Isopropanolamine-alkyl acylamino acid proton-type ionic liquid, preparation method and application thereof

Abstract

The present invention provides a kind of isopropanolamine alkyl acyl amino acid proton type ionic liquid and its preparation method and application, belong to the technical field of lubricating additives. The present invention uses isopropanolamine compounds as cations and alkyl acyl amino acids as anions. There are lone pairs of electrons on the nitrogen atoms in the molecular structure of the isopropanolamine compounds, which have certain weak alkalinity, while the carboxyl group in the molecular structure of the alkyl acyl amino acids has certain acidity. The two synthesize amino acid proton type ionic liquids through a simple proton exchange reaction. The active nitrogen element in the ionic liquid molecular structure can undergo tribochemical reaction with the friction pair to generate a tribochemical reaction film, which can not only improve the friction reduction and anti-wear performance of the water-based lubricant, but also greatly improve its extreme pressure performance. The isopropanolamine compounds make the ionic liquid have good solubility in water, and the carboxylic acid ions can be effectively adsorbed on the metal friction pair to form a firm adsorption film, providing good lubrication performance and corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating additives, and in particular to an isopropanolamine-alkyl acylamino acid proton type ionic liquid, a preparation method thereof, and an application thereof. Background Art

[0002] Friction and wear are major causes of mechanical equipment failure. The proper use of lubricants is an effective means of reducing friction and controlling wear. Currently, oil-based lubricants are widely used across various industrial sectors due to their excellent lubrication properties, significantly reducing friction and energy loss, improving productivity, and extending machine life. However, mineral oils exhibit poor degradation properties, and leakage or release into the environment inevitably causes serious environmental pollution. Furthermore, the increasing scarcity of petroleum resources has led to increasing costs for oil-based lubricants. Therefore, the search for alternatives to mineral oil lubricants has become a research hotspot in the field of tribology.

[0003] Compared to mineral oil lubricants, water-based lubricants have attracted widespread attention due to their outstanding features, such as being environmentally friendly, flame-retardant, safe to operate, and effective cleaning. However, the currently widely used water-based lubricants, which use fatty acid salts or fatty acid esters as lubricant additives, suffer from poor lubrication performance, low viscosity, poor stability, and poor corrosion resistance, which seriously restricts the development of water-based lubrication systems. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide an isopropanolamine-alkyl acyl amino acid proton type ionic liquid and its preparation method and application. The isopropanolamine-alkyl acyl amino acid proton type ionic liquid provided by the present invention is used as a water-based lubricant additive and has good friction reduction, anti-wear and corrosion resistance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an isopropanolamine-alkyl acylamino acid proton type ionic liquid, the general structural formula of which is A + B - , where A + represents an organic cation, B - represents an organic anion;

[0007] The organic cation is an isopropanolamine compound cation, and the organic anion is an alkyl acylamino acid anion.

[0008] Preferably, the isopropanolamine compound cation has a structure shown in any one of Formula I to Formula III:

[0009]

[0010] Preferably, the alkyl acylamino acid anion has a structure shown in Formula IV:

[0011]

[0012] In formula IV, n is any integer from 2 to 11;

[0013] R1 is hydrogen or methyl;

[0014] R is hydrogen, methyl, One of them.

[0015] Preferably, the alkyl acylamino acid anion is one or more of lauroyl glutamate anion, lauroyl sarcosine anion, lauroyl glycine anion, lauroyl aspartic acid anion, lauroyl alanine anion, octanoyl glutamate anion, octanoyl sarcosine anion, octanoyl glycine anion, octanoyl aspartic acid anion and octanoyl alanine anion.

[0016] The present invention provides a method for preparing the above-mentioned isopropanolamine-alkyl acylamino acid proton-type ionic liquid, comprising the following steps:

[0017] The isopropanolamine compound, the alkyl acyl amino acid compound and water are mixed to perform a proton exchange reaction to obtain an isopropanolamine-alkyl acyl amino acid proton type ionic liquid aqueous solution;

[0018] The water content of the isopropanolamine-alkyl acylamino acid proton type ionic liquid aqueous solution is removed to obtain the isopropanolamine-alkyl acylamino acid proton type ionic liquid.

[0019] Preferably, the molar ratio of the amine group of the isopropanolamine compound to the carboxyl group of the alkyl acylamino acid compound is 1:1;

[0020] The mass content of the isopropanolamine-alkylacylamino acid proton type ionic liquid in the isopropanolamine-alkylacylamino acid proton type ionic liquid aqueous solution is 1 to 50%.

[0021] Preferably, the proton exchange reaction is carried out at a temperature of 30 to 100° C. and for a time of 1 to 36 hours.

[0022] The present invention provides the use of the isopropanolamine-alkyl acylamino acid proton type ionic liquid as a water-based lubricant additive.

[0023] The present invention provides a water-based lubricant, comprising a water-based basic lubricating fluid and the above-mentioned isopropanolamine-alkyl acylamino acid proton-type ionic liquid.

[0024] Preferably, the water-based lubricating fluid is one of water, water-ethylene glycol, water-polyethylene glycol, and water-glycerol;

[0025] The mass percentage of the isopropanolamine-alkyl acylamino acid proton type ionic liquid in the water-based lubricant is 0.1-10%.

[0026] The present invention provides an isopropanolamine-alkyl acylamino acid proton type ionic liquid, the general structural formula of which is A + B - , where A + represents an organic cation, B - Represents an organic anion; the organic cation is an isopropanolamine compound cation, and the organic anion is an alkyl acyl amino acid anion. The present invention uses an isopropanolamine compound as a cation and an alkyl acyl amino acid as an anion. The nitrogen atom in the molecular structure of the isopropanolamine compound has a lone pair of electrons, which has a certain weak alkalinity, while the carboxyl group in the molecular structure of the alkyl acyl amino acid has a certain acidity. The two can be synthesized into an amino acid proton-type ionic liquid through a simple proton exchange (acid-base neutralization) reaction. The active nitrogen element in the ionic liquid molecular structure can undergo a tribochemical reaction with the metal friction pair to form a tribochemical reaction film, which not only improves the friction reduction and anti-wear performance of the water-based lubricant, but also greatly improves its extreme pressure performance. The good water solubility of the isopropanolamine compound and the ionic bond generated make the ionic liquid have good solubility in water. The carboxylic acid ion is an organic anion that can effectively adsorb to the metal friction pair to form a strong adsorption film, providing good lubrication performance and corrosion resistance.

[0027] At the same time, the isopropanolamine-alkyl acylamino acid proton-type ionic liquid provided by the present invention contains no phosphorus and sulfur elements, and is a green and environmentally friendly lubricating additive. The raw materials required for its synthesis are widely available and the cost is low.

[0028] The present invention provides a method for preparing the aforementioned isopropanolamine-alkylacylamino acid-based protic ionic liquid. This method requires only a single neutralization reaction to obtain the propanolamine-alkylacylamino acid-based protic ionic liquid. The preparation method is extremely simple, requiring no complex steps such as ion exchange, separation, and purification, making it easy to scale up production. Furthermore, the isopropanolamine-alkylacylamino acid-based protic ionic liquid provided by the present invention can be prepared in situ in aqueous solution, eliminating the need for separation and purification and allowing for direct use. DETAILED DESCRIPTION

[0029] The present invention provides an isopropanolamine-alkyl acylamino acid proton type ionic liquid, the general structural formula of which is A + B-, where A + represents an organic cation, and B- represents an organic anion;

[0030] The organic cation is an isopropanolamine compound cation, and the organic anion is an alkyl acylamino acid anion.

[0031] In the present invention, the isopropanolamine compound cation has a structure shown in any one of Formula I to Formula III:

[0032]

[0033] In the present invention, the isopropanolamine compound is preferably one or more of isopropanolamine, diisopropanolamine and triisopropanolamine.

[0034] In the present invention, the alkyl acylamino acid anion has a structure shown in Formula IV:

[0035]

[0036] In Formula IV, n is any integer of 2 to 11, preferably 3 to 10, and more preferably 5 to 8.

[0037] R1 is hydrogen or methyl;

[0038] R is hydrogen, methyl, One of them.

[0039] In the present invention, the alkyl acylamino acid anion is preferably one or more of lauroyl glutamate anion, lauroyl sarcosine anion, lauroyl glycine anion, lauroyl aspartic acid anion, lauroyl alanine anion, octanoyl glutamate anion, octanoyl sarcosine anion, octanoyl glycine anion, octanoyl aspartic acid anion and octanoyl alanine anion.

[0040] The present invention provides a method for preparing the above-mentioned isopropanolamine-alkyl acylamino acid proton-type ionic liquid, comprising the following steps:

[0041] The isopropanolamine compound, the alkyl acyl amino acid compound and water are mixed to perform a proton exchange reaction to obtain an isopropanolamine-alkyl acyl amino acid proton type ionic liquid aqueous solution;

[0042] The water content of the isopropanolamine-alkyl acylamino acid proton type ionic liquid aqueous solution is removed to obtain the isopropanolamine-alkyl acylamino acid proton type ionic liquid.

[0043] The present invention mixes an isopropanolamine compound, an alkyl acylamino acid compound, and water to perform a proton exchange reaction to obtain an isopropanolamine-alkyl acylamino acid proton-type ionic liquid aqueous solution. In the present invention, the isopropanolamine compound is preferably one or more of isopropanolamine, diisopropanolamine, and triisopropanolamine; and in the present invention, the alkyl acylamino acid compound is preferably one or more of lauroyl glutamic acid, lauroyl sarcosine, lauroyl glycine, lauroyl aspartic acid, lauroyl alanine, octanoyl glutamic acid, octanoyl sarcosine, octanoyl glycine, octanoyl aspartic acid, and octanoyl alanine.

[0044] In the present invention, the molar ratio of the amino group of the isopropanolamine compound to the carboxyl group of the alkyl acylamino acid compound is preferably 1: 1. The present invention has no special requirements for the mixing method, and a mixing method well known to those skilled in the art can be used, such as stirring mixing.

[0045] In the present invention, the temperature of the proton exchange reaction is preferably 10-100°C, more preferably 30-80°C; the time is preferably 1-36 hours, more preferably 5-25 hours, and even more preferably 10-20 hours. In the present invention, the proton exchange reaction is preferably carried out under stirring.

[0046] In the present invention, the mass content of the isopropanolamine-alkylacylamino acid protic ionic liquid in the isopropanolamine-alkylacylamino acid protic ionic liquid aqueous solution is preferably 1-50%, more preferably 5-30%, and further preferably 10-20%.

[0047] After obtaining the isopropanolamine-alkylacylamino acid protic ionic liquid aqueous solution, the present invention removes moisture from the isopropanolamine-alkylacylamino acid protic ionic liquid aqueous solution to obtain the isopropanolamine-alkylacylamino acid protic ionic liquid. In the present invention, the method for removing moisture is preferably rotary evaporation. The present invention has no particular requirements for the rotary evaporation method, and rotary evaporation methods well known to those skilled in the art can be used.

[0048] After the rotary evaporation, the present invention preferably performs drying on the obtained rotary evaporation product. In the present invention, the drying method is preferably vacuum drying.

[0049] The present invention provides the use of the isopropanolamine-alkyl acylamino acid proton type ionic liquid as a water-based lubricant additive.

[0050] In the present invention, the base lubricating fluid in the water-based lubricant is preferably one of water, water-ethylene glycol, water-polyethylene glycol, and water-glycerin. In the present invention, the mass percentage of water in the water-ethylene glycol, water-polyethylene glycol, and water-glycerin systems is preferably 30-70%, more preferably 40-60%.

[0051] In the present invention, the mass percentage of the isopropanolamine-alkyl acylamino acid protic ionic liquid in the water-based lubricant is preferably 0.1-10%, more preferably 0.5-8%, and further preferably 1-5%.

[0052] The present invention provides a water-based lubricant, comprising a water-based basic lubricating fluid and the above-mentioned isopropanolamine-alkyl acylamino acid proton-type ionic liquid.

[0053] In the present invention, the water-based lubricating fluid is preferably one of water, water-ethylene glycol, water-polyethylene glycol, and water-glycerin. In the water-ethylene glycol, water-polyethylene glycol, and water-glycerin systems, the mass percentage of water is preferably 30-70%, more preferably 40-60%.

[0054] In the present invention, the mass percentage of the isopropanolamine-alkyl acylamino acid protic ionic liquid in the water-based lubricant is preferably 0.1-10%, more preferably 0.5-8%, and further preferably 1-5%.

[0055] In the present invention, the isopropanolamine compound and the alkyl acyl amino acid compound are mixed with water and subjected to a proton exchange reaction. The obtained isopropanolamine-alkyl acyl amino acid proton type ionic liquid aqueous solution can be directly used as a water-based lubricant.

[0056] The isopropanolamine-alkyl acylamino acid protic ionic liquid provided by the present invention, its preparation method and application are described in detail below with reference to the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0057] Example 1

[0058] In situ preparation of an isopropanolamine-lauroylglutamate ionic liquid solution: 1.502 g (0.02 mol) of isopropanolamine was added to a 500 mL round-bottom flask and dissolved in 235 g of water. Subsequently, 3.294 g (0.01 mol) of lauroylglutamate was added to the round-bottom flask and stirred at 50°C for 2 hours to obtain a 2 wt% aqueous solution of the ionic liquid. Following this method, aqueous solutions of the ionic liquid with concentrations of 0.5 wt%, 1 wt%, and 3 wt% were prepared.

[0059] The lubricating properties of the ionic liquid of the present invention as a water lubricant additive were evaluated using an SRV-IV vibration friction and wear tester manufactured by Optimol Grease GmbH in Germany. Water was used as a control, and solutions containing 1 wt%, 2 wt%, and 3 wt% of the solution were added for comparative experiments. The tribological test conditions employed were: a load of 100 N, a temperature of 25°C, a frequency of 25 Hz, an amplitude of 1 mm, and a test time of 30 min. The upper test ball was a Φ10 mm AISI 52100 steel ball. In the steel / steel friction pair, the lower test specimen was a Φ24 mm, 7.9 mm thick AISI 52100 steel block with a hardness of 700-750 HV. The wear volume of the lower test specimen was measured using a MicroXAM-800 non-contact three-dimensional surface profilometer. The average friction coefficient and average wear volume of the ionic liquid at different concentrations in the base lubricant are shown in Table 1, with triethanolamine isooctanoic acid ionic liquid and triethanolamine caproic acid ionic liquid used as controls.

[0060] Table 1 Average friction coefficient and average wear volume of ionic liquids with different concentrations in water

[0061]

[0062] Example 2

[0063] In situ preparation of diisopropanolamine-lauroyl glutamate ionic liquid solution: 2.226g (0.02mol) of diisopropanolamine was added to a 500mL round-bottom flask, and 270.5g of water was added to dissolve it. Subsequently, 3.294g (0.01mol) of lauroyl glutamate was added to the round-bottom flask and stirred at 30°C for 5 hours to obtain an ionic liquid aqueous solution with a concentration of 2wt%. According to this method, ionic liquid aqueous solutions with concentrations of 0.5wt%, 1wt% and 3wt% were prepared in sequence. The tribological behavior of the obtained ionic liquid in the base lubricant was evaluated according to the method in Example 1. The test conditions were the same as in Example 1. The test results are shown in Table 2:

[0064] Table 2 Average friction coefficient and average wear volume of the ionic liquid obtained in Example 2 in water

[0065]

[0066] Example 3

[0067] In situ preparation of triisopropanolamine-lauroyl glutamate ionic liquid solution: 3.825g (0.02mol) of triisopropanolamine was added to a 500mL round-bottom flask and dissolved in 349g of water. Subsequently, 3.294g (0.01mol) of lauroyl glutamate was added to the round-bottom flask and stirred at 50°C for 4 hours to obtain an ionic liquid aqueous solution with a concentration of 2wt%. According to this method, ionic liquid aqueous solutions with concentrations of 0.5wt%, 1wt%, and 3wt% were prepared in sequence. The tribological behavior of the obtained ionic liquid in water was evaluated according to the method in Example 1. The test conditions were the same as in Example 1. The test results are shown in Table 3.

[0068] Table 3 Average friction coefficient and average wear volume of the ionic liquid obtained in Example 3 in water

[0069]

[0070] Example 4

[0071] In situ preparation of triisopropanolamine-lauroyl sarcosine ionic liquid solution: 1.913g (0.01mol) of triisopropanolamine was added to a 500mL round-bottom flask, 227g of water was added to dissolve it, and then 2.714g (0.01mol) of lauroyl sarcosine was added to the round-bottom flask and stirred at 25°C for 4 hours to obtain an ionic liquid aqueous solution with a concentration of 2wt%. According to this method, ionic liquid aqueous solutions with concentrations of 0.5wt%, 1wt% and 3wt% were prepared in sequence. The tribological behavior of the obtained ionic liquid in water was evaluated according to the method in Example 1. The test conditions were the same as in Example 1. The test results are shown in Table 4:

[0072] Table 4 Average friction coefficient and average wear volume of the ionic liquid obtained in Example 4 in water

[0073]

[0074] Example 5

[0075] In situ preparation of triisopropanolamine-lauroylglycine ionic liquid solution: 1.913g (0.01mol) of triisopropanolamine was added to a 500mL round-bottom flask, 220g of water was added to dissolve it, and then 2.574g (0.01mol) of lauroylglycine was added to the round-bottom flask and stirred at 40°C for 2 hours to obtain an ionic liquid aqueous solution with a concentration of 2wt%. According to this method, ionic liquid aqueous solutions with concentrations of 0.5wt%, 1wt% and 3wt% were prepared in sequence. The tribological behavior of the obtained ionic liquid in water was evaluated according to the method in Example 1. The test conditions were the same as in Example 1. The test results are shown in Table 5:

[0076] Table 5 Average friction coefficient and average wear volume of the ionic liquid obtained in Example 5 in water

[0077]

[0078] Example 6

[0079] In situ preparation of triisopropanolamine-octanoylglutamate ionic liquid solution: 3.825g (0.02mol) of triisopropanolamine was added to a 500mL round-bottom flask, 332g of water was added to dissolve it, and then 2.953g (0.01mol) of octanoylglutamate was added to the round-bottom flask and stirred at 50°C for 4 hours to obtain an ionic liquid aqueous solution with a concentration of 2wt%. According to this method, ionic liquid aqueous solutions with concentrations of 0.5wt%, 1wt% and 3wt% were prepared in sequence. The tribological behavior of the obtained ionic liquid in water was evaluated according to the method in Example 1. The test conditions were the same as in Example 1. The test results are shown in Table 6:

[0080] Table 6 Average friction coefficient and average wear volume of the ionic liquid obtained in Example 6 in water

[0081]

[0082] Test Example 1 Corrosion Resistance Test

[0083] The ionic liquids prepared in Examples 1 to 6 were prepared into 1% aqueous solutions and subjected to corrosion resistance tests according to GB6144-85, with water serving as the control group. Cast iron sheets of the same specifications were immersed in water, a 1% aqueous solution of Example 1, a 1% aqueous solution of Example 2, a 1% aqueous solution of Example 3, a 1% aqueous solution of Example 4, a 1% aqueous solution of Example 5, and a 1% aqueous solution of Example 6 at 55±2°C. After 24 hours, the sheets were removed, ultrasonically cleaned in acetone, and dried with high-velocity gas. The surfaces of the cast iron sheets were observed under an optical microscope, and the corrosion conditions of the cast iron sheets in the different aqueous solutions were analyzed. The corrosion grades were determined, and the results are shown in Table 7.

[0084] Table 7 Corrosion resistance test results of the ionic liquids obtained in the examples

[0085]

[0086]

[0087] In Table 7, A means no rust and bright as new; B means no rust but slightly tarnished; C means light rust and slightly tarnished; D means heavy rust or serious tarnishing.

[0088] According to the experimental results in Table 7, it can be seen that the isopropanolamine-alkyl acylamino acid proton type ionic liquid provided by the present invention has good corrosion resistance when used as a water-based lubricant additive.

[0089] According to the above examples, the isopropanolamine-alkyl acylamino acid proton type ionic liquid provided by the present invention can greatly improve the friction reduction and anti-wear performance of water lubricating fluid, not only has a lower friction coefficient and excellent anti-wear performance in water, and has excellent corrosion resistance. In addition, the anion of the ionic liquid is prepared using amino acid as raw material, and has been proven by a large number of studies to have good biocompatibility and biodegradability, and the isopropanolamine compound cation does not contain phosphorus and sulfur elements, and is a kind of environmentally friendly ionic liquid. Ionic liquid lubricating additive can be synthesized in situ in water, does not need separation and purification process, is green and pollution-free, safe and non-toxic, and has low synthesis cost, and has broad application prospects as water-based lubricating additive.

[0090] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A water-based lubricant comprising a water-based base lubricant and an isopropanolamine-alkyl acyl amino acid protic ionic liquid; the water-based base lubricant is water, and the mass percentage of the isopropanolamine-alkyl acyl amino acid protic ionic liquid in the water-based lubricant is 1 to 3%; The general structural formula of the isopropanolamine-alkyl acylamino acid proton type ionic liquid is A + B - , where A + represents an organic cation, B - represents an organic anion; The organic cation is a triisopropanolamine cation, and the organic anion is a lauroyl glutamate anion.

2. The water-based lubricant according to claim 1, characterized in that The preparation method of the isopropanolamine-alkyl acylamino acid proton-type ionic liquid comprises the following steps: The isopropanolamine compound, the alkyl acyl amino acid compound and water are mixed to perform a proton exchange reaction to obtain an isopropanolamine-alkyl acyl amino acid proton type ionic liquid aqueous solution; The water content of the isopropanolamine-alkyl acylamino acid proton type ionic liquid aqueous solution is removed to obtain the isopropanolamine-alkyl acylamino acid proton type ionic liquid.

3. The water-based lubricant according to claim 2, characterized in that The molar ratio of the amine group of the isopropanolamine compound to the carboxyl group of the alkyl acylamino acid compound is 1:1; The mass content of the isopropanolamine-alkylacylamino acid proton type ionic liquid in the isopropanolamine-alkylacylamino acid proton type ionic liquid aqueous solution is 1 to 50%.

4. The water-based lubricant according to claim 2, characterized in that The proton exchange reaction is carried out at a temperature of 30 to 100° C. and for a time of 1 to 36 hours.

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