A corrosion inhibitor for cooling liquid and a preparation method thereof, and a cooling liquid

Abstract

This application relates to a corrosion inhibitor for coolants, a method for preparing the same, and a coolant. The corrosion inhibitor comprises: 1 wt% to 5 wt% fatty acid, 0.05 wt% to 0.5 wt% aromatic acid, 0.1 wt% to 1.0 wt% benzotriazole derivative, and 0.1 wt% to 1.0 wt% additives. The benzotriazole derivative has the structural formula shown in Formula I below. In Formula I, R1 to R4 are each independently selected from at least one of fluorine, substituted or unsubstituted C1 to C5 alkyl groups. When substituted, the substituent is selected from fluorine. The corrosion inhibitor for coolants provided in this application, comprising a benzotriazole derivative, can form stable coordination bonds with metal ions in the coolant, thereby reducing the flow resistance of the coolant while improving its corrosion inhibition performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cooling liquid corrosion inhibitor, chemical synthesis, in particular to a kind of corrosion inhibitor for cooling liquid and preparation method thereof, cooling liquid. BACKGROUND

[0002] Cooling liquid is mainly used in the pipeline of cooling system. The pipeline and water pump of cooling system are mainly composed of metal parts, and the main metals include cast aluminum, steel, cast iron, red copper, brass, stainless steel and the like. The contact potential between different metals is different, and electrochemical corrosion will occur in the electrolyte formed by cooling liquid. At present, ethylene glycol and propylene glycol are mainly used as anti-icing agents in cooling liquid. Compared with pure water, the high viscosity characteristics of ethylene glycol and propylene glycol will increase the resistance in the system circulation, increase the pump power consumption, reduce the energy efficiency ratio of water pump, and greatly increase the energy consumption of the system. In view of this problem, at present, only a viscosity reducer is added to reduce the viscosity, but this method introduces new substances, which not only increases the difficulty of production process, but also may affect the original performance of the cooling liquid. At the same time, ethylene glycol will be oxidized under high temperature heat load transport conditions, and metal elements will also promote ethylene glycol to be oxidized into glycolic acid and oxalic acid, which will aggravate the corrosion of the cooling system. In order to improve the performance of cooling liquid, corrosion inhibitor is the most important additive in cooling liquid, which plays a role in corrosion prevention, scale prevention, anti-cavitation and the like in the cooling system.

[0003] The existing corrosion inhibitor has poor release effect on cooling liquid, and can easily affect the flow performance of cooling liquid. The corrosion inhibition effect obviously decays with the circulation of cooling liquid. SUMMARY

[0004] In view of the above problems existing in the prior art, the purpose of the present application is to provide a kind of corrosion inhibitor for cooling liquid and preparation method thereof, cooling liquid, which includes benzotriazole derivative, can form stable coordination bond with metal ions in cooling liquid, reduce the flow resistance of cooling liquid, and improve the corrosion inhibition performance of cooling liquid.

[0005] In the first aspect, the present application provides a kind of corrosion inhibitor for cooling liquid, which includes:

[0006] Fatty acid 1wt%~5wt%, aromatic acid 0.05wt%~0.5wt%, benzotriazole derivative 0.1wt%~1.0wt

[0007] %, and auxiliary agent 0.1wt%~1.0wt%, wherein the structure of the benzotriazole derivative is shown in the following formula I:

[0008]

[0009] In formula I, R1-R4 are each independently selected from at least one of fluorine, substituted or unsubstituted C1-C5 alkyl, and when substituted, the substituent is selected from fluorine.

[0010] In some embodiments, the benzotriazole derivative includes at least one of 5-difluoromethyl benzotriazole, 3-bromo-5-trifluoromethyl benzotriazole, 4-bromo-6-trifluoromethyl benzotriazole, and 5-trifluoromethyl benzotriazole.

[0011] In some embodiments, the fatty acid includes at least two of sebacic acid, azelaic acid, dodecanedioic acid, succinic acid, adipic acid, neodecanoic acid, iso-octanoic acid, octanoic acid, and hexanoic acid.

[0012] In some embodiments, the aromatic acid includes at least one of sodium benzoate, sodium citrate, and sodium p-t-butylbenzoate.

[0013] In some embodiments, the auxiliary agent includes at least one of imidazole, imidazoline, and ethanolamine.

[0014] In a second aspect, the present application provides a coolant fluid:

[0015] In some embodiments, the coolant fluid includes the corrosion inhibitor of the first aspect.

[0016] In some embodiments, the coolant fluid further includes a pH adjuster 0.3wt%-5.0wt%, a buffer 0.3wt%-1.0wt%, an antifoaming agent 0.01wt%-0.1wt%, a dyeing agent 100ppm-1200ppm, and water in remainder.

[0017] In some embodiments, the coolant fluid further includes an anti-icing agent 35wt%-55wt%, the anti-icing agent including at least one of ethylene glycol and propylene glycol.

[0018] In some embodiments, the pH adjuster includes at least one of sodium hydroxide and potassium hydroxide.

[0019] In some embodiments, the buffer includes at least one of an organic phosphate and triethanolamine.

[0020] In some embodiments, the antifoaming agent includes at least one of propylene glycol monobutyl ether, ethylene glycol monobutyl ether, and dimethyl t-butyl ether.

[0021] In a third aspect, the present application provides a preparation method of a corrosion inhibitor for a coolant fluid, including the following steps:

[0022] fluorinating an o-phenylenediamine derivative by an electrochemical fluorination process to obtain a fluorine-substituted o-phenylenediamine derivative;

[0023] The fluorine-substituted o-phenylenediamine derivative is mixed with tert-butyl nitrite and a diazotization reaction is carried out to obtain a fluorobenzotriazole derivative;

[0024] According to the first aspect, the fluorobenzotriazole derivative, the fatty acid, the aromatic acid and the auxiliary agent are mixed to obtain the corrosion inhibitor.

[0025] Compared with the prior art, the present application has at least the following beneficial effects:

[0026] The corrosion inhibitor provided by the present application contains a benzotriazole derivative, which can form a stable coordination bond with metal ions in the cooling liquid, especially copper ions and iron-based metal ions, and then alternately form a chain polymer. The polymer deposits on the inner wall of the pipeline to form a multi-layer protective film, preventing the surface of the pipeline from undergoing an oxidation-reduction reaction. The protective film also improves the hydrophobicity of the inner wall of the pipeline, reducing the fluid resistance of the cooling liquid in the pipeline and greatly improving the energy efficiency ratio of the pump. In addition, the corrosion inhibitor applied in the cooling liquid can greatly improve the corrosion inhibition effect and improve the corrosion inhibition performance of the cooling liquid. DETAILED DESCRIPTION

[0027] In order to better understand the technical solutions of the present application, the embodiments of the present application are described in detail below.

[0028] It should be clear that the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0030] It should be understood that the term "and / or" used herein is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents that the front and rear associated objects are in an "or" relationship.

[0031] In a first aspect, the present application provides a corrosion inhibitor for a cooling liquid, which comprises:

[0032] The fatty acid is 1wt%-5wt%, the aromatic acid is 0.05wt%-0.5wt%, and the benzotriazole derivative is 0.1wt%-1.0wt

[0033] %, and 0.1wt% to 1.0wt% of adjuvants, wherein the structural formula of the benzotriazole derivative is shown in Formula I below:

[0034]

[0035] In Formula I, R1 to R4 are each independently selected from at least one of fluorine, substituted or unsubstituted C1 to C5 alkyl groups, and when substituted, the substituent is selected from fluorine.

[0036] The corrosion inhibitor provided in this application for use in coolants contains benzotriazole derivatives. These benzotriazole derivatives can form stable coordination bonds with metal ions in the coolant, particularly copper and iron-based metal ions, thereby alternating to form chain-like polymers. These polymers deposit on the inner wall of the pipe, forming a multi-layered protective film that prevents redox reactions on the pipe surface. This protective film also improves the hydrophobic properties of the pipe's inner wall, reducing fluid resistance and significantly improving the pump's efficiency ratio. Furthermore, this corrosion inhibitor, when applied to coolant, can substantially enhance the corrosion inhibition effect and improve the coolant's corrosion resistance.

[0037] In some embodiments, the C1-C5 alkyl group can be a chain alkyl group, which can be a straight-chain alkyl group or a branched alkyl group, and the hydrogen on the ring of the cyclic alkyl group can be further replaced by an alkyl group. Specific examples include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, and neopentyl.

[0038] The substituents are selected from fluorine atoms and / or bromine atoms.

[0039] In some embodiments, the benzotriazole derivative has a mass percentage of 0.1wt% to 1.0wt%, specifically 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, or 1.0wt%, or other values ​​within the above range, which are not limited here.

[0040] In some embodiments, the benzotriazole derivative includes at least one of 5-difluoromethylbenzotriazole, 3-bromo-5-trifluoromethylbenzotriazole, 4-bromo-6-trifluoromethylbenzotriazole, and 5-trifluoromethylbenzotriazole.

[0041] In some embodiments, the fatty acid has a mass percentage of 1wt% to 5wt%, specifically, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, or other values within the above range, which are not limited herein.

[0042] In some embodiments, the fatty acid includes at least two of sebacic acid, azelaic acid, dodecanedioic acid, succinic acid, adipic acid, neodecanoic acid, iso-octanoic acid, octanoic acid and hexanoic acid.

[0043] In some embodiments, the aromatic acid has a mass percentage of 0.05wt% to 0.5wt%, specifically, 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt% or 0.5wt%, or other values within the above range, which are not limited herein.

[0044] In some embodiments, the aromatic acid includes at least one of sodium benzoate, sodium citrate and sodium p-t-butylbenzoate.

[0045] In some embodiments, the auxiliary agent has a mass percentage of 0.1wt% to 1.0wt%, specifically, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1.0wt%, or other values within the above range, which are not limited herein.

[0046] In some embodiments, the auxiliary agent includes at least one of imidazole, imidazoline and ethanolamine.

[0047] In the second aspect, the application provides a cooling liquid:

[0048] In some embodiments, the cooling liquid includes the corrosion inhibitor of the first aspect.

[0049] In some embodiments, the cooling liquid further includes a pH regulator of 0.3wt% to 5.0wt%, a buffer of 0.3wt% to 1.0wt%, an antifoaming agent of 0.01wt% to 0.1wt%, a dyeing agent of 100ppm to 1200ppm and water in excess.

[0050] In some embodiments, the cooling liquid further includes an anti-icing agent of 35wt% to 55wt%, specifically, 35wt%, 36wt%, 38wt%, 40wt%, 45wt%, 50wt% or 55wt%, etc., which are not limited herein, and the anti-icing agent includes at least one of ethylene glycol and propylene glycol.

[0051] In some embodiments, the pH regulator has a mass percentage of 0.3wt% to 5.0wt%, specifically 0.3wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, or other values within the above range.

[0052] In some embodiments, the pH regulator comprises at least one of sodium hydroxide and potassium hydroxide.

[0053] In some embodiments, the buffer has a mass percentage of 0.3wt% to 1.0wt%, specifically 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1.0wt%, or other values within the above range.

[0054] In some embodiments, the buffer comprises at least one of organic phosphate and triethanolamine.

[0055] The organic phosphate can be aminotri(methylene)phosphonate (ATMP), ethylenediamine tetra(methylene)phosphonate (EDTMP) or hydroxy(methylene)phosphonate (HEDP), without limitation.

[0056] In some embodiments, the defoaming agent has a mass percentage of 0.01wt% to 0.1wt%, specifically 0.01wt%, 0.02wt%, 0.03wt%, 0.04wt%, 0.05wt%, 0.06wt%, 0.07wt%, 0.08wt%, 0.09wt% or 0.1wt%, or other values within the above range.

[0057] In some embodiments, the defoaming agent comprises at least one of propylene glycol butyl ether, ethylene glycol butyl ether and dimethyl tert-butyl ether.

[0058] In some embodiments, the dyeing agent has a content of 100ppm to 1200ppm, specifically 100ppm, 200ppm, 500ppm, 600ppm, 800ppm, 900ppm, 1000ppm, 1100ppm or 1200ppm, without limitation.

[0059] In a third aspect, the present application provides a preparation method of the corrosion inhibitor for cooling liquid, comprising the following steps:

[0060] S10, using an electrochemical fluorination process to fluorinate the o-phenylenediamine derivative to obtain a fluorine-substituted o-phenylenediamine derivative;

[0061] S20, mixing the fluorine-substituted o-phenylenediamine derivative with tert-butyl nitrite and carrying out diazotization reaction to obtain a fluorobenzotriazole derivative;

[0062] S30, mixing the fluorobenzotriazole derivative, the fatty acid, the aromatic acid and the auxiliary agent according to the mass ratio of the first aspect to obtain the corrosion inhibitor.

[0063] In the above scheme, the o-phenylenediamine derivative is first subjected to fluorination treatment by an electrochemical fluorination process, which can realize direct substitution of alkyl or hydrogen on the benzene ring structure of the o-phenylenediamine derivative with fluorine atoms, so that the fluorination treatment is targeted and efficient, and the production efficiency can be improved. The electrochemical fluorination process is controllable and has few side reactions. Then the fluorine-substituted o-phenylenediamine derivative is mixed with tert-butyl nitrite and diazotization reaction is carried out to obtain a fluorobenzotriazole derivative. In the existing direct fluorination method for synthesizing fluorobenzotriazole derivatives, the fluorination active site of the benzotriazole derivative is on the N atom, which leads to the inability to directly fluorinate on the benzene ring structure, resulting in an increase in reaction byproducts and poor yield.

[0064] The preparation method is specifically introduced as follows:

[0065] S10, o-phenylenediamine derivative is subjected to fluorination treatment by an electrochemical fluorination process to obtain a fluorine-substituted o-phenylenediamine derivative.

[0066] A hydrogen fluoride triethylamine solution (ET3N·3HF) containing 1 mol / L of toluene is added to an electrolytic cell device; three matched electrodes are selected (a platinum electrode is selected as a working electrode and an auxiliary electrode, and a platinum wire is immersed in the electrolyte as a reference electrode), an electrolysis device is assembled, the electrolysis atmosphere is high-purity nitrogen, the electrolysis voltage is controlled to be 1.7-2.3 V, the electrolysis time is 7-12 h, and an electrolysis product is obtained after the electrolysis is completed; the electrolysis product is further separated and purified to obtain 5-difluoromethyl o-phenylenediamine.

[0067] The mechanism of the electrofluorination reaction is shown in the following formula II:

[0068]

[0069] Among them, the hydrogen fluoride triethylamine solution (ET3N·3HF) is used as a fluorine source, and high-purity nitrogen is used as the electrolysis atmosphere to prevent the oxidation of the intermediate product generated during the reaction.

[0070] In some embodiments, the electrolysis voltage is 1.7-2.3 V, and specifically can be 1.7 V, 1.75 V, 1.8 V, 1.9 V, 2.0 V, 2.1 V, 2.2 V or 2.3 V, which is not limited herein. Controlling the electrolysis voltage within the above range can effectively inhibit the generation of byproducts. Preferably, the electrolysis voltage is 2 V.

[0071] In some embodiments, the electrolysis time is 7-12h, which can be 7h, 8h, 9h, 10h, 11h or 12h, etc., and is not limited herein. The electrolysis time is controlled within the above range, which is beneficial to improve the yield. Preferably, the electrolysis time is 10h.

[0072] In other embodiments, the toluene raw material can be replaced by ethylbenzene, n-propylbenzene, isopropylbenzene, isobutylbenzene, tert-butylbenzene or isoamylbenzene to prepare different benzotriazole derivatives.

[0073] S20, the fluorine-substituted o-phenylenediamine derivative is mixed with tert-butyl nitrite and a diazotization reaction is carried out to obtain a fluorobenzotriazole derivative.

[0074] The reaction formula for synthesizing fluorobenzotriazole from fluorinated o-phenylenediamine through diazotization reaction is shown as formula III:

[0075]

[0076] In some embodiments, 5-difluoromethyl o-phenylenediamine (1 equiv) and tert-butyl nitrite (1.5 equiv) are added to a reaction tube, deionized water (20 equiv) is added, and stirring is carried out at a reaction temperature of 15℃ for 30 min. After the reaction is completed, a reaction solution is obtained. Then, the reaction solution is cooled and 10 mL of ethyl acetate is added to extract the reaction solution to obtain ethyl acetate containing the extract. The ethyl acetate containing the extract is dried by adding an excess of a drying agent, filtered, and concentrated under reduced pressure to obtain a concentrate. Finally, the concentrate is separated by column chromatography using petroleum ether and ethyl acetate with a volume ratio of 3:1 as the eluent, the eluate is collected, the solvent is rotary evaporated, and a white solid is obtained, i.e. 5-difluoromethyl benzotriazole.

[0077] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

[0078] First, synthesis of benzotriazole derivatives

[0079] Benzotriazole derivative 1: 5-difluoromethyl benzotriazole

[0080] (1) Electrolyte of hydrogen fluoride triethylamine solution (ET3N-3HF) containing 1 mol / L of toluene is added to an electrolytic cell device; three matched electrodes are selected (a platinum electrode is selected as a working electrode and an auxiliary electrode, and a platinum wire is immersed in the electrolyte as a reference electrode), an electrolysis device is assembled, and the electrolysis atmosphere is high-purity nitrogen; the electrolysis voltage is controlled to be 2.0 V, the electrolysis time is 10 h, and the electrolysis product is obtained after electrolysis; and the electrolysis product is further separated and purified to obtain 5-difluoromethyl o-phenylenediamine.

[0081] (2) 5-difluoromethyl o-phenylenediamine (1 equiv), tert-butyl nitrite (1.5 equiv), and deionized water (20 equiv) are added to a reaction tube, stirred at a reaction temperature of 15°C for 30 min, and then cooled to obtain a reaction liquid; then 10 mL of ethyl acetate is added to the reaction liquid to extract the ethyl acetate containing the extract; the ethyl acetate containing the extract is dried by adding excess anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to obtain a concentrate; and finally, the concentrate is separated by column chromatography with petroleum ether and ethyl acetate in a volume ratio of 3:1 as the eluent, the eluate is collected, the solvent is rotary evaporated, and a white solid is obtained, i.e. 5-difluoromethyl benzotriazole is obtained.

[0082] Benzotriazole derivative 2: 3-bromo-5-trifluoromethyl benzotriazole

[0083] At room temperature, 3-bromo-5-trifluoromethyl o-phenylenediamine (1 equiv), tert-butyl nitrite (1.5 equiv), and water (20 equiv) are added to a reaction tube, stirred at a reaction temperature of 5°C for 30 min, and then cooled to obtain a reaction liquid; then 10 mL of ethyl acetate is added to the reaction liquid to extract the ethyl acetate containing the extract; the ethyl acetate containing the extract is dried by adding excess anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to obtain a concentrate; and finally, the concentrate is separated by column chromatography with petroleum ether and ethyl acetate in a volume ratio of 3:1 as the eluent, the eluate is collected, the solvent is rotary evaporated, and a white solid is obtained, i.e. 3-bromo-5-trifluoromethyl benzotriazole is obtained.

[0084] Benzotriazole derivative 3: 5-methyl benzotriazole

[0085] At room temperature, 5-methyl-ortho-phenylenediamine (1 equiv), tert-butyl nitrite (1.5 equiv) were added into a reaction tube, water (20 equiv) was added, stirred at 5 °C reaction temperature for 30 min, after the reaction was completed to obtain the reaction liquid; then the reaction liquid was cooled and extracted with 10 ml ethyl acetate to obtain ethyl acetate containing extract; then the ethyl acetate containing extract was dried by adding excess anhydrous sodium sulfate, filtered, concentrated under reduced pressure to obtain a concentrate; finally the concentrate was separated by column chromatography, with petroleum ether and ethyl acetate volume ratio of 3:1 as eluent, the eluent was collected, the solvent was rotary evaporated to obtain white solid, i.e. 5-methylbenzotriazole was obtained.

[0086] Benzotriazole derivative 4: 3-bromo-methylbenzotriazole

[0087] At room temperature, 3-bromo-methyl-ortho-phenylenediamine (1 equiv), tert-butyl nitrite (1.5 equiv) were added into a reaction tube, water (20 equiv) was added, stirred at 5 °C reaction temperature for 30 min, after the reaction was completed to obtain the reaction liquid; then the reaction liquid was cooled and extracted with 10 ml ethyl acetate to obtain ethyl acetate containing extract; then the ethyl acetate containing extract was dried by adding excess anhydrous sodium sulfate, filtered, concentrated under reduced pressure to obtain a concentrate; finally the concentrate was separated by column chromatography, with petroleum ether and ethyl acetate volume ratio of 3:1 as eluent, the eluent was collected, the solvent was rotary evaporated to obtain white solid, i.e. 3-bromo-methylbenzotriazole was obtained.

[0088] Preparation of cooling liquid

[0089] First step: prepare the corrosion inhibitors of examples 1-6 and the corrosion inhibitors of comparative examples 1-6 according to the corrosion inhibitor formula shown in table 1.

[0090] Table 1: Corrosion inhibitor formula (in mass percentage)

[0091]

[0092]

[0093] Second step: 1) According to the test solution configuration requirements of GBT-29743 standard, four identical mixed solutions containing 100 ppm of chloride ions, sulfate ions and bicarbonate ions were prepared, then the corrosion inhibitors prepared by examples 1, comparative example 1, example 4 and comparative example 4 were added respectively, and the pH was adjusted to 8.50 with sodium hydroxide, to obtain the full water-based cooling liquid of examples 1 and 4, and the full water-based cooling liquid of comparative examples 1 and 4.

[0094] 2) According to the test solution preparation requirements of GBT-29743 standard, four identical mixed solutions containing 55% ethylene glycol aqueous solution containing 100 ppm of chloride ions, sulfate ions and bicarbonate ions were prepared, then the corrosion inhibitors prepared by example 2, comparative example 2, example 5 and comparative example 5 were added respectively, and the pH was adjusted to 8.50 with sodium hydroxide, to obtain 55% ethylene glycol coolant of example 2, 5, 55% ethylene glycol coolant of comparative example 2, 5 respectively.

[0095] 3) According to the test solution preparation requirements of GBT-29743 standard, four identical mixed solutions containing 55% propylene glycol aqueous solution containing 100 ppm of chloride ions, sulfate ions and bicarbonate ions were prepared, then the corrosion inhibitors prepared by example 3, comparative example 3, example 6 and comparative example 6 were added respectively, and the pH was adjusted to 8.50 with sodium hydroxide, to obtain 55% propylene glycol coolant of example 3, 6, 55% propylene glycol coolant of comparative example 3, 6 respectively.

[0096] Performance test:

[0097] After the preparation of the corresponding coolant, the coolant of example 1 and comparative example 1, the coolant of example 2 and comparative example 2, the coolant of example 3 and comparative example 3, the coolant of example 4 and comparative example 4, the coolant of example 5 and comparative example 5, the coolant of example 6 and comparative example 6 were respectively run under the same working conditions, the pressure in the system pipeline and the energy efficiency ratio of the water pump were measured, and the experimental results were shown in table 2.

[0098] Secondly, the coolant of each group of examples and comparative examples was respectively subjected to electrochemical test on red copper (C1100) metal sheet, the corrosion potential and corrosion current of C1100 red copper were measured according to Tafel test, and the corrosion efficiency of the coolant on copper was obtained according to calculation conversion, and the experimental results were shown in table 2.

[0099] Table 2 performance test results of examples and comparative examples

[0100]

[0101] Comparing the test data of Example 1 and Comparative Example 1 in Table 2, the corrosion inhibitor in Example 1 is 5-difluoromethylbenzotriazole, and the corrosion inhibitor in Comparative Example 1 is 5-methylbenzotriazole. The addition of the corrosion inhibitor in Example 1 can reduce the pressure in the system pipeline by 5% compared to Comparative Example 1, and the energy efficiency ratio of the water pump does not change significantly, both remaining within 80% ± 5%. The addition of the corrosion inhibitor in Example 1 makes the corrosion potential change value of the coolant less than 50 mV compared to Comparative Example 1, and the corrosion current of the coolant in Example 1 is slightly lower than that in Comparative Example 1. According to the corrosion rate = (corrosion current of Comparative Example 1 - corrosion current of Example 1) / corrosion current of Comparative Example 1 * 100%, it is calculated that the corrosion efficiency of the coolant in Example 1 on copper is about 5% higher than that in Comparative Example 1.

[0102] Comparing the test data of Example 4 and Comparative Example 4 in Table 2, the corrosion inhibitor in Example 4 is 3-bromo-5-trifluoromethylbenzotriazole, and the corrosion inhibitor in Comparative Example 4 is 3-bromo-methylbenzotriazole. The addition of the corrosion inhibitor in Example 4 can reduce the pressure in the system pipeline by 5% compared to Comparative Example 4, and the energy efficiency ratio of the water pump does not change significantly, both remaining within 80% ± 5%. The addition of the corrosion inhibitor in Example 4 makes the corrosion potential change value of the coolant less than 50 mV compared to Comparative Example 4, and the corrosion current of the coolant in Example 4 is slightly lower than that in Comparative Example 4. According to the corrosion rate = (corrosion current of Comparative Example 4 - corrosion current of Example 4) / corrosion current of Comparative Example 4 * 100%, it is calculated that the corrosion efficiency of the coolant in Example 4 on copper is about 5% higher than that in Comparative Example 4.

[0103] Comparing the test data of Example 2 and Comparative Example 2 in Table 2, the corrosion inhibitor in Example 2 is 5-difluoromethylbenzotriazole, and the corrosion inhibitor in Comparative Example 2 is 5-methylbenzotriazole. The addition of the corrosion inhibitor in Example 2 can reduce the pressure in the system pipeline by 20% compared to Comparative Example 2, and the energy efficiency ratio of the water pump increases from 50% in Comparative Example 2 to 65% in Example 2. The addition of the corrosion inhibitor in Example 2 makes the corrosion potential change value of the coolant less than 50 mV compared to Comparative Example 2, and the corrosion current of the coolant in Example 2 is slightly lower than that in Comparative Example 2. According to the corrosion rate = (corrosion current of Comparative Example 2 - corrosion current of Example 2) / corrosion current of Comparative Example 2 * 100%, it is calculated that the corrosion efficiency of the coolant in Example 2 on copper is about 5% higher than that in Comparative Example 2.

[0104] Comparing the test data of Example 5 and Comparative Example 5 in Table 2, the corrosion inhibitor in Example 5 is 3-bromo-5-trifluoromethylbenzotriazole, and the corrosion inhibitor in Comparative Example 5 is 3-bromo-methylbenzotriazole with the same dosage. The addition of the corrosion inhibitor in Example 5 can reduce the pressure in the system pipeline by 20% compared with Comparative Example 5, and at the same time, the energy efficiency ratio of the water pump is increased from 55% in Comparative Example 5 to 70% in Example 5. The change in the corrosion potential of the coolant in Example 5 is less than 50 mV compared with Comparative Example 5, and the corrosion current of the coolant in Example 5 is slightly lower than that in Comparative Example 5. According to the corrosion rate = (corrosion current of Comparative Example 5 - corrosion current of Example 5) / corrosion current of Comparative Example 5 * 100%, it is calculated that the corrosion efficiency of the coolant in Example 5 on copper is increased by about 2% compared with Comparative Example 5.

[0105] Comparing the test data of Example 3 and Comparative Example 3 in Table 2, the corrosion inhibitor in Example 3 is 5-difluoromethylbenzotriazole, and the corrosion inhibitor in Comparative Example 3 is 5-methylbenzotriazole with the same dosage. The addition of the corrosion inhibitor in Example 3 can reduce the pressure in the system pipeline by 25% compared with Comparative Example 3, and at the same time, the energy efficiency ratio of the water pump is increased from 40% in Comparative Example 3 to 65% in Example 3. The change in the corrosion potential of the coolant in Example 3 is less than 50 mV compared with Comparative Example 3, and the corrosion current of the coolant in Example 3 is slightly lower than that in Comparative Example 3. According to the corrosion rate = (corrosion current of Comparative Example 3 - corrosion current of Example 3) / corrosion current of Comparative Example 3 * 100%, it is calculated that the corrosion efficiency of the coolant in Example 3 on copper is reduced by about 3% compared with Comparative Example 3.

[0106] Comparing the test data of Example 6 and Comparative Example 6 in Table 2, the corrosion inhibitor in Example 6 is 3-bromo-5-trifluoromethylbenzotriazole, and the corrosion inhibitor in Comparative Example 6 is 3-bromo-methylbenzotriazole with the same dosage. The addition of the corrosion inhibitor in Example 6 can reduce the pressure in the system pipeline by 30% compared with Comparative Example 6, and at the same time, the energy efficiency ratio of the water pump is increased from 50% in Comparative Example 6 to 65% in Example 6. The change in the corrosion potential of the coolant in Example 6 is less than 50 mV compared with Comparative Example 6, and the corrosion current of the coolant in Example 6 is slightly lower than that in Comparative Example 6. According to the corrosion rate = (corrosion current of Comparative Example 6 - corrosion current of Example 6) / corrosion current of Comparative Example 6 * 100%, it is calculated that the corrosion efficiency of the coolant in Example 6 on copper is reduced by about 4% compared with Comparative Example 6.

Claims

1. A corrosion inhibitor for coolant, characterized in that, Based on the mass fraction of the coolant, the corrosion inhibitor in the coolant comprises: 1 wt% to 5 wt% fatty acids, 0.05 wt% to 0.5 wt% aromatic acids, 0.1 wt% to 1.0 wt% benzotriazole derivatives, and 0.1 wt% to 1.0 wt% additives. The benzotriazole derivatives include at least one of 5-difluoromethylbenzotriazole, 3-bromo-5-trifluoromethylbenzotriazole, 4-bromo-6-trifluoromethylbenzotriazole, and 5-trifluoromethylbenzotriazole; The fatty acids include at least two of sebacic acid, azelaic acid, dodecanoic acid, succinic acid, adipic acid, neodecanoic acid, isooctanoic acid, octanoic acid, and hexanoic acid; The aromatic acid includes at least one of sodium benzoate, sodium citrate, and sodium p-tert-butylbenzoate.

2. The corrosion inhibitor according to claim 1, characterized in that, The adjuvant includes at least one of imidazole, imidazoline, and ethanolamine.

3. A coolant, characterized in that, Includes the corrosion inhibitor as described in any one of claims 1-2.

4. The coolant according to claim 3, characterized in that, The coolant also includes a pH adjuster of 0.3 wt% to 5.0 wt%, a buffer of 0.3 wt% to 1.0 wt%, an antifoamer of 0.01 wt% to 0.1 wt%, a dye of 100 ppm to 1200 ppm, and water as the remainder.

5. The coolant according to claim 3, characterized in that, The coolant also includes 35wt% to 55wt% of an anti-icing agent, which includes at least one of ethylene glycol and propylene glycol.

6. The coolant according to claim 4, characterized in that, The coolant includes at least one of the following characteristics (1) to (3): (1) The pH adjuster includes at least one of sodium hydroxide and potassium hydroxide; (2) The buffer includes at least one of an organophosphate and triethanolamine; (3) The defoamer includes at least one of propylene glycol butyl ether, ethylene glycol butyl ether and dimethyl tert-butyl ether.

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