Nonionic surfactant for new energy low conductivity coolant and preparation method thereof

Abstract

The application discloses a non-ionic surfactant for new energy low-conductivity coolant, and the non-ionic surfactant is benzotriazole polyether, and has the following structure: wherein n is an integer of 5-30. A preparation method of the non-ionic surfactant for new energy low-conductivity coolant comprises the following steps: in the presence of trialkylamine, introducing ethylene oxide into a methyl benzotriazole melt to react, and refluxing the reaction mixture to obtain the benzotriazole polyether non-ionic surfactant. The application introduces ethylene oxide (ethoxylation) into the methyl benzotriazole, thereby increasing the solubility of the methyl benzotriazole, increasing the adsorption degree of the methyl benzotriazole on a metal surface, and improving the corrosion inhibition efficiency. In addition, the surfactant has good solubilization and directional adsorption capacity due to the unique amphiphilic property, and can also be used for corrosion inhibition.

Description

Technical Field

[0001] This invention relates to a surface-active corrosion inhibitor, specifically a nonionic surfactant for use in low-conductivity coolants in new energy sources and its preparation method. Background Technology

[0002] The battery thermal management system is a crucial component of new energy batteries. It controls battery temperature through cooling and heating to ensure optimal battery operation, improve the consistency of the battery's operating environment, and thus extend battery life. Cooling is the primary focus of the battery thermal management system and is key to the continuous and safe operation of the battery system. Based on the cooling medium, it is mainly divided into air cooling and liquid cooling. Coolants used in new energy battery systems, in addition to having anti-scaling and antifreeze properties, are required to protect the materials and components of the battery cooling system and also have low conductivity (<100 μS / cm). Corrosion inhibitors provide excellent protection for the battery cooling system.

[0003] Organic corrosion inhibitors are commonly used in antifreeze, especially organic compounds containing heteroatoms such as N, O, and S. Heterocyclic corrosion inhibitors, in particular, utilize heteroatoms that provide lone pairs of electrons. The π electrons in the heterocycles readily undergo chemisorption with the metal, resulting in good corrosion inhibition performance. The corrosion inhibition efficiency depends on the concentration of the inhibitor and its contact time with the metal surface. Currently, existing corrosion inhibitors are used in large quantities; insufficient use can lead to pitting corrosion.

[0004] In the literature MMOsman, AMAOmar, AMSabagh, Mater. Chem. Phys. 50 (1997) 271, benzyltrimethylammonium chloride (BTAC) was ethoxylated to obtain ethoxybenzyltrimethylammonium chloride (EBTAC). The effects of corrosion inhibitor concentration on surface properties, surface coverage and corrosion inhibition efficiency were analyzed. The results showed that the corrosion inhibition effect of EBTAC was better than that of BTAC.

[0005] The corrosion inhibitor prepared by the preparation of oleic amide intermediate, ethoxylation of oleic amide intermediate, and compounding of corrosion inhibitor product as described in patent CN114959714A has the characteristics of small dosage, good film-forming properties, and high corrosion inhibition efficiency. Summary of the Invention

[0006] The purpose of this invention is to provide a nonionic surfactant for low-conductivity coolants in new energy sources, which ethoxylates methylbenzotriazole (TTA). Ethoxylated methylbenzotriazole has surface activity, excellent solubilizing and directional adsorption capabilities, increases its adsorption degree on metal surfaces, and improves its corrosion inhibition efficiency.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A nonionic surfactant for use in low-conductivity coolants in new energy sources, wherein the nonionic surfactant is benzotriazole polyether and has the following structure:

[0009]

[0010] Where n is an integer from 5 to 30.

[0011] A method for preparing a nonionic surfactant for low conductivity coolant in new energy sources includes the following steps: in the presence of trialkylamine, ethylene oxide is introduced to react with methylbenzotriazole melt, and the reaction mixture is refluxed to prepare a benzotriazole polyether nonionic surfactant.

[0012] Preferably, the trialkylamine is one or a mixture of two or more of trimethylamine, triethylamine, tripropylamine, dimethylethylamine, and diethylmethylamine.

[0013] Preferably, the amount of trialkylamine added is 0.01 to 0.2 wt% of the amount of methylbenzotriazole added.

[0014] Preferably, before introducing ethylene oxide, the system temperature is 80–90°C and the pressure is 11–12 kPa.

[0015] Preferably, after ethylene oxide is introduced, the system temperature is raised to the reflux temperature of 159-168°C, and the reflux reaction time of the mixture is 3-5 hours.

[0016] Preferably, after the reflux reaction is completed, the mixture is cooled and flashed off every half hour.

[0017] Preferably, after introducing ethylene oxide monomer, the reaction progress is assessed by monitoring the weight gain of the reaction system.

[0018] By adopting the above technical solution, the present invention has the following beneficial effects:

[0019] Ethoxylation of methylbenzotriazole produces ethoxylated methylbenzotriazole, which is surface-active and has excellent solubilizing and directional adsorption capabilities, increasing its adsorption degree on metal surfaces and improving its corrosion inhibition efficiency. Attached Figure Description

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] Figure 1 This is a line graph showing the relationship between the amount of nonionic surfactant added and the corrosion rate.

[0022] Figure 2This is a line graph showing the relationship between the amount of nonionic surfactant added and the corrosion inhibition rate.

[0023] Figure 3 This represents the change in coolant conductivity over time.

[0024] Figure 4 This is a line graph showing the relationship between the concentration of nonionic surfactants and surface tension. Detailed Implementation

[0025] Example 1

[0026] In a 500 ml four-necked flask equipped with a condenser, magnetic stirrer, thermometer, and ethylene oxide gas inlet and outlet nozzles, 0.1 g of triethylamine was added to 133.15 g of methylbenzotriazole. The mixture was stirred at 85 °C for approximately 15 minutes. Then, under a controlled pressure of 11 kPa, 352 g of ethylene oxide gas was passed through the methylbenzotriazole melt while stirring. The temperature was gradually increased to the reflux temperature, and the reaction mixture was refluxed for approximately 3 hours. It was then cooled and flash-evaporated every half hour. The reaction progress was assessed by monitoring the weight increase due to the introduction of ethylene oxide. Upon completion of the reaction, nonionic surfactant I was prepared.

[0027] Examples 2-5

[0028] Using the same experimental conditions as in Example 1, and adjusting the amount of ethylene oxide introduced through theoretical calculations, nonionic surfactants II to V were prepared. The synthesized products were characterized by nuclear magnetic resonance (NMR), and the results for the synthesized products in Examples 1-5 are shown in Table 1.

[0029] Table 1. Molar amount of ethylene oxide in nonionic surfactants

[0030]

[0031] Example 6

[0032] Example 6 provides an application of the above-mentioned nonionic surfactant: the corrosion inhibition performance of the nonionic surfactant prepared by the present invention is evaluated by the weight loss method.

[0033] Test materials: The coolant consisted of 50% ethylene glycol, corrosion inhibitor, and the remainder ultrapure water. The corrosion inhibitor dosages were 50 ppm, 100 ppm, 150 ppm, 200 ppm, 250 ppm, and 300 ppm. The test pieces were steel sheets.

[0034] Experimental apparatus: wide-mouth glass bottle with ground glass stopper, oven, analytical balance

[0035] Test temperature: 80℃

[0036] Experiment duration: 14 days

[0037] Evaluation method: Weigh the test specimens before and after the test, and calculate the corrosion rate and corrosion inhibition rate based on the weight loss of the test specimens.

[0038] The corrosion rate V is calculated using the following formula:

[0039]

[0040] In the formula, k = 3.45 × 10⁶, T is the corrosion test time (h), and A is the sample surface area (cm²). 2 W is the weight loss (g), and D is the sample density (g / cm³). 3 ).

[0041] The corrosion inhibition rate is calculated using the following formula:

[0042]

[0043] In the formula, W0 is the mass loss (g) of the test piece in the blank test, and W1 is the mass loss (g) of the test piece in the test with added nonionic surfactant.

[0044] Experimental Procedure: The prepared solution of nonionic surfactant I was added to a wide-mouth glass bottle using a pipette at the designed mass concentration, followed by the addition of coolant. A blank test without nonionic surfactant was performed simultaneously. The degreased sample was weighed (accurate to 0.1 mg), suspended and immersed in the test solution, ensuring the sample did not contact the glass bottle wall, and kept at 80°C for 14 days. The sample was then removed, washed sequentially with water, ethanol, and acetone, dried with cold air, and weighed again (accurate to 0.1 mg). The corrosion rate and corrosion inhibition rate were calculated.

[0045] Examples 7-10

[0046] The corrosion inhibition properties of nonionic surfactants II to V were evaluated using the same test method as in Example 6.

[0047] Comparative Example 11

[0048] The corrosion inhibition performance of methylbenztriazole was evaluated using the same test method as in Example 6, and the results were compared with those in Examples 7-10.

[0049] The test results of Examples 6-11 are as follows Figure 1 , Figure 2 As shown.

[0050] Example 12

[0051] The nonionic surfactant prepared in Example 1 was added to the coolant at a concentration of 100 ppm. The coolant composition was the same as in Example 6. The conductivity was then measured at 25°C according to ASTM D1125 standard to detect changes in conductivity stability. The experimental results are as follows: Figure 3 As shown.

[0052] Examples 13-16

[0053] The critical micelle concentration (CMC) is a watershed moment when the properties of a surfactant solution undergo a significant change. At low concentrations, the surfactant exists in a molecular state, dispersed in water. As the concentration increases to a certain level, the surfactant molecules immediately combine to form large groups, creating micelles, which then reach equilibrium with the free surfactant molecules. The CMC can be obtained by plotting surface tension against the logarithm of concentration. When surface adsorption reaches saturation, the curve shows an inflection point; the concentration at this point is the critical micelle concentration.

[0054] Therefore, the critical micelle concentration is related to the amount of surfactant used as a corrosion inhibitor. When the amount of surfactant reaches the critical micelle concentration, the corrosion inhibition rate is the maximum. Therefore, the actual amount of corrosion inhibitor used is based on the critical micelle concentration.

[0055] The surface tension of the nonionic surfactants prepared in Examples 1-5 was tested according to GB / T22237, and the test results are as follows: Figure 4 As shown.

[0056] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A nonionic surfactant for use in coolants, characterized in that, The nonionic surfactant is a benzotriazole polyether, having the following structure: Where n is an integer from 5 to 30.

2. The method for preparing a nonionic surfactant for a coolant as described in claim 1, characterized in that, The process includes the following steps: in the presence of trialkylamine, ethylene oxide is introduced to react with methylbenzotriazole melt, and the reaction mixture is refluxed to prepare benzotriazole polyether nonionic surfactant; Trialkylamines are one or a mixture of two or more of trimethylamine, triethylamine, tripropylamine, dimethylethylamine, and diethylmethylamine.

3. The method for preparing a nonionic surfactant for a coolant according to claim 2, characterized in that: The amount of trialkylamine added is 0.01~0.2wt% of the amount of methylbenzotriazole added.

4. The method for preparing a nonionic surfactant for a coolant according to claim 2, characterized in that: Before introducing ethylene oxide, the system temperature is 80~90℃ and the pressure is 11~12kPa.

5. The method for preparing a nonionic surfactant for a coolant according to claim 2, characterized in that: After ethylene oxide is introduced, the system temperature rises to the reflux temperature of 159-168℃, and the reflux reaction time of the mixture is 3-5 hours.

6. The method for preparing a nonionic surfactant for a coolant according to claim 2, characterized in that: After the reflux reaction is complete, the mixture is cooled and flashed off every half hour.

7. The method for preparing a nonionic surfactant for a coolant according to claim 2, characterized in that: After introducing ethylene oxide monomer, the reaction progress was assessed by monitoring the weight gain of the reaction system.

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