An ultra-high viscosity fluorine-containing synthetic ester, a preparation method and application thereof

Abstract

This invention provides an ultra-high viscosity fluorinated synthetic ester, its preparation method, and its applications. The ultra-high viscosity fluorinated synthetic ester provided by this invention has a specific molecular structure. Its end-capping agent is mostly a common monohydric alcohol, resulting in a higher upper viscosity limit, better viscosity-temperature properties, and better low-temperature fluidity. A portion of the end-capping agent is a perfluoromonohydric alcohol, 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 agent is a perfluoromonohydric alcohol, which also improves the biodegradability of the synthetic ester, making it more environmentally friendly. The preparation method of the high viscosity fluorinated synthetic ester provided by this invention uses a monohydric alcohol as the end-capping agent, comprising 20-50 mol% perfluoromonohydric alcohol. The resulting ultra-high viscosity fluorinated synthetic ester has a higher upper viscosity limit, better thermal stability, oxidation stability, and hydrophobicity. Furthermore, by improving the feeding method and heating method, the product yield and reaction conversion rate are improved.

Description

Technical Field

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

[0002] Synthetic esters belong to Group V base oils and possess excellent lubricity, low-temperature fluidity, thermal and oxidation stability, and biodegradability. They also offer flexible molecular structure design, safety, environmental friendliness, and non-toxicity, making them a green and high-end synthetic base oil. Ultra-high viscosity synthetic esters for transmission equipment are ideal base oils or blending components for transmission oils, gear oils, and high-temperature chain oils. Statistics show that the domestic demand for wind power oils (transmission 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 wind power oils, priced at approximately 50,000 to 80,000 yuan per ton. Developing high-viscosity synthetic ester specialty oils can enrich the product range of synthetic oils in my country. Therefore, the research, development, production, and promotion of ultra-high viscosity synthetic esters for transmission equipment have significant practical implications.

[0003] 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 bridge, 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 not ideal, and the viscosity index of the synthesized ester is difficult to reach a very high level; (2) the 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°C to -32°C. Clearly, the viscosity-temperature properties are not ideal, and its viscosity-temperature characteristics cannot be very high. Chinese patents CN1075107C and CN1231687A disclose a method for synthesizing a base oil using fatty acids, dicarboxylic acids, and polyols as raw materials.

[0004] In summary, the synthetic esters and their synthesis methods reported in the above literature all have certain shortcomings, while the green synthesis of high-performance ester base oils has become an irreversible trend. Summary of the Invention

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

[0006] In a first aspect, the present invention provides an ultra-high viscosity fluorinated synthetic ester having A n+1 B n (C) x (D) y The general molecular formula of , wherein: A is selected from C5H8, C6H 11 C5H 10 C6H 12 O, C 10 H 18 Any one of O; B is (CH2). e (COO)2, C stands for -OOC-(CH2) e -COO-C f H 2f+1 , D stands for -OOC-(CH2) e -COO-C m F 2m+1 , n is a real number from 1 to 5, x is a real number from 1 to 26, y is a real number from 1 to 13, e is an integer from 3 to 10, f is an integer from 5 to 9, and m is an integer from 6 to 10.

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

[0008] The ultra-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 ultra-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 perfluorinated monohydric alcohols, preferably 25-35 mol% of the perfluorinated monohydric alcohols.

[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 monohydric alcohol further includes 50-80 mol% of a common monohydric alcohol, wherein the common monohydric alcohol comprises 50-100 mol% of a branched monohydric alcohol, preferably the common monohydric alcohol comprises 75-100 mol% of a 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-pentanol, 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, and sebacic acid.

[0019] In some embodiments of the present invention, the polyol is selected from at least one of pentaerythritol, dipentaerythritol, neopentyl diol, dipentaerythritol, 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): Mix the dicarboxylic acid, polyol and catalyst to carry out the first step reaction; then add the remaining dicarboxylic acid, monohydric alcohol and catalyst from the formula to carry out the second step reaction; and obtain the reaction mixture. Step (2): The reaction mixture is separated to obtain a high-viscosity synthetic ester. In step (1), the polyol and the catalyst are first mixed, and then the dicarboxylic acid is added intermittently (20-30 wt.%) every 10-20 min.

[0022] The preparation method provided by this invention first mixes the polyol and the catalyst, then intermittently adds the dicarboxylic acid, and finally adds branched / odd-carbon straight-chain monohydric alcohol and perfluorinated monohydric alcohol together for end-capping. This stepwise and gradual feeding method, especially the intermittent and gradual addition of small amounts of dicarboxylic acid (20-30 wt.% added every 10-20 minutes), can effectively increase the 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 160°C to 170°C for 1 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 the 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, in step (1), during the process of gradually adding the dicarboxylic acid to the polyol, the molar ratio of the dicarboxylic acid to the polyol is n:(n+1), where n is an integer.

[0029] 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 element is (7-9):1; the second element is selected from at least one of zirconium, titanium, aluminum, silicon, tungsten, and cobalt.

[0030] 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 remaining total mass of the dicarboxylic acid and monohydric alcohol.

[0031] 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.

[0032] 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.

[0033] In some embodiments of the present invention, step (2) further includes: refining the high-viscosity crude ester synthetic product obtained by vacuum filtration; preferably, the refining is performed 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.

[0034] In a third aspect, the present invention provides the application of the ultra-high viscosity fluorinated synthetic ester and / or the ultra-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.

[0035] The ultra-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 500-5000 mmHg at 40°C. 2 The kinematic viscosity at 100℃ can reach 50-500 mm² / s. 2 / s, viscosity index 150-300, thermal decomposition temperature: 270-360℃, hydrophobicity parameter: 20-70, oxidation induction time 170-210min, pour point -30~-10℃, color 2-4.

[0036] (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

[0037] 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.

[0038] 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.

[0039] Based on this, and addressing the problems of conventional synthetic esters failing to achieve ultra-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 an ultra-high viscosity fluorinated synthetic ester, possessing A... n+1 B n (C) x (D) y The general molecular formula of , wherein: A is selected from C5H8, C6H 11 C5H 10 C6H 12 O, C 10 H 18 Any one of O; B is (CH2) e (COO)2, C stands for -OOC-(CH2) e -COO-C f H 2f+1 , D stands for -OOC-(CH2) e -COO-C m F 2m+1 , n is a real number from 1 to 5, x is a real number from 1 to 26, y is a real number from 1 to 13, e is an integer from 3 to 10, f is an integer from 5 to 9, and m is an integer from 6 to 10.

[0040] Specifically, when n=1, for pentaerythritol A it is C5H8 and x+y=6; for trimethylolpropane A it is C6H8. 11 x+y=4; for trimethylolethane A is C5H9, x+y=4; for neopentyldiol A is C5H 10 x + y = 2; for dipentaerythritol A, C6H 12 O, x+y=10; for bis(trimethylolpropane) A is C 10 H 18 O, x + y = 6.

[0041] When n = 2, for pentaerythritol A it is C5H8, x + y = 8; for trimethylolpropane A it is C6H8. 11 x+y=5; for trimethylolethane A is C5H9, x+y=5; for neopentyldiol A is C5H 10x + y = 2; for dipentaerythritol A, C6H 12 O, x+y=14; for bis(trimethylolpropane) A is C 10 H 18 O, x+y=8; In summary, x+y=(n+1) moles of hydroxyl groups in the bridging structure formed by the polyol and n moles of dicarboxylic acid.

[0042] B: (CH2) e (COO)2, where e is the number of carbon atoms in the dicarboxylic acid minus 2, i.e., 3-10. For example, for adipic acid, e = 4; for pimelic acid, e = 5; for dodecanoic acid, e = 10.

[0043] C: -OOC-(CH2) e -COO-C f H 2f+1 f represents the number of carbon atoms in a common monohydric alcohol, ranging from 5 to 9. D: -OOC-(CH2) e -COO-C m F 2m+1 , where m is the number of carbon atoms in the perfluoromonohydrin, ranging from 6 to 10.

[0044] By incorporating a portion of perfluoromonohydrin, the structure of the synthetic ester has only some end-capping groups that are perfluoroalkyl, which enables the synthetic ester to simultaneously possess high viscosity, thermal stability, oxidation stability, and low-temperature fluidity. Furthermore, the synthetic ester also exhibits good biodegradability.

[0045] Specifically, the ultra-high viscosity fluorinated synthetic ester can have the structures shown in formula (I) and formula (II):

[0046] A novel molecular configuration of fluorinated neopentyl polyol esters exhibits significantly improved viscosity, viscosity index, pour point, hydrophobicity, and thermal oxidation stability. This invention provides an ultra-high viscosity fluorinated synthetic ester. The above general formula (I) is illustrated using pentaerythritol as an example, while general formula (II) is synthesized using trimethylolpropane as a raw material. Examples 1 and 2, however, use 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.

[0047] Accordingly, the present invention also provides a method for preparing the ultra-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-numbered carbon straight-chain monohydric alcohol, preferably 75-100 mol% of branched monohydric alcohol and 0-25 mol% of odd-numbered 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, the dicarboxylic acid, neopentyl polyol, and composite metal oxide catalyst are first mixed (the neopentyl polyol is added first, followed by the dicarboxylic acid added intermittently and gradually (20-30 wt.% every 10-20 min) to maximize the bridging effect 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 h. Then, the remaining dicarboxylic acid, branched / odd-carbon monohydric alcohol, and perfluorinated monohydric acid catalyst are added. The alcohol and the composite metal oxide catalyst are first subjected to a second reaction at 160℃~170℃ for 1~2h, and then the temperature is raised to 170℃~180℃ and the second reaction is continued for more than 4h to obtain a reaction mixture; wherein, the molar ratio of tin to zirconium / aluminum / silicon in the composite metal oxide catalyst is (7-9):1, the synthesis method is hydrothermal method (hydrothermal temperature 120℃~190℃, hydrothermal time 8~24h), and the amount added is 1.0~3.0wt.% 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 for gears. (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.

[0048] 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 employed to increase 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 diacid is added to a large amount of polyol, the concentration of polyols around the diacid will be extremely high, which is conducive to the reaction of each carboxyl group of the diacid with different polyol hydroxyl groups, thus producing a large amount of...). The bridging reaction; conversely, 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, causing each hydroxyl group of the polyol to react with different carboxyl groups of the diacid. The coupling process is beneficial to obtaining the ideal molecular configuration and composition, and also improves the reaction conversion rate. On the other hand, nitrogen is used to replace 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 realizes the full utilization of resources.

[0049] 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, neopentyl glycol, trimethylolpropane, and trimethylolethane.

[0050] 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.

[0051] The branched monohydric alcohol is selected from at least one of 2-ethylhexanol, 3,5,5-trimethylhexanol, 2-methylheptanol, and 2-ethylbutanol. 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 composition ranges within the above ranges, such as 50-100 mol%, 75-100 mol%, etc.

[0052] The odd-carbon straight-chain monohydric alcohol can be at least one of n-pentanol, n-heptanol, and n-nonanol, and its proportion in ordinary monohydric alcohols can be 0, 10 mol%, 20 mol%, 25 mol%, 30 mol%, 40 mol%, 50 mol%, or other suitable amounts and composition ranges within the above ranges, such as 0-50 mol%, 0-25 mol%, etc.

[0053] The composite metal oxide catalyst can be composed of tin and a second element (at least one of zirconium, aluminum, cobalt, and tungsten) in a molar ratio of (7-9):1. The metals can be different combinations of tin and zirconium, tin and aluminum, tin and silicon, or tin and zirconium and silicon, which will not be elaborated here. The molar ratio of tin to the second element can be 7:1, 8:1, and 9:1, or other suitable amounts within the above ranges.

[0054] 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.

[0055] In preparing the ultra-high viscosity fluorinated synthetic ester, the amount of catalyst added is 1-3 wt%, such as 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, and 3 wt%.

[0056] 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 mg KOH / 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.

[0057] 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, mg KOH / 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.

[0058] Kinematic viscosity: Measured according to the national standard GB / T 265-1988 "Determination of kinematic viscosity and calculation of dynamic viscosity of petroleum products".

[0059] 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.

[0060] Color: Measured according to the oxidation induction time of the petrochemical industry standard SH / T 0168-1992 "Determination of Color of Petroleum Products".

[0061] Thermal decomposition temperature: Measured using thermogravimetric analysis (nitrogen atmosphere).

[0062] Hydrophobicity parameter: calculated by logPo w We obtain, where Po w =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.

[0063] Oxidation induction time: Measured according to industry standard SH / T 0193-2008 "Determination of Oxidation Stability of Lubricating Oils - Rotary Bomb Oxygen Method".

[0064] Pour point: Measured according to the national standard GB / T 3535-2006 "Determination of Pour Point of Petroleum Products".

[0065] Biodegradability: Tested according to OECD 301A-F standards.

[0066] 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 mg KOH / g.

[0067] The ultra-high viscosity fluorinated synthetic ester provided / obtained in some embodiments of the present invention has a viscosity of 500-5000 mmHg at 40°C. 2 The kinematic viscosity at 100℃ can reach 50-500 mm² / s. 2 / s, viscosity index 150-300, thermal decomposition temperature: 270-360℃, hydrophobicity parameter: 20-70, oxidation induction time 170-210min, pour point -30~-10℃, color 2-4.

[0068] 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

[0069] All other raw materials used in the embodiments of this invention are commercially available products.

[0070] 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.

[0071] Example 1 This embodiment provides an ultra-high viscosity fluorinated synthetic ester, which has the structures shown in formula (I) and formula (II):

[0072] The ultra-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.

[0073] Example 2 This embodiment provides a method for preparing the ultra-high viscosity fluorinated synthetic ester, wherein trimethylolpropane, adipic acid, perfluoroheptanol, and 2-ethylhexanol are added to the reaction system in two steps at a molar ratio of 2:5:2:2. In the first step, trimethylolpropane and adipic acid are added in a molar ratio of 2:1 (the adipic acid is gradually added to the trimethylolpropane at a rate of 20 wt.% / 10 min); in the second step, adipic acid, perfluoroheptanol, and 2-ethylhexanol are added in a molar ratio of 4:2:2.

[0074] The reaction temperature for the first reaction was 160℃, and the reaction time was 1.5 h. The initial reaction temperature for the second reaction was 170℃, and after 1 h, the temperature was raised to 180℃, and the reaction continued for 4 h. The catalyst dosage was 1% of the total mass of the reactants, and the nitrogen flow rate was 2 mL / min. -1 ·g -1The stirring speed was 800 rpm. After the reaction was completed, the ultra-high viscosity fluorinated synthetic ester and the tin-containing composite oxide catalyst were separated by vacuum filtration. The crude ultra-high viscosity composite trimethylolpropane ester was obtained under the above synthesis conditions.

[0075] The obtained ultra-high viscosity composite fluorinated trimethylolpropane 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 30℃, 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 ultra-high viscosity composite fluorinated trimethylolpropane ester product.

[0076] In this embodiment, the synthesized ester has a structure similar to formula (II). The yield and acid value of the obtained product are 90 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 1396.98 mm. 2 / s, 145.79mm 2 / s, 217, 2, 303℃, 46, 193min and -18℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 75%.

[0077] Example 3 This embodiment provides a method for preparing ultra-high viscosity perfluorinated synthetic esters: pentaerythritol, adipic acid, perfluoroheptanol, and 2-ethylhexanol are added to the reaction system in two steps at a molar ratio of 2:7:3:3. In the first step, pentaerythritol and adipic acid are added in a molar ratio of 2:1 (adipic acid is added gradually to pentaerythritol at a rate of 20 wt.% / 15 min). In the second step, adipic acid, perfluoroheptanol, and 2-ethylhexanol are added in a molar ratio of 6:3:3. The reaction temperature of the first step is 170℃, and the reaction time is 1.5 h. The reaction temperatures of the first and second stages of the second step are 170℃ and 180℃, and the reaction times are 1 h and 4 h, respectively. The catalyst dosage is 1.5% of the total mass of the reactants, and the nitrogen flow rate is 1.5 mL·min. -1 ·g -1 The stirring speed was 800 rpm. After the reaction was completed, the ultra-high viscosity fluorinated synthetic ester and the tin-containing composite oxide catalyst were separated by vacuum filtration. The ultra-high viscosity composite pentaerythritol ester fluorinated crude product was obtained under the above synthesis conditions.

[0078] The obtained ultra-high viscosity composite fluorinated pentaerythritol 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 10℃, 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 185℃.

[0079] In this embodiment, the synthesized ester has a structure similar to formula (I). The yield and acid value of the obtained product are 88 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 1970.55 mm. 2 / s, 246.53mm 2 / s, 268, 2, 313℃, 55, 205min and -15℃, biodegradability evaluation results: the biodegradability rate after 28 days is 70%.

[0080] Example 4 This embodiment provides the application of the ultra-high viscosity fluorinated synthetic ester in Example 1 and the ultra-high viscosity fluorinated synthetic ester obtained by the preparation method in Example 2 in transmission equipment, 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.

[0081] Example 5 This embodiment provides a method for preparing ultra-high viscosity perfluorinated synthetic esters: pentaerythritol, adipic acid, perfluoroheptanol, n-heptanol, and 3,5,5-trimethylhexanol are added to the reaction system in two steps at a molar ratio of 3:10:3:2:3. In the first step, pentaerythritol and adipic acid are added in a molar ratio of 3:2 (adipic acid is gradually added to pentaerythritol at a rate of 20 wt.% / 15 min). In the second step, adipic acid, perfluoroheptanol, n-heptanol, and 3,5,5-trimethylhexanol are added in a molar ratio of 8:3:2:3. The reaction temperature of the first step is 170℃, and the reaction time is 1.5 h. The reaction temperatures of the first and second stages of the second step are 170℃ and 180℃, and the reaction times are 1 h and 4 h, respectively. The catalyst dosage is 1.5% of the total mass of the reactants, and the nitrogen flow rate is 1.5 mL·min. -1 ·g -1The stirring speed was 800 rpm. After the reaction was completed, the ultra-high viscosity fluorinated synthetic ester and the tin-containing composite oxide catalyst were separated by vacuum filtration. The ultra-high viscosity composite pentaerythritol ester fluorinated crude product was obtained under the above synthesis conditions.

[0082] The obtained ultra-high viscosity composite fluorinated pentaerythritol ester crude product was purified by two-stage molecular distillation. The operating conditions for the first-stage molecular distillation were as follows: evaporator temperature 180℃, internal cooler temperature 10℃, 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 185℃.

[0083] In this embodiment, the yield and acid value of the obtained product were 86 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 were 2257.56 mm. 2 / s, 305.73mm 2 / s, 292, 2, 328℃, 61, 209min and -12℃, biodegradability evaluation results: the biodegradability rate after 28 days was 74%.

[0084] Comparative Example 1 This comparative example provides a method for preparing ultra-high viscosity fluorinated synthetic esters, 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.

[0085] The ultra-high viscosity fluorinated synthetic ester obtained in this comparative example had a yield of 87 wt.% and an acid value of 0.07 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 1722.41 mm. 2 / s, 132.12mm 2 / s, 178, 2, 321℃, 55, 205min and -11℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 61%.

[0086] Comparative Example 2 This comparative example provides a method for preparing ultra-high viscosity fluorinated synthetic esters, which is basically the same as that in Example 2, except that all monohydric alcohols are 2-ethylhexanol.

[0087] The ultra-high viscosity fluorinated synthetic ester obtained in this comparative example had a yield of 91 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 1245.07 mm.2 / s, 140.12mm 2 / s, 224, 2, 295℃, 40, 179min and -21℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 81%.

[0088] Comparative Example 3 This comparative example provides a method for preparing ultra-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.

[0089] The ultra-high viscosity fluorinated synthetic ester obtained in this comparative example had a yield of 82 wt.% and an acid value of 0.06 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 1356.52 mm. 2 / s, 141.27mm 2 / s, 215, 2, 300℃, 44, 190min and -17℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 76%.

[0090] Comparative Example 4 This comparative example provides a method for preparing ultra-high viscosity fluorinated synthetic ester, which is basically the same as that in Example 2, except that gradient heating is not used. Specifically, the first reaction is carried out at 170°C and the second reaction is carried out at 175°C.

[0091] The ultra-high viscosity fluorinated synthetic ester obtained in this comparative example had a yield of 88 wt.% and an acid value of 0.07 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 1327.28 mm. 2 / s, 139.33mm 2 / s, 215, 2, 300℃, 45, 188min and -17℃; Biodegradability evaluation results: the biodegradability rate after 28 days was 76%.

[0092] 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 partial addition of perfluorinated monohydric alcohol can improve the thermal stability, oxidative stability, and hydrophobicity of the synthetic ester, and also enable the synthetic ester to have good biodegradability.

[0093] Combining Example 2 and Comparative Examples 3 and 4, it can be seen that the yield of the synthesized ester is significantly lower when using a one-pot feeding method (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, as well as a decrease in viscosity, thermal stability, and oxidative stability. 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 through stepwise feeding and gradient heating.

[0094] 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 n+1 B n (C) x (D) y The general molecular formula of , wherein: A is selected from C5H8, C6H 11 C5H9, C5H 10 C6H 12 O, C 10 H 18 Any one of O; B is (CH2) e (COO)2, C stands for -OOC-(CH2) e -COO-C f H 2f+1 , D stands for -OOC-(CH2) e -COO-C m F 2m+1 , n is a real number from 1 to 5, x is a real number from 1 to 26, y is a real number from 1 to 13, e is an integer from 3 to 10, f is an integer from 5 to 9, and m is an integer from 6 to 10.

2. The ultra-high viscosity fluorinated synthetic ester according to claim 1, characterized in that, Based on the general molecular formula, specifically, for ultra-high viscosity fluorinated synthetic esters synthesized from pentaerythritol, adipic acid, succinic acid, 2-ethylhexanol, 3,5,5-trimethylhexanol, n-heptanol, and perfluoroheptanol as raw materials, the structure of formula (Ⅰ) is as follows: The ultra-high viscosity fluorinated synthetic ester synthesized from trimethylolpropane, adipic acid, succinic acid, 2-ethylhexanol, n-heptanol, 3,5,5-trimethylhexanol, and perfluoroheptanol has the structure shown in formula (II):

3. The method for preparing the ultra-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 further 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 common monohydric alcohol contains 75-100 mol% of a 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-pentanol, 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; Preferably, the polyol is selected from at least one of pentaerythritol, neopentyl diol, dipentaerythritol, trimethylolpropane, and trimethylolethane.

6. The preparation method according to any one of claims 3-5, characterized in that: include: Step (1): The dicarboxylic acid, polyol and catalyst are mixed to carry out the first step reaction; then the monohydric alcohol, the remaining dicarboxylic acid in the formula and the catalyst are added to carry out the second step reaction; and the reaction mixture is obtained. Step (2): The reaction mixture is separated to obtain an ultra-high viscosity fluorinated synthetic ester; In step (1), the polyol and the catalyst are mixed first, and then the dicarboxylic acid is gradually added to the polyol at a rate of 20-30 wt.% every 10-20 min to carry out the first reaction.

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 160℃~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, In step (1), during the entire process of gradually adding dicarboxylic acid to polyol, the molar ratio of dicarboxylic acid to polyol is n:(n+1), where n is an integer; And / or, the catalyst is selected from a composite metal oxide catalyst in which the molar ratio of tin to the second element is (7-9):1; the second element is selected from at least one of zirconium, titanium, aluminum, silicon, tungsten, and cobalt. 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 ultra-high viscosity fluorinated synthetic ester according to claim 1 or 2 and / or the ultra-high viscosity fluorinated synthetic ester obtained by the preparation method according to any one of claims 3-9 in transmission equipment, electrical equipment or materials; Preferably, the transmission device includes 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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