Biodegradable hydraulic oil composition and preparation method of hydraulic oil

Abstract

The invention relates to a biodegradable hydraulic oil composition and a preparation method of hydraulic oil, and relates to the technical field of hydraulic oil compositions.The hydraulic oil composition comprises, by weight, 20-37% of ester oil, 5-10% of refined vegetable oil and 5-10% of a demulsifier, and the total weight of the ester oil, the refined vegetable oil and the demulsifier is 100%. The content of the refined vegetable oil is 62-79.9 wt%, the content of the demulsifier is 0.1-1 wt%, and the preparation method of the refined vegetable oil comprises the following steps: pre-loading a nanocapsule with an antioxidant as an inner core in activated clay, loading the activated clay pre-loaded with the nanocapsule into deacidified oil, and filtering to obtain the refined vegetable oil. The hydraulic oil composition disclosed by the invention has excellent biodegradability and also has the technical effects of relatively good oxidation stability and viscosity-temperature property.

Description

Technical Field

[0001] This application relates to the field of hydraulic oil composition technology, and in particular to a biodegradable hydraulic oil composition and a method for preparing hydraulic oil. Background Technology

[0002] Of the lubricants used worldwide, besides a portion consumed during normal mechanical operation or partially recycled, 4-10% still enters the environment during assembly, disassembly, filling, and mechanical operation. In the European Community alone, this amounts to approximately 6 × 10⁶ annually. 5 Lubricants leak into the environment for various reasons. Traditional lubricants based on mineral oil have poor biodegradability and long retention times in the natural environment. Once they seep into the soil and aquifers, they cause serious environmental damage. With increasing awareness of environmental protection, the pollution and damage caused by lubricants, especially hydraulic oils which account for a significant proportion, has attracted the attention of various countries. Therefore, the development of biodegradable hydraulic oils has received great attention. Existing technologies use vegetable oils as the base oil for hydraulic oils to improve biodegradability. However, vegetable oils have high acid values ​​and poor hydrolytic stability, which affect lubrication and protection. At the same time, they have poor low-temperature fluidity and viscosity index, especially poor oxidation stability. Therefore, existing technologies generally compensate for the antioxidant deficiencies of vegetable oils by adding antioxidants, but this often leads to a decrease in the tribological properties of hydraulic oils. Therefore, extreme pressure anti-wear agents are added to hydraulic oils. However, too many types of additives in hydraulic oils may lead to large batch-to-batch performance differences. Summary of the Invention

[0003] The purpose of this application is to address the shortcomings of existing hydraulic oil preparation technologies that use vegetable oil as a base oil and add antioxidants, which make it difficult to balance the oxidation stability and friction properties of the hydraulic oil. Therefore, this application proposes a biodegradable hydraulic oil composition and a method for preparing the hydraulic oil. The hydraulic oil composition of this invention uses a specific amount of ester oil and a specific amount of refined vegetable oil prepared by a specific method as base oils, and incorporates a specific amount of demulsifier. This allows the hydraulic oil to possess excellent biodegradability while also exhibiting good oxidation stability and viscosity-temperature characteristics.

[0004] In a first aspect, the biodegradable hydraulic oil composition provided in this application adopts the following technical solution: the hydraulic oil composition includes ester oil, refined vegetable oil and demulsifier, and based on the total weight of the ester oil, refined vegetable oil and demulsifier as 100% by weight, the content of the ester oil is 20-37% by weight, the content of the refined vegetable oil is 62-79.9% by weight, the content of the demulsifier is 0.1-1% by weight, and the preparation method of the refined vegetable oil is as follows: preloading nanocapsules with an antioxidant core into activated clay, loading the activated clay preloaded with nanocapsules into deacidified oil, and then filtering to obtain refined vegetable oil.

[0005] Through the above technical solutions, activated clay possesses broad decolorization adsorption and purification capabilities, exhibiting excellent adsorption and decolorization effects in the oil decolorization process. It has strong adsorption capacity for pigments and impurities. By simultaneously loading nanocapsules with activated clay during the decolorization process, the need for separate addition steps is reduced. At the same time, the antioxidants in the nanocapsules are continuously released into the oil phase, which can improve the oxidation stability of hydraulic oil. By using the ester oil, refined vegetable oil, and demulsifier synergistically and limiting the content of each substance, the prepared hydraulic oil can have good oxidation stability, viscosity-temperature, and lubricity, while also possessing high biodegradability.

[0006] In a specific embodiment of the hydraulic oil composition of the present invention, based on the total weight of the ester oil, refined vegetable oil, and demulsifier as 100% by weight, the content of the ester oil is 20-37% by weight, specifically, for example, 20%, 25%, 30%, 35%, or 37% by weight; the content of the refined vegetable oil is 62-79.9% by weight, specifically, for example, 62%, 65%, 70%, 75%, 79%, 79.5%, or 79.9% by weight; and the content of the demulsifier is 0.1-1% by weight, specifically, for example, 0.1%, 0.3%, 0.5%, 0.7%, or 1% by weight. In a preferred embodiment, based on the total weight of the ester oil, refined vegetable oil, and demulsifier as 100% by weight, the content of the ester oil is 27-32% by weight, the content of the refined vegetable oil is 67.5-72.5% by weight, and the content of the demulsifier is 0.5-1% by weight. This allows the prepared hydraulic oil to achieve a biodegradability rate of over 90%, while also exhibiting excellent oxidation stability and viscosity-temperature properties.

[0007] Optionally, the weight ratio of the activated clay to the nanocapsules with an antioxidant core is 8-12:1, specifically, for example, 8:1, 9:1, 10:1, 11:1, or 12:1; the mass concentration of the activated clay is 1-2%, specifically, for example, 1%, 1.5%, or 2%. Controlling the weight ratio of the activated clay to the nanocapsules with an antioxidant core to 8-12:1 allows the nanocapsules to be more uniformly dispersed in the activated clay, increasing the pre-loading amount of the nanocapsules in the activated clay; the mass concentration of the activated clay is the mass concentration of the activated clay in the deacidified oil, limiting the mass concentration of the activated clay to 1-2% can increase the loading amount of the nanocapsules in the deacidified oil, thereby improving the oxidation stability of the hydraulic oil composition.

[0008] In a specific implementation, a fluidized bed process is used to preload nanocapsules with an antioxidant core into activated clay. The airflow velocity in the fluidized bed process is 0.8~1.2 m / s, which allows the nanocapsules to be uniformly dispersed in the activated clay and complete the preloading.

[0009] In a specific embodiment, activated clay preloaded with nanocapsules is placed in a decolorization tower, and deacidified oil is pumped into the decolorization tower. The conditions of the decolorization tower are: temperature 100~120 ℃, vacuum degree -0.08~-0.10 MPa, and contact time 20~40 min. The conditions in the decolorization tower are limited in order to improve the adsorption efficiency and the loading of nanocapsules, so that the loading of nanocapsules in the oil is ≥800 ppm, thereby significantly improving the antioxidant properties of refined vegetable oil. When this refined vegetable oil is used as the base oil of hydraulic oil, the oxidation stability of hydraulic oil can be significantly improved.

[0010] Optionally, the nanocapsule with an antioxidant core is a SiO2@tocopherol nanocapsule. The preparation method of the SiO2@tocopherol nanocapsule is as follows: dissolve tocopherol in ethanol, and add an aqueous solution of hexadecyltrimethylammonium bromide to the tocopherol dissolved in ethanol to form an emulsion. Add a mixed solution of tetraethyl orthosilicate and ammonia to the emulsion dropwise, and then centrifuge, wash, and dry to obtain SiO2@tocopherol nanocapsule.

[0011] Through the above technical solution, the prepared SiO2@tocopherol nanocapsules can achieve sustained release in the oil phase, continuously releasing tocopherol, prolonging the oxidation induction period of the oil, enhancing its antioxidant capacity, maintaining long-term stability, and without affecting the physical properties of the oil. At the same time, the SiO2 coating layer can prevent the decomposition of tocopherol during the high-temperature decolorization stage (110℃), so that the SiO2@tocopherol nanocapsules can be effectively loaded into the deacidified oil.

[0012] Optionally, the ratio of tocopherol, hexadecyltrimethylammonium bromide to tetraethyl orthosilicate is 8-12 g: 1-3 g: 18-22 mL. Specifically, for example, it can be 8 g: 1 g: 18 mL, 9 g: 2 g: 20 mL, 10 g: 2 g: 20 mL, 11 g: 2 g: 22 mL, or 12 g: 3 g: 22 mL.

[0013] By adjusting the ratio of tocopherol, hexadecyltrimethylammonium bromide, and tetraethyl orthosilicate, SiO2@tocopherol nanocapsules with an average particle size of 60-80 nm can be prepared. When the average particle size of the SiO2@tocopherol nanocapsules is in the range of 60-80 nm, the loading of SiO2@tocopherol nanocapsules in oil can be increased, making the loading of nanocapsules in oil ≥1000 ppm.

[0014] In the specific preparation process of the SiO2@tocopherol nanocapsules, in the mixed solution of tetraethyl orthosilicate and ammonia, the molar ratio of tetraethyl orthosilicate to ammonia is 1:1~2; the drying is carried out under vacuum conditions, and the drying conditions are: temperature 60~70℃, time 10~12 h.

[0015] Optionally, the method for preparing the refined vegetable oil further includes: before loading the pre-loaded nanocapsule-containing activated clay onto the deacidified oil, heating the vegetable oil to 48-52°C and adding phospholipase, then adjusting the pH to 4.8-5.2 for enzymatic hydrolysis to obtain enzymatically hydrolyzed oil, and then subjecting the enzymatically hydrolyzed oil to supercritical CO2 extraction for deacidification to obtain deacidified oil. The conditions for supercritical CO2 extraction deacidification are: the temperature of the extraction vessel is 40-50°C and the pressure is 10-15 MPa; the temperature of the separation vessel is 35-45°C and the pressure is 6-10 MPa. In this document, the vegetable oil is selected from one or more of soybean oil, rapeseed oil, peanut oil, castor oil, and palm oil.

[0016] The above technical solutions utilize phospholipase to hydrolyze non-hydrated phospholipids at low temperatures, thereby reducing phospholipid content and avoiding the gum residue caused by traditional acid / alkali treatment. Furthermore, the low temperature process retains antioxidant components such as tocopherols while effectively reducing acid value. Supercritical fluid extraction effectively removes free fatty acids, avoiding the problems associated with traditional high-temperature treatment. Coupled with low-temperature enzymatic degumming and extraction deacidification, the antioxidant components in vegetable oils are effectively preserved. This allows the refined vegetable oil, when used as a base oil for hydraulic oils, to further improve the oxidative stability of the hydraulic oil.

[0017] Further optionally, the method for preparing the refined vegetable oil further includes: before loading the pre-loaded nanocapsule-loaded activated clay onto the deacidified oil, performing molecular distillation on the deacidified oil, wherein the conditions for molecular distillation are: feed temperature of 170~190℃ and vacuum degree of 0.1~0.15 Pa; then mixing the distillate with hydrogen, and reacting the mixture in a nickel-based catalyst bed at 75~85℃ for 30~40 min.

[0018] Through the above technical solutions, molecular distillation is used to separate saturated fatty acids and reduce their content, thereby improving low-temperature fluidity. Under the action of nickel-based catalysts, double bond shift isomerization of cis-unsaturated fatty acids can be promoted, improving oxidation stability, while inhibiting the formation of trans fatty acids and lowering the pour point. The synergistic treatment of molecular distillation and low-temperature isomerization can make the refined vegetable oil prepared have both excellent antioxidant properties and low-temperature fluidity.

[0019] Optionally, the ester oil is trihydroxy oleate and / or glyceryl monooleate, wherein the kinematic viscosity of the ester oil at 40°C is 2~100 mm² / s, and the open-cup flash point is ≥200°C. In this document, the trihydroxy oleate is trimethylolpropane oleate, and the glyceryl monooleate is glyceryl monooleate.

[0020] By using the above technical solution, specific types of ester oils with certain viscosity and open flash point as the base oil of hydraulic oil, the viscosity-temperature performance and fire resistance of hydraulic oil can be effectively improved.

[0021] Optionally, the demulsifier is an alkylbenzene sulfonate, a quaternary ammonium salt, or an alkylphenol. Using a specific demulsifier can improve the anti-emulsification effect of the hydraulic oil.

[0022] In a specific embodiment of the hydraulic oil composition of the present invention, the hydraulic oil composition further includes a metal corrosion inhibitor, which is benzotriazole and / or a benzotriazole derivative. By selecting a specific metal corrosion inhibitor, the corrosion of metal pipelines by the oil can be effectively reduced, and the service life of the machinery can be extended.

[0023] Secondly, this application provides a method for preparing biodegradable hydraulic oil, wherein the raw material for the biodegradable hydraulic oil is the aforementioned biodegradable hydraulic oil composition, and the preparation method includes: placing the ester oil and the refined vegetable oil in a reaction vessel for heating treatment, and then adding the demulsifier to the reaction vessel under vacuum conditions.

[0024] By using the above technical solutions, hydraulic oil can be prepared by adding ester oil, refined vegetable oil and demulsifier in a specific order and under specific processing conditions. This allows the hydraulic oil to have excellent biodegradability, as well as good oxidation stability, low temperature stability and viscosity-temperature properties.

[0025] Optionally, the heating treatment is carried out under stirring conditions, and the heating conditions are: heating rate of 4~6 ℃ / min, heating to 115~125 ℃, stirring rate of 800~1000 rpm; the vacuum conditions are: vacuum degree of -0.09~0.1 MPa.

[0026] By further defining the relevant parameters of the processing conditions through the above technical solution, the biodegradability rate of the prepared hydraulic oil can exceed 90%, and it also has excellent oxidation stability, low-temperature performance and viscosity-temperature properties.

[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. This invention firstly completes the loading of nanocapsules simultaneously in the decolorization process using activated clay, reducing the need for separate addition steps. The antioxidants in the nanocapsules are continuously released in the oil phase, which can improve the oxidation stability of the hydraulic oil. Furthermore, by using the ester oil, refined vegetable oil, and demulsifier in combination and limiting the content of each substance, the prepared hydraulic oil can have good oxidation stability, viscosity-temperature, and lubricity, while also exhibiting high biodegradability. 2. In preferred embodiments, coupling low-temperature enzymatic degumming and extraction deacidification during the vegetable oil refining process can effectively preserve the antioxidant components in the vegetable oil. This allows the refined vegetable oil, when used as a base oil for hydraulic fluids, to further improve the oxidative stability of the hydraulic fluid. Furthermore, selecting specific types of ester oils and combining them with refined vegetable oils as base oils for hydraulic fluids can effectively improve the viscosity-temperature properties and flame-retardant properties of the hydraulic fluid. 3. In a more preferred case, the deacidified oil is treated by a combination of molecular distillation and low-temperature isomerization, which can make the refined vegetable oil prepared have excellent antioxidant properties and low-temperature fluidity. When the refined vegetable oil is used as the base oil, the hydraulic oil has a high biodegradability rate, as well as excellent oxidation stability, low-temperature fluidity and viscosity-temperature properties. Detailed Implementation

[0028] The present application will be further described in detail below with reference to specific embodiments.

[0029] The following examples further illustrate the biodegradable hydraulic oil composition and its preparation method according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0030] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0031] Ester oil: Purchased from Yingkou Xinghuo Chemical Co., Ltd., product code: TMP108B, kinematic viscosity at 40℃: 20 cSt, open flash point: 238℃; Activated clay: Purchased from Tiandong Haorun New Material Technology Co., Ltd., industrial grade activated clay; Tocopherol: Purchased from Wuhan Mingmingde Biochemical Co., Ltd., product model: D-α tocopherol 1430IU; Phospholipase: Purchased from Guanqiu Biotechnology (Shanghai) Co., Ltd.; Composite antifoaming agent: Purchased from Beijing Yilinair Petrochemical Co., Ltd., product model: Kunlun 1# composite antifoaming agent. Example 1

[0032] The preparation method of SiO2@tocopherol nanocapsules includes the following steps: (1) Dissolve 10 g of tocopherol in 50 mL of ethanol, and add 200 mL of an aqueous solution of hexadecyltrimethylammonium bromide (containing 2 g of hexadecyltrimethylammonium bromide) to the tocopherol dissolved in ethanol, and stir at 10000 rpm for 5 min to form an emulsion; (2) Add a mixed solution of tetraethyl orthosilicate and ammonia water (20 mL tetraethyl orthosilicate and 5 mL ammonia water with a concentration of 28%) to the emulsion, stir at 45 °C for 6 h, maintain pH at 9.5, then centrifuge at 8000 rpm for 15 min, wash with ethanol 3 times, and finally vacuum dry at 60 °C for 12 h to obtain SiO2@tocopherol nanocapsules with an average particle size of 65 nm.

[0033] The preparation method of refined vegetable oil includes the following steps: S1. Heat 1 kg of pressed rapeseed oil with an acid value of 4 mg KOH / g to 50 ℃, add 2 g of phospholipase to the pressed rapeseed oil, adjust the pH of the system to 5.0 with citric acid, and react for 2 h at a stirring speed of 150 rpm to obtain enzymatically hydrolyzed oil with a phospholipid content of 6 mg / kg. The enzymatically hydrolyzed oil was pumped into the extraction vessel of a supercritical extraction device. The extraction conditions were: CO2 flow rate of 20 L / min, temperature of 45 ℃, pressure of 10 MPa, and dynamic extraction for 60 min. After deacidification by supercritical CO2 extraction, the oil samples were collected in stages in a separation vessel. The temperature of the separation vessel was 40 ℃ and the pressure was 6 MPa. When the acid value was 0.08 mg KOH / g, the samples were collected in batches to obtain the deacidified oil. S2. The deacidified oil is heated to 180 °C and placed in a molecular distillation apparatus for molecular distillation for 30 min. The evaporation area of ​​the molecular distillation apparatus is 0.2 m². 2The vacuum degree was 0.1 Pa, the scraping speed was 200 rpm, and then the distillate was mixed with H2 at a pressure of 0.5 MPa at a volume ratio of 1:1. The mixture was then passed through a nickel-based catalyst bed (nickel-based catalyst loading of 15%) at 80 °C for 30 min. S3. Activated clay and the SiO2@tocopherol nanocapsules prepared in Example 1 are placed in a fluidized bed with an airflow velocity of 0.8 m / s to obtain activated clay preloaded with nanocapsules. The weight ratio of the activated clay to the SiO2@tocopherol nanocapsules is 10:1. The activated clay preloaded with nanocapsules is then placed in a decolorization tower, and the oil treated in step S2 is pumped into the decolorization tower for decolorization. The temperature of the decolorization tower is 110 ℃, the vacuum degree is -0.09 MPa, and the contact time between the activated clay preloaded with nanocapsules and the oil treated in step S2 is 30 min. The decolorized oil is filtered in a plate and frame filter press. The loading of the SiO2@tocopherol nanocapsules in the oil is 870 ppm, resulting in refined vegetable oil.

[0034] Preparation of biodegradable hydraulic oil, the preparation method comprising: 12.5 kg of ester oil and 37 kg of refined vegetable oil prepared in Example 1 were placed in a reaction vessel, the vessel was sealed, and the mixture was continuously heated and stirred at a stirring rate of 900 rpm and a heating rate of 5 ℃ / min until it reached 120 ℃. Then, the mixture was evacuated and stirred at a constant temperature for 30 min with a vacuum degree of -0.1 MPa. Finally, 0.25 kg of sodium dodecylbenzenesulfonate (demulsifier) ​​and 0.25 kg of benzotriazole (metal corrosion inhibitor) were added to the reaction vessel in sequence and stirred for 10 min. The mixture was then circulated and filtered for 15 min to obtain biodegradable hydraulic oil. Example 2

[0035] The process was carried out in accordance with Example 1, except that, in the preparation of refined vegetable oil, step S1 was replaced by: adding 2 g of 5% saline solution to 1 kg of pressed rapeseed oil with an acid value of 4 mg KOH / g, and hydrating and degumming at 80 °C for 30 min, and then mixing the hydrated and degummed oil with 1 g of 10% sodium hydroxide solution at 70 °C for 1 h to remove acidity. Example 3

[0036] The procedure is the same as in Example 1, except that step S2 is omitted in the preparation of refined vegetable oil. In step S3, the deacidified oil obtained in step S1 is directly pumped into a decolorization tower for decolorization. The specific operation is as follows: S1. Heat 1 kg of pressed rapeseed oil with an acid value of 4 mg KOH / g to 50 ℃, add 2 g of phospholipase to the pressed rapeseed oil, adjust the pH of the system to 5.0 with citric acid, and react for 2 h at a stirring speed of 150 rpm to obtain enzymatically hydrolyzed oil with a phospholipid content of 6 mg / kg. The enzymatically hydrolyzed oil was pumped into the extraction vessel of a supercritical extraction device. The extraction conditions were: CO2 flow rate of 20 L / min, temperature of 45 ℃, pressure of 10 MPa, and dynamic extraction for 60 min. After deacidification by supercritical CO2 extraction, the oil samples were collected in stages in a separation vessel. The temperature of the separation vessel was 40 ℃ and the pressure was 6 MPa. When the acid value was 0.08 mg KOH / g, the samples were collected in batches to obtain the deacidified oil. S2. Activated clay and the SiO2@tocopherol nanocapsules prepared in Example 1 are placed in a fluidized bed with an airflow velocity of 0.8 m / s to obtain activated clay preloaded with nanocapsules. The weight ratio of the activated clay to the SiO2@tocopherol nanocapsules is 10:1. Then, the activated clay preloaded with nanocapsules is placed in a decolorization tower, and the deacidified oil obtained in step S1 is pumped into the decolorization tower for decolorization. The temperature of the decolorization tower is 110 ℃, the vacuum degree is -0.09 MPa, and the contact time between the activated clay preloaded with nanocapsules and the oil treated in step S2 is 30 min. The decolorized oil is filtered in a plate and frame filter press. The loading of the SiO2@tocopherol nanocapsules in the oil is 870 ppm, resulting in refined vegetable oil. Example 4

[0037] The method is implemented in accordance with Example 1, except that in the preparation of refined vegetable oil, the weight ratio of the activated clay and SiO2@tocopherol nanocapsules in step S3 is 5:1. Example 5

[0038] The method is implemented in accordance with Example 1, except that in the preparation of refined vegetable oil, the weight ratio of the activated clay and SiO2@tocopherol nanocapsules in step S3 is 15:1. Example 6

[0039] The procedure was carried out in accordance with Example 1, except that in the preparation of SiO2@tocopherol nanocapsules, the ratio of tocopherol, hexadecyltrimethylammonium bromide to tetraethyl orthosilicate was 15 g: 1 g: 15 mL.

[0040] Comparative Example 1 The procedure was carried out as described in Example 1, except that in preparing the biodegradable hydraulic oil, 12.5 kg of ester oil was replaced with 12.5 kg of refined vegetable oil prepared in Example 1, specifically: 49.5 kg of the refined vegetable oil prepared in Example 1 was placed in a reaction vessel, the vessel was sealed, and the mixture was continuously heated and stirred at a stirring rate of 900 rpm and a heating rate of 5 ℃ / min until it reached 120 ℃. Then, the mixture was evacuated and stirred at a constant temperature for 30 min with a vacuum degree of -0.1 MPa. Finally, 0.25 kg of sodium dodecylbenzenesulfonate (demulsifier) ​​and 0.25 kg of benzotriazole (metal corrosion inhibitor) were added to the reaction vessel in sequence and stirred for 10 min. The mixture was then circulated and filtered for 15 min to obtain hydraulic oil.

[0041] Comparative Example 2 The procedure was carried out as described in Example 1, except that in preparing the biodegradable hydraulic oil, 37 kg of the refined vegetable oil prepared in Example 1 was replaced with 37 kg of ester oil, specifically: 49.5 kg of ester oil was placed in a reaction vessel, the vessel was sealed, and heating and stirring were carried out continuously at a stirring rate of 900 rpm and a heating rate of 5 ℃ / min until the temperature reached 120 ℃. Then, the mixture was evacuated and stirred at a constant temperature for 30 min with a vacuum degree of -0.1 MPa. Finally, 0.25 kg of sodium dodecylbenzenesulfonate (demulsifier) ​​and 0.25 kg of benzotriazole (metal corrosion inhibitor) were added to the reaction vessel in sequence and stirred for 10 min. The mixture was then circulated and filtered for 15 min to obtain hydraulic oil.

[0042] Comparative Example 3 The procedure was carried out as described in Example 1, except that 0.25 kg of sodium dodecylbenzenesulfonate (demulsifier) ​​was replaced with 0.25 kg of composite antifoaming agent when preparing the biodegradable hydraulic oil.

[0043] Comparative Example 4 The procedure was carried out as described in Example 1, except that the contents of ester oil, refined vegetable oil, and demulsifier were adjusted during the preparation of the biodegradable hydraulic oil, specifically as follows: 25 kg of ester oil and 24 kg of refined vegetable oil prepared in Example 1 were placed in a reaction vessel, the vessel was sealed, and the mixture was continuously heated and stirred at a stirring rate of 900 rpm and a heating rate of 5 ℃ / min until it reached 120 ℃. Then, the mixture was evacuated and stirred at a constant temperature for 30 min with a vacuum degree of -0.1 MPa. Finally, 0.5 kg of sodium dodecylbenzenesulfonate (demulsifier) ​​and 0.5 kg of benzotriazole (metal corrosion inhibitor) were added to the reaction vessel in sequence and stirred for 10 min. The mixture was then circulated and filtered for 15 min to obtain hydraulic oil.

[0044] Comparative Example 5 The procedure is carried out as described in Example 1, except that step S3 is replaced with the following when preparing refined vegetable oil: Activated clay is placed in a decolorization tower, and the oil treated in step S2 is pumped into the decolorization tower for decolorization. The temperature of the decolorization tower is 110 ℃ and the vacuum degree is -0.09MPa. The contact time between the activated clay and the oil treated in step S2 is 30 min, and refined vegetable oil is obtained.

[0045] Test case Viscosity-temperature performance testing: Kinematic viscosity (40℃) and kinematic viscosity (100℃) are tested according to GB / T265, and viscosity index is tested according to GB / T1995. Low-temperature fluidity test: The low-temperature fluidity performance of hydraulic oil is evaluated by pour point, and the test adopts GB / T3535. Biodegradability test: OECD 301B biodegradability test was used; Oxidation stability test: Rotary bomb oxidation method (SH / T0193) was used. Flame retardancy test: The flame retardancy of hydraulic oil is evaluated by flash point, and the test adopts GB / T3536; Demulsibility test: GB / T7305 was adopted; Corrosion resistance test: GB / T7326.

[0046] The biodegradable hydraulic oils prepared in Examples 1-6 and the hydraulic oils prepared in Comparative Examples 1-5 were subjected to viscosity-temperature performance tests, low-temperature fluidity tests, biodegradability tests, oxidation stability tests, flame retardancy tests, demulsification tests, and corrosion resistance tests, respectively. The test results are shown in Table 1. Table 1

[0047] As can be seen from the results in Table 1, the excellent adsorption properties of activated clay are used to load the SiO2@tocopherol nanocapsules described in this invention, and the activated clay loaded with SiO2@tocopherol nanocapsules is used to refine deacidified vegetable oil. This can effectively improve the oxidation stability of hydraulic oil with the refined vegetable oil as the base oil, while ensuring that the hydraulic oil has high biodegradability. In conjunction with ester oils and demulsifiers, the viscosity-temperature properties, low-temperature fluidity, and flame retardancy of the hydraulic oil can be improved simultaneously.

[0048] The embodiments described herein are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are indicated by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be included within the scope of protection of this application.

Claims

1. A biodegradable hydraulic oil composition, characterized in that, The hydraulic oil composition comprises ester oil, refined vegetable oil, and demulsifier. Based on the total weight of the ester oil, refined vegetable oil, and demulsifier (100% by weight), the content of the ester oil is 20-37% by weight, the content of the refined vegetable oil is 62-79.9% by weight, and the content of the demulsifier is 0.1-1% by weight. The refined vegetable oil is prepared by pre-loading nanocapsules with an antioxidant core into activated clay, loading the pre-loaded activated clay into deacidified oil, and then filtering to obtain the refined vegetable oil.

2. The biodegradable hydraulic oil composition according to claim 1, characterized in that, The weight ratio of the activated clay to the nanocapsule with an antioxidant core is 8~12:

1.

3. The biodegradable hydraulic oil composition according to claim 1 or 2, characterized in that, The nanocapsules with an antioxidant core are SiO2@tocopherol nanocapsules. The preparation method of the SiO2@tocopherol nanocapsules is as follows: tocopherol is dissolved in ethanol, and an aqueous solution of hexadecyltrimethylammonium bromide is added to the tocopherol dissolved in ethanol and mixed to form an emulsion. A mixed solution of tetraethyl orthosilicate and ammonia is added dropwise to the emulsion, and then the mixture is centrifuged, washed, and dried to obtain SiO2@tocopherol nanocapsules.

4. The biodegradable hydraulic oil composition according to claim 3, characterized in that, The ratio of tocopherol, hexadecyltrimethylammonium bromide, and tetraethyl orthosilicate is 8-12 g: 1-3 g: 18-22 mL.

5. The biodegradable hydraulic oil composition according to claim 1 or 2, characterized in that, The method for preparing the refined vegetable oil further includes: before loading the pre-loaded nanocapsule-loaded activated clay onto the deacidified oil, heating the vegetable oil to 48-52 ℃ and adding phospholipase, then adjusting the pH to 4.8-5.2 to carry out enzymatic hydrolysis to obtain enzymatically hydrolyzed oil, and then subjecting the enzymatically hydrolyzed oil to supercritical CO2 extraction for deacidification to obtain deacidified oil. The conditions for supercritical CO2 extraction for deacidification are: the temperature of the extraction vessel is 40-50 ℃ and the pressure is 10-15 MPa, and the temperature of the separation vessel is 35-45 ℃ and the pressure is 6-10 MPa.

6. The biodegradable hydraulic oil composition according to claim 5, characterized in that, The method for preparing the refined vegetable oil further includes: before loading the pre-loaded nanocapsule-loaded activated clay onto the deacidified oil, the deacidified oil is first subjected to molecular distillation under the following conditions: feed temperature of 170~190 ℃ and vacuum degree of 0.1~0.15 Pa; then the distillate is mixed with hydrogen, and the mixture is reacted in a nickel-based catalyst bed at 75~85 ℃ for 30~40 min.

7. The biodegradable hydraulic oil composition according to claim 1, characterized in that, The ester oil is trihydroxy oleate and / or monoglyceride oleate, and the kinematic viscosity of the ester oil at 40°C is 2~100 mm. 2 / s, open flash point ≥200 ℃.

8. The biodegradable hydraulic oil composition according to claim 1, characterized in that, The demulsifier is an alkylbenzene sulfonate, a quaternary ammonium salt, or an alkylphenol.

9. A method for preparing a biodegradable hydraulic oil, wherein the raw material for the biodegradable hydraulic oil is the biodegradable hydraulic oil composition according to any one of claims 1 to 8, characterized in that, The preparation method includes: placing the ester oil and the refined vegetable oil in a reaction vessel for heating treatment, and then adding the demulsifier to the reaction vessel under vacuum conditions.

10. The method for preparing hydraulic oil according to claim 9, characterized in that, The heating treatment is carried out under stirring conditions, and the heating conditions are as follows: heating rate of 4~6 ℃ / min, heating to 115~125 ℃, stirring rate of 800~1000 rpm; the vacuum conditions are: vacuum degree of -0.09~0.1 MPa.

Images