High viscosity fluorine-containing synthetic ester, and preparation method and application thereof

Abstract

The application provides a high-viscosity fluorine-containing synthetic ester and a preparation method and application thereof. The high-viscosity fluorine-containing synthetic ester provided by the application has a specific molecular structure, most of the end-capping agents are common monohydric alcohols, the viscosity upper limit of the fluorine-containing synthetic ester is higher, the viscosity-temperature performance and low-temperature fluidity are better, and a part of the end-capping agents are perfluoro monohydric alcohols, so that the thermal stability, oxidation stability and hydrophobicity of the synthetic ester are improved. Meanwhile, in the above structure, only part of the end-capping agents are perfluoro monohydric alcohols, so that the biodegradability of the synthetic ester is also improved, and the synthetic ester is more environmentally friendly. The preparation method of the high-viscosity fluorine-containing synthetic ester provided by the application uses monohydric alcohol as an end-capping agent, the monohydric alcohol includes 20-50 mol% of perfluoro monohydric alcohol, the obtained high-viscosity fluorine-containing synthetic ester has a higher viscosity upper limit, better thermal stability, oxidation stability and hydrophobicity; and through improvement of feeding modes, temperature rising modes and the like, the product yield and reaction conversion rate and the like are improved.

Description

Technical Field

[0001] This invention belongs to the field of specialty oils, and more specifically, relates to a high-viscosity fluorinated synthetic ester, its preparation method, and its application. Background Technology

[0002] Lubricating oil is an oily liquid primarily used to reduce equipment load, improve working efficiency, and reduce equipment wear. Besides lubrication, it also provides cooling, rust prevention, corrosion prevention, cleaning, sealing, buffering, power transmission, and electrical insulation, thus being widely used in transportation, industry, agriculture, military, medicine, aerospace, and daily life. In recent years, with the rapid development of the national economy and the continuous growth of automobile ownership, my country's total lubricating oil consumption has ranked among the world's highest. Against the backdrop of dual-carbon goals and rapid social development, the requirements for high performance, environmental friendliness, safety, and self-sufficiency in specialty oils are gradually increasing. The ever-growing demand for high-performance lubricating oils is constantly forcing the structural upgrading of my country's lubricating oil industry, prompting the industry to shift from a quantity-driven growth model to a quality-driven development model, indicating that high-performance lubricating oils have broad market application prospects.

[0003] Mineral base oils, currently the most widely used base oils, generally have limited overall performance, are difficult to biodegrade in the natural environment, and their raw materials are non-renewable. While bio-based oils offer advantages such as good lubricity, biodegradability, and renewable raw materials, they contain many non-ideal components, resulting in poor oxidation stability, thermal stability, and low-temperature fluidity, thus limiting their widespread application. Synthetic esters, belonging to Group V base oils, possess excellent lubricity, low-temperature fluidity, thermal and oxidation stability, biodegradability, and are safe and non-toxic, making them a viable option as a green, high-end synthetic base oil or blending component. High-viscosity synthetic esters are ideal base oils or blending components for gear oils and transmission equipment oils. Statistics show that the domestic demand for wind power oils (gear oils, etc.) exceeds 60,000 tons per year. Currently, most wind turbine gearboxes in China use imported gear oils, with Mobil, Shell, Fuchs, Castrol, and BASF accounting for over 90% of the wind power oil market, priced at approximately 50,000 to 80,000 yuan per ton. Developing high-viscosity synthetic esters can enrich my country's product range in the synthetic oil sector and reduce over-reliance on foreign oil products.

[0004] Among the high-viscosity synthetic esters reported so far, Cai Guoxing, Wei Meiying, and others synthesized a composite neopentyl polyol ester with a "dumbbell structure". They first used neopentyl polyol to esterify with dicarboxylic acid to synthesize a polyhydroxy oligomer, and then used a monocarboxylic acid as a capping agent to esterify the unreacted hydroxyl groups. Although the introduction of dicarboxylic acid can increase the chain length of the ester molecule to improve viscosity and viscosity index, this method has the following drawbacks: (1) The molecular configuration design is unreasonable, and it is difficult to achieve a high viscosity and viscosity index in the clarified state; (2) p-toluenesulfonic acid catalyst will lead to excessive sulfur content in the product and more reaction byproducts; (3) using toluene as a water-carrying agent is harmful to the health of operators, easily causes environmental pollution and increases energy consumption; (4) the alkaline washing refining method results in a large amount of wastewater discharge and low product yield. US Patent US6774093B2 discloses a method for synthesizing polypentaerythritol mixed esters using straight-chain fatty acids, branched fatty acids and pentaerythritol as raw materials. This method utilizes the intermolecular etherification reaction of pentaerythritol to extend the main chain length. The kinematic viscosity (100℃), viscosity index, and pour point of the purified polypentaerythritol mixed ester are 19.2 mm. 2 ·s -1 The viscosity of this base oil is 97℃, and it reaches -32℃. Clearly, the viscosity of this base oil cannot be very high, and its viscosity-temperature properties are not ideal. Ji Hairui et al. synthesized pentaerythritol levulinate using pentaerythritol and levulinic acid; its kinematic viscosity, viscosity index, and pour point at 100℃ were 19.14 mm. 2 ·s -1 The data shows that introducing acyl groups can effectively increase the viscosity of the synthesized ester, but it will severely reduce its viscosity-temperature properties and low-temperature fluidity. Summary of the Invention

[0005] The present invention aims to at least partially solve one of the technical problems in the prior art. Therefore, one object of the present invention is to provide a high-viscosity fluorinated synthetic ester that simultaneously possesses high viscosity and an ultra-high viscosity index, as well as good thermal stability, oxidation stability, hydrophobicity, and low-temperature fluidity.

[0006] In a first aspect, the present invention provides a high-viscosity fluorinated synthetic ester having A(B) x (C) y The general molecular formula of the structure, where A is selected from C5H8, C6H 11 C5H9, C5H 10 C6H 12 O, C 10 H 18 Any one of O; B stands for -OOC-(CH2) a -COO-C n H 2n+1 ; C stands for -OOC-(CH2) a -COO-C m F 2m+1 ; x is a real number from 1 to 6, y is a real number from 1 to 3, a is an integer from 3 to 10, n is an integer from 6 to 9, and m is an integer from 6 to 10.

[0007] In some embodiments of the present invention, the high-viscosity fluorinated synthetic ester has the structures shown in formula (I) and formula (II):

[0008] The high-viscosity fluorinated synthetic ester provided by this invention uses common monohydric alcohols as end-capping agents, resulting in a higher upper limit of viscosity, better viscosity-temperature performance, and better low-temperature fluidity. A portion of the end-capping agents are perfluorinated monohydric alcohols, which improves the thermal stability, oxidation stability, and hydrophobicity of the synthetic ester. Furthermore, in the above structure, only a portion of the end-capping agents are perfluorinated monohydric alcohols, which also improves the biodegradability of the synthetic ester, making it more environmentally friendly.

[0009] In a second aspect, the present invention provides a method for preparing the high-viscosity fluorinated synthetic ester, wherein the raw materials include dicarboxylic acids and polyols, and a monohydric alcohol is used as a capping agent, wherein the monohydric alcohol includes 20-50 mol% of a perfluoromonohydric alcohol, preferably 25-35 mol% of the perfluoromonohydric alcohol.

[0010] The preparation method provided by this invention, using a monohydric alcohol as a capping agent, produces a synthetic ester with a higher upper viscosity limit, better viscosity-temperature properties, and better low-temperature fluidity. The incorporation of a portion of a perfluorinated monohydric alcohol improves the thermal stability, oxidative stability, and hydrophobicity of the synthetic ester, while maintaining its biodegradability. When the amount of perfluorinated monohydric alcohol is within the above-mentioned range, the resulting synthetic ester exhibits better thermal stability, oxidative stability, and hydrophobicity, while also possessing good biodegradability.

[0011] In some embodiments of the present invention, the perfluoromonohydrin is selected from at least one of perfluorohexanol, perfluoroheptanol, perfluorooctanol, perfluorononanol, and perfluorodecanol. The preparation method provided by the present invention, which selects perfluoromonohydrins having 5-9 carbon atoms, has the advantages of high conversion rate, thermal stability, and good oxidative stability.

[0012] In some embodiments of the present invention, the ordinary monohydric alcohol comprises 50-100 mol% of branched monohydric alcohol, preferably comprising 75-100 mol% of branched monohydric alcohol.

[0013] In some embodiments of the present invention, the branched monohydric alcohol is selected from at least one of 2-ethylhexanol, 3,5,5-trimethylhexanol, 2-methylheptanol, and 2-ethylbutanol.

[0014] In some embodiments of the present invention, the common monohydric alcohol further includes 0-50 mol% of an odd-carbon straight-chain monohydric alcohol.

[0015] In some embodiments of the present invention, the odd-carbon straight-chain monohydric alcohol is selected from at least one of n-hexanol, n-heptanol, and n-nonanol.

[0016] The preparation method provided by this invention, by employing branched monohydric alcohols and / or odd-carbon straight-chain monohydric alcohols, can increase the structural asymmetry of the ester molecules in the obtained synthetic ester structure, thereby giving the obtained synthetic ester better low-temperature fluidity. When the amount of the branched monohydric alcohols and / or odd-carbon straight-chain monohydric alcohols is within the aforementioned specific range, it can further increase the structural asymmetry of the ester molecules in the obtained synthetic ester structure, thereby giving the obtained synthetic ester better low-temperature fluidity. Furthermore, by further optimizing the specific selection of the branched monohydric alcohols and / or odd-carbon straight-chain monohydric alcohols, this invention further increases the structural asymmetry of the ester molecules in the obtained synthetic ester structure, thereby giving the obtained synthetic ester better low-temperature fluidity.

[0017] In some embodiments of the present invention, the polyol is selected from 2-6 polyols, and / or the dicarboxylic acid is selected from C5-12 dicarboxylic acids.

[0018] In some embodiments of the present invention, the dicarboxylic acid is selected from at least one of glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, undecanoic acid, and dodecanoic acid.

[0019] In some embodiments of the present invention, the polyol is selected from at least one of pentaerythritol, dipentaerythritol, neopentyl glycol, trimethylolpropane, and trimethylolethane.

[0020] The preparation method provided by this invention uses polyols selected from 2-6 polyols, which have the effect of improving oil viscosity. In particular, when the polyol is selected from pentaerythritol, it also improves viscosity, thermal stability, and oxidation stability. Simultaneously, the preparation method provided by this invention uses dicarboxylic acids selected from C5-12 dicarboxylic acids, which have the effect of improving the oil viscosity index. In particular, when the dicarboxylic acids are selected from picric acid, pimelic acid, azelaic acid, and sebacic acid, they can significantly improve the oil viscosity index while maintaining good low-temperature fluidity.

[0021] In some embodiments of the present invention, the preparation method includes: Step (1): The dicarboxylic acid, polyol and catalyst are mixed to carry out the first step reaction; then a monohydric alcohol and catalyst are added to carry out the second step reaction; and a reaction mixture is obtained. Step (2) involves separating the reaction mixture to obtain a high-viscosity synthetic ester; In step (1), the dicarboxylic acid and the catalyst are first mixed, and then the polyol is added intermittently (20-30 wt.%) every 15-20 min.

[0022] The preparation method provided by this invention first mixes a dicarboxylic acid and a catalyst, then intermittently and gradually adds the polyol, and finally adds a branched / odd-carbon straight-chain monohydric alcohol and a perfluorinated monohydric alcohol together for end-capping. This stepwise and gradual feeding method, especially the intermittent and gradual addition of small amounts of polyol (20-30 wt.% added every 15-20 minutes), can effectively reduce bridging between polyols, guide molecular design, improve the yield of the target product, and overcome the reduced yield of the target product caused by the disordered "one-pot" method.

[0023] In some embodiments of the present invention, in step (1), the temperature of the first reaction is 150°C to 170°C, and the reaction time is 1.5 to 2 hours. The first reaction is carried out at the specified temperature and time, which has the effect of improving the reaction conversion rate and reducing bridging reactions.

[0024] In some embodiments of the present invention, the amount of protective nitrogen introduced in step (1) is ≤2 mL·min. -1 ·g -1 .

[0025] On the other hand, replacing toxic water-carrying agents such as toluene, xylene, or cyclohexane with nitrogen reduces environmental pollution and lowers energy consumption.

[0026] In some embodiments of the present invention, in step (1), the second reaction is first carried out at 150°C to 170°C for 1.5 to 2 hours, and then the temperature is raised to 170°C to 180°C for more than 4 hours.

[0027] The preparation method provided by this invention adopts a stepwise heating method, which is beneficial to obtaining ideal molecular configuration and composition, and at the same time improves the reaction conversion rate; at the same time, controlling the temperature and time within the above range has the effect of reducing energy consumption.

[0028] In some embodiments of the present invention, the catalyst is selected from a composite metal oxide catalyst in which the molar ratio of tin to the second metal is (6-12):1; the second metal is selected from at least one of zirconium, titanium, aluminum, cobalt and tungsten.

[0029] In some embodiments of the present invention, the amount of catalyst added is 1.0 to 3.0 wt.% of the total mass of the reactants. In the first reaction, the amount of catalyst used is 1.0 to 3.0 wt.% of the total mass of the dicarboxylic acid and polyol; in the second reaction, the amount of catalyst used is 1.0 to 3.0 wt.% of the mass of the monohydric alcohol.

[0030] The preparation method provided by this invention uses the aforementioned composite metal oxide catalyst to reduce reaction byproducts, product emulsification, and equipment corrosion while ensuring a high conversion rate. It also provides a basis for simplifying the refining process and reducing wastewater discharge.

[0031] In some embodiments of the present invention, the separation method in step (2) is vacuum filtration, and the temperature of vacuum filtration is 120-140°C.

[0032] In some embodiments of the present invention, step (2) further includes: refining the high-viscosity synthetic ester crude product obtained by vacuum filtration; preferably, the refining is carried out by two-stage or three-stage molecular distillation to finally obtain a refined product. The preparation method provided by the present invention uses two-stage or three-stage molecular distillation for separation, which increases the depth of refining, improves product quality, reduces environmental pollution, and also enables full utilization of resources.

[0033] In a third aspect, the present invention provides the application of the high-viscosity fluorinated synthetic ester and / or the high-viscosity fluorinated synthetic ester obtained by the preparation method in transmission mechanisms, electrical equipment or materials; Preferably, the transmission mechanism is selected from at least one of gears, gearboxes, chains, and bearings; Preferably, the electrical equipment or material is selected from at least one of transformers, capacitors, power cables, etc. Preferably, the high-viscosity fluorinated synthetic ester is used as a base oil for gear oil, transmission oil, chain oil, bearing oil, and insulating fluid and / or blending component.

[0034] The high-viscosity fluorinated synthetic ester and its preparation method provided by this invention fundamentally optimize the performance of the synthesized ester by starting with the molecular configuration. Compared with existing high-viscosity synthetic esters and their synthesis processes, it has the following advantages: (1) The molecular configuration is ideally designed, and the target product has high viscosity and ultra-high viscosity index, as well as a lower pour point; the high-viscosity fluorinated synthetic ester provided / obtained by this invention can reach a viscosity of 100-500 mmHg at 40°C. 2 The kinematic viscosity at 100℃ can reach 13-55 mm / s. 2 / s, viscosity index 140-170, thermal decomposition temperature: 280-380℃, hydrophobicity parameter: 15-50, oxidation induction time 180-220min, pour point -50~-20℃, color 2-4.

[0035] (2) Some perfluorinated monohydric alcohols were added to the reactants, which significantly improved the hydrophobicity, thermal stability and oxidation stability of the target product, while also giving it good biodegradability. (3) The synthesis process is more efficient. This invention adopts stepwise feeding and guided molecular design to improve the yield of the target product; further coupled with gradient heating process, it is not only conducive to obtaining ideal molecular configuration and composition, but also improves reaction conversion rate. Detailed Implementation

[0036] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0037] Through numerous experiments, the inventors discovered that the composite neopentyl polyol ester synthesized using common monohydric alcohols as end-capping agents has a higher upper limit of viscosity, better viscosity-temperature performance, and better low-temperature fluidity. However, its thermal stability, oxidation stability, and hydrophobicity need further improvement. The inventors also discovered that using perfluorinated monohydric alcohols as end-capping agents can effectively improve the thermal stability, oxidation stability, and hydrophobicity of oil products.

[0038] Based on this, and addressing the problems of conventional synthetic esters being unable to achieve high viscosity and ultra-high viscosity index, as well as their generally poor thermal oxidation stability and weak water resistance, the first aspect of this invention proposes a high-viscosity fluorinated synthetic ester with A(B) characteristics. x (C) y The general molecular formula is given by: A is selected from C5H8 and C6H. 11 C5H9, C5H 10 C6H 12 O, C 10 H 18 Any one of O; B stands for -OOC-(CH2) a -COO-C n H 2n+1 ; C stands for -OOC-(CH2) a -COO-C m F 2m+1 ; x is a real number from 1 to 6, y is a real number from 1 to 3, a is an integer from 3 to 10, n is an integer from 6 to 9, and m is an integer from 6 to 10.

[0039] Specifically, for pentaerythritol A, which is C5H8, x + y = 4; for trimethylolpropane A, which is C6H8, x + y = 4. 11 x+y=3; for trimethylolethane A is C5H9, x+y=3; for neopentyldiol A is C5H 10 x + y = 2; for dipentaerythritol A, C6H 12 O, x+y=6; for bis(trimethylolpropane) A is C 10 H 18 O, x+y=4; B: -OOC-(CH2) a -COO-C n H 2n+1 'a' represents the number of carbon atoms in a dicarboxylic acid minus 2, which is 3-10; 'n' represents the number of carbon atoms in a common monohydric alcohol, which is 6-9. C: -OOC-(CH2) a -COO-C m F 2m+1 , where m is the number of carbon atoms in the perfluoromonohydrin, ranging from 6 to 10.

[0040] By incorporating a portion of perfluoromonohydrin, the structure of the synthesized ester has only some end-capping groups that are perfluoroalkyl, which enables the synthesized ester to simultaneously possess high viscosity, thermal stability, oxidation stability, and good biodegradability.

[0041] Specifically, the high-viscosity fluorinated synthetic ester can have the structures shown in formula (I) and formula (II):

[0042] A novel molecular configuration of fluorinated neopentyl polyol ester exhibits significantly improved viscosity, viscosity index, pour point, hydrophobicity, and thermal oxidation stability. This invention provides a high-viscosity fluorinated synthetic ester. The above general formula (I) is illustrated using trimethylolpropane as an example, formula (II) is synthesized using pentaerythritol as a raw material, and Example 2 uses trimethylolpropane as the neopentyl polyol raw material. In fact, trimethylolpropane, pentaerythritol, neopentyl glycol, bis(trimethylolpropane), and bis(pentaerythritol) can all be used as neopentyl polyol raw materials.

[0043] Accordingly, the present invention also provides a method for preparing the high-viscosity fluorinated synthetic ester, wherein a dicarboxylic acid and a polyol are used as raw materials for esterification reaction, and 20-50 mol% of a perfluorinated monohydric alcohol and 50-80 mol% of a common monohydric alcohol (composed of 50-100 mol% of branched monohydric alcohol and 0-50 mol% of odd-carbon straight-chain monohydric alcohol, preferably composed of 75-100 mol% of branched monohydric alcohol and 0-25 mol% of odd-carbon straight-chain monohydric alcohol) are used as end-capping agents, and a composite metal oxide is used as a catalyst; the specific synthesis process is as follows: (1) Nitrogen gas (inlet flow rate ≤ 2 mL·min) -1 ·g -1 For example, 1.5-2 mL / min -1 ·g -1 Under protective conditions, a dicarboxylic acid, neopentyl polyol, and a composite metal oxide catalyst are first mixed (the dicarboxylic acid is added first, followed by intermittent, gradual addition of the polyol (such as neopentyl polyol) at 20-30 wt.% every 15-20 minutes, to minimize bridging between the neopentyl polyols and thus improve the yield of the target product). The first step reaction is carried out at 150℃~170℃ for 1.5~2 hours. Then, a common monohydric alcohol, a perfluorinated monohydric alcohol, and the composite metal oxide catalyst are added. The catalyst is an oxide catalyst. A second reaction is first carried out at 150℃~170℃ for 1~2 hours, then the temperature is raised to 170℃~180℃, and the second reaction continues for more than 4 hours to obtain a reaction mixture. The molar ratio of tin to zirconium / aluminum / cobalt / tungsten in the composite metal oxide catalyst is (6~12):1. The synthesis method is a hydrothermal method (hydrothermal temperature 120℃~190℃, hydrothermal time 8~24 hours), and the amount added is 1.0~3.0 wt.% of the total mass of the reactants. (2) The composite metal oxide catalyst and non-ideal components in the reaction mixture obtained in step (1) are vacuum filtered at a temperature of 120-140°C to separate the synthetic ester and obtain a high-viscosity fluorinated synthetic ester. (3) The crude product of high viscosity fluorinated synthetic ester obtained by vacuum filtration is refined. According to the specific performance requirements, a two- or three-stage molecular distillation separation method is selected to finally obtain the refined product.

[0044] The preparation method described in the embodiments of this invention fully utilizes the characteristics of different raw materials, combining the advantages of diesters, polyol esters, and fluorinated oils to synthesize a composite fluorinated neopentyl polyol ester with a novel molecular structure possessing high viscosity, ultra-high viscosity index, low pour point, good thermal oxidation stability, and good water resistance. Using composite metal oxides as catalysts can reduce reaction byproducts, product emulsification, and equipment corrosion while ensuring high conversion rates, while simplifying the refining process and reducing wastewater discharge. In terms of the synthesis process, stepwise feeding is adopted to reduce bridging between polyols, guide molecular design, and improve the yield of the target product. Simultaneously, gradient heating is used for the second reaction and stepwise feeding (this can be analyzed using extreme thinking; if a very small amount of polyol is added to a large amount of diacid, the concentration of diacid around the polyol will be extremely high, which is beneficial for the reaction of each hydroxyl group of the polyol with different carboxyl groups of the diacid; conversely, if a very small amount...). Adding a large amount of diacid to a large amount of polyol will result in an extremely high concentration of polyol around the diacid, causing the two carboxyl groups of the diacid to react with the hydroxyl groups of different polyol molecules, thus resulting in a large number of bridging reactions. This coupling process is beneficial for obtaining ideal molecular configuration and composition and improves reaction conversion rate. On the other hand, nitrogen is used instead of toxic water-carrying agents such as toluene, xylene or cyclohexane, which reduces environmental pollution and energy consumption. In terms of product refining, this invention uses molecular distillation refining instead of traditional alkaline washing refining, which increases the refining depth, improves product quality, reduces environmental pollution, and also enables full utilization of resources.

[0045] In a specific embodiment, the dicarboxylic acid is selected from at least one of glutaric acid, adipic acid, pimelic acid, azelaic acid, and sebacic acid, and the polyol is selected from at least one of pentaerythritol, dipentaerythritol, trimethylolpropane, and trimethylolethane.

[0046] The perfluoromonohydrin can be at least one of perfluorohexanol, perfluoroheptanol, perfluorooctanol, perfluorononanol, and perfluorodecanol, and the amount added can be 20 mol%, 25 mol%, 30 mol%, 35 mol%, 40 mol%, 45 mol%, 50 mol%, or other suitable amounts and composition ranges within the above ranges.

[0047] The branched monohydric alcohol is selected from at least one of 2-ethylhexanol, 3,5,5-trimethylhexanol, 2-methylheptanol and 2-ethylbutanol, and its proportion in the ordinary monohydric alcohol can be 50 mol%, 60 mol%, 70 mol%, 75 mol%, 80 mol%, 90 mol%, 100 mol%, or other suitable amounts and ranges of composition within the above ranges.

[0048] The odd-carbon straight-chain monohydric alcohol can be at least one of n-hexanol, n-heptanol, and n-nonanol, and its addition amount can be 0, 10 mol%, 20 mol%, 30 mol%, 40 mol%, 50 mol%, or other suitable amounts and composition ranges within the above ranges.

[0049] The composite metal oxide catalyst can be composed of tin and a second metal (at least one of zirconium, aluminum, cobalt, and tungsten) in a molar ratio of (6-12):1. The types of metal can be different combinations of tin and zirconium, tin and aluminum, tin and cobalt, tin and tungsten, or tin and zirconium and tungsten, which will not be elaborated here. The molar ratio of tin to the second metal can be 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, and 12:1, or other suitable amounts and proportions within the ranges mentioned above.

[0050] Taking the tin-zirconium composite oxide catalyst as an example, its preparation method is as follows: (1) Prepare a mixed salt solution with a volume of about 80 mL by mixing 0.2 mol / L ZrOCl2 solution, SnCl2·2H2O powder and deionized water in a certain proportion. Add an appropriate amount of ammonia water under rapid stirring to adjust its pH to about 9.0±0.1; (2) After stirring at room temperature for 1 h, pour the catalyst mother liquor into a 100 mL hydrothermal reactor with a polytetrafluoroethylene liner, and purge the air above the liquid surface with nitrogen gas. Perform hydrothermal treatment in an oil bath according to a certain temperature and time; (3) Filter the product after the reaction, and wash the precipitate alternately with deionized water and anhydrous ethanol until the filtrate can no longer be detected with silver nitrate solution; (4) Place the filtered solid in a vacuum drying oven and dry it at 60℃ for 12 h to obtain the tin-zirconium composite oxide. The hydrothermal temperature is 120℃~190℃ and the hydrothermal time is 8~24 h.

[0051] In preparing the high-viscosity fluorinated synthetic ester, the catalyst is added in an amount of 1-3 wt%, such as 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, and 3 wt%.

[0052] In the following examples, the yield, acid value, kinematic viscosity at 40°C and 100°C, viscosity index, color, oxidation induction time, and pour point of the obtained synthetic ester were tested. The acid value, expressed as mgKOH / g equivalent content, was used to evaluate the free acid content in the oil and to calculate the carboxyl conversion rate; kinematic viscosity was used to evaluate the viscosity of the synthetic ester, and the viscosity index was calculated based on the kinematic viscosity at 40°C and 100°C; kinematic viscosity was used to evaluate the viscosity-temperature properties of the synthetic ester; color was used to evaluate the color of the oil; oxidation induction time was used to evaluate the oxidation stability of the oil; and pour point was used to evaluate low-temperature fluidity.

[0053] The specific testing methods for the above tests are as follows: Yield: Y = m2 / m1 × 100%; Where Y represents the yield, m2 represents the mass of the product obtained after molecular distillation and purification, and m1 represents the theoretical mass of the oil calculated based on the added raw materials. Acid value: AV = 56.11 × (V - V0) × C KOH / m oil ; Where AV represents the acid value, mgKOH / g; C KOH The concentration of the potassium hydroxide isopropanol solution is in mol / L. m oil The mass of the oil sample is in grams. V and V0 are the volumes (in mL) of potassium hydroxide isopropanol solution consumed when the oil-containing solution and the blank solution reach the titration endpoint, respectively.

[0054] Kinematic viscosity: Measured according to the national standard GB / T 265-1988 "Determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products".

[0055] Viscosity index: Calculated according to the national standard GB / T 1995-1998 "Calculation method of viscosity index of petroleum products" and the kinematic viscosity values ​​of oil at 40°C and 100°C.

[0056] Color: Measured according to the oxidation induction time of the petrochemical industry standard SH / T 0168-1992 "Determination of Color of Petroleum Products".

[0057] Thermal decomposition temperature: Measured using thermogravimetric analysis (nitrogen atmosphere).

[0058] Hydrophobicity parameter: calculated by logP ow We obtain, where P ow =c n-o / C w , is the equilibrium coefficient of oil in n-octanol and water, and the larger the value, the stronger the hydrophobicity.

[0059] Oxidation induction time: Measured according to industry standard SH / T 0193-2008 "Determination of Oxidation Stability of Lubricating Oils - Rotary Bomb Oxygen Method".

[0060] Pour point: Measured according to the national standard GB / T 3535-2006 "Determination of Pour Point of Petroleum Products".

[0061] Biodegradability: Tested according to OECD 301A-F standards.

[0062] Reaction conversion rate: X = (1 - AV) f / AV0)×100%, Where X represents the conversion rate, and AV0 and AVf The values ​​are the acid values ​​of the system before and after the reaction, in mgKOH / g.

[0063] The present invention provides / obtains a high-viscosity fluorinated synthetic ester, the viscosity of which at 40°C can reach 100-500 mmHg. 2 The kinematic viscosity at 100℃ can reach 13-55 mm / s. 2 / s, viscosity index 140-170, thermal decomposition temperature: 280-380℃, hydrophobicity parameter: 15-50, oxidation induction time 180-220min, pour point -50~-20℃, color 2-4.

[0064] The information regarding the raw materials, reagents, instruments, and equipment involved in the following embodiments is as follows: name Specification Manufacturers tin(II) chloride dihydrate AR, 98% Macklin Zirconium oxychloride octahydrate AR, 99% Aladdin Deionized water Secondary distillation self made Ammonia (25 wt.%) AR Tianjin Fuyu Fine Chemical Co., Ltd. Anhydrous ethanol AR Beijing Chemical Plant silver nitrate AR Shanghai No.1 Reagent Factory

[0065] All other raw materials used in the embodiments of this invention are commercially available products.

[0066] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0067] Example 1 This embodiment provides a high-viscosity fluorinated synthetic ester, which has the structures shown in formula (I) and formula (II):

[0068] The high-viscosity fluorinated synthetic ester provided in this embodiment can be prepared by Example 2 or 3 of the preparation method provided in the following embodiments of this application.

[0069] Example 2 This embodiment provides a method for preparing the high-viscosity fluorinated synthetic ester, wherein trimethylolpropane (neopentyl polyol), adipic acid (dicarboxylic acid), 2-ethylhexanol (branched monohydric alcohol), and perfluoroheptanol (perfluoro monohydric alcohol) are added to the reaction system in two steps at a molar ratio of 1:3:2:1. The first step involves adding trimethylolpropane, adipic acid, and a tin(II) zirconium oxide catalyst in a molar ratio of 1:3 (the adipic acid and tin(II) zirconium oxide catalyst are added first, and trimethylolpropane is added intermittently at a rate of 20 wt.% / 15 min to minimize bridging between trimethylolpropane molecules and thus improve the yield of the target product), forming a "skeleton structure." The second step involves adding 2-ethylhexanol, perfluoroheptanol, and a tin(II) zirconium oxide catalyst (at 1% of the mass of 2-ethylhexanol and perfluoroheptanol) for "heading treatment."

[0070] The first reaction was carried out at a temperature of 160℃ for 1.5 hours. The second reaction was initiated at 160℃, increased to 170℃ after 1 hour, and continued for another 4 hours. The catalyst dosage was 1 wt.% of the total mass of the reactants, and the nitrogen flow rate was 2 mL / min. -1 ·g -1 The stirring speed was 800 rpm. After the reaction was completed, the high-viscosity fluorinated synthetic ester and the composite metal oxide catalyst were separated by vacuum filtration. The crude high-viscosity fluorinated synthetic ester product was obtained under the above synthesis conditions.

[0071] The obtained high-viscosity fluorinated synthetic ester crude product was purified by two-stage molecular distillation. The operating conditions for the first-stage molecular distillation were as follows: evaporator temperature 170℃, internal cooler temperature 25℃, absolute pressure 2Pa, and scraping film speed 360rpm. Keeping other conditions unchanged, the second-stage molecular distillation was carried out at an evaporation temperature of 180℃ to obtain the purified high-viscosity synthetic ester for gears.

[0072] In this embodiment, the obtained high-viscosity fluorinated synthetic ester has a similar structure to that provided by formula (I) in Example 1, and the yield and acid value of the obtained product are 93 wt.% and 0.05 mg KOH / g, respectively. The kinematic viscosity, viscosity index, color, thermal decomposition temperature, hydrophobic parameter, oxidation induction time, and pour point at 40°C and 100°C are 249.5 mm. 2 / s, 28.9mm 2 / s, 153, 2, 315℃, 34, 198min and -32℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 81%.

[0073] Example 3 This embodiment provides a method for preparing a high-viscosity perfluorinated synthetic ester: pentaerythritol, adipic acid, perfluoroheptanol, and 2-ethylhexanol are added to the reaction system in two steps at a molar ratio of 1:4:1:3. In the first step, pentaerythritol and adipic acid are added in a molar ratio of 1:4 (adipic acid is added first, and pentaerythritol is added intermittently at a rate of 20 wt.% / 15 min to minimize the bridging effect between pentaerythritols and thus improve the yield of the target product), forming a "skeleton structure". In the second step, 2-ethylhexanol, perfluoroheptanol, and tin(II)zirconium composite oxide catalyst (1% of the mass of 2-ethylhexanol and perfluoroheptanol) are added for "heading treatment".

[0074] The first reaction was carried out at a temperature of 170℃ for 1.5 hours. The second reaction was initiated at 170℃, then increased to 180℃ after 1 hour, and continued for another 4 hours. The catalyst dosage was 1% of the total mass of the reactants, and the nitrogen flow rate was 2 mL / min. -1·g -1 The stirring speed was 800 rpm. After the reaction was completed, the high-viscosity fluorinated synthetic ester was separated from the composite metal oxide catalyst by vacuum filtration to obtain the crude product of the high-viscosity fluorinated synthetic ester.

[0075] The obtained high-viscosity fluorinated synthetic ester crude product was purified by two-stage molecular distillation. The operating conditions for the first-stage molecular distillation were as follows: evaporator temperature 175℃, internal cooler temperature 20℃, absolute pressure 2Pa, and scraping film speed 360rpm. Keeping other conditions unchanged, the second-stage molecular distillation was carried out at an evaporation temperature of 180℃ to obtain the purified high-viscosity synthetic ester for gears.

[0076] In this embodiment, the obtained high-viscosity fluorinated synthetic ester has the structure provided by formula (II) in Example 1, and the yield and acid value of the obtained product are 92 wt.% and 0.06 mg KOH / g, respectively. The kinematic viscosity, viscosity index, color, thermal decomposition temperature, hydrophobic parameter, oxidation induction time, and pour point at 40°C and 100°C are 266.7 mm. 2 / s, 31.9mm 2 / s, 162, 2, 335℃, 41, 212min and -30℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 78%.

[0077] Example 4 This embodiment provides the application of the high-viscosity fluorinated synthetic ester in Example 1 and the high-viscosity fluorinated synthetic ester obtained by the preparation method in Example 2 in transmission structures, electrical equipment or materials.

[0078] The transmission mechanism is selected from at least one of gears, gearboxes, chains, and bearings; the electrical equipment or materials are selected from at least one of transformers, capacitors, and power cables. Specifically, the high-viscosity fluorinated synthetic ester is used as a base oil for gear oil, transmission oil, chain oil, bearing oil, and insulating fluid and / or blending component.

[0079] Example 5 This embodiment provides a method for preparing a high-viscosity perfluorinated synthetic ester: pentaerythritol, adipic acid, perfluoroheptanol, n-heptanol, and 2-ethylhexanol are added to the reaction system in two steps at a molar ratio of 1:4:1:1:2. In the first step, pentaerythritol and adipic acid are added in a molar ratio of 1:4 (adipic acid is added first, and pentaerythritol is added intermittently and gradually at a rate of 20 wt.% / 15 min to minimize the bridging effect between pentaerythritols and thus improve the yield of the target product), forming a "skeleton structure". In the second step, n-heptanol, 2-ethylhexanol, perfluoroheptanol, and tin(II)zirconium composite oxide catalyst (1% of the mass of n-heptanol, 2-ethylhexanol, and perfluoroheptanol) are added for "heading treatment".

[0080] The first reaction was carried out at a temperature of 170℃ for 1.5 hours. The second reaction was initiated at 170℃, then increased to 180℃ after 1 hour, and continued for another 4 hours. The catalyst dosage was 1% of the total mass of the reactants, and the nitrogen flow rate was 2 mL / min. -1 ·g -1 The stirring speed was 800 rpm. After the reaction was completed, the high-viscosity fluorinated synthetic ester was separated from the composite metal oxide catalyst by vacuum filtration to obtain the crude product of the high-viscosity fluorinated synthetic ester.

[0081] The obtained high-viscosity fluorinated synthetic ester crude product was purified by two-stage molecular distillation. The operating conditions for the first-stage molecular distillation were as follows: evaporator temperature 175℃, internal cooler temperature 20℃, absolute pressure 2Pa, and scraping film speed 360rpm. Keeping other conditions unchanged, the second-stage molecular distillation was carried out at an evaporation temperature of 180℃ to obtain the purified high-viscosity synthetic ester for gears.

[0082] In this embodiment, the obtained high-viscosity fluorinated synthetic ester has the structure provided by formula (II) in Example 1, and the yield and acid value of the obtained product are 93 wt.% and 0.05 mg KOH / g, respectively. The kinematic viscosity, viscosity index, color, thermal decomposition temperature, hydrophobic parameter, oxidation induction time, and pour point at 40°C and 100°C are 276.1 mm. 2 / s, 33.7mm 2 / s, 167, 2, 340℃, 38, 215min and -35℃; Biodegradability evaluation results: 80% biodegradability rate after 28 days.

[0083] Comparative Example 1 This comparative example provides a method for preparing a high-viscosity fluorinated synthetic ester, which is basically the same as that in Example 2, except that all the monohydric alcohols are perfluoromonohydric alcohols, that is, all the end-capping groups are perfluoroalkyl.

[0084] The high-viscosity fluorinated synthetic ester obtained in this comparative example had a yield of 92 wt.% and an acid value of 0.05 mg KOH / g. Its kinematic viscosity, viscosity index, color, thermal decomposition temperature, hydrophobic parameter, oxidation induction time, and pour point at 40℃ and 100℃ were 279.4 mm. 2 / s, 29.5mm 2 / s, 142, 2, 325℃, 39, 215min and -23℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 51%.

[0085] Comparative Example 2 This comparative example provides a method for preparing a high-viscosity fluorinated synthetic ester, which is basically the same as that in Example 2, except that the monohydric alcohol is entirely 2-ethylhexanol.

[0086] The high-viscosity fluorinated synthetic ester obtained in this comparative example had a yield of 93 wt.% and an acid value of 0.05 mg KOH / g. Its kinematic viscosity, viscosity index, color, thermal decomposition temperature, hydrophobic parameter, oxidation induction time, and pour point at 40℃ and 100℃ were 236.7 mm. 2 / s, 30.9mm 2 / s, 173, 2, 309℃, 30, 185min and -35℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 89%.

[0087] Comparative Example 3 This comparative example provides a method for preparing a high-viscosity fluorinated synthetic ester, which is basically the same as that in Example 2, except that a one-pot method is used, in which trimethylolpropane (neopentyl polyol), adipic acid (dicarboxylic acid), 2-ethylhexanol (branched monohydric alcohol), perfluoroheptanol (perfluoro monohydric alcohol), and the catalyst are all added and reacted simultaneously.

[0088] The high-viscosity fluorinated synthetic ester obtained in this comparative example had a yield of 81 wt.% and an acid value of 0.05 mg KOH / g. Its kinematic viscosity, viscosity index, color, thermal decomposition temperature, hydrophobic parameter, oxidation induction time, and pour point at 40℃ and 100℃ were 262.4 mm. 2 / s, 30.8mm 2 / s, 157, 2, 311℃, 35, 191min and -34℃; Biodegradability evaluation results: 80% biodegradability rate after 28 days.

[0089] Comparative Example 4 This comparative example provides a method for preparing a high-viscosity fluorinated synthetic ester, which is basically the same as that in Example 2, except that gradient heating is not used. Specifically, the reaction temperature of the first reaction and the second reaction is 165°C.

[0090] The high-viscosity fluorinated synthetic ester obtained in this comparative example had a yield of 89 wt.% and an acid value of 0.08 mg KOH / g. Its kinematic viscosity, viscosity index, color, thermal decomposition temperature, hydrophobic parameter, oxidation induction time, and pour point at 40℃ and 100℃ were 247.3 mm. 2 / s, 28.4mm 2 / s, 151, 2, 312℃, 33, 190min and -31℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 81%.

[0091] Combining Example 2 and Comparative Examples 1 and 2, it can be seen that when the amount of perfluorinated monohydric alcohol added is 0, the thermal stability, oxidative stability, and hydrophobicity of the resulting synthetic ester are significantly worse; when perfluorinated monohydric alcohol is used entirely as the end-capping agent, the biodegradability of the resulting synthetic ester is significantly worse. These results indicate that the partial addition of perfluorinated monohydric alcohol can improve the thermal stability, oxidative stability, and hydrophobicity of the synthetic ester, and also give the synthetic ester good biodegradability.

[0092] Combining Example 2 and Comparative Examples 3 and 4, it can be seen that the yield of the synthesized ester is significantly lower when the one-pot feeding method is used (Comparative Example 3). In Comparative Example 4, no gradient heating is used, and the results show that the reduced conversion rate also leads to a decrease in the yield of the target product and a deterioration in performance. The above results indicate that the preparation method provided by the present invention effectively improves the product yield and reaction conversion rate of the synthesized ester by step feeding and gradient heating.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-viscosity fluorinated synthetic ester, characterized in that, Having A(B) x (C) y The general molecular formula is given by: A is selected from C5H8 and C6H. 11 C5H9, C5H 10 C6H 12 O, C 10 H 18 Any one of O; B stands for -OOC-(CH2) a -COO-C n H 2n+1 ; C stands for -OOC-(CH2) a -COO-C m F 2m+1 ; x is a real number from 1 to 6, y is a real number from 1 to 3, a is an integer from 3 to 10, n is an integer from 6 to 9, and m is an integer from 6 to 10.

2. The high-viscosity fluorinated synthetic ester according to claim 1, characterized in that, It has the structure shown in equations (I) and (II):

3. The method for preparing the high-viscosity fluorinated synthetic ester according to claim 1 or 2, characterized in that, Its raw materials include dicarboxylic acids and polyols, with monohydric alcohols as end-capping agents, wherein the monohydric alcohols include 20-50 mol% perfluoromonohydric alcohols; Preferably, the monohydric alcohol comprises 25-35 mol% of the perfluoromonohydric alcohol; Preferably, the perfluoromonohydrin is selected from at least one of perfluorohexanol, perfluoroheptanol, perfluorooctanol, perfluorononanol, and perfluorodecanol.

4. The preparation method according to claim 3, characterized in that, The monohydric alcohol also includes 50-80 mol% of a common monohydric alcohol, wherein 50-100 mol% of the common monohydric alcohol is a branched monohydric alcohol; Preferably, the ordinary monohydric alcohol comprises 75-100 mol% branched monohydric alcohol; Preferably, the branched monohydric alcohol is selected from at least one of 2-ethylhexanol, 3,5,5-trimethylhexanol, 2-methylheptanol, and 2-ethylbutanol; Preferably, the common monohydric alcohol further includes 0-50 mol% of an odd-carbon straight-chain monohydric alcohol; Preferably, the odd-carbon straight-chain monohydric alcohol is selected from at least one of n-hexanol, n-heptanol, and n-nonanol.

5. The preparation method according to claim 3 or 4, characterized in that, The polyol is selected from 2-6 alcohols, and / or the dicarboxylic acid is selected from C5-12 dicarboxylic acids; Preferably, the dicarboxylic acid is selected from at least one of glutaric acid, adipic acid, pimelic acid, azelaic acid and sebacic acid, undecanoic acid, and dodecanoic acid; Preferably, the polyol is selected from at least one of pentaerythritol, dipentaerythritol, neopentyl glycol, trimethylolpropane, and trimethylolethane.

6. The preparation method according to any one of claims 3-5, characterized in that: include: Step (1): Mix dicarboxylic acid, polyol and catalyst to carry out the first step reaction; then add monohydric alcohol and catalyst to carry out the second step reaction; The reaction mixture is obtained; Step (2): The reaction mixture is separated to obtain a high-viscosity fluorinated synthetic ester; In step (1), the dicarboxylic acid and the catalyst are first mixed, and then the polyol is added intermittently and gradually at a rate of 20-30 wt.% every 15-20 min.

7. The preparation method according to claim 6, characterized in that, In step (1), the temperature of the first reaction is 150℃~170℃, and the reaction time is 1.5~2h; And / or, in step (1), the second reaction is first carried out at 150℃~170℃ for 1~2h, and then the temperature is raised to 170℃~180℃ for more than 4h.

8. The preparation method according to claim 6 or 7, characterized in that, The catalyst is selected from a composite metal oxide catalyst in which the molar ratio of tin to the second metal element is (6-12):1; the second metal element is selected from at least one of zirconium, titanium, aluminum, cobalt and tungsten. Preferably, the amount of catalyst added is 1.0 to 3.0 wt.% of the total mass of the reactants.

9. The preparation method according to any one of claims 6-8, characterized in that, The separation described in step (2) is performed by vacuum filtration at a temperature of 120-140℃; And / or, step (2) further includes: refining the high-viscosity synthetic ester crude product obtained by vacuum filtration; Preferably, the refining process employs a two- or three-stage molecular distillation separation method to ultimately obtain a refined product.

10. The use of the high-viscosity fluorinated synthetic ester according to claim 1 or 2 and / or the high-viscosity fluorinated synthetic ester obtained by the preparation method according to any one of claims 3-9 in transmission mechanisms, electrical equipment or materials; Preferably, the transmission mechanism is selected from at least one of gears, gearboxes, chains, and bearings; Preferably, the electrical equipment or material is selected from at least one of transformers, capacitors, power cables, etc. Preferably, the high-viscosity fluorinated synthetic ester is used as a base oil for gear oil, transmission oil, chain oil, bearing oil, and insulating fluid and / or blending component.

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