A low-temperature resistant new energy vehicle brake fluid and preparation method thereof

Abstract

The present invention relates to the technical field of new energy vehicle brake fluid, and specifically discloses a low-temperature resistant new energy vehicle brake fluid and a preparation method thereof. A low-temperature resistant new energy vehicle brake fluid comprises triethylene glycol methyl ether, tetraethylene glycol methyl ether, tetraethylene glycol butyl ether, polyethylene glycol, composite polyethylene glycol monoether borate, polyether polyol, antioxidant, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate, tributyl phosphate and pH regulator. The new energy vehicle brake fluid of the present application has good low temperature resistance, high temperature resistance and corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicle brake fluid, and in particular to a low-temperature resistant new energy vehicle brake fluid and a preparation method thereof. Background Art

[0002] As the global energy crisis and environmental pollution become increasingly serious, new energy vehicles are gradually becoming an important development direction of the automobile industry with their clean, efficient and environmentally friendly characteristics. The braking system of new energy vehicles, especially electric vehicles, has obvious changes compared with traditional fuel vehicles. Although the brake fluid of traditional fuel vehicles has achieved a high level in braking performance and safety, such as DOT-4 or DOT-5 brake fluid, these brake fluids still cannot meet the actual requirements of new energy vehicles for brake fluid. The braking system of new energy vehicles not only includes the traditional friction braking part, but also introduces the energy recovery braking system (i.e., regenerative braking system), which makes the heat generated by new energy vehicles during braking and the energy recovery demand much higher than that of traditional fuel vehicles, which also puts higher requirements on the low temperature resistance of new energy vehicle brake fluid. In a low temperature environment, if the brake fluid becomes viscous or solidified, the response speed of the braking system will slow down, and may even cause brake failure. For new energy vehicles with more complex braking systems and higher requirements for braking response speed, the fluidity of brake fluid at low temperatures is particularly important. At the same time, due to the existence of the energy recovery braking system, the viscous brake fluid may also reduce the energy recovery efficiency of new energy vehicles and even cause safety hazards.

[0003] Therefore, there is an urgent need to develop a new energy vehicle brake fluid with excellent low-temperature resistance to meet the high performance requirements of new energy vehicles for brake fluid and ensure the braking performance and safety of new energy vehicles. Summary of the invention

[0004] In order to develop a new energy vehicle brake fluid with excellent low temperature resistance, the present application provides a low temperature resistant new energy vehicle brake fluid and a preparation method thereof. The new energy vehicle brake fluid of the present application belongs to a low viscosity and high boiling point type brake fluid, which is prepared by selecting specific alcohol ethers, boric acid esters and other raw materials, compounding antioxidants, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate, and tributyl phosphate to obtain a new energy vehicle brake fluid with good low temperature resistance, high temperature resistance and corrosion resistance.

[0005] In the first aspect, the present application provides a low-temperature resistant new energy vehicle brake fluid adopts the following technical solution:

[0006] A low-temperature resistant new energy vehicle brake fluid comprises the following raw materials in parts by weight: 28-32 parts of triethylene glycol methyl ether, 8-12 parts of tetraethylene glycol methyl ether, 8-12 parts of tetraethylene glycol butyl ether, 6-10 parts of polyethylene glycol, 35-40 parts of composite polyethylene glycol monoether borate, 5-10 parts of polyether polyol, 0.1-0.5 parts of antioxidant, 0.5-1 parts of trimethylolpropane oleate, 0.5-1 parts of pentaerythritol tetraethylhexanoate, 0.5-1 parts of tributyl phosphate, and 0.3-1.5 parts of pH regulator.

[0007] In the above technical scheme, the present application not only improves the high and low temperature performance of the brake fluid by introducing a composite polyglycol monoether borate, but also absorbs a certain amount of water, and eliminates the free water formed by atmospheric moisture inside the brake to a certain extent, so as to maintain the stability of the boiling point of the brake fluid, and maintain the stability of the brake fluid's better dry and wet equilibrium reflux boiling point. At the same time, it also protects metal parts from corrosion, reduces the influence of temperature on the brake fluid, and improves the weather resistance of the brake fluid; by selecting a mixture of triethylene glycol methyl ether, tetraethylene glycol methyl ether, and tetraethylene glycol butyl ether as the main raw material alcohol ether The compound is more conducive to controlling the low-temperature viscosity of the brake fluid and significantly reduces the low-temperature viscosity of the brake fluid; by adding polyether polyols, the swelling of the brake fluid on the rubber is greatly reduced, and the compatibility of the brake fluid with the rubber is improved; by selecting three additives, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate, and tributyl phosphate, the swelling of the brake fluid on the rubber is further reduced, and the corrosiveness of the brake fluid is further reduced, the corrosion of the brake fluid on metal parts is reduced, and the rust resistance of metal parts is improved, thereby better protecting the more sophisticated new energy vehicle braking system.

[0008] Preferably, the preparation method of the composite polyethylene glycol monoether borate comprises the following steps:

[0009] Step 1: Put polyethylene glycol monoether, boric acid and water-carrying agent into an esterification kettle, control the temperature of the reactor at 110°C, and reflux the reaction mixture in the kettle for 1 hour;

[0010] Step 2: gradually increase the temperature to distill the water generated by the reaction and the water-carrying agent in the state of azeotrope. When the kettle temperature reaches 150°C and the steam temperature reaches 94°C, and no liquid escapes, change the atmospheric distillation to reduced pressure distillation, and control the vacuum degree within 0.095MPa~0.096MPa. When the kettle temperature reaches 150°C and the steam temperature reaches 110°C, take the liquid in the kettle to determine the equilibrium reflux boiling point. When the equilibrium reflux boiling point is greater than 260°C, stop heating and reduced pressure distillation to obtain composite polyethylene glycol monoether borate.

[0011] In the above technical scheme, the present application forms a composite polyglycol monoether borate ester by a condensation reaction between boric acid and an oxygen atom of polyglycol monoether, wherein the oxygen atom of polyglycol monoether and the hydroxyl group of boric acid are connected. By controlling the reaction conditions, the high purity and stability of the composite polyglycol monoether borate ester are ensured, thereby giving the brake fluid better stability of the dry and wet equilibrium reflux boiling points.

[0012] Preferably, the polyglycol monoether is one or more of triethylene glycol methyl ether, tetraethylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol ethyl ether and triethylene glycol ethyl ether.

[0013] Preferably, the polyethylene glycol monoether is a mixture of triethylene glycol methyl ether and diethylene glycol ethyl ether in a mass ratio of 1:1.

[0014] In the above technical solution, the present application specifies that the polyglycol monoether is a mixture of triethylene glycol methyl ether and diethylene glycol ethyl ether in a mass ratio of 1:1, which can further improve the dry and wet equilibrium reflux boiling points of the brake fluid, thereby ensuring the performance stability of the brake fluid under extreme temperature conditions. At the same time, the present application selects a specific proportion of mixed polyglycol monoethers to further optimize the low-temperature fluidity of the brake fluid and reduce its freezing point, thereby meeting the use requirements of new energy vehicles in cold environments.

[0015] Preferably, the water-carrying agent is an aromatic hydrocarbon solvent, and the amount of the water-carrying agent added is 4 to 5 times the mass of water produced after the poly(ethylene glycol) monoether and borate esterification reaction.

[0016] In the above technical scheme, the present application selects aromatic hydrocarbon solvents as water-carrying agents, which can effectively form azeotropes with water generated by the reaction, thereby improving the distillation efficiency of water and ensuring the separation of water from the composite poly(ethylene glycol) monoether borate.

[0017] Preferably, the average molecular weight of the polyether polyol is between 200 and 600.

[0018] In the above technical scheme, the present application can ensure that the brake fluid maintains good fluidity and lubrication properties in a low-temperature environment by selecting a polyether polyol with an average molecular weight between 200 and 600 when preparing a low-temperature resistant new energy vehicle brake fluid, while reducing the swelling effect on rubber seals and improving the compatibility and durability of the brake fluid.

[0019] In the second aspect, the present application provides a method for preparing a low-temperature resistant new energy vehicle brake fluid using the following technical solution:

[0020] A method for preparing a low-temperature resistant new energy vehicle brake fluid comprises the following steps:

[0021] Step 1: add triethylene glycol methyl ether, tetraethylene glycol methyl ether, tetraethylene glycol butyl ether, polyethylene glycol, composite polyethylene glycol monoether borate and polyether polyol, mix and stir evenly, and then dehydrate to a moisture content of ≤0.1% to obtain a solvent;

[0022] Step 2: Cool the solvent to below 60° C., add antioxidant, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate, tributyl phosphate in sequence, and finally add pH adjuster, stir for 2 hours, filter, and obtain low-temperature resistant new energy vehicle brake fluid.

[0023] In the above technical solution, the present application ensures the uniformity and stability of the brake fluid by precisely controlling the order of addition and reaction time of each raw material during the preparation process. The resulting new energy vehicle brake fluid has good low temperature resistance and corrosion inhibition, meeting the high requirements of new energy vehicles for brake fluid.

[0024] Preferably, the specific operation of dehydration includes: vacuum dehydration at 140-150° C. and -0.098 to -0.093 MPa.

[0025] In the above technical solution, the present application ensures the complete removal of water in the solvent by controlling the temperature and vacuum degree during the dehydration process, thereby further improving the high and low temperature resistance of the brake fluid.

[0026] In summary, the present application includes at least one of the following beneficial technical effects:

[0027] The present application introduces composite polyglycol monoether borate into the brake fluid, thereby not only effectively improving the high and low temperature performance of the brake fluid, but also maintaining the stability of the dry and wet equilibrium reflux boiling points of the brake fluid, protecting metal parts from corrosion, reducing the impact of temperature on the brake fluid, and improving the weather resistance of the brake fluid.

[0028] The present application selects a mixture of triethylene glycol methyl ether, tetraethylene glycol methyl ether and tetraethylene glycol butyl ether as the main raw material of the brake fluid, thereby significantly reducing the low-temperature viscosity of the brake fluid.

[0029] The present application adds polyether polyol into the brake fluid, thereby effectively reducing the swelling of the brake fluid on the rubber, improving the compatibility of the brake fluid with the rubber, and further reducing the low-temperature viscosity of the brake fluid.

[0030] The present application selects three additives, namely, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate and tributyl phosphate, to further reduce the impact of brake fluid on the braking system of new energy vehicles, especially further reduce the damage of brake fluid to rubber and metal parts of new energy vehicles. DETAILED DESCRIPTION

[0031] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0032] Preparation Example 1

[0033] A method for preparing a composite polyglycol monoether borate ester comprises the following steps:

[0034] Step 1: put appropriate amount of polyethylene glycol monoether, boric acid and water-carrying agent into an esterification kettle, control the temperature of the reactor at 110°C, and allow the reaction mixture to reflux in the kettle for 1 hour;

[0035] Step 2: gradually increase the temperature to distill the water generated by the reaction and the water-carrying agent in the state of azeotrope. When the kettle temperature reaches 150°C and the steam temperature reaches 94°C, and no liquid escapes, change the atmospheric distillation to reduced pressure distillation, and the vacuum degree can be controlled at 0.095MPa. When the kettle temperature reaches 150°C and the steam temperature reaches 110°C, take the liquid in the kettle to determine the equilibrium reflux boiling point. When the equilibrium reflux boiling point is >260°C, stop heating and reduced pressure distillation to obtain composite polyethylene glycol monoether borate.

[0036] Among them, polyethylene glycol monoether is a mixture of tetraethylene glycol methyl ether and diethylene glycol ethyl ether in a mass ratio of 1:1.

[0037] The water-carrying agent is toluene, and the amount of toluene added is 4 times the mass of water produced after the reaction of polyethylene glycol monoether and borate esterification.

[0038] Among them, tetraethylene glycol methyl ether was purchased from Wuxi Jinzhuxing Chemical Technology Co., Ltd.

[0039] Among them, diethylene glycol ethyl ether was purchased from Wuxi Jinzhuxing Chemical Technology Co., Ltd.

[0040] Preparation Example 2

[0041] A method for preparing a composite polyglycol monoether borate ester, which is different from Preparation Example 1, comprises the following steps:

[0042] Step 1: put appropriate amount of polyethylene glycol monoether, boric acid and water-carrying agent into an esterification kettle, control the temperature of the reactor at 110°C, and allow the reaction mixture to reflux in the kettle for 1 hour;

[0043] Step 2: gradually increase the temperature to distill the water generated by the reaction and the water-carrying agent in the state of azeotrope. When the kettle temperature reaches 150°C and the steam temperature reaches 94°C, and no liquid escapes, change the atmospheric distillation to reduced pressure distillation, and the vacuum degree can be controlled at 0.095MPaMPa. When the kettle temperature reaches 150°C and the steam temperature reaches 110°C, take the liquid in the kettle to determine the equilibrium reflux boiling point. When the equilibrium reflux boiling point is >260°C, stop heating and reduced pressure distillation to obtain composite polyethylene glycol monoether borate.

[0044] Among them, polyethylene glycol monoether is a mixture of triethylene glycol methyl ether and triethylene glycol ethyl ether in a mass ratio of 1:1.

[0045] The water-carrying agent is toluene, and the amount of toluene added is 5 times the mass of water produced after the reaction of polyethylene glycol monoether and boric acid esterification.

[0046] Among them, triethylene glycol methyl ether was purchased from Wuxi Jinzhuxing Chemical Technology Co., Ltd.

[0047] Among them, triethylene glycol ethyl ether was purchased from Wuxi Jinzhuxing Chemical Technology Co., Ltd.

[0048] Preparation Example 3

[0049] A method for preparing a composite polyglycol monoether borate ester, which is different from Preparation Example 1, comprises the following steps:

[0050] Step 1: put appropriate amount of polyethylene glycol monoether, boric acid and water-carrying agent into an esterification kettle, control the temperature of the reactor at 110°C, and allow the reaction mixture to reflux in the kettle for 1 hour;

[0051] Step 2: gradually increase the temperature to distill the water generated by the reaction and the water-carrying agent in the state of azeotrope. When the kettle temperature reaches 150°C and the steam temperature reaches 94°C, and no liquid escapes, change the atmospheric distillation to reduced pressure distillation, and the vacuum degree can be controlled at 0.096MPa. When the kettle temperature reaches 150°C and the steam temperature reaches 110°C, take the liquid in the kettle to determine the equilibrium reflux boiling point. When the equilibrium reflux boiling point is >260°C, stop heating and reduced pressure distillation to obtain composite polyethylene glycol monoether borate.

[0052] Among them, polyethylene glycol monoether is a mixture of tetraethylene glycol methyl ether and triethylene glycol ethyl ether in a mass ratio of 1:1.

[0053] The water-carrying agent is toluene, and the amount of toluene added is 5 times the mass of water produced after the reaction of polyethylene glycol monoether and boric acid esterification.

[0054] Preparation Example 4

[0055] A method for preparing a composite polyglycol monoether borate ester. The difference from Preparation Example 1 is that the polyglycol monoether is prepared by mixing triethylene glycol methyl ether and diethylene glycol ethyl ether in a mass ratio of 1:1. Example 1

[0056] A low-temperature resistant new energy vehicle brake fluid comprises 300 g of triethylene glycol methyl ether, 100 g of tetraethylene glycol methyl ether, 100 g of tetraethylene glycol butyl ether, 80 g of polyethylene glycol, 380 g of composite polyethylene glycol monoether borate, 80 g of polyether polyol, 3 g of antioxidant, 8 g of trimethylolpropane oleate, 8 g of pentaerythritol tetraethylhexanoate, 8 g of tributyl phosphate, and 4 g of pH regulator.

[0057] Wherein, the composite polyethylene glycol monoether borate is prepared by the preparation method of Preparation Example 1.

[0058] Among them, tetraethylene glycol butyl ether was purchased from Wuxi Jinzhuxing Chemical Technology Co., Ltd.

[0059] Among them, polyethylene glycol was purchased from Wuxi Jinzhuxing Chemical Technology Co., Ltd., model: PEG-200.

[0060] Among them, the average molecular weight of polyether polyol is between 200 and 600.

[0061] Wherein, the antioxidant is the antioxidant BHT.

[0062] The trimethylolpropane oleate was purchased from Xipeng Environmental Protection Technology (Luoyang) Co., Ltd. as TMPTO trimethylolpropane oleate Palmester 2083.

[0063] Wherein, pentaerythritol tetraethylhexanoate is pentaerythritol tetra(2-ethylhexanoate) purchased from Hubei Zhenbo Chemical Co., Ltd.

[0064] Among them, tributyl phosphate was purchased from Taizhou Xianhe Pharmaceutical Biotechnology Co., Ltd., item number: 126-73-8.

[0065] Among them, the preparation method of low-temperature resistant new energy vehicle brake fluid comprises the following steps:

[0066] Step 1: Add triethylene glycol methyl ether, tetraethylene glycol methyl ether, tetraethylene glycol butyl ether, polyethylene glycol, composite polyethylene glycol monoether borate and polyether polyol, mix and stir evenly, and then vacuum dehydrate at 145° C. and -0.0986 MPa until the moisture content is ≤0.1% to obtain a solvent.

[0067] Step 2: Cool the solvent to below 60° C., add antioxidant, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate, tributyl phosphate in sequence, and finally add pH adjuster, stir for 2 hours, filter, and obtain low-temperature resistant new energy vehicle brake fluid. Example 2

[0068] A low-temperature resistant new energy vehicle brake fluid, which is different from Example 1 in that it includes 280g of triethylene glycol methyl ether, 120g of tetraethylene glycol methyl ether, 80g of tetraethylene glycol butyl ether, 60g of polyethylene glycol, 400g of composite polyethylene glycol monoether borate, 50g of polyether polyol, 1g of antioxidant, 5g of trimethylolpropane oleate, 10g of pentaerythritol tetraethylhexanoate, 5g of tributyl phosphate, and 3g of pH regulator.

[0069] Wherein, the composite polyethylene glycol monoether borate is prepared by the preparation method of Preparation Example 2.

[0070] Among them, the preparation method of low-temperature resistant new energy vehicle brake fluid comprises the following steps:

[0071] Step 1: Add triethylene glycol methyl ether, tetraethylene glycol methyl ether, tetraethylene glycol butyl ether, polyethylene glycol, composite polyethylene glycol monoether borate and polyether polyol, mix and stir evenly, and then vacuum dehydrate at 150° C. and -0.093 MPa until the moisture content is ≤0.1% to obtain a solvent.

[0072] Step 2: Cool the solvent to below 60° C., add antioxidant, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate, tributyl phosphate in sequence, and finally add pH adjuster, stir for 2 hours, filter, and obtain low-temperature resistant new energy vehicle brake fluid. Example 3

[0073] A low-temperature resistant new energy vehicle brake fluid, which is different from Example 1 in that it includes 320g of triethylene glycol methyl ether, 80g of tetraethylene glycol methyl ether, 120g of tetraethylene glycol butyl ether, 100g of polyethylene glycol, 350g of composite polyethylene glycol monoether borate, 100g of polyether polyol, 5g of antioxidant, 10g of trimethylolpropane oleate, 5g of pentaerythritol tetraethylhexanoate, 10g of tributyl phosphate, and 3g of pH regulator.

[0074] Wherein, the composite polyethylene glycol monoether borate is prepared by the preparation method of Preparation Example 2.

[0075] Among them, the preparation method of low-temperature resistant new energy vehicle brake fluid comprises the following steps:

[0076] Step 1: Add triethylene glycol methyl ether, tetraethylene glycol methyl ether, tetraethylene glycol butyl ether, polyethylene glycol, composite polyethylene glycol monoether borate and polyether polyol, mix and stir evenly, and then vacuum dehydrate at 140° C. and -0.098 MPa until the moisture content is ≤0.1% to obtain a solvent.

[0077] Step 2: Cool the solvent to below 60° C., add antioxidant, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate, tributyl phosphate in sequence, and finally add pH adjuster, stir for 2 hours, filter, and obtain low-temperature resistant new energy vehicle brake fluid. Example 4

[0078] A low-temperature resistant new energy vehicle brake fluid. Different from Example 1, the composite poly(ethylene glycol) monoether borate is prepared by the preparation method of Preparation Example 4.

[0079] Comparative Example 1

[0080] A new energy vehicle brake fluid, which is different from Example 1 in that the average molecular weight of the polyether polyol is between 600 and 800.

[0081] Comparative Example 2

[0082] A new energy vehicle brake fluid, which is different from Example 1 in that it does not contain trimethylolpropane oleate.

[0083] Comparative Example 3

[0084] A new energy vehicle brake fluid, which is different from Example 1 in that it does not contain pentaerythritol tetraethylhexanoate and tributyl phosphate.

[0085] Comparative Example 4

[0086] A new energy vehicle brake fluid, which is different from Example 1 in that it does not contain tributyl phosphate.

[0087] Performance Testing

[0088] With reference to the testing standard of GB 12981-2012 "Motor Vehicle Brake Fluid", various indicators of the new energy vehicle brake fluid of the above-mentioned embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0089] Table 1:

[0090]

[0091] As can be seen from Table 1, all indicators of the new energy vehicle brake fluids of Examples 1 to 4 meet the technical requirements of GB12981-2012 "Motor Vehicle Brake Fluid". In particular, key performance indicators such as -40°C kinematic viscosity, 100°C kinematic viscosity, dry equilibrium reflux boiling point and wet equilibrium reflux boiling point all meet or exceed the standard requirements, showing good low temperature resistance and corrosion inhibition. At the same time, the test results of the rubber cup swelling also show that the brake fluid of the present application has good compatibility with rubber and low swelling.

[0092] Combining the analysis of Example 1 and Example 4, Example 4 has a lower kinematic viscosity at -40°C, a higher kinematic viscosity at 100°C, and good performance in dry equilibrium reflux boiling point and wet equilibrium reflux boiling point. It can be seen that in the preparation process, by adjusting the type and proportion of polyglycol monoether, the performance of the brake fluid can be further optimized, so that the brake fluid has better high and low temperature resistance.

[0093] Combining the analysis of Example 1 and Comparative Example 1, the kinematic viscosity of the brake fluid of Comparative Example 1 at -40°C is significantly higher than that of Example 1, which indicates that when the average molecular weight of the polyether polyol is between 600 and 800, the low-temperature performance of the brake fluid decreases. At the same time, in the rubber cup swelling test, the hardness reduction value and volume increase value of the brake fluid of Comparative Example 1 are higher than those of Example 1, which indicates that the brake fluid of Comparative Example 1 has poor compatibility with rubber and may cause accelerated aging of rubber parts. It can be seen that the present application further improves the performance of the brake fluid of new energy vehicles by controlling the molecular weight of the polyether polyol to meet the use requirements in different environments.

[0094] Combining the analysis of Example 1 and Comparative Examples 2-4, the brake fluid of Comparative Examples 2-4 performed poorly in the corrosion and rubber cup swelling tests, indicating that the lack of three additives, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate and tributyl phosphate, would reduce the compatibility of the brake fluid with rubber and reduce the sustained release of the brake fluid.

[0095] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A low temperature resistant new energy vehicle brake fluid, characterized in that: The invention is composed of the following raw materials in parts by weight: 28-32 parts of triethylene glycol methyl ether, 8-12 parts of tetraethylene glycol methyl ether, 8-12 parts of tetraethylene glycol butyl ether, 6-10 parts of polyethylene glycol, 35-40 parts of composite polyethylene glycol monoether borate, 5-10 parts of polyether polyol, 0.1-0.5 parts of antioxidant, 0.5-1 parts of trimethylolpropane oleate, 0.5-1 parts of pentaerythritol tetraethylhexanoate, 0.5-1 parts of tributyl phosphate, and 0.3-1.5 parts of pH regulator; The preparation method of the composite polyethylene glycol monoether borate comprises the following steps: Step 1: Put polyethylene glycol monoether, boric acid and water-carrying agent into an esterification kettle, control the temperature of the reactor at 110°C, and reflux the reaction mixture in the kettle for 1 hour; Step 2: gradually increase the temperature to distill the water generated by the reaction and the water-carrying agent in the state of azeotrope. When the kettle temperature reaches 150°C and the steam temperature reaches 94°C, and no liquid escapes, change the atmospheric distillation to reduced pressure distillation, and control the vacuum degree within 0.095MPa~0.096MPa. When the kettle temperature reaches 150°C and the steam temperature reaches 110°C, take the liquid in the kettle to determine the equilibrium reflux boiling point. When the equilibrium reflux boiling point is greater than 260°C, stop heating and reduced pressure distillation to obtain composite polyethylene glycol monoether borate; The average molecular weight of the polyether polyol is between 200 and 600; The polyglycol monoether is a mixture of triethylene glycol methyl ether and diethylene glycol ethyl ether in a mass ratio of 1:1, or a mixture of tetraethylene glycol methyl ether and diethylene glycol ethyl ether in a mass ratio of 1:1, or a mixture of triethylene glycol methyl ether and triethylene glycol ethyl ether in a mass ratio of 1:

1.

2. The low-temperature resistant new energy vehicle brake fluid according to claim 1, characterized in that: The water-carrying agent is an aromatic hydrocarbon solvent, and the amount of the water-carrying agent added is 4 to 5 times the mass of water produced after the poly(ethylene glycol) monoether and borate esterification reaction.

3. A method for preparing a low-temperature resistant new energy vehicle brake fluid as claimed in claim 1 or 2, characterized in that: The following steps are involved: Step 1: add triethylene glycol methyl ether, tetraethylene glycol methyl ether, tetraethylene glycol butyl ether, polyethylene glycol, composite polyethylene glycol monoether borate and polyether polyol, mix and stir evenly, and then dehydrate to a moisture content of ≤0.1% to obtain a solvent; Step 2: Cool the solvent to below 60° C., add antioxidant, trimethylolpropane oleate, pentaerythritol tetraethylhexanoate, tributyl phosphate in sequence, and finally add pH adjuster, stir for 2 hours, filter, and obtain low-temperature resistant new energy vehicle brake fluid.

4. The method for preparing a low-temperature resistant new energy vehicle brake fluid according to claim 3, characterized in that: The specific operation of the dehydration includes: vacuum dehydration at 140-150° C. and -0.098 to -0.093 MPa.

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