Process for the production of biodegradable greases

Abstract

The application discloses a production process of biodegradable lubricating grease and belongs to the technical field of lubricating materials. The raw material formula comprises the following components in a mass fraction: 80-90 parts of vegetable oil, 1-10 parts of thickening agent and 1-15 parts of additive. The vegetable oil is used as base oil to give the lubricating grease degradability; and the production process is improved, the thickening agent is added in the production process, and the nitrogen protects the vegetable oil from being hydrolyzed and oxidized in the production process; the thickening agent avoids the problems of structure damage and performance reduction of the vegetable oil caused by hydrolysis; and the nitrogen can prevent the oxidation of the vegetable oil. In addition, the addition of the additive improves the extreme pressure and wear resistance and lubricity of the lubricating grease, and also gives the lubricating grease the antioxidant property and excellent compatibility with the vegetable oil. Therefore, the prepared lubricating grease has important application significance in the field of lubricating materials.

Description

Technical Field

[0001] This invention belongs to the field of lubricating materials technology, specifically relating to a production process for a biodegradable lubricating grease. Background Technology

[0002] Currently, the vast majority of lubricating greases on the market are made primarily from mineral oil. However, these greases are generally difficult to degrade, causing serious environmental pollution. In recent years, with increasing environmental awareness and the popularization of sustainable development concepts, biodegradable lubricating greases have gradually gained attention and favor.

[0003] Most known biodegradable greases use vegetable oils, ester oils, and low-viscosity PAO base oils or combinations thereof as base oils. The production process is mostly the same as that of mineral oil base oils. However, because vegetable oils and ester oils contain ester groups, they are prone to hydrolysis under acid, alkali, and water conditions, which leads to structural changes, performance degradation, and even thickening failure. In addition, vegetable oils have poor oxidation properties and are easily oxidized during the high-temperature refining stage of grease production, which also results in a darker appearance of the final product and a reduction in antioxidant and structural properties.

[0004] The relevant technology disclosure number CN112143551A Chinese invention patent application discloses a method for producing biodegradable grease, which mainly uses vegetable oil, ester oil and other rapidly biodegradable lubricating oils as base oils to prepare grease. However, its production method and process are not significantly different from traditional lubricating grease production. Antioxidants and anti-wear agents are added only after cooling, without taking into account the hydrolysis and oxidation of the base oil during the production process. Moreover, the added antioxidants and anti-wear agents have poor compatibility with vegetable oils, which makes it difficult for the performance of the reagents to be fully utilized and fails to meet the higher requirements of the lubrication material technology field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a production process for biodegradable grease.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] This invention provides a process for producing biodegradable lubricating grease, comprising the following steps:

[0008] A1. Add vegetable oil to a clean reaction vessel, then add thickener and additives, seal the reaction vessel, and purge with nitrogen for protection. Heat to 200℃-220℃ within 1-2 hours.

[0009] A2. Add vegetable oil and additives to a clean mixing vessel, seal the mixing vessel, and purge with nitrogen for protection. Preheat to 150℃-170℃.

[0010] A3. When the temperature of the reactor in step A1 reaches 200℃-220℃, keep it at that temperature for 15min-30min, seal it with nitrogen and transfer it to a preheated mixing vessel to obtain a concentrated solution.

[0011] A4. Start the homogenizer and maintain the temperature at 150-170℃. Homogenize the concentrate 2-3 times.

[0012] A5. Add cold oil to cool down the mixing vessel;

[0013] A6. When the temperature drops to 80-100℃, add the additives, adjust the cone penetration to the appropriate range, grind 2-3 times to form grease, and obtain biodegradable grease.

[0014] Using vegetable oil as the base oil imparts biodegradability to the grease; and by improving the production process, thickeners and nitrogen are added during the grease production process to protect the vegetable oil from hydrolysis and oxidation. The thickeners prevent the structural damage and performance degradation of vegetable oil caused by hydrolysis; nitrogen acts as a protective gas during the production process to prevent the oxidation of vegetable oil.

[0015] Furthermore, the raw material formula includes, by weight parts: 80-90 parts vegetable oil, 1-10 parts thickener, and 1-15 parts additives.

[0016] Furthermore, the vegetable oil is one or more of soybean oil, castor oil, rapeseed oil, and peanut oil.

[0017] Furthermore, the thickener is one of lithium stearate soap, 12-hydroxylithium stearate soap, calcium stearate soap, 12-hydroxycalcium stearate soap, or polyurea thickener.

[0018] Furthermore, the additive is prepared by the following steps:

[0019] S1. In a three-necked flask equipped with a stirrer, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 2-methylene-1,3-propanediol, dibutyltin oxide (catalyst), DCC (dicyclohexylcarbodiimide, dehydrating agent), and acetonitrile were mixed and reacted at 80°C for 3 hours. After the reaction was completed, most of the solvent was removed by rotary evaporation, and then purified by column chromatography (the eluent was a mixed solvent of benzene and ethyl acetate, with a volume ratio of 2:3). The eluent was removed by rotary evaporation to obtain intermediate 1; the ratio of the amounts of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 2-methylene-1,3-propanediol, dibutyltin oxide, DCC, and acetonitrile was 27.8 g: 10.8 g: 2 g: 20.6 g: 100 mL.

[0020] Catalyzed by dibutyltin oxide and DCC, the carboxyl group on 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and the hydroxyl group on 2-methylene-1,3-propanediol undergo an esterification reaction. By controlling the molar ratio of the two to be close to 1:1 and with a slight excess of 2-methylene-1,3-propanediol, an -OH group on 2-methylene-1,3-propanediol is introduced into the reaction, yielding intermediate 1. The specific reaction process is shown below:

[0021]

[0022] S2. In a three-necked flask equipped with a stirrer, intermediate 1, phosphorus oxychloride, dibutyltin oxide (catalyst), triethylamine, and toluene are mixed and stirred until homogeneous. The mixture is then slowly heated to 90°C and reacted for 8 hours. Once the reaction is complete, triethylamine hydrochloride is removed by filtration, and toluene is removed by vacuum distillation. The mixture is then purified by column chromatography (using a mixed solvent of benzene and ethyl acetate in a volume ratio of 6:5). The eluent is removed by rotary evaporation to obtain intermediate 2. The ratio of intermediate 1, phosphorus oxychloride, dibutyltin oxide, triethylamine, and toluene is 110.2 g: 15.6 g: 5 g: 75 mL: 200 mL.

[0023] In the presence of dibutyltin oxide as a catalyst, intermediate 1 undergoes an esterification reaction with phosphorus oxychloride. By controlling the molar ratio of the two to be close to 3:1 and with intermediate 1 in slight excess, the three -Cl groups on phosphorus oxychloride participate in the reaction. Triethylamine removes the hydrogen chloride generated in the reaction to obtain intermediate 2. The specific reaction process is shown below:

[0024]

[0025] S3. Add intermediate 2, AIBN (azobisisobutyronitrile), mercaptoacetic acid, and toluene to a three-necked flask and stir until homogeneous. Maintain the temperature of the system at 80℃ and react for 5 hours. After the reaction is complete, remove part of the solvent by rotary evaporation, and then purify by column chromatography (using a mixed solvent of ethyl acetate and benzene as the eluent, with a volume ratio of 2:3). Remove the eluent by rotary evaporation to obtain the auxiliary agent. The ratio of intermediate 2, AIBN, mercaptoacetic acid, and toluene is 108.8 g: 3 g: 30.5 g: 200 mL.

[0026] Under the action of AIBN, the unsaturated carbon-carbon double bond on intermediate 2 undergoes a mercapto-alkene click reaction with the mercapto group of mercaptoacetic acid. By controlling the molar ratio of the two to be close to 1:3 and with a slight excess of mercaptoacetic acid, all three double bonds on intermediate 2 participate in the reaction, yielding the auxiliary agent; the structure of the auxiliary agent is shown in the figure below:

[0027]

[0028] The prepared additive is mainly composed of phosphate esters, which not only ensures compatibility with vegetable oils but also acts as an extreme pressure agent. The phosphate esters are first adsorbed onto the metal surface and then hydrolyzed into acidic phosphate esters, which can form an organometallic phosphate protective film with the metal. Under extreme pressure friction conditions, it further decomposes to form an inorganic iron phosphite film, which provides extreme pressure anti-wear performance. In addition, the molecule contains ester groups, hindered phenols, carboxyl groups, and thioether structures. The ester groups improve the compatibility of the additive with vegetable oils; the hindered phenols have excellent antioxidant capacity, which not only prevents the vegetable oil from being oxidized during the production process but also imparts significant antioxidant properties to the vegetable oil; the introduction of carboxyl groups further enhances the compatibility of the additive with various vegetable oils, ensuring that the various properties of the additive are fully utilized, and as a polar group, it can form an adsorption film on the metal surface, thereby preventing contact friction between metals and improving lubrication performance; finally, the thioether can further improve the extreme pressure anti-wear performance of the grease.

[0029] The beneficial effects of this invention are:

[0030] The biodegradable grease of this invention uses vegetable oil, a thickener, and additives as raw materials. Using vegetable oil as the base oil imparts biodegradability to the grease. By improving the production process, a thickener and nitrogen are added during production to protect the vegetable oil from hydrolysis and oxidation. The thickener prevents structural damage and performance degradation caused by hydrolysis of the vegetable oil, while nitrogen prevents oxidation. Furthermore, the addition of additives improves the extreme pressure anti-wear properties and lubricity of the grease, imparts antioxidant properties, and exhibits excellent compatibility with vegetable oil. Therefore, the resulting grease has significant application value in the field of lubrication materials. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] Preparation aids

[0034] S1. In a three-necked flask equipped with a stirrer, 27.8 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 10.8 g of 2-methylene-1,3-propanediol, 2 g of dibutyltin oxide, 20.6 g of DCC and 100 mL of acetonitrile were mixed and reacted at 80 °C for 3 h. After the reaction was completed, most of the solvent was removed by rotary evaporation, and then purified by column chromatography (the eluent was a mixed solvent of benzene and ethyl acetate with a volume ratio of 2:3). The eluent was removed by rotary evaporation to obtain intermediate 1.

[0035] S2. In a three-necked flask equipped with a stirrer, 110.2 g of intermediate 1, 15.6 g of phosphorus oxychloride, 5 g of dibutyltin oxide, 75 mL of triethylamine and 200 mL of toluene were mixed and stirred until homogeneous. The mixture was then slowly heated to 90 °C and reacted for 8 h. After the reaction was complete, the triethylamine hydrochloride was removed by filtration, the toluene was removed by vacuum distillation, and the mixture was purified by column chromatography (using a mixed solvent of benzene and ethyl acetate in a volume ratio of 6:5). The eluent was removed by rotary evaporation to obtain intermediate 2.

[0036] S3. Add 108.8g of intermediate 2, 3g of AIBN, 30.5g of mercaptoacetic acid and 200mL of toluene to a three-necked flask and stir until homogeneous. Maintain the temperature of the system at 80℃ and react for 5h. After the reaction is complete, remove part of the solvent by rotary evaporation and then purify by column chromatography (using a mixed solvent of ethyl acetate and benzene with a volume ratio of 2:3 as the eluent). Remove the eluent by rotary evaporation to obtain the auxiliary agent.

[0037] Example 2

[0038] S1. In a three-necked flask equipped with a stirrer, 55.6 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 21.6 g of 2-methylene-1,3-propanediol, 4 g of dibutyltin oxide, 41.2 g of DCC and 200 mL of acetonitrile were mixed and reacted at 80 °C for 3 h. After the reaction was completed, most of the solvent was removed by rotary evaporation, and then purified by column chromatography (the eluent was a mixed solvent of benzene and ethyl acetate with a volume ratio of 2:3). The eluent was removed by rotary evaporation to obtain intermediate 1.

[0039] S2. In a three-necked flask equipped with a stirrer, 220.4 g of intermediate 1, 31.2 g of phosphorus oxychloride, 10 g of dibutyltin oxide, 150 mL of triethylamine and 400 mL of toluene were mixed and stirred until homogeneous. The mixture was then slowly heated to 90 °C and reacted for 8 h. After the reaction was complete, the triethylamine hydrochloride was removed by filtration, the toluene was removed by vacuum distillation, and the mixture was purified by column chromatography (using a mixed solvent of benzene and ethyl acetate in a volume ratio of 6:5). The eluent was removed by rotary evaporation to obtain intermediate 2.

[0040] S3. Add 217.6g of intermediate 2, 6g of AIBN, 61g of mercaptoacetic acid and 400mL of toluene to a three-necked flask and stir until homogeneous. Maintain the temperature of the system at 80℃ and react for 5h. After the reaction is complete, remove part of the solvent by rotary evaporation and then purify by column chromatography (using a mixed solvent of ethyl acetate and benzene with a volume ratio of 2:3 as the eluent). Remove the eluent by rotary evaporation to obtain the auxiliary agent.

[0041] Example 3

[0042] A1. Add 45 parts of rapeseed oil to a clean reaction vessel, then add 10 parts of lithium stearate soap (Jiangxi Hongyuan Chemical Co., Ltd., HY-201) and 1 part of the additive prepared in Example 1. Seal the reaction vessel and purge with nitrogen for protection. Heat to 200°C within 1 hour.

[0043] A2. Add 35 parts rapeseed oil and 1 part of the additive prepared in Example 1 to a clean mixing vessel, seal the mixing vessel, and purge with nitrogen for protection. Preheat the mixture to 150°C.

[0044] A3. When the temperature of the reactor in step A1 reaches 200℃, keep it at that temperature for 15 minutes, seal it with nitrogen gas, and transfer it to a preheated mixing vessel to obtain a concentrated solution.

[0045] A4. Start the homogenizer and maintain the temperature at 150℃. Homogenize the concentrate twice.

[0046] A5. Add cold oil to cool down the mixing vessel;

[0047] A6. When the temperature drops to 80°C, add 3 parts of the additive prepared in Example 1, adjust the cone penetration to a suitable range, grind twice, and form grease to obtain biodegradable grease.

[0048] Example 4

[0049] A1. Add 40 parts of peanut oil to a clean reaction vessel, then add 10 parts of 12-hydroxystearic acid lithium soap (Jiangxi Hongyuan Chemical Co., Ltd., HY-202) and 2 parts of the additive prepared in Example 2. Seal the reaction vessel and purge with nitrogen for protection. Heat to 210°C within 1.5 hours.

[0050] A2. Add 42 parts of peanut oil and 2 parts of the additive prepared in Example 2 to a clean mixing vessel, seal the mixing vessel, and purge with nitrogen for protection. Preheat the mixture to 155°C.

[0051] A3. When the temperature of the reactor in step A1 reaches 210℃, keep it at that temperature for 20 minutes, seal it with nitrogen gas, and transfer it to a preheated mixing vessel to obtain a concentrated solution.

[0052] A4. Start the homogenizer and maintain the temperature at 160℃. Homogenize the concentrate three times.

[0053] A5. Add cold oil to cool down the mixing vessel;

[0054] A6. When the temperature drops to 85°C, add 6 parts of the additive prepared in Example 2, adjust the cone penetration to a suitable range, grind 3 times, form grease, and obtain biodegradable grease.

[0055] Example 5

[0056] A1. Add 35 parts of soybean oil to a clean reactor, then add 9 parts of polyurea thickener (Shandong Hongxing Chemical Co., Ltd., DP01) and 3 parts of the additive prepared in Example 1. Seal the reactor and purge with nitrogen for protection. Heat to 220°C within 2 hours.

[0057] A2. Add 50 parts soybean oil and 3 parts of the additive prepared in Example 1 to a clean mixing vessel, seal the mixing vessel, and purge with nitrogen for protection. Preheat the mixture to 170°C.

[0058] A3. When the temperature of the reactor in step A1 reaches 220℃, keep it at that temperature for 30 minutes, seal it with nitrogen gas, and transfer it to a preheated mixing vessel to obtain a concentrated solution.

[0059] A4. Start the homogenizer and maintain the temperature at 170℃. Homogenize the concentrate three times.

[0060] A5. Add cold oil to cool down the mixing vessel;

[0061] A6. When the temperature drops to 100°C, add 9 parts of the additive prepared in Example 1, adjust the cone penetration to a suitable range, grind 3 times, form grease, and obtain biodegradable grease.

[0062] Comparative Example 1

[0063] A1. Add 50 parts of soybean oil to a clean reaction vessel, heat to 80°C, then add 9 parts of polyurea thickener (Shandong Hongxing Chemical Co., Ltd., DP01), wait for the temperature to rise to 100°C, then add 20 parts of lithium hydroxide aqueous solution (mass fraction 60%) dropwise, and react for 2 hours.

[0064] A2. Continue heating to 125℃ to begin dehydration;

[0065] A3. After dehydration is complete, continue to raise the temperature to the maximum refining temperature of 210°C, and add 35 parts of soybean oil during the heating process.

[0066] A4. When the temperature of the reactor reaches 210℃, keep it at that temperature for 15 minutes.

[0067] A5. Transfer to the mixing kettle, add an appropriate amount of cold oil, and lower the temperature to 160℃. Start the circulating stirring.

[0068] A6. When the temperature drops to 90℃, add 15 parts of antioxidant, grind 3 times to form grease, and obtain biodegradable lubricating grease.

[0069] Comparative Example 2

[0070] The additives in Example 5 were replaced with antioxidant 1010, manufactured by Ciba Fine Chemicals, Switzerland, of the same mass as the additives, and the remaining steps were the same as in Example 5.

[0071] The greases prepared in Example 5 and Comparative Example 1 were molded into corresponding shapes according to different test standards, and the test results are shown in Table 1:

[0072] Table 1

[0073]

[0074] The analysis results in Table 1 show that the grease prepared by the direct saponification method in Comparative Example 1, without nitrogen protection and the addition of antioxidants during production, resulted in a significantly affected appearance and performance of the final product. The grease was darker, and its thickening ability, dropping point, colloidal stability (oil separation on a steel mesh), oxidation stability, evaporation loss, and biodegradability were all deteriorated. This is mainly due to the hydrolysis of the base oil during production, leading to structural damage. The process method provided by this invention is a dedicated production process suitable for biodegradable greases based on vegetable oils and other similar base oils.

[0075] The greases prepared in Examples 3-5 and Comparative Example 2 were molded into corresponding shapes according to different test standards, and the following performance tests were conducted:

[0076] The oxidation induction period was determined according to SH-T 0719-2002 "Determination of Oxidation Induction Period of Lubricating Oil";

[0077] The diameter of long-term wear scars was determined using SH / T 0189-2017 "Determination of Anti-wear Properties of Lubricating Oil (Four-ball machine method)" under experimental conditions of 1500 r / min, 80℃, and 30 min.

[0078] High-temperature oxidation tests were conducted using GJB 563-1988;

[0079] The measurement results are shown in Table 2:

[0080] Table 2

[0081]

[0082] As shown in Table 2, the grease prepared in the example has higher wear resistance, oxidation resistance and oxidation stability than antioxidant 1010 due to the use of additives. Therefore, the grease prepared has important application significance in the field of lubrication materials.

[0083] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A production process for a biodegradable lubricating grease, characterized in that, Includes the following steps: A1. Add vegetable oil, thickener and additives to the reaction vessel, seal the reaction vessel, introduce nitrogen gas, and heat to 200℃-220℃ within 1-2 hours. A2. Add vegetable oil and additives to the mixing kettle, seal the mixing kettle, introduce nitrogen gas, and preheat to 150℃-170℃; A3. When the temperature of the reactor in step A1 reaches 200℃-220℃, keep it at that temperature for 15min-30min, seal it with nitrogen and transfer it to a preheated mixing vessel to obtain a concentrated solution. A4. Start the homogenizer and maintain the temperature at 150-170℃. Homogenize the concentrate 2-3 times. A5. Add cold oil to cool down the mixing vessel; A6. When the temperature drops to 80-100℃, add the additives, adjust the cone penetration to a suitable range, grind 2-3 times to form grease, and obtain biodegradable grease. The auxiliary agent is prepared through the following steps: S1. 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 2-methylene-1,3-propanediol, dibutyltin oxide, DCC, and acetonitrile were mixed and reacted at 80°C for 3 hours. The mixture was then rotary evaporated, using a mixed solvent of benzene and ethyl acetate in a volume ratio of 2:3 as the eluent. This yielded intermediate 1. The ratio of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 2-methylene-1,3-propanediol, dibutyltin oxide, DCC, and acetonitrile was 27.8 g:10.8 g:2 g:20.6 g:100 mL. The structural formula of intermediate 1 is as follows: ； S2. Intermediate 1, phosphorus oxychloride, dibutyltin oxide, triethylamine, and toluene were mixed and stirred until homogeneous. The mixture was reacted at 90°C for 8 hours, filtered, and purified by vacuum distillation and column chromatography. The eluent was a mixed solvent of benzene and ethyl acetate in a volume ratio of 6:

5. The mixture was then rotary evaporated to obtain intermediate 2. The ratio of intermediate 1, phosphorus oxychloride, dibutyltin oxide, triethylamine, and toluene was 110.2 g:15.6 g:5 g:75 mL:200 mL. The structural formula of intermediate 2 is as follows: ； S3. Intermediate 2, AIBN, mercaptoacetic acid, and toluene were stirred and mixed evenly, reacted at 80℃ for 5 h, purified by rotary evaporation and column chromatography, using a mixed solvent of ethyl acetate and benzene in a volume ratio of 2:3 as the eluent, and obtained the auxiliary agent by rotary evaporation; the ratio of intermediate 2, AIBN, mercaptoacetic acid, and toluene was 108.8 g:3 g:30.5 g:200 mL; the structural formula of the auxiliary agent is as follows: 。 2. The production process of a biodegradable lubricating grease according to claim 1, characterized in that, The vegetable oil is one or more of soybean oil, castor oil, rapeseed oil, and peanut oil.

3. The production process of a biodegradable lubricating grease according to claim 1, characterized in that, The thickener is one of lithium stearate soap, 12-hydroxylithium stearate soap, calcium stearate soap, 12-hydroxycalcium stearate soap, or polyurea thickener.

4. The production process of a biodegradable lubricating grease according to claim 1, characterized in that, The raw material formula, by weight, includes: 80-90 parts vegetable oil, 1-10 parts thickener, and 1-15 parts additives.

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