Cooling fluid compositions, methods of making and using the same

Abstract

This invention discloses a coolant composition, its preparation method, and its application. The coolant composition comprises a base liquid and a diphenylamine compound represented by Formula I. The base liquid comprises water and ethylene glycol. Based on the weight of the base liquid, the amount of the diphenylamine compound is about 10 to about 1000 ppm. In Formula I, R1 and R2 are each independently hydrogen or C1-C12 hydrocarbon groups. The coolant composition of this invention has improved antioxidant properties.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering, and relates to coolant compositions, their preparation methods and applications, and specifically to coolants based on ethylene glycol and water, their preparation methods and applications. Background Technology

[0002] Coolants such as fuel cell coolant (FC coolant) and engine coolant typically use water and ethylene glycol as base fluids. Such base fluids will deteriorate due to acidification when operating at high temperatures for a long time.

[0003] The advantages and disadvantages of water and ethylene glycol as base fluids for coolants are as follows: Water has excellent specific heat and viscosity, but poor freeze resistance; ethylene glycol has excellent viscosity and melting point, making it an excellent base material.

[0004] In coolants based on ethylene glycol and water, ethylene glycol (EG) undergoes oxidation during use. Depending on the conditions, the oxidation products of ethylene glycol can include aldehydes, ketones, acids, and dioxanes, and the amount of these decomposition products increases with temperature, time, and the presence of metal catalysts such as copper, aluminum, and iron. The primary thermal oxidation product of ethylene glycol is glycolic acid, with oxalic acid as the final product, which is highly corrosive to the system. This process is also accompanied by a decrease in pH, color change, and the development of an unpleasant odor.

[0005] Methods to inhibit EC oxidation mainly include: (1) scavenging free radicals to inhibit the reaction process; (2) lowering the ambient temperature; and (3) removing dissolved oxygen. Methods (2) and (3) depend on the system environment, therefore, antioxidants with free radical scavenging and deoxygenation effects are usually used.

[0006] The type and amount of antioxidants can both affect the results. For example, US Patent 8187763B discloses a coolant composition comprising an alkyl alcohol containing an unsaturated bond, such as 2-buten-1-ol, 3-buten-1-ol, 4-penten-1-ol, 3-hexyn-2,5-diol, or other C2-C20 alkyl alcohols, at a content of 0.01 to 15 parts by weight per 100 parts by weight of the base component, thereby maintaining low electrical conductivity.

[0007] In addition, sodium hydroxide or potassium hydroxide is usually added to engine coolant to raise its pH value, neutralizing the acid produced by ethylene glycol oxidation and mitigating the corrosion problem caused by the coolant. However, this approach is limited by pH value and reserve alkalinity.

[0008] Therefore, it is still necessary to provide a coolant with high antioxidant properties. Summary of the Invention

[0009] In view of this, the purpose of this invention is to address the shortcomings of the prior art by providing a coolant composition, its preparation method, and its application. The coolant composition of this invention has improved antioxidant properties.

[0010] The objective of this invention is achieved through the following technical solutions.

[0011] In a first aspect, the present invention provides a coolant composition comprising a base liquid and a diphenylamine compound of Formula I, wherein the base liquid comprises water and ethylene glycol, and the amount of the diphenylamine compound is about 10 to about 1000 ppm based on the weight of the base liquid;

[0012]

[0013] In Formula I, R1 and R2 are each independently hydrogen or C1-C12 hydrocarbon groups.

[0014] The inventors of this application have discovered that by adding diphenylamine compounds to a base liquid comprising water and ethylene glycol, the diphenylamine compounds are dispersed in the base liquid, thereby obtaining a coolant composition that exhibits excellent antioxidant properties.

[0015] According to the coolant composition provided by the present invention, the present invention does not impose any particular limitation on the volume ratio of water to ethylene glycol in the base fluid, which can be determined according to the specific application of the coolant composition. In some embodiments, the volume ratio of water to ethylene glycol in the base fluid is about 9:1 to about 1:9. For example, the volume ratio of water to ethylene glycol in the base fluid can be about 9:1, about 8:2, about 7:3, about 6:4, about 5:5, about 4:6, about 3:7, about 2:8, about 1:9, or a range thereof.

[0016] According to the coolant composition provided by the present invention, in Formula I, R1 and R2 may be the same or different, each independently being hydrogen or a C1-C12 alkyl group. In some embodiments, each independently being hydrogen or a C1-C8 alkyl group. Examples of C1-C8 alkyl groups suitable for use in the present invention include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl. In some specific embodiments, the diphenylamine compound is octylbutyldiphenylamine (68411-46-1).

[0017] According to the coolant composition provided by the present invention, the positions of R1 and R2 are not particularly required. For example, R1 is located on carbon at positions 2, 3, 4, 5, or 6, and R2 is located on carbon at positions 2', 3', 4', 5', or 6'.

[0018] In this invention, the diphenylamine compound can be prepared in-house or commercially available. For example, IRGANOX L57 antioxidant purchased from BASF can be used.

[0019] According to the coolant composition provided by the present invention, the amount of the diphenylamine compound is from about 10 to about 1000 ppm based on the weight of the base liquid. For example, the amount of the diphenylamine compound, based on the weight of the base liquid, can be from about 10 ppm, about 20 ppm, about 50 ppm, about 80 ppm, about 100 ppm, about 150 ppm, about 200 ppm, about 300 ppm, about 400 ppm, about 500 ppm, about 600 ppm, about 700 ppm, about 800 ppm, about 900 ppm, about 1000 ppm, or a range thereof. In some preferred embodiments, the amount of the diphenylamine compound is from about 50 ppm to about 500 ppm based on the weight of the base liquid; in some preferred embodiments, it is from about 80 ppm to about 500 ppm; and in some preferred embodiments, it is from about 100 ppm to about 200 ppm.

[0020] According to the coolant composition provided by the present invention, the coolant composition has an oxidation induction period of about 17.5 min or more, preferably about 20 min or more, at 150°C, as measured according to ASTM D5483.

[0021] According to the coolant composition provided by the present invention, the coolant composition may further include additional additives. The additional additives are selected from at least one of inorganic salt additives, organic carboxylates, non-metallic ion inhibitors, and pH adjusters.

[0022] Examples of inorganic salt additives or organic carboxylates suitable for use in this invention include, but are not limited to: sodium silicate, trisodium phosphate, sebacic acid, and isooctanoic acid.

[0023] Examples of pH adjusters suitable for use in this invention include, but are not limited to, sodium hydroxide and potassium hydroxide.

[0024] This invention does not impose any particular limitation on the amount of other additives such as inorganic salt additives, organic carboxylates, and pH adjusters, and conventional amounts used in the art can be adopted. For example, the amount of inorganic salt additives and organic carboxylates added can typically be about 0.01 to 3% by weight, and their main function is to prevent metal corrosion.

[0025] In a second aspect, the present invention provides a method for preparing a coolant composition, wherein the preparation method includes the following steps: adding a diphenylamine compound to a base liquid and mixing to obtain a coolant composition.

[0026] In some specific embodiments, diphenylamine compounds are dispersed in the base liquid to obtain a coolant composition.

[0027] According to the preparation method provided by the present invention, a coolant composition can be prepared by adding a diphenylamine compound to a base liquid comprising water and ethylene glycol.

[0028] Thirdly, the present invention provides the application of the above-mentioned diphenylamine compounds in improving the oxidation resistance of coolants, wherein the amount of the diphenylamine compounds is preferably about 10 to about 1000 ppm, more preferably about 50 ppm to about 500 ppm, further preferably about 80 ppm to about 500 ppm, and most preferably about 100 ppm to about 200 ppm.

[0029] Fourthly, the present invention provides the application of coolant compositions in fuel cells or engines, such as internal combustion engines.

[0030] Fifthly, the present invention provides a fuel cell unit, wherein the fuel cell unit includes a fuel cell stack and a cooling system, the cooling system including a coolant composition.

[0031] In this invention, the coolant composition is used as an internal circulating coolant in the cooling system to cool it.

[0032] This invention has the following advantages:

[0033] (1) The coolant composition of the present invention has improved antioxidant properties and can increase service life by more than 25%, making it suitable for both traditional engines (such as internal combustion engines) and fuel cells, with a wide range of applications. For example, in Example 1, the oxidation induction period of the coolant composition was increased from 15 minutes to 21.4 minutes. For pure electric vehicles (fuel cells), based on an expected service life of 10 years, the coolant composition of the present invention can increase this to 14.3 years, demonstrating a significant effect. Simultaneously, the coolant composition of the present invention exhibits good corrosion resistance and excellent overall performance.

[0034] (2) The diphenylamine compounds used in the coolant composition of the present invention are nonionic antioxidants. Their use will not affect the conductivity of the coolant composition and can meet the requirements of fuel cells and other devices for low conductivity of coolant. Detailed Implementation

[0035] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0036] Oxidation induction period

[0037] The oxidation induction period of the coolant composition at 150°C was measured using high-pressure differential scanning calorimetry (PDSC) according to ASTM D5483.

[0038] Example 1

[0039] 100 ppm of IRGANOX L57 antioxidant (purchased from BASF) was added to a base solution composed of water and ethylene glycol, and the mixture was dispersed to obtain a coolant composition. The volume ratio of water to ethylene glycol in the base solution was 1:1.

[0040] The oxidation induction period of the coolant composition of Example 1 was measured, and the results are shown in Table 1.

[0041] Example 2

[0042] 200 ppm of IRGANOX L57 antioxidant (purchased from BASF) was added to a base solution composed of water and ethylene glycol, and the mixture was dispersed to obtain a coolant composition. The volume ratio of water to ethylene glycol in the base solution was 1:1.

[0043] The oxidation induction period of the coolant composition of Example 2 was measured, and the results are shown in Table 1.

[0044] Example 3

[0045] An antioxidant of 80 ppm (purchased from BASF) was added to a base solution composed of water and ethylene glycol, and the mixture was dispersed to obtain a coolant composition. The volume ratio of water to ethylene glycol in the base solution was 1:1.

[0046] The oxidation induction period of the coolant composition of Example 3 was measured, and the results are shown in Table 1.

[0047] Example 4

[0048] 500 ppm of IRGANOX L57 antioxidant (purchased from BASF) was added to a base solution composed of water and ethylene glycol, and the mixture was dispersed to obtain a coolant composition. The volume ratio of water to ethylene glycol in the base solution was 1:1.

[0049] The oxidation induction period of the coolant composition of Example 4 was measured, and the results are shown in Table 1.

[0050] Example 5

[0051] 1000 ppm of IRGANOX L57 antioxidant (purchased from BASF) was added to a base solution composed of water and ethylene glycol, and the mixture was dispersed to obtain a coolant composition. The volume ratio of water to ethylene glycol in the base solution was 1:1.

[0052] The oxidation induction period of the coolant composition of Example 5 was measured, and the results are shown in Table 1.

[0053] Example 6

[0054] An antioxidant, 1% by weight of BASF's IRGANOXL57, was added to a base liquid composed of water and ethylene glycol, and the mixture was dispersed to obtain a coolant composition. The volume ratio of water to ethylene glycol in the base liquid was 1:1.

[0055] The coolant composition was observed to be incompletely dissolved by IRGANOX L57 antioxidant. The oxidation induction period of the coolant composition in Example 6 was measured, and the results are shown in Table 1.

[0056] Example 7

[0057] 100 ppm of IRGANOX L57 antioxidant (purchased from BASF) was added to a base solution composed of water and ethylene glycol, and the mixture was dispersed to obtain a coolant composition. The volume ratio of water to ethylene glycol in the base solution was 7:3.

[0058] The oxidation induction period of the coolant composition of Example 7 was measured, and the results are shown in Table 1.

[0059] Example 8

[0060] 100 ppm of IRGANOX L57 antioxidant (purchased from BASF) was added to a base solution composed of water and ethylene glycol, and the mixture was dispersed to obtain a coolant composition. The volume ratio of water to ethylene glycol in the base solution was 3:7.

[0061] The oxidation induction period of the coolant composition of Example 8 was measured, and the results are shown in Table 1.

[0062] Example 9

[0063] 100 ppm of diphenylamine was added to a base solution composed of water and ethylene glycol, and the mixture was dispersed to obtain a cooling liquid composition. The volume ratio of water to ethylene glycol in the base solution was 1:1.

[0064] The oxidation induction period of the coolant composition of Example 9 was measured, and the results are shown in Table 1.

[0065] Comparative Example 1

[0066] The formulation of the coolant composition is basically the same as that in Example 1, except that the amount of IRGANOX L57 antioxidant is 0.

[0067] Comparative Example 2

[0068] The oxidation induction period of the coolant composition prepared by replacing the IRGANOX L57 antioxidant in Example 1 with triethanolamine is shown in Table 1.

[0069] Comparative Example 3

[0070] The oxidation induction period of the prepared coolant composition was shown in Table 1, using Irgamet 42 (a methyltriazole derivative) purchased from BASF instead of the IRGANOXL57 antioxidant in Example 1.

[0071] Comparative Example 4

[0072] The oxidation induction period of the prepared coolant composition was shown in Table 1, using 2,6-di-tert-butyl-p-methylphenol (antioxidant 264) instead of the IRGANOX L57 antioxidant in Example 1.

[0073] Table 1 Oxidation induction period of coolant composition

[0074] Base liquid (volume ratio) antioxidants Oxidation induction period (min) Example 1 Water: Ethylene glycol, 1:1 IRGANOX L57, 100ppm 21.4 Example 2 Water: Ethylene glycol, 1:1 IRGANOX L57, 200ppm 23.6 Example 3 Water: Ethylene glycol, 1:1 IRGANOX L57, 80ppm 19.5 Example 4 Water: Ethylene glycol, 1:1 IRGANOX L57, 500ppm 25.6 Example 5 Water: Ethylene glycol, 1:1 IRGANOX L57, 1000ppm 26.3 Example 6 Water: Ethylene glycol, 1:1 IRGANOX L57, 1% by weight 25.9 Example 7 Water: Ethylene glycol, 7:3 IRGANOX L57, 100ppm 23.4 Example 8 Water: Ethylene glycol, 3:7 IRGANOX L57, 100ppm 20.5 Example 9 Water: Ethylene glycol, 1:1 Diphenylamine, 100 ppm 20.7 Comparative Example 1 Water: Ethylene glycol, 1:1 -- 15.0 Comparative Example 2 Water: Ethylene glycol, 1:1 Triethanolamine, 100 ppm 15.2 Comparative Example 3 Water: Ethylene glycol, 1:1 Irgamet 42, 100ppm 15.4 Comparative Example 4 Water: Ethylene glycol, 1:1 Antioxidant 264, 100ppm 17.1

[0075] As shown in Table 1, the coolant composition of the present invention exhibits excellent antioxidant properties. In particular, it can be observed from Examples 1-6 and Comparative Example 1 that the antioxidant properties increase with increasing dosage of diphenylamine compounds.

[0076] Application Examples 1-6

[0077] A coolant composition was prepared using Great Wall FD-2 coolant (an engine coolant based on water and ethylene glycol) and IRGANOX L57 antioxidant. The formula is shown in Table 2.

[0078] The coolant corrosion test was conducted according to test cases 1-6 of ASTM D 1384 "Test Method for Corrosion of Engine Coolant in Glassware"; the metal samples were as follows: steel UNS G10200 (SAE 1020), copper UNS C11000 (SAE CA110), brass Alloy UNS C26000 (SAE CA260), cast iron Alloy UNS F10007 (SAEG3500), cast aluminum Alloy UNS A23190 (SAE 329), and solder (brass coated with Alloy Grade 30A (SAE 3A) solder). The temperature was 88°C and the time was 1076 hours. No corrosive water was added.

[0079] In addition, the corrosion performance of Great Wall FD-2 coolant without the addition of IRGANOX L57 antioxidant was measured as a control example.

[0080] The corrosion properties of the coolant compositions in Application Examples 1-6 and the control examples are shown in Table 2.

[0081] Table 2 Corrosion properties

[0082]

[0083] As shown in Table 2, the coolant composition of the present invention has improved corrosion resistance. From Application Examples 1-6 and the Comparative Examples, it can be seen that the amount of diphenylamine compound used is 80 ppm to 500 ppm. With increasing amount of diphenylamine compound, the corrosivity of the coolant composition increases slightly; however, when the amount of diphenylamine compound exceeds 1000 ppm, the corrosivity increases significantly.

[0084] Therefore, in the coolant composition of the present invention, the amount of diphenylamine compound is 80ppm to 500ppm, especially 100ppm to 200ppm, which results in excellent overall performance.

[0085] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A coolant composition, characterized in that, The coolant composition consists of a base liquid and a diphenylamine compound represented by Formula I. The base liquid comprises water and ethylene glycol in a volume ratio of 3:7 to 7:

3. Based on the weight of the base liquid, the amount of the diphenylamine compound is 80-200 ppm. I In Formula I, R1 and R2 are both hydrogen, or R1 is octyl and R2 is butyl.

2. The coolant composition according to claim 1, characterized in that, Based on the weight of the base liquid, the amount of the diphenylamine compound used is 100 ppm to 200 ppm.

3. The coolant composition according to claim 1 or 2, characterized in that, According to ASTM D5483, the oxidation induction period of the coolant composition at 150°C is greater than 20 minutes.

4. The method for preparing the coolant composition according to any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: adding diphenylamine compounds to a base liquid and mixing them to obtain a cooling liquid composition.

5. The use of the coolant composition according to any one of claims 1 to 3 in a fuel cell or engine.

6. The application according to claim 5, characterized in that, The engine includes an internal combustion engine.

7. A fuel cell unit, characterized in that, The fuel cell unit includes a fuel cell stack and a cooling system, the cooling system comprising the coolant composition of any one of claims 1 to 3.

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