A castor oil-based lubricating oil anti-wear additive, its preparation method and application

Abstract

This invention discloses a castor oil-based anti-wear additive for lubricating oil, its preparation method, and its application. Belonging to the field of anti-wear technology for lubricating oil, the method involves placing castor oil and maleic anhydride in a reaction vessel, heating and stirring under inert gas protection to carry out an esterification reaction, obtaining an esterification reaction intermediate. Then, methacrylate monomers and an initiator are added to the reaction system containing the esterification reaction intermediate, followed by heating and stirring under inert gas protection to carry out a polymerization reaction, obtaining a castor oil-based polymer, which is the castor oil-based anti-wear additive for lubricating oil. This fills the application gap of castor oil-based materials in the field of anti-wear function of lubricating oil.

Description

Technical Field

[0001] This invention belongs to the field of lubricating oil anti-wear technology, specifically relating to a castor oil-based lubricating oil anti-wear additive, its preparation method, and its application. Background Technology

[0002] Lubricating oil is a crucial basic material for the stable operation of modern industrial equipment. Anti-wear additives, as the core functional components of lubricating oil, directly determine the wear level and service life of equipment friction pairs. While traditional petroleum-based anti-wear additives can meet basic industrial operating conditions, most contain harmful elements such as sulfur, phosphorus, and chlorine, exhibiting ecotoxicity and being difficult to biodegrade. Leaks or waste can easily cause soil and water pollution, and their use is strictly limited in sensitive scenarios such as food processing and pharmaceutical production. Currently, developing sulfur-, phosphorus-, and chlorine-free, renewable, and environmentally friendly vegetable oil-based anti-wear additives has become an urgent need for industry development.

[0003] Castor oil, a typical non-edible vegetable oil, is widely available and cost-effective. Its main component is ricinoleic acid (approximately 85%–95%), and its molecular structure contains multiple active sites such as unsaturated double bonds and hydroxyl groups. Functional groups can be introduced through chemical modification, making it a preferred alternative to petroleum-based raw materials for preparing environmentally friendly lubricant additives. Current research on castor oil in lubricant additives generally focuses on the development of viscosity index improvers, utilizing its molecular structure characteristics to optimize the viscosity-temperature properties of lubricants. Related technologies and products are relatively mature.

[0004] However, research on the development and application of anti-wear properties of castor oil-based materials is currently lacking in the industry. In industrial production, wear failure of equipment friction pairs is one of the main causes of equipment failure, making the demand for efficient and environmentally friendly anti-wear additives extremely urgent. At the same time, traditional vegetable oil-based anti-wear additives are mostly made from soybean oil and other raw materials, and their anti-wear properties are limited by molecular structure, making it difficult to adapt to diverse industrial conditions.

[0005] Based on this, in view of the problem that the research direction of castor oil-based lubricant additives is singular and the development of anti-wear function is lacking in the existing technology, it is necessary to develop a lubricant anti-wear additive with castor oil as raw material, fill the application gap of castor oil in the field of lubricant anti-wear, and provide a new raw material selection and technical path for environmentally friendly lubricant anti-wear additives. This has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of limited research direction and lack of development of anti-wear function in lubricating oil additives, and to propose a castor oil-based anti-wear additive for lubricating oil, its preparation method and application.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a castor oil-based lubricating oil anti-wear additive, comprising the following steps: Castor oil and maleic anhydride were placed in a reaction vessel and heated and stirred under inert gas protection to carry out an esterification reaction to obtain an esterification reaction intermediate. After adding methacrylate monomers and initiators to the reaction system containing the esterification reaction intermediate, the polymerization reaction is carried out under inert gas protection with heating and stirring to obtain castor oil-based polymer, which is castor oil-based lubricating oil anti-wear additive.

[0008] Furthermore, the inert gas protection specifically involves evacuating the system and then filling it with nitrogen.

[0009] Furthermore, the initiator is benzoyl peroxide, which is added to the reaction system in the form of a xylene solution.

[0010] Furthermore, the methacrylate monomer is tetradecyl methacrylate; The mass ratio of castor oil, maleic anhydride and tetradecyl methacrylate is 1.0:0.1:(1.0~4.2). The amount of benzoyl peroxide added is 0.1% to 1.0% of the total mass of castor oil, maleic anhydride and tetradecyl methacrylate.

[0011] Furthermore, the methacrylate monomer is methyl methacrylate; The mass ratio of castor oil, maleic anhydride and methyl methacrylate is 1.0:0.1:(1.0~3.4). The amount of benzoyl peroxide added is 0.1% to 1.5% of the total mass of castor oil, maleic anhydride and methyl methacrylate.

[0012] Furthermore, the methacrylate monomer is isobornyl methacrylate; The mass ratio of castor oil, maleic anhydride and isobornyl methacrylate is 1.0:0.1:(1.0~2.6). The amount of benzoyl peroxide added is 0.1% to 2.0% of the total mass of castor oil, maleic anhydride and isobornyl methacrylate.

[0013] Furthermore, the isothermal reaction temperature for the polymerization reaction is 70℃~120℃, and the isothermal reaction time is 3-7h.

[0014] Furthermore, after the polymerization reaction is completed, the reaction system is placed in an ice-cold anhydrous ethanol solution to terminate the reaction. After sedimentation, purification, and drying, castor oil-based lubricating oil anti-wear additive is obtained.

[0015] Secondly, the present invention provides a castor oil-based lubricating oil anti-wear additive, which is prepared using a method for preparing a castor oil-based lubricating oil anti-wear additive.

[0016] Thirdly, the present invention provides an application of castor oil-based anti-wear additive in lubricating oil base oil. The castor oil-based anti-wear additive is added to the lubricating oil base oil at a mass fraction of 0.10% to 1.50%, which reduces the wear scar diameter of the lubricating oil base oil by 0.143-0.574 mm.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: This invention proposes a method for preparing a castor oil-based anti-wear additive for lubricating oil. Under catalyst-free conditions, a copolymer system of castor oil and methacrylate monomers with different structures is constructed by solution polymerization to obtain the castor oil-based anti-wear additive for lubricating oil. The preparation method is simple and easy to implement, the reaction conditions are mild, the raw material is non-edible vegetable oil and the cost is low, and it has great potential for industrial scale-up. It has broad application prospects in the preparation of environmentally friendly anti-wear additives for lubricating oil and expands the path and scope of high-value utilization of castor oil.

[0018] Furthermore, methacrylate monomers encompass short-chain, long-chain, and bridged ring structures; this invention systematically reveals the structure-property relationship between the molecular structure and anti-wear properties of castor oil-based polymers; for the first time, castor oil is modified and polymerized with tetradecyl methacrylate / methyl methacrylate / isoborneol methacrylate to prepare a lubricating oil anti-wear agent, filling the application gap of castor oil-based materials in the field of lubricating oil anti-wear function.

[0019] This invention proposes a castor oil-based anti-wear additive for lubricating oils, which has a small addition amount and significant anti-wear effect; it solves the problems of traditional petroleum-based anti-wear additives containing sulfur / phosphorus / chlorine, being difficult to biodegrade, and being limited in sensitive scenarios. The castor oil-based anti-wear additive proposed in this invention is free of harmful elements, has good biocompatibility, and combines excellent anti-wear performance with environmental friendliness. Attached Figure Description The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a schematic diagram of the structure of unsaturated fatty acids in castor oil. Figure 2 The infrared spectrum of poly(castor oil-maleic anhydride-tetradecyl methacrylate); Figure 3 The NMR spectrum of poly(castor oil-maleic anhydride-tetradecyl methacrylate) is shown. Figure 4The infrared spectrum of poly(castor oil-maleic anhydride-methyl methacrylate); Figure 5 The NMR spectrum of poly(castor oil-maleic anhydride-methyl methacrylate) is shown. Figure 6 The infrared spectrum of poly(castor oil-maleic anhydride-isobornyl methacrylate); Figure 7 The NMR spectrum of poly(castor oil-maleic anhydride-isobornyl methacrylate); Figure 8 The synthetic route for castor oil-maleic anhydride-tetradecyl methacrylate copolymer; Figure 9 Synthetic routes for castor oil-maleic anhydride-methyl methacrylate copolymer and castor oil-maleic anhydride-isobornyl methacrylate copolymer; Figure 10 The structural formula (I) is for a castor oil-based polymer. Figure 11 The structural formula (II) is for a castor oil-based polymer. Figure 12 The structural formula (Ⅲ) is for a castor oil-based polymer. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of 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 skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] The present invention will now be described in further detail: A method for preparing a castor oil-based anti-wear additive for lubricating oil involves modifying castor oil with maleic anhydride esterification and then polymerizing it with a solution of tetradecyl methacrylate / methyl methacrylate / isobornyl methacrylate to prepare the castor oil-based anti-wear additive. The preparation method of the castor oil-based anti-wear additive for lubricating oil is as follows: Step 1: Add castor oil and maleic anhydride to the polymerization reaction tube and seal it. Evacuate and purge with nitrogen. Specifically, add a certain amount of castor oil and maleic anhydride to the polymerization reaction tube and seal it. Evacuate and purge with nitrogen 3-4 times using a Schlenk anhydrous and oxygen-free apparatus. Heat and stir the reaction under nitrogen protection until it is completed. Then cool to room temperature to obtain the esterification reaction intermediate.

[0023] Step II: Vacuum and nitrogen are purged again. Under nitrogen protection, methacrylate monomers and initiators are injected to react, ultimately yielding a castor oil-based anti-wear additive for lubricating oil. Specifically, the reactants from Step I are evacuated and purged with nitrogen 3-4 times. During the final nitrogen purging, tetradecyl methacrylate (or methyl methacrylate / isobornyl methacrylate) and a xylene solution of benzoyl peroxide (BPO) are injected into the system. The mixture is stirred and heated to the reaction temperature. After a certain period of constant temperature reaction, a castor oil-based polymer copolymer is obtained, which is the castor oil-based anti-wear additive for lubricating oil. The constant temperature reaction range is 70℃-120℃, and the time is 3-7 hours. After the reaction in Step II is completed, the polymerization reaction tube is placed in an ice-cold anhydrous ethanol solution to terminate the reaction. After sedimentation, purification, and drying, the product is obtained.

[0024] The mass ratio of castor oil, maleic anhydride and tetradecyl methacrylate is 1.0:0.1:(1.0~4.2); the amount of benzoyl peroxide added is 0.1% to 1.0% of the total mass of castor oil, maleic anhydride and tetradecyl methacrylate in step I.

[0025] The mass ratio of castor oil, maleic anhydride and methyl methacrylate is 1.0:0.1:(1.0~3.4); the amount of benzoyl peroxide added is 0.1% to 1.5% of the total mass of castor oil, maleic anhydride and methyl methacrylate in step I.

[0026] The mass ratio of castor oil, maleic anhydride and isobornyl methacrylate is 1.0:0.1:(1.0~2.6); the amount of benzoyl peroxide added is 0.1% to 2.0% of the total mass of castor oil, maleic anhydride and isobornyl methacrylate in step I.

[0027] The application of castor oil-based anti-wear additives in lubricating oils: Adding castor oil-based anti-wear additives to lubricating oil base oils at a mass fraction of 0.10%–1.50% can reduce the wear scar diameter of the lubricating oil by 0.143–0.574 mm, significantly improving the anti-wear performance of the lubricating oil. This invention provides the application of castor oil-based polymers as anti-wear additives for castor oil-based lubricating oils. The structure-property relationship between the molecular structure and anti-wear properties of polymers obtained by copolymerizing castor oil with short-chain, long-chain, and bridged-ring methacrylate monomers of different structures was systematically investigated, filling the research gap of castor oil-based polymers with different structures as anti-wear additives for castor oil-based lubricating oils and expanding the application scope of castor oil-based polymers in the industrial field.

[0028] This invention utilizes solution polymerization to construct copolymer systems of castor oil with short-chain, long-chain, and bridged-ring methacrylate monomers under catalyst-free conditions, synthesizing a series of castor oil-based anti-wear additives for lubricants. Castor oil-maleic anhydride-methyl methacrylate copolymer, castor oil-maleic anhydride-tetradecyl methacrylate copolymer, and castor oil-maleic anhydride-isobornyl methacrylate copolymer are typical examples. The structure-property relationship between the molecular structure of various polymers and their anti-wear properties is systematically investigated. The synthetic route of the castor oil-maleic anhydride-tetradecyl methacrylate copolymer is as follows: Figure 8 The synthetic routes for castor oil-maleic anhydride-methyl methacrylate copolymer and castor oil-maleic anhydride-isobornyl methacrylate copolymer are as follows: Figure 9 The structural formulas of various castor oil-based polymers are as follows: Figure 10 , Figure 11 , Figure 12 .

[0029] It is worth noting that castor oil has advantages such as wide availability, multiple active sites in its molecular structure including hydroxyl groups and unsaturated double bonds, and good biodegradability. However, it also has disadvantages such as insufficient hydrolytic stability and weak anti-wear performance when used directly. To fully utilize the structural and resource advantages of castor oil while compensating for its performance shortcomings as a lubricant additive, chemical modification and structural alteration of castor oil are necessary. Existing technologies mainly involve chemical modification of castor oil such as transesterification, esterification, and ring-opening to prepare castor oil-based polyesteramines, coatings, plasticizers, and other products. Simultaneously, castor oil can also undergo thermal polymerization and free radical polymerization reactions with monomers such as acrylates. The resulting polymers are mostly developed as lubricant viscosity index improvers, with little research and application of modified products for the anti-wear function of lubricants.

[0030] This invention achieves the efficient construction of a copolymer system of castor oil with short-chain, long-chain, and bridged-ring methacrylate monomers without a catalyst. It is the first time that this type of castor oil-based polymer has been applied to the field of castor oil-based lubricant anti-wear additives, filling the research gap of castor oil-based copolymers with different structures as lubricants and anti-wear agents, and expanding the industrial application scope and high-value utilization path of castor oil-based copolymers.

[0031] Furthermore, considering that castor oil is a non-edible vegetable oil, it does not compete with food crops or land, and possesses the natural advantages of readily available and stable supply. Its molecular structure contains multiple active sites, including hydroxyl groups and unsaturated double bonds, further endowing it with significant modification potential. Therefore, castor oil-based polymers obtained by polymerizing castor oil as a reactant exhibit excellent anti-wear properties and good biodegradability. They can be used as environmentally friendly castor oil-based anti-wear additives for lubricants. The preparation method is simple, the raw material cost is low, and the economic advantages are significant, making them a promising candidate for application in the field of lubricant additives.

[0032] This invention provides castor oil-based polymers and their application in lubricating oil additives, and effectively carries out copolymerization reactions of castor oil-maleic anhydride-tetradecyl methacrylate, castor oil-maleic anhydride-methyl methacrylate, and castor oil-maleic anhydride-isoborneol methacrylate under catalyst-free conditions.

[0033] Furthermore, the present invention also discloses the chemical structures of poly(castor oil-maleic anhydride-tetradecyl methacrylate), poly(castor oil-maleic anhydride-methyl methacrylate), and poly(castor oil-maleic anhydride-isoborneol methacrylate), and infrared and nuclear magnetic resonance characterizations demonstrate the successful synthesis of the copolymers.

[0034] The present invention will be further explained below with reference to the embodiments. The present invention can synthesize copolymers with three structures. Three embodiments are set for each copolymer. Among them, poly(castor oil-maleic anhydride-tetradecyl methacrylate) corresponds to Embodiments 1-3, poly(castor oil-maleic anhydride-methyl methacrylate) corresponds to Embodiments 4-6, and poly(castor oil-maleic anhydride-isobornyl methacrylate) corresponds to Embodiments 7-9. Example 1 A method for preparing a castor oil-based anti-wear additive for lubricating oil specifically includes the following steps: At room temperature, 1.0 g of castor oil and 0.1 g of maleic anhydride were weighed into a clean polymerization tube, sealed and connected to a Schlenk anhydrous and oxygen-free apparatus. After evacuating and purging with nitrogen three to four times, the reaction temperature was adjusted to 120°C. The reaction was stopped after stirring for a period of time and then cooled to room temperature to obtain the esterification intermediate (CO-MA). Then, the reaction was evacuated and purged with nitrogen three to four times again. During the last nitrogen purging, 2.6 g of tetradecyl methacrylate and a xylene solution of benzoyl peroxide were injected, and the mixture was stirred and heated to a reaction temperature of 90°C. After 5 hours of reaction, the reaction was stopped with ice-cold anhydrous ethanol solution. After precipitation, purification, and drying, poly(castor oil-maleic anhydride-tetradecyl methacrylate) was obtained.

[0035] The synthesized poly(castor oil-maleic anhydride-tetradecyl methacrylate) was subjected to infrared spectroscopy, and the results are as follows: Figure 2 As shown.

[0036] Infrared analysis showed that the depth was 3419 cm. -1 A stretching vibration peak of -OH appears at 3008 cm⁻¹. -1 A stretching vibration peak of =CH appears at 2927 cm⁻¹. -1 A stretching vibration peak of -CH3 appears at 2855 cm⁻¹. -1 A stretching vibration peak of -CH2 appears at 1739 cm⁻¹. -1Stretching vibrations occur at C=O, 1646 cm. -1 A C=C stretching vibration peak appears at 1464 cm⁻¹. -1 A bending vibration peak of -CH2 appears at 1167 cm⁻¹. -1 A peak of asymmetric stretching vibration of COC appears at 2927 cm⁻¹. -1 A stretching vibration peak of -CH3 appears at 2854 cm⁻¹. -1 A stretching vibration peak of -CH2 appears at 1720 cm⁻¹. -1 A stretching vibration peak of C=O appears at 1639 cm⁻¹. -1 A C=C stretching vibration peak appears at 1464 cm⁻¹. -1 A bending vibration peak of -CH2 appears at 1164 cm⁻¹. -1 A stretching vibration peak of -COC- appears at 723 cm⁻¹. -1 A planar rocking vibration peak of -(CH2)n- (n>4) appears at 2925 cm⁻¹. -1 A stretching vibration peak of -CH3 appears at 2854 cm⁻¹. -1 A stretching vibration peak of -CH2 appears at 1729 cm⁻¹. -1 A C=O stretching vibration peak appears at 1464 cm⁻¹. -1 A bending vibration peak of -CH2 appears at 1151 cm⁻¹. -1 A COC asymmetric stretching vibration peak appears at 3008 cm⁻¹. This is relative to castor oil and tetradecyl methacrylate. -1 The CH stretching vibration peak disappears at 1646 cm⁻¹. -1 The weakening of the C=C stretching vibration peak at the point of origin proves that poly(castor oil-maleic anhydride-tetradecyl methacrylate) was successfully synthesized.

[0037] The synthesized poly(castor oil-maleic anhydride-tetradecyl methacrylate) was subjected to... 1 H NMR characterization, results as follows Figure 3 As shown.

[0038] NMR analysis revealed that the proton peaks at chemical shifts of 6.18–6.46, 5.55, and 5.41 were proton peaks on the double bond; the proton peak at chemical shift 5.25 was a proton peak on the methylene group of the triglyceride structure; a proton peak on the tertiary carbon appeared at chemical shifts of 4.85–5.05; a -CH2 proton peak on the triglyceride structure appeared at chemical shifts of 4.11–4.30; a proton peak on the tertiary carbon bonded to the hydroxyl group appeared at chemical shift 3.60; a -CH2 proton peak bonded to the ester group appeared at chemical shift 2.30; a -CH2 proton peak adjacent to the double bond appeared at chemical shifts of 2.03–2.20; a -CH2 proton peak on the alkyl chain not adjacent to the ester group appeared at chemical shifts of 1.45–1.60; a -CH2 proton peak on the alkyl chain appeared at chemical shift 1.29; and a -CH3 proton peak at the end of the alkyl chain appeared at chemical shift 0.88. The chemical shift at 3.90 represents the -CH2 proton peak attached to the ester group in tetradecyl methacrylate; the chemical shift at 3.60 represents the proton peak on the tertiary carbon attached to the hydroxyl group in castor oil. Compared with the NMR spectrum of castor oil, this peak is significantly weaker, indicating that maleic anhydride and the -OH group of castor oil have undergone esterification; the chemical shift at 2.30 represents the -CH2 proton peak attached to the ester group in castor oil; the chemical shifts from 1.45 to 1.60 represent the -CH2 proton peak on the alkyl long chain of castor oil that is not adjacent to the ester group; the chemical shift at 1.26 represents the -CH2 proton peak on the alkyl long chain; and the chemical shift at 0.88 represents the -CH3 proton peak at the end of the alkyl long chain in castor oil. The proton peaks at chemical shifts of 6.18-6.46, 5.55, and 5.41 on the double bonds have largely disappeared, indicating that a polymerization reaction has occurred on the double bonds to obtain poly(castor oil-maleic anhydride-tetradecyl methacrylate).

[0039] Based on infrared and nuclear magnetic resonance analysis, the structure of poly(castor oil-maleic anhydride-tetradecyl methacrylate) is as follows: Figure 10 As shown in equation (I).

[0040] Finally, this experiment obtained the optimal polymerization conditions by changing factors such as the monomer ratio of castor oil, maleic anhydride, and tetradecyl methacrylate, the amount of initiator, the polymerization temperature, and the polymerization time: monomer mass ratio m (CO): m (MA): m The ratio of (TMA) is 1.0:0.1:2.6, and the initiator dosage is 0.5%. w When the reaction time was 5 h and the reaction temperature was 90 ℃, a relatively high yield of poly(castor oil-maleic anhydride-tetradecyl methacrylate) of 87.33% was obtained. The relative molecular mass and polydispersity index of the polymer synthesized under optimized conditions were determined. The number-average relative molecular mass of the obtained poly(castor oil-maleic anhydride-tetradecyl methacrylate) was Mn = 1.4 × 10⁻⁶.5 The polydispersity index (PDI) is 2.3.

[0041] Example 2 A method for preparing a castor oil-based anti-wear additive for lubricating oils, the specific steps of which are as follows: At room temperature, 1.0 g of castor oil and 0.1 g of maleic anhydride were weighed into a clean polymerization tube, sealed and connected to a Schlenk anhydrous and oxygen-free apparatus. After evacuating and purging with nitrogen three to four times, the reaction temperature was adjusted to 120°C. The reaction was stopped after stirring for a period of time and then cooled to room temperature to obtain the esterification intermediate (CO-MA). Then, the reaction was evacuated and purged with nitrogen three to four times again. During the last nitrogen purging, 4.2 g of tetradecyl methacrylate and a xylene solution of benzoyl peroxide were injected, and the mixture was stirred and heated to the reaction temperature of 100°C. Three hours after the reaction was completed, the reaction was terminated with ice-cold anhydrous ethanol solution. After precipitation, purification, and drying, poly(castor oil-maleic anhydride-tetradecyl methacrylate) was obtained.

[0042] Example 3 A method for preparing a castor oil-based anti-wear additive for lubricating oil specifically includes the following steps: At room temperature, 1.0 g of castor oil and 0.1 g of maleic anhydride were weighed into a clean polymerization tube, sealed and connected to a Schlenk anhydrous and oxygen-free apparatus. After evacuating and purging with nitrogen three to four times, the reaction temperature was adjusted to 120 °C. The reaction was stopped after stirring for a period of time and then cooled to room temperature to obtain the esterification intermediate (CO-MA). Then, the reaction was evacuated and purged with nitrogen three to four times again. During the last nitrogen purging, 1.0 g of tetradecyl methacrylate and a xylene solution of benzoyl peroxide were injected, and the mixture was stirred and heated to a reaction temperature of 70 °C. After 6 hours of reaction, the reaction was stopped with ice-cold anhydrous ethanol solution. After precipitation, purification, and drying, poly(castor oil-maleic anhydride-tetradecyl methacrylate) was obtained.

[0043] Example 4 A method for preparing a castor oil-based anti-wear additive for lubricating oil specifically includes the following steps: At room temperature, 1.0 g of castor oil and 0.1 g of maleic anhydride were weighed into a clean polymerization tube, sealed and connected to a Schlenk anhydrous and oxygen-free apparatus. After evacuating and purging with nitrogen three to four times, the reaction temperature was adjusted to 120 °C. The reaction was stopped after stirring for a period of time and then cooled to room temperature to obtain the esterification intermediate (CO-MA). Then, the reaction was evacuated and purged with nitrogen three to four times again. During the last nitrogen purging, 1.0 g of methyl methacrylate and a xylene solution of benzoyl peroxide were injected, and the mixture was stirred and heated to the reaction temperature of 120 °C. After 7 hours of reaction, the reaction was stopped with ice-cold anhydrous ethanol solution. After precipitation, purification, and drying, poly(castor oil-maleic anhydride-methyl methacrylate) was obtained.

[0044] Example 5 A method for preparing a castor oil-based anti-wear additive for lubricating oil specifically includes the following steps: At room temperature, 1.0 g of castor oil and 0.1 g of maleic anhydride were weighed into a clean polymerization tube, sealed and connected to a Schlenk anhydrous and oxygen-free apparatus. After evacuating and purging with nitrogen three to four times, the reaction temperature was adjusted to 120 °C. The reaction was stopped after stirring for a period of time and then cooled to room temperature to obtain the esterification intermediate (CO-MA). Then, the reaction was evacuated and purged with nitrogen three to four times again. During the last nitrogen purging, 2.2 g of methyl methacrylate and a xylene solution of benzoyl peroxide were injected, and the mixture was stirred and heated to a reaction temperature of 90 °C. After 5 hours of reaction, the reaction was stopped with ice-cold anhydrous ethanol solution. After precipitation, purification, and drying, poly(castor oil-maleic anhydride-methyl methacrylate) was obtained.

[0045] The synthesized poly(castor oil-maleic anhydride-methyl methacrylate) was characterized by infrared spectroscopy analysis, and the results are as follows: Figure 4 As shown.

[0046] Infrared analysis showed that the depth was 3419 cm. -1 A stretching vibration peak of -OH appears at 3008 cm⁻¹. -1 A stretching vibration peak of =CH appears at 2927 cm⁻¹. -1 A stretching vibration peak of -CH3 appears at 2855 cm⁻¹. -1 A stretching vibration peak of -CH2 appears at 1739 cm⁻¹. -1 Stretching vibrations occur at C=O, 1646 cm. -1 A C=C stretching vibration peak appears at 1464 cm⁻¹. -1 A bending vibration peak of -CH2 appears at 1167 cm⁻¹. -1 A peak of asymmetric stretching vibration of COC appears at 2956 cm⁻¹. -1 A stretching vibration peak of -CH3 appears at 1726 cm⁻¹. -1 A stretching vibration peak of C=O appears at 1637 cm⁻¹. -1 A C=C stretching vibration peak appears at 1164 cm. -1 A stretching vibration peak of -COC- appears at 2952 cm⁻¹. -1 A stretching vibration peak of -CH3 appears at 1731 cm⁻¹. -1 A C=O stretching vibration peak appears at 1452 cm⁻¹. -1 A bending vibration peak of -CH2 appears at 1145 cm⁻¹. -1 A COC asymmetric stretching vibration peak appears at 3008 cm⁻¹. This is relative to castor oil and methyl methacrylate.-1 The CH stretching vibration peak disappears at 1646 cm⁻¹. -1 The weakening of the C=C stretching vibration peak at the point of origin proves that poly(castor oil-maleic anhydride-methyl methacrylate) was successfully synthesized.

[0047] The synthesized poly(castor oil-maleic anhydride-methyl methacrylate) was subjected to... 1 H NMR characterization, results as follows Figure 5 As shown.

[0048] NMR analysis revealed that the proton peaks at chemical shifts of 6.18–6.46, 5.55, and 5.41 were proton peaks on the double bond; the proton peak at chemical shift 5.25 was a proton peak on the methylene group of the triglyceride structure; a proton peak on the tertiary carbon appeared at chemical shifts of 4.85–5.05; a -CH2 proton peak on the triglyceride structure appeared at chemical shifts of 4.11–4.30; a proton peak on the tertiary carbon bonded to the hydroxyl group appeared at chemical shift 3.60; a -CH2 proton peak bonded to the ester group appeared at chemical shift 2.30; a -CH2 proton peak adjacent to the double bond appeared at chemical shifts of 2.03–2.20; a -CH2 proton peak on the alkyl chain not adjacent to the ester group appeared at chemical shifts of 1.45–1.60; a -CH2 proton peak on the alkyl chain appeared at chemical shift 1.29; and a -CH3 proton peak at the end of the alkyl chain appeared at chemical shift 0.88. Chemical shifts of 6.09 and 5.55 represent proton peaks on double bonds, chemical shift 3.74 represents a -CH3 proton peak attached to an ester group, and chemical shift 1.94 represents a -CH3 proton peak adjacent to a double bond. Chemical shift 3.60 represents a proton peak on the tertiary carbon attached to a hydroxyl group in castor oil, chemical shift 2.31 represents a -CH2 proton peak attached to an ester group in castor oil, chemical shift 1.80 represents a -CH3 proton peak adjacent to a double bond in methyl methacrylate, chemical shifts 1.45-1.60 represent -CH2 proton peaks on the alkyl chain of castor oil that are not adjacent to an ester group, and chemical shifts of 1.02 and 0.83 represent a -CH2 proton peak on the alkyl chain of castor oil and a -CH3 proton peak at the end of the alkyl chain, respectively. The proton peaks at chemical shifts of 5.55 and 5.41 on the double bond have almost disappeared, indicating that a polymerization reaction has occurred on the double bond to obtain poly(castor oil-maleic anhydride-methyl methacrylate).

[0049] Based on infrared and nuclear magnetic resonance analysis, the structure of poly(castor oil-maleic anhydride-methyl methacrylate) is as follows: Figure 11 As shown in equation (Ⅱ).

[0050] Finally, this experiment obtained the optimal polymerization conditions by changing factors such as the monomer ratio of castor oil, maleic anhydride, and methyl methacrylate, the amount of initiator, the polymerization temperature, and the polymerization time: monomer mass ratio m (CO):m (MA): m The ratio of MMA to initiator is 1.0:0.1:2.2, and the initiator dosage is 0.5%. w When the reaction time was 5 h and the reaction temperature was 90 ℃, a relatively high yield of poly(castor oil-maleic anhydride-methyl methacrylate) of 86.84% was obtained. The relative molecular mass and polydispersity index of the polymer synthesized under optimized conditions were determined. The number-average relative molecular mass of the obtained poly(castor oil-maleic anhydride-methyl methacrylate) was Mn = 1.2 × 10⁻⁶. 5 The polydispersity index (PDI) is 2.2.

[0051] Example 6 A method for preparing a castor oil-based anti-wear additive for lubricating oil specifically includes the following steps: At room temperature, 1.0 g of castor oil and 0.1 g of maleic anhydride were weighed into a clean polymerization tube, sealed and connected to a Schlenk anhydrous and oxygen-free apparatus. After evacuating and purging with nitrogen three to four times, the reaction temperature was adjusted to 120 °C. The reaction was stopped after stirring for a period of time and then cooled to room temperature to obtain the esterification intermediate (CO-MA). Then, the reaction was evacuated and purged with nitrogen three to four times again. During the last nitrogen purging, 3.4 g of methyl methacrylate and a xylene solution of benzoyl peroxide were injected, and the mixture was stirred and heated to the reaction temperature of 100 °C. After 4 hours of reaction, the reaction was stopped with ice-cold anhydrous ethanol solution. After precipitation, purification, and drying, poly(castor oil-maleic anhydride-methyl methacrylate) was obtained.

[0052] Example 7 A method for preparing a castor oil-based anti-wear additive for lubricating oil specifically includes the following steps: At room temperature, 1.0 g of castor oil and 0.1 g of maleic anhydride were weighed into a clean polymerization tube, sealed and connected to a Schlenk anhydrous and oxygen-free apparatus. After evacuating and purging with nitrogen three to four times, the reaction temperature was adjusted to 120 °C. The reaction was stopped after stirring for a period of time and then cooled to room temperature to obtain the esterification intermediate (CO-MA). Then, the reaction was evacuated and purged with nitrogen three to four times again. During the last nitrogen purging, 1.0 g of isobornyl methacrylate and a xylene solution of benzoyl peroxide were injected, and the mixture was stirred and heated to a reaction temperature of 70 °C. After a reaction time of 7 hours, the reaction was stopped with anhydrous ethanol solution. After precipitation, purification, and drying, poly(castor oil-maleic anhydride-isobornyl methacrylate) was obtained.

[0053] Example 8 A method for preparing a castor oil-based anti-wear additive for lubricating oil specifically includes the following steps: At room temperature, 1.0 g of castor oil and 0.1 g of maleic anhydride were weighed into a clean polymerization tube, sealed and connected to a Schlenk anhydrous and oxygen-free apparatus. After evacuating and purging with nitrogen three to four times, the reaction temperature was adjusted to 120 °C. The reaction was stopped after stirring for a period of time and then cooled to room temperature to obtain the esterification intermediate (CO-MA). Then, the reaction was evacuated and purged with nitrogen three to four times again. During the last nitrogen purging, 1.8 g of isobornyl methacrylate and a xylene solution of benzoyl peroxide were injected, and the mixture was stirred and heated to the reaction temperature of 100 °C. After 5 hours of reaction, the reaction was stopped with ice-cold anhydrous ethanol solution. After precipitation, purification, and drying, poly(castor oil-maleic anhydride-isobornyl methacrylate) was obtained.

[0054] The synthesized poly(castor oil-maleic anhydride-isoborneol methacrylate) was characterized by infrared spectroscopy analysis, and the results are as follows: Figure 6 As shown.

[0055] Infrared analysis showed that the depth was 3419 cm. -1 A stretching vibration peak of -OH appears at 3008 cm⁻¹. -1 A stretching vibration peak of =CH appears at 2927 cm⁻¹. -1 A stretching vibration peak of -CH3 appears at 2855 cm⁻¹. -1 A stretching vibration peak of -CH2 appears at 1739 cm⁻¹. -1 Stretching vibrations occur at C=O, 1646 cm. -1 A C=C stretching vibration peak appears at 1464 cm⁻¹. -1 A bending vibration peak of -CH2 appears at 1167 cm⁻¹. -1 A peak of asymmetric stretching vibration of COC appears at 2950 cm⁻¹. -1 A stretching vibration peak of -CH3 appears at 2879 cm⁻¹. -1 A -CH2 stretching vibration peak appears at 1718 cm⁻¹. -1 A stretching vibration peak of C=O appears at 1635 cm⁻¹. -1 A C=C stretching vibration peak appears at 1452 cm⁻¹. -1 A stretching vibration peak of -CH2 appears at 2954 cm⁻¹. -1 A stretching vibration peak of -CH3 appears at 1724 cm⁻¹. -1 A C=O stretching vibration peak appears at 1456 cm⁻¹. -1 A bending vibration peak of -CH2 appears at 1151 cm⁻¹. -1 A COC asymmetric stretching vibration peak appears at 3008 cm⁻¹. This is relative to castor oil and isobornyl methacrylate. -1 The CH stretching vibration peak disappears and the 1646cm peak is reached. -1The weakening of the C=C stretching vibration peak at the point of origin proves that poly(castor oil-maleic anhydride-isobornyl methacrylate) was successfully synthesized.

[0056] The synthesized poly(castor oil-maleic anhydride-isoborneol methacrylate) was subjected to... 1 H NMR characterization, results as follows Figure 7 As shown.

[0057] NMR analysis revealed that the proton peaks at chemical shifts of 6.18–6.46, 5.55, and 5.41 were proton peaks on the double bond; the proton peak at chemical shift 5.25 was a proton peak on the methylene group of the triglyceride structure; a proton peak on the tertiary carbon appeared at chemical shifts of 4.85–5.05; a -CH2 proton peak on the triglyceride structure appeared at chemical shifts of 4.11–4.30; a proton peak on the tertiary carbon bonded to the hydroxyl group appeared at chemical shift 3.60; a -CH2 proton peak bonded to the ester group appeared at chemical shift 2.30; a -CH2 proton peak adjacent to the double bond appeared at chemical shifts of 2.03–2.20; a -CH2 proton peak on the alkyl chain not adjacent to the ester group appeared at chemical shifts of 1.45–1.60; a -CH2 proton peak on the alkyl chain appeared at chemical shift 1.29; and a -CH3 proton peak at the end of the alkyl chain appeared at chemical shift 0.88. Chemical shifts of 6.06 and 5.51 represent proton peaks on the double bond, chemical shift of 4.70 represents a methylene proton peak attached to the ester group, chemical shift of 1.92 represents a -CH3 proton peak adjacent to the double bond, chemical shifts of 1.68-1.84 represent methylene proton peaks on the ring structure, chemical shifts of 1.56 and 1.01-1.21 represent -CH2 proton peaks on the ring structure, and chemical shifts of 1.01 and 0.85 represent -CH3 proton peaks. The chemical shifts at 4.13-4.29 represent the -CH2 proton peaks on the triglyceride structure of castor oil; at 3.60, the proton peak on the tertiary carbon bonded to the hydroxyl group; at 2.30, the -CH2 proton peak bonded to the ester group; at 1.92, the -CH3 proton peak of the adjacent double bond in isobornyl methacrylate; at 1.71, the methylene proton peak on the cyclic structure of isobornyl methacrylate; and at 1.29 and 0.88, the -CH2 and -CH3 proton peaks on the alkyl chain and the terminal alkyl chain, respectively, are present in castor oil. The proton peaks on the double bonds at chemical shifts of 5.55 and 5.41 essentially disappear, indicating that a polymerization reaction occurred at the double bonds, yielding poly(castor oil-maleic anhydride-isobornyl methacrylate).

[0058] Based on infrared and nuclear magnetic resonance analysis, the structure of poly(castor oil-maleic anhydride-isoborneol methacrylate) is as follows: Figure 12 As shown in equation (Ⅲ).

[0059] Finally, this experiment obtained the optimal polymerization conditions by changing factors such as the monomer ratio of castor oil, maleic anhydride, and isobornyl methacrylate, the amount of initiator, the polymerization temperature, and the polymerization time: monomer mass ratio m (CO): m (MA): m The ratio of IBOMA was 1.0:0.1:1.8, and the initiator dosage was 0.5%. w When the reaction time was 5 h and the reaction temperature was 90 ℃, a relatively high yield of poly(castor oil-maleic anhydride-isoborneol methacrylate) was obtained (81.52%). The relative molecular mass and polydispersity index of the polymer synthesized under optimized conditions were determined. The number-average relative molecular mass of the obtained poly(castor oil-maleic anhydride-isoborneol methacrylate) was Mn = 1.3 × 10⁻⁶. 5 The polydispersity index (PDI) is 2.1.

[0060] Example 9 A method for preparing a castor oil-based anti-wear additive for lubricating oil specifically includes the following steps: At room temperature, 1.0 g of castor oil and 0.1 g of maleic anhydride were weighed into a clean polymerization tube, sealed and connected to a Schlenk anhydrous and oxygen-free apparatus. After evacuating and purging with nitrogen three to four times, the reaction temperature was adjusted to 120 °C. The reaction was stopped after stirring for a period of time and then cooled to room temperature to obtain the esterification intermediate (CO-MA). Then, the reaction was evacuated and purged with nitrogen three to four times again. During the last nitrogen purging, 2.6 g of isobornyl methacrylate and a xylene solution of benzoyl peroxide were injected, and the mixture was stirred and heated to the reaction temperature of 100 °C. After 5 hours of reaction, the reaction was stopped with ice-cold anhydrous ethanol solution. After precipitation, purification, and drying, poly(castor oil-maleic anhydride-isobornyl methacrylate) was obtained.

[0061] The performance of the synthesized castor oil-based polymer as an anti-wear additive for lubricating oil will be further verified below: The wear scar diameter of the copolymer was determined according to NB / SH / T0189-2017 "Determination of Anti-wear Properties of Lubricating Oils (Four-ball Method)". W SD The specific testing steps are as follows: (1) Put the clean steel ball into the oil box of the four-ball machine, and then add oil to the oil box. The liquid level after adding the oil should cover the surface of the steel ball, and ensure that there are no air bubbles in the oil in the oil box.

[0062] (2) Under the test conditions of test load 392 N, rotation speed 1200 r / min and test temperature 75℃, the test time is 1 h.

[0063] (3) Take out the oil box, extract the experimental oil from the oil box, remove the oil from the surface of the steel ball after the experiment, place the oil box under a special microscope to measure the wear mark diameter and vertical wear mark diameter of each steel ball.

[0064] (4) The arithmetic mean of the above measurements is the wear scar diameter. W SD ).

[0065] Specifically, the castor oil-based polymer obtained in Example 1 under optimized conditions was added to 150SN base oil in different proportions to measure the wear scar diameter before and after adding the copolymer. W SD ) Decrease (Δ W SD Using 1000 ppm as the standard, the effect of copolymer addition on the anti-wear performance of lubricating oil was investigated, and the results are shown in Table 1.

[0066] Table 1. Effects of different addition amounts of poly(castor oil-maleic anhydride-tetradecyl methacrylate) on the anti-wear properties of lubricating oils.

[0067] As shown in Table 1, the wear scar diameters of oils containing poly(castor oil-maleic anhydride-tetradecyl methacrylate) are all smaller than those of 150SN base oils. W SD =0.997 mm), indicating that poly(castor oil-maleic anhydride-tetradecyl methacrylate) has a certain anti-wear effect on 150SN base oil. With the increase of poly(castor oil-maleic anhydride-tetradecyl methacrylate) additive, the wear scar diameter shows a trend of first decreasing and then increasing. When the poly(castor oil-maleic anhydride-tetradecyl methacrylate) addition is 0.50%, the wear scar diameter decreases from 0.997 mm to 0.423 mm, a reduction of 58%, indicating good anti-wear performance at this point. This is because the polar ester groups contained in the polymer molecular structure can be adsorbed onto the surface of the steel ball, forming a dense adsorption film on the steel ball surface, hindering direct contact between the steel balls, thus leading to a reduction in the wear scar diameter.

[0068] Furthermore, the castor oil-based polymer obtained under optimized conditions in Examples 5 and 8 was added to 150SN base oil at a ratio of 0.5% to measure the wear scar diameter before and after adding the copolymer. W SD ) Decrease (Δ W SD Using 1000 polymers as the standard, the effects of polymers with different structures on the anti-wear properties of lubricating oils were investigated, and the results are shown in Table 2.

[0069] Table 2. Effects of polymers with different structures on the anti-wear properties of 150SN base oil

[0070] Table 2 shows that the wear scar diameters of oils with 0.5% P(CO-MA-MMA) and P(CO-MA-IBOMA) added were both smaller than those of the 150SN base oil. This indicates that both castor oil-based copolymers have anti-wear effects in lubricating oil bases, and the anti-wear performance of P(CO-MA-MMA) is superior to that of P(CO-MA-IBOMA). This may be because the side chains of isoborneol methacrylate are large-volume isoborneol groups, resulting in greater steric hindrance. This causes the P(CO-MA-IBOMA) molecular chains to be coiled, resulting in a large number of voids inside the adsorption film, which cannot effectively isolate contact with the metal surface. In contrast, the side chains of methyl methacrylate are small-volume -COOCH3 groups, with minimal steric hindrance. The P(CO-MA-MMA) molecular chains can fully extend after adsorption and are tightly arranged on the metal surface, making it easier to form a continuous and dense adsorption film.

[0071] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing and the full scope of its equivalents. For purposes of completeness, all articles and references, including disclosures in patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

[0072] The above content provides a further detailed description of the present invention. It should not be construed that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the defined protection scope of the present invention.

Claims

1. A process for the preparation of a castor oil based lubricating oil antiwear additive characterized in that, Includes the following steps: Castor oil and maleic anhydride were placed in a reaction vessel and heated and stirred under inert gas protection to carry out an esterification reaction to obtain an esterification reaction intermediate. After adding methacrylate monomers and an initiator to the reaction system containing the esterification reaction intermediate, the polymerization reaction is carried out under inert gas protection with heating and stirring to obtain castor oil-based polymer, which is the castor oil-based lubricating oil anti-wear additive.

2. A process for the preparation of a castor oil based lubricating oil antiwear additive according to claim 1, characterized in that, The inert gas protection specifically involves evacuating the system and then filling it with nitrogen.

3. A process for the preparation of a castor oil based lubricating oil antiwear additive according to claim 1, characterized in that, The initiator is benzoyl peroxide, which is added to the reaction system in the form of a xylene solution.

4. A process for the preparation of a castor oil based lubricating oil antiwear additive according to claim 3, characterized in that, The methacrylate monomer is tetradecyl methacrylate; The mass ratio of castor oil, maleic anhydride and tetradecyl methacrylate is 1.0:0.1:(1.0~4.2). The amount of benzoyl peroxide added is 0.1% to 1.0% of the total mass of castor oil, maleic anhydride and tetradecyl methacrylate.

5. A process for the preparation of a castor oil based lubricating oil antiwear additive according to claim 3, characterized in that, The methacrylate monomer is methyl methacrylate; The mass ratio of castor oil, maleic anhydride and methyl methacrylate is 1.0:0.1:(1.0~3.4). The amount of benzoyl peroxide added is 0.1% to 1.5% of the total mass of castor oil, maleic anhydride and methyl methacrylate.

6. A process for the preparation of a castor oil based lubricating oil antiwear additive according to claim 3, characterized in that, The methacrylate monomer is isobornyl methacrylate; The mass ratio of castor oil, maleic anhydride and isobornyl methacrylate is 1.0:0.1:(1.0~2.6). The amount of benzoyl peroxide added is 0.1% to 2.0% of the total mass of castor oil, maleic anhydride and isobornyl methacrylate.

7. A process for the preparation of a castor oil based lubricating oil antiwear additive according to claim 1, characterized by, The polymerization reaction is carried out at a constant temperature of 70℃ to 120℃ for 3-7 hours.

8. A process for the preparation of a castor oil based lubricating oil antiwear additive according to claim 1, characterized by, After the polymerization reaction is completed, the reaction system is placed in an ice-cold anhydrous ethanol solution to terminate the reaction. After sedimentation, purification and drying, the castor oil-based lubricating oil anti-wear additive is obtained.

9. A castor oil based lubricating oil antiwear additive characterized in that, It is prepared using the method for preparing a castor oil-based lubricating oil anti-wear additive as described in any one of claims 1-8.

10. The application of the castor oil-based anti-wear additive of claim 9 in a lubricating oil base oil, characterized in that, The castor oil-based lubricant anti-wear additive is added to the lubricant base oil at a mass fraction of 0.10% to 1.50%, which reduces the wear scar diameter of the lubricant base oil by 0.143-0.574 mm.

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