A highly alcoholysis and transesterification resistant stable polyol ester and a method for preparing the same

Abstract

The application belongs to the technical field of functional synthetic ester materials and special lubricating oil additives, and particularly discloses a high-anti-alcoholysis anti-ester exchange stable polyol ester and a preparation method thereof. A high steric hindrance compound polyol + branched chain saturated fatty acid molecular structure design is adopted, a molecular sieve solid acid deep end-capping esterification process is matched, carboxyl end-capping is realized through low-temperature normal-pressure pre-esterification, high-temperature vacuum deep esterification and short-range molecular distillation extreme vacuum deacidification and dehydration, and finally free hydroxyl is eliminated by means of fatty acyl chloride, so that the ester exchange inducing sites are completely eliminated. The product is stable in structure under the coexistence of high-concentration ethanol and methanol in a high-temperature environment, has no obvious ester exchange cracking, and has a very high viscosity retention rate, thereby solving the problem of poor long-term stability of alcohol-based lubricating systems and biodiesel blending systems, and the process is environmentally friendly, the product has strong stability and is suitable for large-scale industrial application.

Description

Technical Field

[0001] This invention belongs to the technical field of functional synthetic ester materials and special lubricating oil additives, specifically relating to a highly resistant alcoholysis and transesterification stable polyol ester and its preparation method. Background Technology

[0002] Polyol esters are widely used in various industrial lubricating media due to their excellent lubricity, thermal stability, and oxidation resistance. However, existing conventional polyol esters generally suffer from extremely poor resistance to alcoholysis. For example, in systems containing polar low-carbon alcohols such as methanol and ethanol, they are prone to reversible transesterification and alcoholysis reactions under heating and trace acidic or alkaline conditions, leading to the breakage and decomposition of large-molecule polyol esters into small-molecule fatty acid methyl esters, ethyl esters, and free polyols.

[0003] This defect directly leads to problems such as a significant decrease in the viscosity of the lubrication system, lubrication failure, oil turbidity and stratification, precipitation of impurities, and accelerated equipment wear, which seriously restricts the application of polyol esters in ethanol gasoline lubricating oil, biodiesel blending additives, alcohol-based industrial circulating media, and alcohol-containing refrigerant lubrication systems.

[0004] Currently, common straight-chain fatty acid polyol esters in the industry lack steric hindrance protection structures and cannot inhibit alcoholysis and transesterification. Conventional modification processes can only slightly improve thermal stability and cannot solve the problem of ester bond cleavage induced by ethanol and methanol at the molecular level. Therefore, developing a special polyol ester with high molecular steric hindrance, extremely low content of active hydroxyl / carboxyl groups, strong resistance to transesterification, and resistance to alcoholysis is the key to breaking through the bottleneck of lubricating materials for alcohol-containing applications. Summary of the Invention

[0005] To address the problems of easy alcoholysis, easy transesterification, and poor stability of alcohol systems in existing polyol esters, this invention provides a highly alcoholysis-resistant and transesterification-resistant stable polyol ester and its preparation method. Through the design of a highly sterically hindered molecular structure, the transesterification reaction of low-carbon alcohols is completely suppressed. At the same time, a high-vacuum deep end-capping esterification preparation process is provided. The product maintains structural stability and performance without deterioration under harsh conditions of coexistence of ethanol and methanol and high temperature.

[0006] This invention innovatively employs a sterically hindered complex polyol + branched saturated fatty acid molecular structure design, coupled with a molecular sieve solid acid deep-end esterification process. A highly sterically hindered alcohol skeleton is constructed by complexing trimethylolpropane with neopentyl glycol, and the ester bonds are encapsulated by C7-C9 isomeric branched fatty acids, hindering the nucleophilic attack of lower-carbon alcohols at the molecular level. Carboxyl end-capping is achieved through low-temperature atmospheric pressure pre-esterification, high-temperature vacuum deep esterification, and extreme vacuum deacidification and dehydration via short-path molecular distillation. Finally, fatty acyl chlorides are used to eliminate free hydroxyl groups, completely eliminating transesterification induction sites. The product of this invention exhibits structural stability under high-temperature conditions with high concentrations of ethanol and methanol, with no significant transesterification cracking and extremely high viscosity retention. This solves the problem of poor long-term stability in alcohol-based lubrication systems and biodiesel blending systems. The process is environmentally friendly, the product has strong stability, and it is suitable for large-scale industrial applications.

[0007] The core innovative mechanism of this invention is as follows: 1. Highly sterically hindered molecular framework: Trimethylolpropane and neopentyl glycol have inherent steric hindrance from tertiary carbon branches, which significantly enhances the molecular spatial shielding effect compared to pentaerythritol; 2. Branched-chain fatty acid encapsulation protection: Isomeric branched-chain fatty acids wrap around the active sites of ester bonds, blocking the nucleophilic attack of small molecules such as methanol and ethanol, and inhibiting transesterification at the source. 3. Carboxyl group capping: Three-stage esterification is carried out through low-temperature atmospheric pressure pre-esterification, high-temperature high-vacuum esterification, and short-path molecular distillation carboxyl group capping to eliminate active carboxyl groups and inhibit autocatalytic reactions under acidic conditions; 4. Hydroxyl group elimination: The high reactivity of fatty acyl chlorides is used to completely eliminate hydroxyl groups, thereby eliminating alcohol adsorption and hydrogen bond-induced transesterification side reactions.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: A highly resistant alcoholysis and transesterification stable polyol ester is prepared by deep end-capping esterification of a complex of highly hindered polyols and C7-C9 branched saturated isomeric fatty acids. The molar ratio of the carboxyl groups in the C7-C9 branched mixed isomeric fatty acids to the hydroxyl groups in the complex of highly hindered polyols is 1:1.02-1:1.08, preferably 1:1.05.

[0009] The compounded high-steric polyol is a mixture of neopentyl glycol and trimethylolpropane, with a molar ratio of 1:5 to 1:9, preferably 1:7.

[0010] The C7-C9 branched mixed isomeric fatty acids are a complex system of isoheptanoic acid, isooctanoic acid, and isononanoic acid, with a molar ratio of 1:1 to 3:1 to 5, preferably 1:2.5:4.

[0011] The deep end-capping esterification uses a solid acid catalyst, which is HZSM-5 molecular sieve, and its dosage is 0.4%-0.9% of the total mass of the compound high steric hindrance polyol and C7-C9 branched mixed isomeric fatty acids, preferably 0.6%.

[0012] This invention further provides a method for preparing the above-mentioned highly resistant to alcoholysis and transesterification stable polyol ester, the specific steps of which are as follows: (1) Feeding and mixing: Add the compound high steric hindrance polyol and C7-C9 branched mixed isomeric fatty acids into the reactor, add solid acid catalyst, and stir evenly.

[0013] (2) Low temperature and normal pressure pre-esterification: Heat to 100-150℃ and react at normal pressure for 2-6 hours. Use a water separator to separate the water generated in the early stage of the reaction to complete the preliminary esterification.

[0014] In step (2), the preferred reaction temperature is a gradient increase: 105℃±5℃ for 1 h, 125℃±5℃ for 1 h, and 145℃±5℃ for 2 h.

[0015] (3) High temperature and high vacuum esterification: After turning on the vacuum system of the water separator, control the vacuum degree of the system to -0.085 to -0.095 MPa, raise the temperature to 190 to 250°C, and perform constant temperature and negative pressure deep esterification for 5 to 7 hours; after the end, filter and fine filter, and use the filtrate for later use.

[0016] In step (3), the preferred reaction temperature is 210℃±5℃, the preferred reaction time is 6 h, and the acid value of the product should be less than 0.2 mg KOH / g after the reaction is completed. Otherwise, the reaction time should be extended and the acid value should be determined according to HG / T 2708-1995.

[0017] The filtration in step (3) is pressure filtration with a pressure of 0.4 MPa, and the fine filtration is using a 0.22 μm nylon filter membrane with a pressure of 0.4 MPa.

[0018] (4) Short-path molecular distillation carboxyl end capping: The filtrate obtained in step (3) is subjected to short-path molecular distillation to remove acid and water. A scraped membrane short-path molecular distillation device is used, with a distillation temperature of 190-250℃, an empty pressure of less than 20Pa, a feed pressure of less than 40Pa (otherwise the feed rate should be reduced or a second molecular distillation should be performed), and a rotation speed of 120±10r / min.

[0019] In step (4), the distillation temperature is preferably 210℃±5℃, and the acid value of the product after the reaction is completed should be less than 0.02 mgKOH / g. The purpose of step (4) is to promote terminal esterification and achieve carboxyl group capping.

[0020] (5) Hydroxyl elimination: Pre-cool the reaction solution system of step (4) in an ice bath. When the temperature drops to 0°C, start adding fatty acyl chloride dropwise while simultaneously pulling up the vacuum. The reaction lasts for 6-12 hours.

[0021] In step (5), the fatty acyl chloride is one or more of isooctanoyl chloride, isoheptanoyl chloride, and isononanoyl chloride, preferably isononanoyl chloride. The molar ratio of the dosage to the excess hydroxyl group in step (1) is 1-1.1, preferably 1. The excess hydroxyl group is the total number of hydroxyl groups in the compound high steric hindrance polyol minus the total number of carboxyl groups in the C7-C9 branched saturated isomeric fatty acids.

[0022] In step (5), the preferred reaction temperature is 0℃±5℃, the preferred reaction time is 10h, the preferred reaction vacuum is -0.085~-0.095 MPa, the hydroxyl value at the end of the reaction is less than 0.02 mg KOH / g, and the hydroxyl value is determined according to HG / T 2709-2022.

[0023] (6) Short-path molecular distillation for deacidification and deacylation: The reaction solution obtained in step (5) is subjected to short-path molecular distillation for deacidification and deacylation. A scraped-film short-path molecular distillation device is used, with a temperature of 190-250℃, an empty pressure of less than 20Pa, a feed pressure of less than 40Pa (otherwise the feed rate should be reduced or a second molecular distillation should be performed), and a rotation speed of 120±10r / min.

[0024] The preferred reaction temperature in step (6) is 210℃±5℃. The purpose of step (6) is to remove HCl produced by the decomposition of acyl chloride and acyl chloride that has not participated in the reaction.

[0025] (7) Refining and purification: Inert powder adsorption is used to remove impurities, filtration and precision filtration are used to obtain a high-stability anti-ester exchange polyol ester product.

[0026] In step (7), the inert powder is one or more of sodium carbonate, sodium bicarbonate, potassium bicarbonate, potassium carbonate, and diatomaceous earth, and the amount added is 0.4%-1.2% of the mass of the reaction solution obtained in step (6). More preferably, it is a combination of sodium bicarbonate and diatomaceous earth. The amount of sodium bicarbonate is 0.2%-0.6% of the mass of the reaction solution obtained in step (6), and the amount of diatomaceous earth is 0.2%-0.6% of the mass of the reaction solution obtained in step (6).

[0027] In step (7), the preferred adsorption temperature is 25℃±15℃, and the preferred adsorption time is 3 h; the filtration condition is pressure filtration with a pressure of 0.4 MPa; the preferred precision filtration condition is a nylon filter membrane with a pore size of 0.22 μm and a pressure of 0.4 MPa.

[0028] The highly stable transesterification-resistant polyol ester obtained by the above preparation method has an acid value of less than 0.01 mg KOH / g, a hydroxyl value of less than 0.01 mg KOH / g, and a viscosity of 32-34 mm at 40℃. 2 / s.

[0029] The highly stable anti-ester exchange polyol ester obtained by the above preparation method was mixed with anhydrous ethanol at a mass ratio of 1:1 and kept at a sealed constant temperature of 120℃ for 8 h. The system showed no stratification, no precipitation, no cleavage of small molecule products, viscosity retention rate ≥96%, acid value increase <0.03 mg KOH / g, hydroxyl value increase <0.03 mg KOH / g, and no obvious ester exchange reaction occurred.

[0030] Compared with the prior art, the present invention achieves the following technical effects: 1. This invention solves the core pain point in the industry of polyol esters being easily alcoholized and transesterified when they encounter ethanol and methanol at the molecular structure level, and the high temperature stability of the alcohol system far exceeds that of existing conventional products. 2. The product has excellent viscosity, acid value, component stability and resistance to alcoholysis. It does not decompose, fail or produce impurities when used in alcohol-containing conditions for a long time, and its service life is greatly extended. 3. Using molecular sieve solid acid catalysis, there are fewer side reactions, the product has high purity and light color, the process is green and environmentally friendly, no complicated post-processing is required, and it is suitable for large-scale industrial production. 4. The product is specifically adapted to special working conditions such as ethanol gasoline lubrication, biodiesel blending, alcohol-based industrial media, and alcohol-containing refrigeration lubrication, and has broad market application prospects. Detailed Implementation

[0031] The present invention will be further illustrated below with reference to embodiments, which will help those skilled in the art to further understand the present invention, but will not limit the present invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Unless otherwise specified, the experimental methods described in the following embodiments are conventional methods; the instruments and reagents used, unless otherwise specified, can be obtained through normal commercial channels.

[0032] Example 1: A method for preparing a highly resistant alcoholysis and transesterification stable polyol ester, comprising the following steps: (1) Feeding and mixing: Weigh 41.09g of neopentyl glycol, 370.57g of trimethylolpropane, 150g of isoheptanoic acid, 415.38g of isooctanoic acid, 729.23g of isononanoic acid and 10.24g of HZMS-5 molecular sieve into a 2000mL reaction flask and stir to mix well; (2) Low temperature and normal pressure pre-esterification: The reaction is carried out at normal pressure and heated to 105℃±5℃ for 1h, 125℃±5℃ for 1h, and 145℃±5℃ for 2h. The water generated in the early stage of the reaction is separated by a water separator to complete the preliminary esterification. (3) High temperature and high vacuum esterification: After turning on the vacuum system of the water separator, the temperature is raised to 210℃±5℃, and the vacuum degree of the system is controlled at -0.085~-0.095 MPa. The constant temperature and negative pressure are used for deep esterification for 6 h. When the acid value of the product is less than 0.2mg KOH / g, the reaction is stopped. After cooling to room temperature, the product is filtered by pressure at 0.4MPa. The product is then finely filtered through a 0.22μm nylon filter membrane (pressure 0.4MPa). The filtrate is kept for later use. (4) Short-path molecular distillation carboxyl end capping: The filtrate obtained in step (3) is subjected to short-path molecular distillation to remove acid and water. A scraped membrane short-path molecular distillation device is used. The distillation temperature is 210℃±5℃, the no-load pressure is less than 20Pa, the feed pressure is less than 40Pa, the rotation speed is 120r / min, and the acid value of the product is less than 0.02 mg KOH / g after the reaction is completed. (5) Hydroxyl elimination: The reaction solution from the previous step was transferred into a reaction flask, and the system was pre-cooled in an ice bath. When the temperature dropped to 0℃, isooctanoyl chloride (the molar ratio of its amount to the excess hydroxyl group in step (1) was 1) was added dropwise while simultaneously pulling up the vacuum to control the reaction temperature to be less than 5℃; after the addition was completed, the reaction was kept at the temperature for 10h, and the vacuum was controlled at -0.085 to -0.095 MPa during the heat preservation period; when the reaction ended, the hydroxyl value was detected to be less than 0.02 mg KOH / g; (6) Short-path molecular distillation for deacidification and deacylation: The reaction solution obtained in step (5) is subjected to short-path molecular distillation for deacidification and deacylation. The distillation temperature is 210℃±5℃, the no-load pressure is less than 20Pa, the rotation speed is 120r / min, the feed rate is adjusted during feeding, and the pressure is controlled to be less than 40Pa. (7) Purification: The material from the previous step is transferred into a reaction flask and stirred at 25°C. 0.2% sodium bicarbonate and 0.2% diatomaceous earth from the previous step are weighed and added to the reaction system. The mixture is kept warm and stirred for 3 hours. After the reaction is complete, the mixture is first filtered under pressure of 0.4 MPa. Then, it is filtered through a nylon membrane with a pore size of 0.22 μm under pressure of 0.4 MPa to obtain a high-stability anti-ester exchange polyol ester product.

[0033] Example 2: A method for preparing a highly resistant alcoholysis and transesterification stable polyol ester, comprising the following steps: Except for weighing 55.59g of neopentyl glycol, 358.12g of trimethylolpropane, and 10.25g of HZMS-5 molecular sieve in step (1), the rest are the same as in Example 1.

[0034] Example 3: A method for preparing a highly resistant alcoholysis and transesterification stable polyol ester, comprising the following steps: Except for the weighing of 32.59g of neopentyl glycol, 377.87g of trimethylolpropane, and 10.23g of HZMS-5 molecular sieve in step (1), the rest are the same as in Example 1.

[0035] Example 4: A method for preparing a highly resistant alcoholysis and transesterification stable polyol ester, comprising the following steps: Except for the molar ratio of isooctanoyl chloride in step (5) to the excess hydroxyl group in step (1) being 1.1, all other steps are the same as in Example 1.

[0036] Example 5: A method for preparing a highly resistant alcoholysis and transesterification stable polyol ester, comprising the following steps: Except for weighing 39.91g of neopentyl glycol, 359.98g of trimethylolpropane, and 10.17g of HZMS-5 molecular sieve in step (1), the rest is the same as in Example 1.

[0037] Example 6: A method for preparing a highly resistant alcoholysis and transesterification stable polyol ester, comprising the following steps: Except for weighing 42.26g of neopentyl glycol, 381.16g of trimethylolpropane and 10.31g of HZMS-5 molecular sieve in step (1), the rest is the same as in Example 1.

[0038] Example 7: A method for preparing a highly resistant alcoholysis and transesterification stable polyol ester, comprising the following steps: (1) Feeding and mixing: Weigh 16.43g of neopentyl glycol, 148.23g of trimethylolpropane, 150g of isoheptanoic acid, 166.15g of isooctanoic acid, 182.31g of isononanoic acid and 3.46g of HZMS-5 molecular sieve into a 1000mL reaction flask and stir to mix well; the rest is the same as in Example 1.

[0039] Example 8: A method for preparing a highly resistant alcoholysis and transesterification stable polyol ester, comprising the following steps: (1) Feeding and mixing: Weigh 49.30g of neopentyl glycol, 444.69g of trimethylolpropane, 150g of isoheptanoic acid, 498.46g of isooctanoic acid, 911.54g of isononanoic acid, and 12.32g of HZMS-5 molecular sieve into a 3000mL reaction flask and stir to mix well; the rest is the same as in Example 1.

[0040] Comparative Example 1: A method for preparing a polyol ester, comprising the following steps: Except for the short-range molecular distillation deacidification and dehydration without step (4), the other steps are the same as in Example 1.

[0041] Comparative Example 2: A method for preparing a polyol ester, comprising the following steps: Except for the molar ratio of isooctanoyl chloride added in step (5) to the excess hydroxyl group in step (1) being 0.9, the other steps are the same as in Example 1.

[0042] Comparative Example 3: A method for preparing a polyol ester, comprising the following steps: Except for the fact that the molar ratio of the amount of isooctanoyl chloride added in step (5) to the excess hydroxyl group in step (1) is 1.15, the other steps are the same as in Example 1.

[0043] Comparative Example 4: A method for preparing a polyol ester, comprising the following steps: Except for step (5), which uses atmospheric pressure, the other steps are the same as in Example 1.

[0044] Comparative Example 5: A method for preparing a polyol ester, comprising the following steps: Except for the short-range molecular distillation deacidification and deacylation in step (6), the other steps are the same as in Example 1.

[0045] The polyol ester products prepared in Examples 1-8 and Comparative Examples 1-5 were subjected to alcoholysis resistance tests. The operating conditions were as follows: the polyol ester and anhydrous ethanol were mixed at a mass ratio of 1:1, kept at 120°C in a sealed constant temperature for 8 h, and the ethanol was removed by molecular distillation at 60°C. The acid value, hydroxyl value, viscosity retention rate and system conditions are shown in Table 1.

[0046] Table 1. Results of alcoholysis resistance tests for the examples and comparative products. .

[0047] After alcoholysis, the polyol esters obtained in Examples 1-8 showed an increase in acid value of <0.03 mg KOH / g, a viscosity retention rate of over 96%, and an increase in hydroxyl value of <0.03 mg KOH / g. KOH / g; Compared with Comparative Example 1, Example 1 lacks short-path molecular distillation for carboxyl end-capping, resulting in incomplete carboxyl reaction and a slightly higher product acid value. The residual carboxyl group has a certain catalytic effect on alcoholysis, leading to a lower viscosity retention rate. Compared with Comparative Example 2, Example 1 has an acyl chloride dosage of only 0.9 times the excess hydroxyl group, resulting in incomplete hydroxyl reaction and a higher product hydroxyl value. The hydroxyl group has a catalytic effect on alcoholysis, leading to a significant decrease in viscosity retention rate. Compared with Comparative Example 3, Example 1 has an excess of acyl chloride. The acidity of the excess acyl chloride is close to that of hydrogen chloride, which has a significant destructive effect on the ester, resulting in higher product acid value and hydroxyl value, and a significant decrease in viscosity retention rate. Compared with Comparative Example 4, Example 1 lacks vacuum operation during acyl chloride addition, preventing the timely removal of hydrogen chloride byproducts from the system, resulting in poor product quality and a significant decrease in viscosity retention rate. Compared with Comparative Example 5, Example 1 lacks short-path molecular distillation for deacidification and deacylation. The HCl produced by the decomposition of acyl chloride and the residual acyl chloride remain in the system, resulting in a high product acid value and a significant decrease in viscosity retention rate.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the spirit and principle of the present invention without any creative effort should be included within the protection scope of the present invention.

Claims

1. A highly resistant alcoholysis and transesterification stable polyol ester, characterized in that, It is prepared by deep end-capping esterification of a complex of highly hindered polyols and C7-C9 branched saturated isomeric fatty acids, wherein the molar ratio of the carboxyl group in the C7-C9 branched mixed isomeric fatty acid to the hydroxyl group in the complex of highly hindered polyols is 1:1.02-1:1.

08. The compounded high-steric polyol is a mixture of neopentyl glycol and trimethylolpropane, with a molar ratio of 1:5 to 1:

9. The C7-C9 branched mixed isomeric fatty acids are a complex system of isoheptanoic acid, isooctanoic acid, and isononanoic acid, with a molar ratio of 1:1 to 3:1 to 5. The deep end-capping esterification uses a solid acid catalyst, which is HZSM-5 molecular sieve, and its dosage is 0.4%-0.9% of the total mass of the compound high steric hindrance polyol and C7-C9 branched mixed isomeric fatty acids.

2. The highly resistant alcoholysis and transesterification stable polyol ester according to claim 1, characterized in that, The molar ratio of the carboxyl group in the C7-C9 branched mixed isomeric fatty acid to the hydroxyl group in the compound high-hindrance polyol is 1:1.05; the molar ratio of neopentyl glycol to trimethylolpropane is 1:7; the molar ratio of isoheptanoic acid, isooctanoic acid, and isononanoic acid is 1:2.5:4; and the amount of the solid acid catalyst HZSM-5 molecular sieve is 0.6% of the total mass of the compound high-hindrance polyol and the C7-C9 branched mixed isomeric fatty acid.

3. The method for preparing the highly resistant alcoholysis and transesterification stable polyol ester according to claim 1, characterized in that, The specific steps are as follows: (1) Feeding and mixing: Add the compound high steric hindrance polyol and C7-C9 branched mixed isomeric fatty acids into the reactor, add solid acid catalyst, and stir evenly; (2) Low temperature and normal pressure pre-esterification: Heat to 100-150℃, react at normal pressure for 2-6 hours, and separate the water generated in the early stage of the reaction with a water separator to complete the preliminary esterification; (3) High temperature and high vacuum esterification: After turning on the vacuum system of the water separator, control the vacuum degree of the system to -0.085 to -0.095 MPa, raise the temperature to 190 to 250°C, and perform constant temperature and negative pressure deep esterification for 5 to 7 hours; after the end, filter and fine filter, and use the filtrate for later use. (4) Short-path molecular distillation carboxyl end capping: The filtrate obtained in step (3) is deacidified and dehydrated by short-path molecular distillation. A scraped membrane short-path molecular distillation device is used, with a distillation temperature of 190-250℃, an empty pressure of less than 20Pa, a feed pressure of less than 40Pa, and a rotation speed of 120±10r / min. (5) Hydroxyl elimination: Pre-cool the reaction solution system of step (4) in an ice bath. When it drops to 0°C, start adding fatty acyl chloride dropwise while simultaneously pulling up a vacuum. React for 6-12 hours. (6) Short-path molecular distillation for deacidification and deacylation: The reaction solution obtained in step (5) is subjected to short-path molecular distillation for deacidification and deacylation. A scraped-film short-path molecular distillation device is used, with a temperature of 190-250℃, an empty pressure of less than 20Pa, a feed pressure of less than 40Pa, and a rotation speed of 120±10r / min. (7) Refining and purification: Inert powder adsorption is used to remove impurities, filtration and precision filtration are used to obtain a high-stability anti-ester exchange polyol ester product.

4. The method for preparing the highly resistant alcoholysis and transesterification stable polyol ester according to claim 3, characterized in that, In step (2), the reaction temperature is increased in a gradient: 105℃±5℃ for 1 h, 125℃±5℃ for 1 h, and 145℃±5℃ for 2 h.

5. The method for preparing a highly resistant alcoholysis and transesterification stable polyol ester according to claim 3, characterized in that, In step (3), the reaction temperature is 210℃±5℃, the reaction time is 6 h, and the acid value of the product should be less than 0.2 mgKOH / g after the reaction is completed; the filtration in step (3) is pressure filtration with a pressure of 0.4MPa, and the fine filtration is using a 0.22μm nylon filter membrane with a pressure of 0.4MPa.

6. The method for preparing the highly resistant alcoholysis and transesterification stable polyol ester according to claim 3, characterized in that, In step (4), the distillation temperature is 210℃±5℃, and the acid value of the product should be less than 0.02 mg KOH / g after the reaction is completed.

7. The method for preparing a highly resistant alcoholysis and transesterification-stable polyol ester according to claim 3, characterized in that, In step (5), the fatty acyl chloride is one or more combinations of isooctanoyl chloride, isoheptanoyl chloride, and isononanoyl chloride. The molar ratio of the dosage to the excess hydroxyl group in step (1) is 1-1.

1. The excess hydroxyl group is the total number of hydroxyl groups in the compound high steric hindrance polyol minus the total number of carboxyl groups in C7-C9 branched saturated isomeric fatty acids. In step (5), the reaction temperature is 0℃±5℃ and the reaction time is 10h; the reaction vacuum degree is -0.085~-0.095 MPa; the hydroxyl value detected at the end of the reaction is less than 0.02 mg KOH / g.

8. The method for preparing a highly resistant alcoholysis and transesterification stable polyol ester according to claim 7, characterized in that, The fatty acyl chloride mentioned in step (5) is isonononyl chloride, and the molar ratio of the amount of fatty acyl chloride added to the excess hydroxyl group in step (1) is 1.

9. The method for preparing a highly resistant alcoholysis- and transesterification-stable polyol ester according to claim 3, characterized in that, In step (6), the reaction temperature is 210℃±5℃. In step (7), the inert powder is one or more combinations of sodium carbonate, sodium bicarbonate, potassium bicarbonate, potassium carbonate, and diatomaceous earth, and the amount added is 0.4%-1.2% of the mass of the reaction solution obtained in step (6). In step (7), the adsorption temperature is 25℃±15℃ and the adsorption time is 3 h. The filtration conditions are pressure filtration with a pressure of 0.4 MPa. The precision filtration conditions are a nylon filter membrane with a pore size of 0.22 μm and a pressure of 0.4 MPa.

10. The method for preparing a highly resistant alcoholysis- and transesterification-stable polyol ester according to claim 9, characterized in that, In step (7), the inert powder is a combination of sodium bicarbonate and diatomaceous earth. The amount of sodium bicarbonate is 0.2%-0.6% of the mass of the reaction solution obtained in step (6), and the amount of diatomaceous earth is 0.2%-0.6% of the mass of the reaction solution obtained in step (6).