Preparation method of cooling insulating oil for electric vehicle

Abstract

The invention relates to a preparation method of electric vehicle cooling insulating oil, and belongs to the technical field of lubricating oil. The antioxidant is prepared firstly, then the antioxidant is used for preparing the electric vehicle cooling insulating oil with good oxidation stability, the natural ester, the polyol ester and the pour point depressant are mixed firstly, the viscosity of the natural ester is reduced, and the fluidity of the natural ester is improved; and sequentially adding a passivator and an antioxidant into the mixed oil, and carrying out ultrasonic dispersion, mixing and modification to prepare the cooling insulating oil for the electric vehicle. The preparation method is simple, the proportion is controllable, and the prepared cooling insulating oil for the electric vehicle reserves the fire-fighting performance of natural ester, is stable in chemical property, good in oxidation resistance, capable of keeping good insulating performance for a long time, high in fluidity, capable of achieving a better heat dissipation effect and capable of being widely applied to the field of new energy automobiles.

Description

Technical Field

[0001] The present invention belongs to the technical field of lubricating oils, and in particular, relates to a method for preparing cooling insulating oil for electric vehicles. Background Art

[0002] Natural ester insulating oil, also known as vegetable insulating oil, is mainly composed of triglyceride fatty acid esters. It has good environmental compatibility and biodegradability, is safe and non-toxic, and will not cause harm to the environment and organisms. The flash point of natural ester insulating oil is generally higher than 350°C, while the flash point of mineral oil is only about 170°C. Compared with mineral oil, natural ester insulating oil has better fire safety, which also makes natural ester insulating oil the preferred material for electric vehicle transformer insulating oil. However, due to its own chemical properties, natural ester has poor antioxidant properties, which will accelerate the deterioration rate of natural ester insulating oil during operation, causing the insulation ability of the oil to decrease, and ultimately leading to transformer In order to reduce the failure rate of transformers and extend the service life of transformers, it is crucial to improve the antioxidant properties of vegetable oils. Although antioxidants exist in the prior art, insulating oils need to withstand high operating temperatures for a long time, so the effects of conventional antioxidants are relatively limited; in addition, natural esters have long carbon chains, asymmetric molecular structures, and strong intermolecular interactions, which also lead to large kinematic viscosity and poor fluidity of natural ester insulating oils. The cooling performance may not meet the requirements, and they cannot pass through the narrow oil passages in the transformer or the gaps between coils, resulting in the risk of local overheating. Based on this, the present invention provides a method for preparing cooling insulating oil for electric vehicles. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing cooling insulating oil for electric vehicles, so as to solve the problems mentioned in the above background technology.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A method for preparing electric vehicle cooling insulating oil comprises the following steps:

[0006] The first step is to mix 2,6-di-tert-butyl-p-cresol, N-bromosuccinimide and carbon tetrachloride in a three-necked flask, install a condenser and a thermometer, turn on the magnetic stirring, raise the system temperature to 80°C, then add benzoyl peroxide to the three-necked flask, and react at a temperature of 80°C for 24 hours. After the reaction is completed, vacuum filtration is performed, and the obtained filtrate is spin-dried, washed with deionized water and dried to obtain intermediate 1;

[0007] Step 2: Mix the intermediate 1, urotropine and chloroform in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, react at 60°C for 3 hours, then cool the system to room temperature and vacuum filter, and mix the obtained solid with ethanol and concentrated hydrochloric acid in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, continue to react at 80-90°C for 4 hours, then cool to room temperature, adjust the pH to 7-8 with a 10-20% mass fraction sodium hydroxide aqueous solution, extract with dichloromethane, separate the organic layer with a separatory funnel, and rotary evaporate the organic layer to obtain the intermediate 2;

[0008] Step 3: Mix 5,6-dihydroxyisobenzofuran-1,3-dione, ethanol and intermediate 2 in a three-necked flask, install a condenser and a thermometer, start magnetic stirring, and react at 70°C for 1 hour. After the reaction is completed, remove the solvent by rotary evaporation, wash the remaining solid with deionized water and dry it to obtain an antioxidant;

[0009] Step 4: Add natural ester, polyol ester and pour point depressant into a container, heat to 40-60°C, and then stir at high speed to mix evenly to obtain a mixed oil;

[0010] The fifth step is to heat the mixed oil to a temperature of 60-80°C, then add a passivator and an antioxidant to the mixed oil in sequence, stir at a high speed to mix evenly, disperse by ultrasonic, and then cool to room temperature to obtain an electric vehicle cooling insulating oil.

[0011] Furthermore, the pour point depressant is ACLUBE P-2100.

[0012] Furthermore, the passivator is one of passivator TTZ, passivator T551 and passivator T561.

[0013] Furthermore, the natural ester is one of soybean oil, rapeseed oil, palm oil and camellia seed oil.

[0014] Furthermore, the polyol ester is one of glycerol triacetate and trimethylolpropane triacetate.

[0015] Furthermore, the amount ratio of 2,6-di-tert-butyl-p-cresol, N-bromosuccinimide, carbon tetrachloride and benzoyl peroxide used in the first step is 0.1 mol: 0.1 mol: 50-60 mL: 2-4 g.

[0016] Furthermore, the concentrated hydrochloric acid used in the second step is a 30% by mass HCl aqueous solution.

[0017] Furthermore, the dosage ratio of the intermediate 1, hexamethylenetetramine, chloroform, ethanol and concentrated hydrochloric acid used in the second step is 0.08 mol: 0.08-0.1 mol: 60-80 mL: 40-50 mL: 25-35 mL.

[0018] Furthermore, the amount ratio of 5,6-dihydroxyisobenzofuran-1,3-dione, ethanol and intermediate 2 used in the third step is 0.07-0.08 mol: 40-50 mL: 0.07 mol.

[0019] Furthermore, in the fourth step, the rotation speed of the high-speed stirring is 400-600 rpm, and the stirring time is 90-120 min.

[0020] Furthermore, in the fifth step, the rotation speed condition of high-speed stirring is 600-800 rpm, the stirring time condition is 40-60 min, the power condition of ultrasonic dispersion is 600-700 W, and the ultrasonic dispersion time condition is 30 min.

[0021] Furthermore, the natural ester, polyol ester, pour point depressant, passivator and antioxidant are used in a ratio of 3-5 parts: 20 parts: 0.06-0.1 parts: 0.02-0.025 parts: 0.2-0.3 parts by mass.

[0022] Beneficial effects of the present invention:

[0023] 1) The present invention uses 2,6-di-tert-butyl-p-cresol as a raw material and N-bromosuccinimide as a halogenating agent, and uses N-bromosuccinimide to cause a halogenation reaction at the benzyl position of 2,6-di-tert-butyl-p-cresol under the action of an initiator benzoyl peroxide to obtain an intermediate 1, and then uses the intermediate 1 and urotropine as raw materials, and uses the bromine atom of the intermediate 1 to react with urotropine to obtain an intermediate 2, and finally uses the intermediate 2 and 5,6-dihydroxyisobenzofuran-1,3-dione as raw materials, and uses the amino group of the intermediate 2 to react with 5,6-dihydroxyisobenzofuran-1,3-dione to obtain an enhancing auxiliary agent. The antioxidant structure of the present invention contains a benzoheterocyclic structure and has good thermal stability. In addition, the antioxidant structure also has a large number of phenolic hydroxyl groups and a large number of hindering steric groups, has good antioxidant properties, is stable in nature, and is not easily oxidized.

[0024] 2) The present invention prepares an antioxidant first, and then uses the antioxidant to prepare an electric vehicle cooling insulating oil with good oxidation stability. The present invention first mixes natural ester, polyol ester, and pour point depressant to reduce the viscosity of the natural ester and improve the fluidity of the natural ester, and then adds a passivator and an antioxidant to the mixed oil in sequence and ultrasonically disperses and mixes and modifies the mixed oil to prepare an electric vehicle cooling insulating oil. The preparation method of the present invention is simple and the proportion is controllable. The prepared electric vehicle cooling insulating oil retains the fire-fighting performance of the natural ester, has stable chemical properties, good oxidation resistance, can maintain good insulation performance for a long time, has strong fluidity, can achieve better heat dissipation effect, and can be widely used in the field of new energy vehicles. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example 1

[0027] A method for preparing electric vehicle cooling insulating oil comprises the following steps:

[0028] The first step is to mix 0.1 mol of 2,6-di-tert-butyl-p-cresol, 0.1 mol of N-bromosuccinimide and 50 mL of carbon tetrachloride in a three-necked flask, install a condenser and a thermometer, turn on the magnetic stirring, raise the system temperature to 80°C, then add 2 g of benzoyl peroxide to the three-necked flask, and react at a temperature of 80°C for 24 hours. After the reaction is completed, vacuum filtration is performed, and the obtained filtrate is spin-dried, washed with deionized water and dried to obtain intermediate 1;

[0029] Step 2: 0.08 mol of intermediate 1, 0.08 mol of urotropine and 60 mL of chloroform were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, and the reaction was carried out at a temperature of 60°C for 3 hours. The system was then cooled to room temperature and vacuum filtered, and the obtained solid was mixed with 40 mL of ethanol and 25 mL of a 30% by mass HCl aqueous solution in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, and the reaction was continued at a temperature of 80°C for 4 hours, and then cooled to room temperature, and the pH was adjusted to 7 with a 10% by mass sodium hydroxide aqueous solution, and then extracted with dichloromethane, and the organic layer was separated with a separatory funnel, and the organic layer was rotary evaporated to obtain intermediate 2;

[0030] Step 3: 0.07 mol of 5,6-dihydroxyisobenzofuran-1,3-dione, 40 mL of ethanol and 0.07 mol of intermediate 2 were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, and the reaction was carried out at a temperature of 70°C for 1 hour. After the reaction was completed, the solvent was removed by rotary evaporation, and the remaining solid was washed with deionized water and dried to obtain an antioxidant;

[0031] Step 4: Add soybean oil, triacetin and pour point depressant ACLUBE P-2100 into a container, heat to 40° C., and then stir at 400 rpm for 90 min to obtain a mixed oil;

[0032] The fifth step is to heat the mixed oil to a temperature of 60°C, then add the passivator TTZ and the antioxidant to the mixed oil in sequence, stir at a speed of 600 rpm for 40 minutes to mix evenly, disperse at an ultrasonic power of 600 W for 30 minutes, and then cool to room temperature to obtain an electric vehicle cooling insulating oil.

[0033] Calculated by mass, the soybean oil, triacetin, pour point depressant ACLUBE P-2100, passivator TTZ, and antioxidant used in this embodiment are used in a ratio of 3 parts: 20 parts: 0.06 parts: 0.02 parts: 0.2 parts.

[0034] Example 2

[0035] A method for preparing electric vehicle cooling insulating oil comprises the following steps:

[0036] The first step is to mix 0.1 mol of 2,6-di-tert-butyl-p-cresol, 0.1 mol of N-bromosuccinimide and 55 mL of carbon tetrachloride in a three-necked flask, install a condenser and a thermometer, turn on the magnetic stirring, raise the system temperature to 80°C, then add 3 g of benzoyl peroxide to the three-necked flask, and react at a temperature of 80°C for 24 hours. After the reaction is completed, vacuum filter, spin dry the obtained filtrate, wash with deionized water and dry to obtain intermediate 1;

[0037] Step 2: Mix 0.08 mol of intermediate 1, 0.09 mol of urotropine and 70 mL of chloroform in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, react at 60 ° C for 3 hours, then cool the system to room temperature and vacuum filter, and mix the obtained solid with 45 mL of ethanol and 30 mL of 30% HCl aqueous solution in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, continue to react at 85 ° C for 4 hours, then cool to room temperature, and adjust the pH to 7.5 with a 15% sodium hydroxide aqueous solution, extract with dichloromethane, separate the organic layer with a separatory funnel, and evaporate the organic layer to obtain intermediate 2;

[0038] Step 3: 0.075 mol of 5,6-dihydroxyisobenzofuran-1,3-dione, 45 mL of ethanol and 0.07 mol of intermediate 2 were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, and the reaction was carried out at a temperature of 70°C for 1 hour. After the reaction was completed, the solvent was removed by rotary evaporation, and the remaining solid was washed with deionized water and dried to obtain an antioxidant;

[0039] Step 4: Add rapeseed oil, triacetin, and pour point depressant ACLUBE P-2100 into a container, heat to 50° C., and then stir at 500 rpm for 105 min to obtain a mixed oil;

[0040] The fifth step is to heat the mixed oil to a temperature of 70°C, then add the passivator T551 and the antioxidant to the mixed oil in sequence, stir at a speed of 700 rpm for 50 minutes to mix evenly, disperse at an ultrasonic power of 650 W for 30 minutes, and then cool to room temperature to obtain an electric vehicle cooling insulating oil.

[0041] Calculated by mass, the rapeseed oil, triacetin, pour point depressant ACLUBE P-2100, passivator T551, and antioxidant used in this embodiment are used in a ratio of 4 parts: 20 parts: 0.08 parts: 0.0225 parts: 0.25 parts.

[0042] Example 3

[0043] A method for preparing electric vehicle cooling insulating oil comprises the following steps:

[0044] The first step is to mix 0.1 mol of 2,6-di-tert-butyl-p-cresol, 0.1 mol of N-bromosuccinimide and 60 mL of carbon tetrachloride in a three-necked flask, install a condenser and a thermometer, turn on the magnetic stirring, raise the system temperature to 80°C, then add 4 g of benzoyl peroxide to the three-necked flask, and react at a temperature of 80°C for 24 hours. After the reaction is completed, vacuum filter, spin dry the filtrate, wash with deionized water and dry to obtain intermediate 1;

[0045] Step 2: Mix 0.08 mol of intermediate 1, 0.1 mol of urotropine and 80 mL of chloroform in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, react at 60°C for 3 h, then cool the system to room temperature and vacuum filter, and mix the obtained solid with 50 mL of ethanol and 35 mL of a 30% by mass HCl aqueous solution in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, continue to react at 90°C for 4 h, then cool to room temperature, adjust the pH to 8 with a 20% by mass sodium hydroxide aqueous solution, extract with dichloromethane, separate the organic layer with a separatory funnel, and rotary evaporate the organic layer to obtain intermediate 2;

[0046] Step 3: 0.08 mol of 5,6-dihydroxyisobenzofuran-1,3-dione, 50 mL of ethanol and 0.07 mol of intermediate 2 were mixed in a three-necked flask, a condenser and a thermometer were installed, magnetic stirring was turned on, and the reaction was carried out at a temperature of 70°C for 1 hour. After the reaction was completed, the solvent was removed by rotary evaporation, and the remaining solid was washed with deionized water and dried to obtain an antioxidant;

[0047] Step 4: Add palm oil, trimethylolpropane triacetate and pour point depressant ACLUBE P-2100 into a container, heat to 60° C., and then stir at 600 rpm for 120 min to obtain a mixed oil;

[0048] Step 5: Heat the mixed oil to 80°C, then add the passivator T561 and the antioxidant to the mixed oil in sequence, stir at 600 rpm for 60 minutes to mix evenly, disperse at 700 W ultrasonic power for 30 minutes, and then cool to room temperature to obtain an electric vehicle cooling insulating oil.

[0049] Calculated by mass, the usage ratio of palm oil, trimethylolpropane triacetate, pour point depressant ACLUBEP-2100, passivator T561, and antioxidant used in this embodiment is 5 parts: 20 parts: 0.1 parts: 0.025 parts: 0.3 parts.

[0050] Comparative Example 1

[0051] The homemade antioxidant in Example 3 was replaced with a commercially available antioxidant.

[0052] The first step is to add palm oil, trimethylolpropane triacetate and pour point depressant ACLUBE P-2100 into a container, heat to 60°C, and then stir at 600 rpm for 120 minutes to obtain a mixed oil;

[0053] The second step is to heat the mixed oil to a temperature of 80°C, then add the passivator T561 and the commercially available antioxidant to the mixed oil in sequence, stir at a speed of 600 rpm for 60 minutes to mix evenly, disperse at an ultrasonic power of 700 W for 30 minutes, and then cool to room temperature to obtain an electric vehicle cooling insulating oil.

[0054] Calculated by weight, the usage ratio of palm oil, trimethylolpropane triacetate, pour point depressant ACLUBEP-2100, passivator T561, and commercially available antioxidant used in this embodiment is 5 parts: 20 parts: 0.1 parts: 0.025 parts: 0.3 parts.

[0055] Comparative Example 2

[0056] This comparative example is a commercially available natural ester insulating oil.

[0057] The electric vehicle cooling insulating oil in Examples 1-3 and Comparative Example 1 and the commercially available natural ester insulating oil in Comparative Example 2 were respectively subjected to performance tests. The kinematic viscosity of each component insulating oil at a temperature of 40° C. was tested with reference to the national standard GB / T 265 "Method for determination of kinematic viscosity of petroleum products and method for calculation of dynamic viscosity". The oxidation stability of each component insulating oil was tested with reference to NB / SH / T0811 "Test method for oxidation stability of unused hydrocarbon insulating oil". The test time was 120 days and the test temperature was 140° C. The oxidation stability of each component insulating oil was compared by comparing the oil color. The test results are shown in Table 1:

[0058] Table 1

[0059] project <![CDATA[Kinematic viscosity (mm 2 ·s -1 )]]> Oil color Example 1 26.34 Light yellow Example 2 25.17 Light yellow Example 3 24.66 Light yellow Comparative Example 1 24.63 Dark yellow Comparative Example 2 32.73 Dark yellow

[0060] It can be seen from Table 1 that the kinematic viscosity of the electric vehicle cooling insulating oil in Examples 1-3 of the present invention is lower than that of the commercially available natural ester insulating oil, and the color of the oil can remain light yellow after the oxidation stability test, indicating that the electric vehicle cooling insulating oil of the present invention has better fluidity and oxidation stability than the commercially available natural ester insulating oil, and can be widely used in the field of new energy vehicles.

[0061] The above is a detailed introduction to a method for preparing an electric vehicle cooling insulating oil provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enables any technician in the field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combination method. It should be pointed out that for ordinary technicians in this technical field, the present invention can also be improved and modified without departing from the principle of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention can be combined with each other in any way. The reason why these combinations are not exhaustively described in this specification is only for the consideration of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A method for preparing electric vehicle cooling insulating oil, characterized in that: The following steps are involved: The first step is to mix 2,6-di-tert-butyl-p-cresol, N-bromosuccinimide and carbon tetrachloride in a container, stir evenly, raise the system temperature to 80°C, then add benzoyl peroxide to the container, and react at 80°C for 24 hours to obtain intermediate 1; Step 2: Mix the intermediate 1, urotropine and chloroform in a container, stir evenly, react at 60°C for 3h, then cool the system to room temperature and filter out the solid, mix the obtained solid with ethanol and concentrated hydrochloric acid in a container, stir evenly, continue to react at 80-90°C for 4h, then cool to room temperature, and adjust the pH to 7-8 with a 10-20% by mass sodium hydroxide aqueous solution to obtain the intermediate 2; Step 3: Mix 5,6-dihydroxyisobenzofuran-1,3-dione, ethanol and intermediate 2 in a container, stir evenly, and react at 70°C for 1h to obtain an antioxidant; Step 4: Add natural ester, polyol ester and pour point depressant into a container, heat to 40-60°C, and then stir at high speed to mix evenly to obtain a mixed oil; The fifth step is to heat the mixed oil to a temperature of 60-80°C, then add a passivator and an antioxidant to the mixed oil in sequence, stir at a high speed to mix evenly, disperse by ultrasonic, and then cool to room temperature to obtain an electric vehicle cooling insulating oil.

2. The method for preparing electric vehicle cooling insulating oil according to claim 1, characterized in that: The pour point depressant is ACLUBE P-2100, and the passivator is one of passivator TTZ, passivator T551, and passivator T561.

3. The method for preparing electric vehicle cooling insulating oil according to claim 1, characterized in that: The natural ester is one of soybean oil, rapeseed oil and palm oil.

4. The method for preparing electric vehicle cooling insulating oil according to claim 1, characterized in that: The polyol ester is one of glycerol triacetate and trimethylolpropane triacetate.

5. The method for preparing electric vehicle cooling insulating oil according to claim 1, characterized in that: The dosage ratio of 2,6-di-tert-butyl-p-cresol, N-bromosuccinimide, carbon tetrachloride and benzoyl peroxide used in the first step is 0.1 mol: 0.1 mol: 50-60 mL: 2-4 g.

6. The method for preparing electric vehicle cooling insulating oil according to claim 1, characterized in that: The dosage ratio of 2,6-di-tert-butyl-p-cresol, N-bromosuccinimide, carbon tetrachloride and benzoyl peroxide used in the first step is 0.1 mol: 0.1 mol: 50-60 mL: 2-4 g.

7. The method for preparing electric vehicle cooling insulating oil according to claim 1, characterized in that: The concentrated hydrochloric acid used in the second step is a 30% by mass HCl aqueous solution, and the amount ratio of the intermediate 1, hexamethylenetetramine, chloroform, ethanol, and concentrated hydrochloric acid used is 0.08 mol: 0.08-0.1 mol: 60-80 mL: 40-50 mL: 25-35 mL.

8. The method for preparing electric vehicle cooling insulating oil according to claim 1, characterized in that: The amount ratio of 5,6-dihydroxyisobenzofuran-1,3-dione, ethanol and intermediate 2 used in the third step is 0.07-0.08 mol: 40-50 mL: 0.07 mol.

9. The method for preparing electric vehicle cooling insulating oil according to claim 1, characterized in that: In the fourth step, the speed condition of high-speed stirring is 400-600rpm, and the stirring time condition is 90-120min; in the fifth step, the speed condition of high-speed stirring is 600-800rpm, and the stirring time condition is 40-60min, the power condition of ultrasonic dispersion is 600-700W, and the ultrasonic dispersion time condition is 30min.

10. The method for preparing cooling insulating oil for electric vehicles according to claim 1, characterized in that: Calculated by weight, the usage ratio of the natural ester, polyol ester, pour point depressant, passivator and antioxidant is 3-5 parts: 20 parts: 0.06-0.1 parts: 0.02-0.025 parts: 0.2-0.3 parts.