in alkaline coolants, the carbonyl oxygen (C=O) and hydroxyl oxygen (-OH) in mandelic acid esters provide lone pairs of electrons to the empty d orbitals on the metal surface, forming coordinate bonds, effectively blocking corrosive media and inhibiting electrochemical corrosion. Their long carbon chain structure also enhances the hydrophobicity and corrosion inhibition durability of the film. However, these substances mainly rely on physical barrier and adsorption, and their inhibitory effect on localized corrosion (pitting corrosion, galvanic corrosion) is not as prominent as imidazoles, molybdates, and rare earth salts. Under extreme high temperatures, the film stability is insufficient, making it prone to localized failure. Imidazole molecules contain two proton-accepting nitrogen atoms, which can combine with hydrogen ions in the system at high temperatures to form stable imidazole ions, stabilizing pH and delaying acidification. Their conjugated ring structure can capture free radicals, inhibiting the oxidative degradation of ethylene glycol, reducing the generation of acidic substances at the source. Furthermore, they are not easily volatilized or decomposed at high temperatures, providing a long-lasting buffering effect. However, imidazoles have limited corrosion inhibition effects when used alone and cannot be applied independently. Combining them with alkanolamines can improve overall protective performance while maintaining excellent anti-acidification capabilities. 2,6-Di-tert-butyl-p-cresol (BHT), as a free radical scavenger, mainly works by capturing oxidative free radicals in coolant, terminating the oxidation chain reaction of organic components, reducing the generation of acidic substances, and indirectly assisting in corrosion inhibition. At the same time, it can decompose peroxides to avoid aggravating corrosion. Its advantages are good high-temperature stability, long-lasting effect, low cost, and environmental friendliness and non-toxicity.

[0017] This invention overcomes the bottleneck of poor synergy in traditional compound formulations, abandoning the existing design concept of "single corrosion inhibitor + single alkali source" and "disconnect between corrosion inhibition and anti-oxidation" in coolants. It precisely combines mandelic acid esters, organic bases, and free radical scavengers to construct a ternary synergistic compound system. After compounding, the system exhibits good compatibility, forming a stable and homogeneous liquid phase system that is not prone to stratification, precipitation, or sedimentation. Specifically, the organic base provides a weakly alkaline environment, promoting ester hydrolysis and film formation, and enhancing the solubility of antioxidants; the free radical scavenger inhibits oxidative degradation, reduces the formation of acidic substances, and protects the passivation film; and the mandelic acid esters provide the main corrosion inhibition. This compound system exhibits excellent high-temperature stability, minimal component loss, and intact film layer during long-term operation, combining corrosion inhibition, acid resistance, and system stability. The three components are not simply superimposed, but form a synergistic relationship of mutual promotion and complementary effects. This solves the technical problems of antagonism between alkali source and corrosion inhibitor, poor compatibility between free radical scavenger and other components, and unbalanced acid resistance and corrosion inhibition performance in traditional compound systems, and achieves simultaneous improvement of the three core properties of high alkali reserve, long-term corrosion inhibition and high-temperature acid resistance.

[0018] This invention proposes an optimal ratio of 3:2:1 for the synergistic combination of mandelic acid corrosion inhibitor, organic base (imidazolium corrosion inhibitor and alkanolamine), and free radical scavenger. Mandelic acid ester, as the core film-forming corrosion inhibitor, constitutes the largest proportion (3 parts), ensuring continuous passivation film formation on the metal surface and guaranteeing long-term corrosion protection. The organic base constitutes 2 parts, a suitable proportion that maintains a stable buffer pH, providing an alkaline environment for ester activation and hydrolysis while avoiding excessive alkalinity that could trigger side reactions, and continuously neutralizing acidic substances. The free radical scavenger constitutes the smallest proportion (1 part), requiring only a trace amount to efficiently capture free radicals and inhibit high-temperature oxidative degradation of each component; excessive amounts can easily cause compatibility imbalances. This formulation precisely matches film-forming consumption, acid-base buffering, and antioxidant load, achieving synergistic stability among the three components, avoiding excessive antagonism from any single component, and maximizing the overall performance of high-temperature acid resistance and corrosion inhibition.

[0019] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: (1) The coolant obtained by the present invention has a high reserve alkalinity, generally up to 10 mL, and up to 12 mL; (2) The coolant obtained by the present invention has excellent anti-acidification performance under high-temperature service conditions of 140℃, and its pH change is around 0.2 after 30 days of service; (3) The coolant obtained by the present invention has excellent long-term corrosion inhibition performance, and after 336 hours of service at 80℃, the mass change of the metal sample is not significant, with a maximum of only 5.4 mg / sample and a minimum of only 0.2 mg / sample. g / sample; (4) The preparation method described in this invention takes into account both environmental protection and practicality, and is suitable for multiple application scenarios. It breaks through the existing design of adding harmful components to some coolants to improve performance. It selects environmentally friendly organic corrosion inhibitors, which do not contain harmful substances such as amines (except environmentally friendly alcohol amines), phosphorus, and nitrites. The free radical scavenger is selected as a non-toxic and easily degradable substance. All components meet the requirements of environmental protection regulations and OEM manufacturers. At the same time, it not only meets the performance requirements of high alkali storage, high temperature acid resistance, and long-term corrosion inhibition, but also achieves the unity of environmental protection and practicality, thus broadening the application range of coolant. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the embodiments.

[0021] Example 1

[0022] The coolant of this invention comprises, by mass percentage, the following raw materials: 50% ethylene glycol, 0.27% n-octyl mandelate as a mandelate corrosion inhibitor, 0.09% imidazole as an imidazole corrosion inhibitor, 0.09% triethanolamine as an alkanolamine, 0.09% BHT as a free radical scavenger, 0.0001% polyether defoamer, and the balance being deionized water. The polyether defoamer is a GPE-type polyether copolymer of ethylene oxide and propylene oxide with a molecular weight of 3000.

[0023] The coolant of this invention is prepared at room temperature, and the specific preparation method includes the following steps: (1) Ethylene glycol and deionized water were stirred at 30 r / min for 10 min to obtain the first mixture; (2) Under stirring conditions of 30 r / min, deionized water and triethanolamine with a mass ratio of 6:1 were added to another container and stirred for 15 min. Then, mandelic acid ester corrosion inhibitor was added and stirred for another 30 min to dissolve evenly to obtain the composite package. (3) Under stirring conditions of 30 r / min, add the composite packet and imidazole corrosion inhibitor to the first mixture in sequence, and continue stirring for 30 min to make it dissolve evenly to obtain the second mixture; (4) Under stirring conditions of 30 r / min, add free radical scavenger to the second mixture and continue stirring for 20 min to dissolve it evenly to obtain the third mixture; (5) Under stirring conditions of 30 r / min, add polyether defoamer to the third mixture and continue stirring for 20 min to dissolve it evenly to obtain a coolant.

[0024] Example 2

[0025] The similarities with Example 1 will not be repeated here, except that the mandelic acid ester corrosion inhibitor is isobutyl mandelic acid ester.

[0026] Example 3

[0027] The similarities with Example 1 will not be repeated here, except that the mandelic acid ester corrosion inhibitor is isooctyl mandelic acid ester.

[0028] Example 4

[0029] The similarities with Example 1 will not be repeated here, except that the imidazole corrosion inhibitor is 2-methylimidazole.

[0030] Example 5

[0031] The similarities with Example 1 will not be repeated here, except that the imidazole corrosion inhibitor is 4-methylimidazole.

[0032] Example 6

[0033] The similarities with Example 1 will not be repeated here, except that the alcohol amine is diethanolamine.

[0034] Example 7

[0035] The similarities with Example 1 will not be repeated here. The difference is that the feeding ratio of mandelic acid ester corrosion inhibitor, organic base (imidazolium corrosion inhibitor and alkanolamine), and free radical scavenger is 2:1.5:0.5, that is, 0.18% mandelic acid n-octyl ester, 0.0675% imidazolium, 0.0675% triethanolamine, and 0.045% BHT.

[0036] Example 8

[0037] The similarities with Example 1 will not be repeated here. The difference is that the feeding ratio of mandelic acid ester corrosion inhibitor, organic base (imidazolium corrosion inhibitor and alkanolamine), and free radical scavenger is 4:2.5:1.5, that is, 0.36% mandelic acid n-octyl ester, 0.1125% imidazolium, 0.1125% triethanolamine, and 0.135% BHT.

[0038] Comparative Example 1 The similarities with Example 1 will not be repeated here, except that the amounts of octyl mandelate, triethanolamine and imidazole added are all 0.

[0039] Comparative Example 2 The similarities with Example 1 will not be repeated here, except that the amount of octyl mandelic acid added is 0.

[0040] Comparative Example 3 The similarities with Example 1 will not be repeated here, except that the amount of imidazole added is 0.

[0041] Comparative Example 4 The similarities with Example 1 will not be repeated here, except that the amount of triethanolamine added is 0.

[0042] Comparative Example 5 The similarities with Example 1 will not be repeated here, except that the amount of BHT added is 0.

[0043] Comparative Example 6 The similarities with Example 1 will not be repeated here. The difference is that the ratio of mandelic acid ester corrosion inhibitor, organic base (imidazolium corrosion inhibitor and alkanolamine), and free radical scavenger is 1:1:1, that is, 0.09% mandelic acid n-octyl ester, 0.0045% imidazolium, 0.0045% triethanolamine, and 0.09% BHT.

[0044] Comparative Example 7 The similarities with Example 1 will not be repeated here. The difference is that the feeding ratio of mandelic acid ester corrosion inhibitor, organic base (imidazolium corrosion inhibitor and alkanolamine), and free radical scavenger is 9:3:2, that is, 0.81% mandelic acid n-octyl ester, 0.135% imidazolium, 0.135% triethanolamine, and 0.18% BHT.

[0045] Comparative Example 8 The similarities with Example 1 will not be repeated here. The difference is that the amount of mandelic acid ester corrosion inhibitor, organic base (imidazolium corrosion inhibitor and alkanolamine), and free radical scavenger is increased to 5 times, namely 1.35% mandelic acid n-octyl ester, 0.45% imidazolium, 0.45% triethanolamine, and 0.45% BHT.

[0046] Comparative Example 9 The similarities with Example 1 will not be repeated here. The difference is that the amount of mandelic acid ester corrosion inhibitor, organic base (imidazolium corrosion inhibitor and alkanolamine), and free radical scavenger is reduced to 20%, namely 0.054% mandelic acid n-octyl ester, 0.018% imidazolium, 0.018% triethanolamine, and 0.018% BHT.

[0047] Tables 1 and 2 visually represent the experimental conditions.

[0048] Table 1. Components and proportions (wt%) of each embodiment

[0049] Table 2. Components and proportions (wt%) of each comparative example

[0050] The coolants prepared in each experiment were tested, including: pH value, high-temperature pH stability, reserve alkalinity, and metal corrosion inhibition performance. The performance test results of the examples and comparative examples are shown in Tables 3 and 4, respectively.

[0051] 1. pH value test: The pH value of the coolant shall be measured at 140℃ using a pH meter in accordance with the test method SH / T 0069.

[0052] 2. pH high temperature stability test: Add 100ml of coolant to a polytetrafluoroethylene high-pressure tank and store it at 140℃ for 7 days, 14 days and 30 days, and then test its pH change value, formic acid and glycolic acid content.

[0053] 3. Reserve alkalinity test: The reserve alkalinity of the coolant shall be determined by titration in accordance with test method SH / T 0091.

[0054] 4. Static corrosion performance test: Referring to the static corrosion test in GB29743.2-2025 "Motor vehicle coolant Part 2: Electric vehicle coolant", the coolant was tested at 80±2°C for 336 hours to conduct static corrosion tests on brass, copper, steel, ZL101A cast aluminum, 3003 aluminum, 4043 aluminum and 6063 aluminum. After the experiment, the change in the anti-corrosion performance of the coolant was evaluated by the change in the mass of the metal test pieces.

[0055] Table 3 Performance test results for each embodiment

[0056] Table 4 Performance test results of each comparative example

[0057] Note: Since the conductivity of Comparative Example 8 does not meet the requirement of ≤100uS / cm, its reserve alkalinity and corrosion inhibition performance will not be tested.

[0058] Analysis of the test results in Table 3 shows that the coolant prepared using the formula described in this invention has excellent performance. The freezing point can reach -36℃, the conductivity at 25℃ meets the requirement of ≤100uS / cm, and it has strong high-temperature acid resistance and reserve alkalinity. According to Examples 1-6, changing the type of mandelic acid ester corrosion inhibitor, imidazole corrosion inhibitor, or alkanolamine can yield coolants with excellent performance: the reserve alkalinity can reach 10ml, and under high-temperature conditions of 140℃, the pH change after 30 days is at most 0.3 (Example 1). It exhibits excellent corrosion inhibition performance on metals; under conditions of 80℃ for 336 hours of metal corrosion, the mass change of the metal sample can be maintained within ±5.5mg, with the lowest change being only 0.2. According to the test results of Examples 7-8, the coolant exhibits better performance when the mass ratio of mandelic acid ester corrosion inhibitor, organic alkali corrosion inhibitor, and free radical scavenger is 2:1.5:0.5 or 4:2.5:1.5. While Example 7 has a high reserve alkalinity of 12 ml, its high-temperature acid resistance is weak: at 140°C, the pH changes by 0.41 after 30 days. Example 8, while exhibiting better high-temperature acid resistance, has a reserve alkalinity of only 8 ml. Based on the analysis of the formulation data from all examples, Example 3 demonstrates the most outstanding metal corrosion resistance and reserve alkalinity, with relatively low conductivity and pH change after 30 days. Therefore, this example balances conductivity, reserve alkalinity, metal corrosion inhibition, and high-temperature acid resistance, meeting the requirements for a coolant with high reserve alkalinity and high-temperature acid resistance. When the optimal mass ratio of mandelate corrosion inhibitor, organic base corrosion inhibitor, and free radical scavenger is 3:2:1 (Examples 1-6), the effect of the coolant is significantly better than that of Examples 7-8.

[0059] Analysis of Table 4 shows that the coolant prepared without the formulation described in this invention has weaker reserve alkalinity and high-temperature acid resistance, with the lowest reserve alkalinity being only 1 ml. When no mandelic acid ester corrosion inhibitors, imidazole corrosion inhibitors, or alkanolamines are added (Comparative Example 1), the coolant's acid resistance, reserve alkalinity, and metal corrosion inhibition are all weak: after 30 days, the pH change is as high as 3.4, the reserve alkalinity is only 2 ml, and after corroding metal at 80℃ for 336 hours, the mass change of the metal sample is above ±6.5 mg. Analysis of Comparative Examples 2-5 shows that when any one of the following substances—mandelic acid ester corrosion inhibitors, imidazole corrosion inhibitors, alkanolamines, or free radical scavengers—is missing from the formulation, the coolant's performance cannot achieve the technical effects described in this invention. When the mass ratio of mandelic acid ester corrosion inhibitor, organic alkali corrosion inhibitor, and free radical scavenger is not within the range of 36:(22-27):(9-14) (Comparative Examples 6-7), the resulting coolant exhibits poor metal corrosion inhibition. After 336 hours of service at 80°C, the mass change of the metal sample is as high as 9.3 mg / sample and 12.1 mg / sample, respectively. When the amount of the three additives (mandelic acid ester corrosion inhibitor, organic alkali corrosion inhibitor, and free radical scavenger) added is as high as 5 times (Comparative Example 8), the conductivity of the coolant reaches as high as 584.1 uS / cm, far exceeding the highest value of 8.21 uS / cm in Examples 1-8. Excessive conductivity will lead to a sharp decline in the insulation performance of the coolant, which may cause the following risks: electrical breakdown and short circuit, leakage and electric shock hazards, a sharp drop in the efficiency of the heat dissipation system, and increased operation and maintenance costs. When the amount of the three additives was reduced to 20% (Comparative Example 9), the data on metal corrosion and high-temperature acid resistance deteriorated sharply, indicating that although the optimal ratio of the three additives was 3:2:1, it was insufficient to effectively add them.

[0060] A comprehensive analysis of Tables 3 and 4, combined with the experimental results of Example 1 and Comparative Examples 1-5, shows that mandelic acid ester corrosion inhibitors, organic base corrosion inhibitors, and free radical scavengers are all indispensable. Moreover, when all three are introduced at the same time, their effects are not simply additive, but rather form a synergistic relationship of complementary enhancement.

Claims

1. A coolant, characterized in that, By weight percentage, it includes the following raw materials: 45-50% ethylene glycol, 0.18-0.36% mandelate corrosion inhibitor, 0.1-0.3% organic base corrosion inhibitor, 0.04-0.15% free radical scavenger, 0.0001-0.001% polyether defoamer, and the balance is water.

2. The coolant according to claim 1, characterized in that, The mandelic acid ester corrosion inhibitor is one or more of n-octyl mandelate, isobutyl mandelate, isooctyl mandelate, and ethyl mandelate.

3. The coolant according to claim 1, characterized in that, The organic base corrosion inhibitors include imidazole corrosion inhibitors and alcohol amines.

4. The coolant according to claim 1, characterized in that, The free radical scavenger is one or more of 2,6-di-tert-butyl-p-cresol, 4-methyl-6-tert-butylphenol, and p-methylbenzoic acid.

5. The coolant according to claim 3, characterized in that, The imidazole corrosion inhibitor is one or more of imidazole, 2-methylimidazolium, 4-methylimidazolium, 2-hydroxyimidazolium, and 2-ethylimidazolium.

6. The coolant according to claim 3, characterized in that, The alkanolamine is one or more of triethanolamine, diethanolamine, and ethanolamine.

7. The coolant according to claim 1, characterized in that, The mass ratio of the mandelate corrosion inhibitor, the organic base corrosion inhibitor, and the free radical scavenger is 36:(22-27):(9-14).

8. The coolant according to claim 1, characterized in that, The polyether defoamer is a GPE-type polyether copolymerized from ethylene oxide and propylene oxide.

9. The method for preparing the coolant according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Mix ethylene glycol and water to obtain the first mixture; (2) After mixing water and alcohol amine, add mandelic acid ester corrosion inhibitor to prepare composite package; (3) Add the composite packet and imidazole corrosion inhibitor to the first mixture in sequence to obtain the second mixture; (4) Add a free radical scavenger to the second mixture to obtain a third mixture; (5) Add polyether defoamer to the third mixture to obtain coolant.

10. The preparation method according to claim 9, characterized in that, In step (2), the mass ratio of water to alcohol amine is (6-7):1.

Images