Imidazoline rust preventive and method of making same

Abstract

The imidazoline rust inhibitor has a structural general formula as shown in the description, wherein R is a straight-chain or branched-chain hydrocarbon group of C 10 ~C 21 The imidazoline rust inhibitor has a structural general formula as shown in the description, wherein R is a straight-chain or branched-chain hydrocarbon group of C The preparation method of the imidazoline rust inhibitor is specifically implemented according to the following steps: a polyene polyamine and dodecenyl succinic acid are added into a reactor, and stirring is performed while heating, so that a dodecenyl succinimide intermediate is generated by reaction; a fatty acid is added into the dodecenyl succinimide intermediate of S1, heating is performed, and the target product is generated by two-step reaction to obtain a crude product; the crude product of the target product obtained in S2 is subjected to molecular distillation treatment, and heavy phase distillate is collected to obtain the imidazoline rust inhibitor. The imidazoline rust inhibitor has good oil solubility, has no acid value and ash content, has excellent rust prevention performance, and can be used in industrial oil products such as gear oil, turbine oil and ash-free hydraulic oil.

Description

Technical Field

[0001] This invention belongs to the field of lubricating oil additive technology, specifically relating to an imidazoline rust inhibitor, and also to a method for preparing the above-mentioned imidazoline rust inhibitor. Background Technology

[0002] Imidazolides, due to their low toxicity in marine environments, can be used in offshore oil extraction and natural gas production. However, heterocyclic rust inhibitors such as imidazolines have poor solubility in base oils. To address this oil solubility issue, they are currently often compounded with oil-soluble rust inhibitors such as sulfonates and organic carboxylic acids, but this leads to an increase in oil ash content and acid value. Literature (Publication No.: CN113698350A, Publication Date: 20211126) discloses a method for preparing a highly efficient imidazoline-type rust inhibitor. This method uses oleic acid, polyene polyamines, and dodecenylsuccinic anhydride to prepare the imidazoline-type rust inhibitor. However, while this method addresses the oil solubility problem of imidazoline derivatives, it also introduces a structure with acid value, resulting in an increased acid value in the prepared product, limiting its application in operating conditions where acid value is critical. Summary of the Invention

[0003] The purpose of this invention is to provide an imidazoline rust inhibitor that has the characteristics of good oil solubility and no acid value.

[0004] Another objective of this invention is to provide a method for preparing the above-mentioned imidazoline rust inhibitor, which employs molecular distillation technology to effectively remove residual fatty acids and dodecenylsuccinic acid.

[0005] The technical solution adopted in this invention is an imidazoline rust inhibitor, with the following general structural formula:

[0006]

[0007] Where R is C 10 ~C 21 The straight-chain or branched hydrocarbon group, where n is an integer from 0 to 2.

[0008] Another technical solution adopted in this invention is a method for preparing imidazoline rust inhibitors, specifically implemented according to the following steps:

[0009] S1. Add polyene polyamine and dodecenyl succinic acid to the reactor, stir and heat simultaneously to generate dodecenyl succinimide intermediate;

[0010] S2. Add fatty acids to the dodecenyl succinimide intermediate obtained in S1, and heat to generate the target crude product through a two-step reaction.

[0011] S3. Perform molecular distillation on the crude product of the target product obtained in S2, and collect the heavy phase distillate to obtain imidazoline rust inhibitor.

[0012] Another feature of the technical solution of the present invention is that:

[0013] In step S1, the polyene polyamine is any one of diethylenetriamine, triethylenetetramine, or tetraethylenepentamine.

[0014] In step S1, the molar ratio of dodecenylsuccinic acid to polyene polyamine is 0.8 to 1.05:1.

[0015] The reaction in step S1 is the first amidation reaction, with a reaction temperature of 130℃~150℃ and a reaction time of 5h~8h.

[0016] In step S2, the fatty acid is any one of 10-undecenoic acid, dodecenoic acid, myristic acid, tetradecenoic acid, or erucic acid.

[0017] In step S2, the molar ratio of fatty acids to polyenes and polyamines is 0.8 to 3.1:1.

[0018] When n is 0 in formula (I), the polyene polyamine is diethylenetriamine, and the molar ratio of fatty acid to diethylenetriamine is 0.8 to 1.1:1;

[0019] When n is 1 in formula (I), the polyene polyamine is triethylenetetramine, and the molar ratio of fatty acid to triethylenetetramine is 1.8 to 2.1:1;

[0020] When n is 2 in formula (I), the polyene polyamine is tetraethylenepentamine, and the molar ratio of fatty acid to tetraethylenepentamine is 2.8 to 3.1:1.

[0021] Step S2 involves two steps: first, heating to 120℃~160℃ for amidation reaction for 1h~4h, then heating to 180℃~220℃ for cyclization reaction for 2h~8h.

[0022] In step S3, the specific operation is to carry out molecular distillation at an evaporation temperature of 100℃~150℃ and a vacuum degree of 0.01Pa~50Pa. Unreacted fatty acids and dodecenyl succinic acid are distilled off in the light phase. The feed rate, discharge rate and mechanical stirring speed of the molecular distillation are adjusted. When the mass of the light phase distillate accounts for 1%~5% of the total distillate, the heavy phase distillate is collected as the imidazoline rust inhibitor.

[0023] The beneficial effects of this invention are:

[0024] (1) The imidazoline rust inhibitor of the present invention has no acid value, good oil solubility, and excellent rust prevention performance. It can be used in industrial oils such as gear oil, turbine oil, and ashless hydraulic oil.

[0025] (2) The imidazoline rust inhibitor of the present invention does not react with acidic rust inhibitors during application and does not affect the overall rust prevention performance of the oil.

[0026] (2) The preparation method of the imidazoline rust inhibitor of the present invention adopts molecular distillation technology, which can effectively remove residual fatty acids and dodecenyl succinic acid. Attached Figure Description

[0027] Figure 1 This is the mass spectrum of the imidazoline rust inhibitor of this invention. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] The imidazoline rust inhibitor of the present invention has the following general structural formula:

[0030]

[0031] In equation (I), R is C 10 ~C 21 The straight-chain or branched hydrocarbon group, where n is an integer from 0 to 2.

[0032] The preparation method of the imidazoline rust inhibitor of the present invention is specifically implemented according to the following steps:

[0033] S1. Add polyene polyamine and dodecenyl succinic acid to the reactor, and heat to 130℃~150℃ while mechanically stirring to carry out the first amidation reaction. After 5h~8h of reaction, dodecenyl succinimide intermediate is generated. The polyene polyamine is any one of diethylenetriamine, triethylenetetramine or tetraethylenepentamine.

[0034] The molar ratio of dodecenylsuccinic acid to polyene polyamine is 0.8–1.05:1. The purpose is to ensure that half of the primary amines in the polyene polyamine molecule react with dodecenylsuccinic acid to form dodecenylsuccinamide. If the molar ratio is less than 0.8:1, a bicyclic imidazoline will be formed in the next step, resulting in poor oil solubility of the product. If the molar ratio is greater than 1.05:1, all primary amines in the polyene polyamine will participate in the reaction, making it impossible to prepare the target product in the next step.

[0035] S2. Add fatty acids to the dodecenyl succinimide intermediate obtained in S1. The molar ratio of fatty acids to polyene polyamine is 0.8–3.1:1. First, heat to 120℃–160℃ for amidation reaction for 1–4 hours, then heat to 180℃–220℃ for cyclization reaction for 2–8 hours to generate the target crude product. The fatty acid is one of 10-undecenoic acid, dodecenoic acid, myristic acid, tetradecenoic acid, or erucic acid.

[0036] The molar ratio of fatty acids to polyenes and polyamines is 0.8 to 3.1:1. If the amount of fatty acids added is too low, not all imino groups can react, causing unreacted imino groups in the imidazoline rust inhibitor to react with the acidic rust inhibitor. If the amount of fatty acids added is too high, the excess fatty acids will react with all amino / imino groups in the polyenes and polyamines, preventing the cyclization reaction from taking place.

[0037] When n is 0 in formula (I), the polyene polyamine is diethylenetriamine, and the molar ratio of fatty acid to diethylenetriamine is 0.8 to 1.1:1.

[0038] When n is 1 in formula (I), the polyene polyamine is triethylenetetramine, and the molar ratio of fatty acid to triethylenetetramine is 1.8 to 2.1:1.

[0039] When n is 2 in formula (I), the polyene polyamine is tetraethylenepentamine, and the molar ratio of fatty acid to tetraethylenepentamine is 2.8 to 3.1:1.

[0040] S3. The crude product obtained in S2 is subjected to molecular distillation at an evaporation temperature of 100℃~150℃ and a vacuum degree of 0.01Pa~50Pa. Unreacted fatty acids and dodecenyl succinic acid, i.e., light phase distillate, are removed by molecular distillation. The feed rate, discharge rate and mechanical stirring speed of molecular distillation are adjusted to maintain the mass of light phase distillate at 1%~5% of the total mass of the total distillate. The heavy phase distillate is collected as imidazoline rust inhibitor.

[0041] This step removes unreacted fatty acids and dodecenyl succinic acid in the form of light phase distillate, and collects the target product in the form of heavy phase distillate.

[0042] Comparative Example 1

[0043] Imidazolyl rust inhibitors were synthesized according to the method disclosed in patent CN113698350A.

[0044] Comparative Example 2

[0045] Bicyclic imidazoline type rust inhibitors were synthesized according to the method disclosed in patent CN111574453A.

[0046] Comparative Example 3

[0047] To better illustrate the key technical features of the present invention, the crude product of the target product was prepared according to the preparation methods S1 and S2 of the present invention, and then the target rust inhibitor was prepared by conventional vacuum distillation as a post-treatment process. This was used as Comparative Example 3 to illustrate the present invention.

[0048] In a four-necked jacketed reaction flask equipped with a mechanical stirrer and a thermometer, 1 mol of triethylenetetramine and 1 mol of dodecenylsuccinic acid were added, and the mechanical stirrer was started. The first amidation reaction was carried out at 140°C for 6 hours to generate a solution of dodecenylsuccinimide intermediate. Then, 2 mol of erucic acid was added to the intermediate solution, and the temperature was raised to 140°C for an amidation reaction for 2 hours. The temperature was then raised to 200°C for a cyclization reaction for 5 hours. After vacuum distillation, the imidazoline rust inhibitor product was obtained.

[0049] Example 1

[0050] In a four-necked jacketed reaction flask equipped with a mechanical stirrer and a thermometer, 1 mol of triethylenetetramine and 1 mol of dodecenylsuccinic acid were added, and the mechanical stirrer was started. The reaction was carried out at 140°C for 6 hours to generate a solution of dodecenylsuccinimide intermediate; then 2 mol of erucic acid was added to the intermediate solution, the temperature was raised to 140°C and reacted for 2 hours, and then the temperature was raised to 200°C and reacted for 5 hours to obtain the crude imidazoline rust inhibitor product.

[0051] The crude product was then introduced into a molecular distillation apparatus to remove light-phase impurities. The evaporation temperature was set to 130℃, the vacuum degree to 10 Pa, and the mechanical stirring speed to 370 rpm. The feed rate, discharge rate, and mechanical stirring speed of the molecular distillation were adjusted to maintain the light-phase distillate at 5% of the total distillate mass. The collected heavy-phase distillate was the imidazoline rust inhibitor. The product structure was characterized by mass spectrometry, and the results are as follows: Figure 1 As shown.

[0052] Example 2

[0053] In a four-necked jacketed reaction flask equipped with a mechanical stirrer and a thermometer, 1 mol of tetraethylenepentamine and 0.8 mol of dodecenylsuccinic acid were added. The mechanical stirrer was started, and the reaction was carried out at 130°C for 8 hours to generate a dodecenylsuccinimide intermediate solution. Then, 3.1 mol of 10-undecenoic acid was added to the intermediate solution, the temperature was raised to 160°C, and the reaction was carried out for 1 hour. The temperature was then raised to 220°C, and the reaction was carried out for 2 hours to obtain the crude imidazoline rust inhibitor product.

[0054] The crude product was introduced into a molecular distillation apparatus to remove light phase impurities. The evaporation temperature was set to 100℃, the vacuum degree to 0.01Pa, and the mechanical stirring speed to 370 rpm. The feed rate, discharge rate, and mechanical stirring speed of the molecular distillation were adjusted so that the mass of the light phase distillate accounted for 3% of the total distillate mass. The collected heavy phase distillate was the imidazoline rust inhibitor.

[0055] Example 3

[0056] In a four-necked jacketed reaction flask equipped with a mechanical stirrer and a thermometer, 1 mol of diethylenetriamine and 1.05 mol of dodecenylsuccinic acid were added. The mechanical stirrer was started, and the reaction was carried out at 150°C for 5 hours to generate a dodecenylsuccinimide intermediate solution. Then, 0.8 mol of dodecenoic acid was added to the intermediate solution, the temperature was raised to 120°C, and the reaction was carried out for 4 hours. The temperature was then raised to 180°C and the reaction was carried out for 8 hours to obtain the crude imidazoline rust inhibitor product.

[0057] The crude product is fed into a molecular distillation apparatus to remove light phase impurities. The evaporation temperature is set to 150℃ and the vacuum degree to 50Pa. The feed rate, discharge rate, and mechanical stirring speed of the molecular distillation are adjusted so that the mass of the light phase distillate accounts for 1% of the total distillate mass. The collected heavy phase distillate is the imidazoline rust inhibitor.

[0058] The acid value of the product was tested using the standard method GB / T4945. The rust-preventive performance of the product was evaluated using the standard method GB / T1114 liquid phase corrosion (synthetic seawater), and the results are shown in Table 1. Table 1 shows that, compared to the commercially available product T703 of the same type, the imidazoline rust inhibitor of this invention has a lower acid value, superior rust-preventive performance, and better oil solubility. Comparative Example 1 is an imidazoline-type rust inhibitor synthesized according to the method disclosed in patent (publication number: CN113698350A, publication date: 20200825). Table 1 shows that this imidazoline-type rust inhibitor has a high acid value. Although it has good oil solubility, adding 0.1% to HVIP8 oil in liquid phase corrosion (synthetic seawater) resulted in severe rust. Comparative Example 2 is a bicyclic imidazoline-type rust inhibitor synthesized according to the method disclosed in patent CN111574453A(). Although this rust inhibitor has a low acid value, its oil solubility in Group II base oils is poor, thus affecting its rust-preventive performance. Comparative Example 3 describes the imidazoline rust inhibitor prepared according to steps S1 and S2 of the preparation method of the present invention. After the reaction, conventional vacuum distillation was used as the post-treatment process. As shown in Table 1, it has good solubility and rust prevention properties in HVIP8 base oil. However, conventional vacuum distillation cannot remove residual fatty acids and dodecenyl succinic acid, resulting in a high acid value. However, compared with the imidazoline rust inhibitors of T703 and Comparative Example 1, its acid value has decreased significantly. As shown in Examples 1-3, after molecular distillation treatment, the acid value of the products decreased significantly, while the products still maintained excellent rust prevention properties and oil solubility. This indicates that the imidazoline rust inhibitor of the present invention has excellent rust prevention and oil solubility properties, and its preparation method can effectively reduce the acid value of the product to expand its application range.

[0059] Table 1. Acid value, liquid phase corrosion and oil solubility tests

[0060]

[0061] Table 2. Tests on Acid Value and Rust-Preventing Performance of Oils

[0062]

[0063] The imidazoline rust inhibitors of Comparative Examples 1, 3, and Examples 1-3, which have good oil solubility, were used to replace the original rust inhibitors in KTL(EP)32 turbine oil. The effects on the oil's acid value and rust prevention performance were investigated, and the results are shown in Table 2. Table 2 shows that due to the high acid value, the imidazoline rust inhibitor of Comparative Example 1, when applied to KTL(EP)32 turbine oil, exceeded the requirements of Q / SY RH2087-2012, and its rust prevention performance was poor. Although the imidazoline rust inhibitor of Comparative Example 3 met the rust prevention performance requirements, the oil's acid value reached the upper limit, and according to SH / T 0565-2008, the oxidized sludge test of the oil showed that the acid value exceeded the standard after 1000 hours. In contrast, the imidazoline rust inhibitors of Examples 1-3, when applied to KTL(EP)32 turbine oil, met all the requirements for physicochemical properties. This further illustrates that the imidazoline rust inhibitor of the present invention has excellent rust prevention performance, oil solubility and low acid value. Through further post-processing using the preparation method of the present invention, the acid value of the product can be significantly reduced, making it applicable to oils with high acid value requirements.

Claims

1. A method for preparing an imidazoline rust inhibitor, characterized in that, The specific steps are as follows: S1. Add polyene polyamine and dodecenyl succinic acid to the reactor, stir and heat simultaneously to generate dodecenyl succinimide intermediate; S2. Add fatty acids to the dodecenyl succinimide intermediate obtained in S1, and heat to generate the target crude product through a two-step reaction. S3. Perform molecular distillation on the crude target product obtained in S2, and collect the heavy phase distillate to obtain imidazoline rust inhibitor; The general structural formula of the imidazoline rust inhibitor is: （I） Where R is C 10 ~C 21 The straight-chain or branched hydrocarbon group, where n is an integer from 0 to 2.

2. The method for preparing the imidazoline rust inhibitor according to claim 1, characterized in that, In step S1, the polyene polyamine is any one of diethylenetriamine, triethylenetetramine, or tetraethylenepentamine.

3. The method for preparing the imidazoline rust inhibitor according to claim 1, characterized in that, In step S1, the molar ratio of the dodecenylsuccinic acid to the polyene polyamine is 0.8 to 1.05:

1.

4. The method for preparing the imidazoline rust inhibitor according to claim 1, characterized in that, In step S1, the reaction is a first amidation reaction, the reaction temperature is 130℃~150℃, and the reaction time is 5 h~8 h.

5. The method for preparing the imidazoline rust inhibitor according to claim 1, characterized in that, In step S2, the fatty acid is any one of 10-undecenoic acid, dodecenoic acid, myristic acid, tetradecenoic acid, or erucic acid.

6. The method for preparing the imidazoline rust inhibitor according to claim 1, characterized in that, In step S2, the molar ratio of the fatty acid to the polyene polyamine is 0.8 to 3.1:

1.

7. The method for preparing the imidazoline rust inhibitor according to claim 1, characterized in that: When n is 0 in formula (I), the polyene polyamine is diethylenetriamine, and the molar ratio of fatty acid to diethylenetriamine is 0.8 to 1.1:1; When n is 1 in formula (I), the polyene polyamine is triethylenetetramine, and the molar ratio of fatty acid to triethylenetetramine is 1.8 to 2.1:1; When n is 2 in formula (I), the polyene polyamine is tetraethylenepentamine, and the molar ratio of fatty acid to tetraethylenepentamine is 2.8 to 3.1:

1.

8. The method for preparing the imidazoline rust inhibitor according to claim 1, characterized in that, In step S2, the two-step reaction specifically involves first heating to 120℃~160℃ for an amidation reaction for 1 h~4 h, and then heating to 180℃~220℃ for a cyclization reaction for 2 h~8 h.

9. The method for preparing the imidazoline rust inhibitor according to claim 1, characterized in that, S3 specifically involves molecular distillation at an evaporation temperature of 100℃~150℃ and a vacuum of 0.01Pa~50Pa. Unreacted fatty acids and dodecenyl succinic acid are distilled off in the light phase. The feed rate, discharge rate, and mechanical stirring speed of the molecular distillation are adjusted. When the mass of the light phase distillate accounts for 1%~5% of the total distillate mass, the heavy phase distillate is collected as the imidazoline rust inhibitor.

Images