Montmorillonite-tetradecyl methacrylate nano pour point depressant as well as preparation method and application thereof in improving low-temperature flowing property of shiny-leaved yellowhorn oil-based lubricating oil

Abstract

The invention provides a montmorillonite-tetradecyl methacrylate nano pour point depressant as well as a preparation method and application thereof in improving the low-temperature flowing property of shiny-leaved yellowhorn oil-based lubricating oil, and belongs to the technical field of lubricating oil. According to the montmorillonite-tetradecyl methacrylate nano pour point depressant, tetradecyl methacrylate is taken as a monomer, free radical polymerization reaction is carried out in the presence of an initiator, and the tetradecyl methacrylate is grafted to the surface of modified montmorillonite, so that the nano montmorillonite-tetradecyl methacrylate nano pour point depressant is obtained. The montmorillonite-tetradecyl methacrylate nano pour point depressant is added into the xanthoceras sorbifolia bunge oil according to the adding amount of 0.05-0.30 wt%, so that the low-temperature flowing property of the xanthoceras sorbifolia bunge oil-based lubricating oil can be improved.

Description

Technical Field

[0001] This invention belongs to the field of lubricating oil technology, and particularly relates to a montmorillonite-tetradecyl methacrylate nanoparticle pour point depressant, its preparation method, and its application in improving the low-temperature flow properties of Xanthoceras sorbifolium oil-based lubricating oil. Background Technology

[0002] Vegetable oil-based lubricants are gradually becoming alternatives to mineral oils due to their renewability, biodegradability, and excellent lubrication properties. However, their poor low-temperature fluidity (high pour point) severely limits their application scenarios, mainly because the high saturated fatty acid content in vegetable oils leads to a significant tendency for crystallization at low temperatures. To address this bottleneck, the scientific community has developed various pour point depressing technologies. Currently, these technologies primarily include chemical modification, the addition of pour point depressants, and biotechnology modification.

[0003] In the process of chemical modification, the low-temperature performance can be improved by reconstructing the fatty acid chain structure through transesterification. Wang et al. (see Wang L et al. Study on the performance of transesterified vegetable oil. Lubrication and Sealing, 2020, 45(6):112-118.) used sodium methoxide to catalyze the transesterification of soybean oil with pentaerythritol, and the pour point of the product was reduced to -21℃. This technology effectively inhibits the ordered arrangement of crystals by introducing branched alcohols to increase molecular steric hindrance. García-Zapateiro M et al. (see García-Zapateiro M, Valencia C, Franco JM. Synthesis and characterization of neopentyl glycolesters for bio-based lubricants with enhanced low-temperature properties[J].ACS Sustainable Chemistry & Engineering, 2020, 8(12): 1234-1245.) synthesized a novel diester by transesterification of neopentyl glycol and methyl palmitate, achieving a pour point of -42℃. Nuclear magnetic resonance (NMR) and molecular dynamics simulations revealed the mechanism by which the branched structure inhibits crystallization. The viscosity index (VI) of the product was as high as 180, which is superior to that of traditional mineral oil (VI≈95). However, this technology still faces the problem of difficulty in controlling the branch length and the influence of excessive branching on thermal stability.

[0004] In addition, the overall performance can be improved by introducing epoxy groups through epoxidation treatment. Liu et al. (see Liu Q et al. Analysis of synergistic effect of epoxy modification. Materials Science and Engineering, 2022, 40(2):234-240.) prepared epoxidized soybean oil by in-situ peroxy acid method, and combined with 0.5% polymethyl methacrylate pour point depressant, the pour point of the system was reduced to -33℃. The polar characteristics of epoxy groups changed the intermolecular interaction mode, and the synergistic effect was produced by the nucleation modification effect of the pour point depressant. R. Kumar et al. (Kumar R, Jain S, Verma P. Epoxidized soybean oil as a sustainable lubricant additive: Tribological and rheological characterization[J]. Tribology International, 2021, 156(5): 1071-1078.) studied the tribological properties of epoxidized soybean oil (ESO) as a lubricant additive, demonstrating that it can reduce the coefficient of friction by 30% under high load conditions. It forms a protective film through the chemical adsorption of epoxy groups on the metal surface, significantly improving extreme pressure performance (PB value increased to 1200N). The pour point of the epoxidized vegetable oil is reduced to -18℃, which is better than that of unmodified soybean oil (-5℃).

[0005] Compared with chemical modification, modification by adding pour point depressants shows unique advantages. Zhao M et al. (Zhao M et al. Research on nanocomposite additives. Nanotechnology and Precision Engineering, 2022, 24(3):45-52.) compounded 0.8% poly-α-olefin with 0.2% nano titanium dioxide, which can reduce the pour point of rapeseed oil-based lubricating oil by 22℃. The nanoparticles inhibit crystal nucleus growth through surface effect, and produce a multiplier effect with the steric hindrance of polymer additives. Furthermore, by introducing responsive additives, the molecular conformation can be automatically adjusted with temperature changes. Hernández Battez A et al. (Hernández Battez A, González R, Viesca JL. Ionic liquids as hybrid additives in bio-based lubricants: Synergistic effects on thermal stability and anti-wear performance[J]. Wear, 2022, 500-501: 2045-2050.) compounded ionic liquid [C8MIM][NTf2] with nano-BN, reducing the wear volume of sunflower seed oil-based lubricating oil by 82%. The ionic liquid formed a fluorinated protective layer at the friction interface through an adsorption-reaction mechanism, and synergistically, the ball-bearing effect of nanoparticles extended the oxidation induction period (OIT) of the modified lubricating oil to 210 minutes. However, the problem of nanoparticle agglomeration needs to be addressed in the modification process of the pour point depressant.

[0006] In addition, green catalytic systems have become a research hotspot. Zhou et al. (Zhou T et al. Innovation of ionic liquid catalytic systems. Catalysis Science and Technology, 2021, 11(7):2150-2158.) designed [BMIm][H S O4] ionic liquid catalyzed esterification reaction, with a conversion rate of 98% in 6 hours at 80℃. Compared with traditional sulfuric acid catalysis, the product color (Gardner value <2) and acid value (<0.5mg KOH / g) were significantly improved, and the system can be recycled more than 10 times without activity decay. Gryglewicz S et al. ([8] Gryglewicz S, A, Kula E. Enzymatic synthesis of trimethylolpropane-based esters as eco-friendly lubricants: Optimization and low-temperature behavior[J]. Biotechnology for Biofuels and Bioproducts, 2023, 16(1): 234-245.) The esterification of trimethylolpropane (TMP) with oleic acid was catalyzed by immobilized lipase (Lipozyme 435), resulting in a product with a pour point as low as -48℃. Response surface methodology was used to optimize the reaction conditions (temperature 55℃, enzyme loading 8%, vacuum dehydration), achieving an esterification rate exceeding 98%. The biodegradability (OECD 301B standard) of the biomodified product reached 92%, far exceeding that of mineral oil (20-30%), but the issue of catalyst-product separation efficiency still needs to be addressed.

[0007] Based on the foregoing, existing pour point depressing technologies for vegetable oil-based lubricants suffer from the following shortcomings regarding their poor low-temperature fluidity: First, while chemical pour point depressants can inhibit wax crystal growth, their compatibility with the molecular structure of vegetable oils is poor, resulting in limited low-temperature pour point depressing efficiency (typically only reducing the pour point by 5-15°C), and excessive addition may lead to a decrease in oxidative stability. Second, although transesterification modification can improve low-temperature performance by adjusting the fatty acid chain structure, the process is complex and costly, and may reduce the viscosity index and biodegradability of the lubricant. Third, while compounding with esters or mineral oils can achieve synergistic effects, it weakens the green and environmentally friendly advantages of vegetable oil-based lubricants, contradicting sustainable development goals. Furthermore, existing technologies often focus on improving a single performance aspect, lacking synergistic regulation of comprehensive properties such as low-temperature fluidity, oxidative stability, and anti-wear properties. This makes it difficult for modified lubricants to meet the demands of extreme operating conditions, and the methods for chemically modifying the lubricating properties of vegetable oils are cumbersome, costly, and polluting due to the various chemical reagents used. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention proposes a montmorillonite-tetradecyl methacrylate nanoparticle pour point depressant, its preparation method, and its application in improving the low-temperature flow properties of Xanthoceras sorbifolium oil-based lubricating oils. This invention uses Xanthoceras sorbifolium oil as the base oil and tetradecyl methacrylate (C... 14 Using benzoyl peroxide (BPO) as an initiator, montmorillonite (MA) was used as a monomer and grafted onto the surface of modified montmorillonite (OMMT) via free radical polymerization to prepare nano-montmorillonite-tetradecyl methacrylate nano-pour depressant (Nano-C). 14 MA / MMT), then Nano-C 14MA / MMT were uniformly dispersed in *Xanthoceras sorbifolium* oil to prepare a *Xanthoceras sorbifolium* oil-based lubricant with excellent low-temperature flow properties.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] One of the technical solutions of the present invention:

[0011] A montmorillonite-tetradecyl methacrylate nanoparticle (Nano-C) 14 The preparation method of MA / MMT pour point depressant involves using tetradecyl methacrylate as a monomer, and grafting it onto the surface of modified montmorillonite via free radical polymerization in the presence of an initiator to obtain the nano-montmorillonite-tetradecyl methacrylate nano pour point depressant, including the following steps:

[0012] OMMT was dispersed in DMF at room temperature (25±3℃) to obtain a suspension. The suspension was washed with N2 (to remove oxygen and prevent it from reacting with free radicals and causing polymerization inhibition, thus ensuring efficient graft polymerization of tetradecyl methacrylate on the montmorillonite surface). Then, C20 was added. 14 MA and BPO are reacted under heat to obtain a matrix. The matrix is ​​then washed and vacuum dried to obtain the Nano-C. 14 MA / MMT pour point depressant.

[0013] Furthermore, the OMMT is obtained by modifying montmorillonite (MMT) with hexadecyltrimethylammonium bromide (CTAB).

[0014] Furthermore, the initiator is benzoyl peroxide (BPO).

[0015] Furthermore, the ratio of the modified montmorillonite, N,N-dimethylformamide, tetradecyl methacrylate, and initiator is 1 g: 50 mL: 0.2 mol: 0.6 mmol.

[0016] Furthermore, the free radical polymerization reaction is carried out at a temperature of 80°C for 4 hours.

[0017] For example, the Nano-C 14 The preparation method of MA / MMT pour point depressant specifically includes the following steps:

[0018] 1 g OMMT was dispersed in 50 mL DMF at room temperature (25 ± 3 °C) and ultrasonically dispersed for 1 h to obtain a suspension. The resulting suspension was then suspended in a flask, washed with N2 for 30 min, and then 0.2 mol C was added. 14MA and 0.6 mmol BPO were added, and the reaction system was heated to 80 °C. In situ free radical polymerization was carried out under a N2 atmosphere for 4 h to obtain the matrix. The prepared matrix was washed with ethanol and vacuum dried for 24 h to obtain Nano-C. 14 MA / MMT pour point depressant.

[0019] The second technical solution of the present invention:

[0020] A montmorillonite-tetradecyl methacrylate nanoparticle (Nano-C) 14 MA / MMT pour point depressant, prepared by the above preparation method.

[0021] The third technical solution of the present invention:

[0022] A Nano-C 14 Application of MA / MMT pour point depressant in improving the low-temperature flow properties of Xanthoceras sorbifolium oil-based lubricating oil.

[0023] The fourth technical solution of the present invention:

[0024] A modified Xanthoceras sorbifolium oil-based lubricant (XSBO-based lubricants), the raw materials of which include Xanthoceras sorbifolium oil and the aforementioned Nano-C 14 MA / MMT pour point depressant.

[0025] Furthermore, the Nano-C 14 The amount of MA / MMT pour point depressant added to *Sapindus mukorossi* oil is 0.05-0.30 wt%.

[0026] The fifth technical solution of the present invention:

[0027] A method for preparing the XSBO-based lubricants, comprising Nano-C 14 MA / MMT pour point depressant was added to Xanthoceras sorbifolium oil and stirred evenly to obtain the XSBO-based lubricants.

[0028] Furthermore, the stirring temperature is 60°C, and the mixture is cooled to room temperature after being stirred evenly.

[0029] Technical principle of the invention:

[0030] (1) Nano-C of the present invention 14 MA / MMT pour point depressant is a nanomaterial with high surface energy. The small particulate crystals of the nanomaterial can maintain the energy stability of the solid-liquid system, release the encapsulated crystallizing liquid from the three-dimensional network structure, reduce energy inequality, and form a stable solid-liquid surface.

[0031] (2) Nano-C of the present invention 14 MA / MMT pour point depressants act as nucleation points, promoting the formation of wax crystals in lubricating oil, resulting in finer and more uniformly distributed wax crystals, thereby delaying the formation of large wax crystal networks; additionally, Nano-C 14 MA / MMT pour point depressants can not only disperse in lubricating oil, increasing the distance between wax crystals, hindering their interconnection, and delaying the formation of wax crystal networks, but also adsorb on the surface of wax crystals, inhibiting their growth and aggregation, preventing the formation of large wax crystal networks, and further lowering the pour point.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] (1) This invention uses *Sapindus mukorossi* oil as the base oil and tetradecyl methacrylate (C... 14 Using benzoyl peroxide (BPO) as an initiator, montmorillonite (MA) was used as a monomer and grafted onto the surface of modified montmorillonite (OMMT) via free radical polymerization to prepare nano-montmorillonite-tetradecyl methacrylate (Nano-C) nanoparticles. 14 MA / MMT) pour point depressant, then Nano-C 14 MA / MMT were uniformly dispersed in Xanthoceras sorbifolium oil to prepare XSBO-based lubricants with excellent low-temperature flow properties.

[0034] (2) Nano-C of the present invention 14 MA / MMT pour point depressants significantly improved the low-temperature flow properties of lubricating oils. Experimental results show that, after Nano-C... 14 XSBO-based lubricants modified with MA / MMT pour point depressants are extra-high viscosity index lubricants with a pour point (SP) reduced to -37°C, a decrease of -19°C compared to unmodified Xanthoceras sorbifolium oil (XSBO), significantly widening their operating temperature range and exhibiting excellent viscosity-temperature properties. Furthermore, XSBO-based lubricants demonstrate superior thermal and oxidative stability within the 0-250°C range, significantly improving their friction-reducing and anti-wear properties. Their lubrication performance is superior to XSBO, with a contact angle of 20.6°, resulting in better wetting and surface compatibility. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0036] Figure 1 Nano-C prepared in Example 1 14 The dispersion of MA / MMT pour point depressant in trioleic acid glycerides;

[0037] Figure 2 Nano-C prepared in Example 1 14 Infrared spectrum of MA / MMT pour point depressant;

[0038] Figure 3 Nano-C prepared in Example 1 14 XPS C1S spectra of MA / MMT pour point depressant;

[0039] Figure 4 Nano-C prepared in Example 1 14 XPS O1S spectrum of MA / MMT pour point depressant;

[0040] Figure 5 XSBO-based lubricants (0.25 wt% Nano-C) prepared as a modified *Sapindus mukorossi* oil-based lubricant for Example 5 14 Infrared spectrum of MA / MMT;

[0041] Figure 6 XSBO-based lubricants (0.25 wt% Nano-C) prepared as a modified *Sapindus mukorossi* oil-based lubricant for Example 5 14 The TG-DSC curves of MA / MMT are shown, where (a) is the TG analysis result of Xanthoceras sorbifolium oil and lubricating oil in nitrogen (N2) atmosphere, (b) is the TG analysis result of Xanthoceras sorbifolium oil and lubricating oil in air atmosphere, (c) is the DSC analysis result of Xanthoceras sorbifolium oil and lubricating oil in N2 atmosphere, and (d) is the DSC analysis result of Xanthoceras sorbifolium oil and lubricating oil in air atmosphere.

[0042] Figure 7 These are polarizing microscope images;

[0043] Figure 8 A photograph of the crystals precipitated from *Sapindus mukorossi* oil in Comparative Example 1 at -5°C;

[0044] Figure 9 A photograph of the crystals precipitated from *Sapindus mukorossi* oil in Comparative Example 1 at -10°C;

[0045] Figure 10 A photograph of the crystals precipitated from *Sapindus mukorossi* oil in Comparative Example 1 at -15°C;

[0046] Figure 11 A photograph of the crystals precipitated from *Sapindus mukorossi* oil in Comparative Example 1 at -18°C;

[0047] Figure 12 A photograph of the modified lubricating oil of Example 5 precipitating crystals at -5°C;

[0048] Figure 13A photograph of the modified lubricating oil of Example 5 precipitating crystals at -10°C;

[0049] Figure 14 A photograph of the modified lubricating oil of Example 5 precipitating crystals at -15°C;

[0050] Figure 15 A photograph of the modified lubricating oil of Example 5 precipitating crystals at -20°C;

[0051] Figure 16 A photograph of the modified lubricating oil of Example 5 precipitating crystals at -25°C;

[0052] Figure 17 A photograph of the modified lubricating oil of Example 5 precipitating crystals at -30°C;

[0053] Figure 18 A photograph of the modified lubricating oil of Example 5 precipitating crystals at -37°C;

[0054] Figure 19 The shear stress-shear rate curves (a), shear stress-viscosity curves (b), and viscosity-temperature curves (c) of the XSBO-based lubricants of Example 5 and the XSBO of Comparative Example 1 are shown.

[0055] Figure 20 The diagrams show the contact angles of the lubricating oils obtained in Example 5 and Comparative Example 1, where (a) is Comparative Example 1 and (b) is Example 5. Detailed Implementation

[0056] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0057] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0058] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0059] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0060] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0061] This invention provides a montmorillonite-tetradecyl methacrylate nanoparticle (Nano-C) 14 MA / MMT) pour point depressant, raw materials include modified montmorillonite (OMMT), N,N-dimethylformamide (DMF), and tetradecyl methacrylate (C... 14 The ratio of modified montmorillonite, N,N-dimethylformamide, tetradecyl methacrylate and initiator was 1 g: 50 mL: 0.2 mol: 0.6 mmol.

[0062] In a preferred embodiment of the present invention, OMMT is obtained by modifying montmorillonite (MMT) with hexadecyltrimethylammonium bromide (CTAB).

[0063] In a preferred embodiment of the present invention, the initiator is benzoyl peroxide (BPO).

[0064] This invention also proposes a Nano-C 14 The preparation method of MA / MMT pour point depressant involves using tetradecyl methacrylate as a monomer, and grafting it onto the surface of modified montmorillonite via free radical polymerization in the presence of an initiator to obtain the nano-montmorillonite-tetradecyl methacrylate nano-pour point depressant, including the following steps:

[0065] OMMT was dispersed in DMF at room temperature (25±3℃) to obtain a suspension. The suspension was washed with N2, and then C was added. 14 MA and BPO were reacted under heating to obtain a matrix. The matrix was then washed and vacuum dried to obtain Nano-C. 14 MA / MMT pour point depressant.

[0066] In a preferred embodiment of the present invention, the temperature of the free radical polymerization reaction is 80°C and the time is 4 hours.

[0067] For example, Nano-C 14 The preparation method of MA / MMT pour point depressant specifically includes the following steps:

[0068] 1 g OMMT was dispersed in 50 mL DMF at room temperature (25 ± 3 °C) and ultrasonically dispersed for 1 h to obtain a suspension. The resulting suspension was then suspended in a flask, washed with N2 for 30 min, and then 0.2 mol C was added. 14 MA and 0.6 mmol BPO were added, and the reaction system was heated to 80 °C. In situ free radical polymerization was carried out under a N2 atmosphere for 4 h to obtain the matrix. The prepared matrix was washed with ethanol and vacuum dried for 24 h to obtain Nano-C. 14 MA / MMT pour point depressant.

[0069] This invention also proposes a Nano-C 14 Application of MA / MMT pour point depressant in improving the low-temperature flow properties of Xanthoceras sorbifolium oil-based lubricating oil.

[0070] This invention also proposes a modified Xanthoceras sorbifolium oil-based lubricant (XSBO-based lubricants), the raw materials of which include Xanthoceras sorbifolium oil and Nano-C. 14 MA / MMT pour point depressant.

[0071] In a preferred embodiment of the present invention, Nano-C 14 The amount of MA / MMT pour point depressant added to *Sapindus mukorossi* oil is 0.05-0.30 wt%.

[0072] This invention also proposes a method for preparing XSBO-based lubricants, using Nano-C 14 MA / MMT pour point depressant was added to Xanthoceras sorbifolium oil and stirred evenly to obtain XSBO-based lubricants.

[0073] In a preferred embodiment of the present invention, the stirring temperature is 60°C, and the mixture is cooled to room temperature after being stirred evenly.

[0074] All raw materials used in the embodiments of this invention were purchased commercially.

[0075] Nano-C prepared in the embodiments of the present invention 14 MA / MMT pour point depressants are not only suitable for improving the low-temperature flow properties of Xanthoceras sorbifolium oil-based lubricants, but also for all vegetable oils including, but not limited to, coconut oil, palm oil, and olive oil.

[0076] All raw materials used in the embodiments of this invention were purchased commercially.

[0077] The technical solution of the present invention will be further illustrated by the following embodiments.

[0078] Example 1

[0079] Preparation process of a modified Xanthoceras sorbifolium oil-based lubricant:

[0080] CTAB and MMT were mixed at a mass ratio of 1:5 and mechanically stirred in a water bath at 70°C for 3 hours to modify MMT with CTAB, thus obtaining OMMT.

[0081] 1 g OMMT was dispersed in 50 mL DMF at room temperature (25 ± 3 °C) and ultrasonically dispersed for 1 h to obtain a suspension. The resulting suspension was then suspended in a 205 mL flask, washed with N2 for 30 min, and then 0.2 mol C was added. 14 MA and 0.6 mmol BPO were added, and the reaction system was heated to 80 °C. In situ free radical polymerization was carried out under a N2 atmosphere for 4 h to obtain the matrix. The prepared matrix was washed with ethanol and vacuum dried for 24 h to obtain Nano-C. 14 MA / MMT pour point depressant;

[0082] Extracting Sapindus mukorossi oil and Nano-C 14 MA / MMT pour point depressants were simultaneously added to a three-necked flask (Nano-C) at room temperature. 14 The amount of MA / MMT pour point depressant added to the *Xanthoceras sorbifolium* oil was 0.05 wt%. The mixture was stirred and dispersed at 60°C. After complete dispersion and dissolution, it was allowed to cool naturally to room temperature. The oil was then removed from the container and allowed to stand for 24 hours to obtain modified *Xanthoceras sorbifolium* oil-based lubricants XSBO-based lubricants (denoted as 0.05 wt% Nano-C). 14 MA / MMT).

[0083] Example 2

[0084] Preparation process of a modified Xanthoceras sorbifolium oil-based lubricant:

[0085] Nano-C 14 The preparation method of MA / MMT pour point depressant is the same as in Example 1;

[0086] Extracting Sapindus mukorossi oil and Nano-C 14 MA / MMT pour point depressants were simultaneously added to a three-necked flask (Nano-C) at room temperature. 14The amount of MA / MMT pour point depressant added to the *Xanthoceras sorbifolium* oil was 0.10 wt%. The mixture was stirred and dispersed at 60°C. After complete dispersion and dissolution, it was allowed to cool naturally to room temperature. The oil was then removed from the container and allowed to stand for 24 hours to obtain modified *Xanthoceras sorbifolium* oil-based lubricants XSBO-based lubricants (denoted as 0.10 wt% Nano-C). 14 MA / MMT).

[0087] Example 3

[0088] Preparation process of a modified Xanthoceras sorbifolium oil-based lubricant:

[0089] Nano-C 14 The preparation method of MA / MMT pour point depressant is the same as in Example 1;

[0090] Extracting Sapindus mukorossi oil and Nano-C 14 MA / MMT pour point depressants were simultaneously added to a three-necked flask (Nano-C) at room temperature. 14 The amount of MA / MMT pour point depressant added to the *Xanthoceras sorbifolium* oil was 0.15 wt%. The mixture was stirred and dispersed at 60°C. After complete dispersion and dissolution, it was allowed to cool naturally to room temperature. The oil was then removed from the container and allowed to stand for 24 hours to obtain modified *Xanthoceras sorbifolium* oil-based lubricants XSBO-based lubricants (denoted as 0.15 wt% Nano-C). 14 MA / MMT).

[0091] Example 4

[0092] Preparation process of a modified Xanthoceras sorbifolium oil-based lubricant:

[0093] Nano-C 14 The preparation method of MA / MMT pour point depressant is the same as in Example 1;

[0094] Extracting Sapindus mukorossi oil and Nano-C 14 MA / MMT pour point depressants were simultaneously added to a three-necked flask (Nano-C) at room temperature. 14 The amount of MA / MMT pour point depressant added to the *Xanthoceras sorbifolium* oil was 0.20 wt%. The mixture was stirred and dispersed at 60°C. After complete dispersion and dissolution, it was allowed to cool naturally to room temperature. The oil was then removed from the container and allowed to stand for 24 hours to obtain modified *Xanthoceras sorbifolium* oil-based lubricants XSBO-based lubricants (denoted as 0.20 wt% Nano-C). 14 MA / MMT).

[0095] Example 5

[0096] Preparation process of a modified Xanthoceras sorbifolium oil-based lubricant:

[0097] Nano-C14 The preparation method of MA / MMT pour point depressant is the same as in Example 1;

[0098] Extracting Sapindus mukorossi oil and Nano-C 14 MA / MMT pour point depressants were simultaneously added to a three-necked flask (Nano-C) at room temperature. 14 The amount of MA / MMT pour point depressant added to the *Xanthoceras sorbifolium* oil was 0.25 wt%. The mixture was stirred and dispersed at 60°C. After complete dispersion and dissolution, it was allowed to cool naturally to room temperature. The oil was then removed from the container and allowed to stand for 24 hours to obtain modified *Xanthoceras sorbifolium* oil-based lubricants XSBO-based lubricants (denoted as 0.25 wt% Nano-C). 14 MA / MMT).

[0099] Example 6

[0100] Preparation process of a modified Xanthoceras sorbifolium oil-based lubricant:

[0101] Nano-C 14 The preparation method of MA / MMT pour point depressant is the same as in Example 1;

[0102] Extracting Sapindus mukorossi oil and Nano-C 14 MA / MMT pour point depressants were simultaneously added to a three-necked flask (Nano-C) at room temperature. 14 The amount of MA / MMT pour point depressant added to the *Xanthoceras sorbifolium* oil was 0.30 wt%. The mixture was stirred and dispersed at 60°C. After complete dispersion and dissolution, it was allowed to cool naturally to room temperature. The oil was then removed from the container and allowed to stand for 24 hours to obtain modified *Xanthoceras sorbifolium* oil-based lubricants XSBO-based lubricants (denoted as 0.30 wt% Nano-C). 14 MA / MMT).

[0103] Comparative Example 1

[0104] Preparation process of a *Sapindus mukorossi* oil-based lubricant:

[0105] Add *Xanthoceras sorbifolium* oil to a three-necked flask at room temperature, stir and disperse at 60°C, and allow to cool naturally to room temperature. After removing the oil from the container, let it stand for 24 hours to obtain *Xanthoceras sorbifolium* oil-based lubricating oil XSBO (denoted as 0wt% Nano-C). 14 MA / MMT).

[0106] Comparative Example 2

[0107] Preparation process of a modified Xanthoceras sorbifolium oil-based lubricant:

[0108] Add *Sapindus mukorossi* oil and OMMT simultaneously to a three-necked flask at room temperature (the amount of OMMT added to *Sapindus mukorossi* oil is 0.25 wt%). Stir and disperse at 60°C. After complete dispersion and dissolution, allow to cool naturally to room temperature. Remove the oil from the container and let it stand for 24 hours to obtain modified *Sapindus mukorossi* oil-based lubricants XSBO-based lubricants (denoted as 0.25 wt% MMT).

[0109] Comparative Example 3

[0110] Preparation process of a modified Xanthoceras sorbifolium oil-based lubricant:

[0111] Nano-C 14 The preparation method of MA / MMT pour point depressant is the same as in Example 1;

[0112] Extracting Sapindus mukorossi oil and Nano-C 14 MA / MMT pour point depressants were simultaneously added to a three-necked flask (Nano-C) at room temperature. 14 The amount of MA / MMT pour point depressant added to the *Xanthoceras sorbifolium* oil was 0.25 wt%. The mixture was stirred and dispersed at room temperature. After complete dispersion and dissolution, it was allowed to cool naturally to room temperature. The oil was then removed from the container and allowed to stand for 24 hours to obtain modified *Xanthoceras sorbifolium* oil-based lubricants XSBO-based lubricants (denoted as 0.25 wt% Nano-C). 14 MA / MMT-1).

[0113] Comparative Example 4

[0114] Preparation process of a modified Xanthoceras sorbifolium oil-based lubricant:

[0115] Nano-C 14 The preparation method of MA / MMT pour point depressant is the same as in Example 1;

[0116] Extracting Sapindus mukorossi oil and Nano-C 14 MA / MMT pour point depressants were simultaneously added to a three-necked flask (Nano-C) at room temperature. 14 The amount of MA / MMT pour point depressant added to the *Xanthoceras sorbifolium* oil was 0.25 wt%. After complete dispersion and dissolution in a water bath at 80°C, the mixture was naturally cooled to room temperature. The oil was then removed from the container and allowed to stand for 24 hours to obtain modified *Xanthoceras sorbifolium* oil-based lubricants XSBO-based lubricants (denoted as 0.25 wt% Nano-C). 14 MA / MMT-2).

[0117] Performance testing

[0118] (1) Solubility

[0119] Nano-C prepared in Example 1 14MA / MMT pour point depressant was dispersed in trioleic acid glyceride at a dosage of 0.25 wt% for 1 hour. The results are shown in the figure. Figure 1 Nano-C 1 hour later 14 The MA / MMT pour point depressant was uniformly dispersed in trioleic acid glycerides (which have similar polarity and chemical properties to vegetable oils and are used to simulate the environment of vegetable oils) without exhibiting turbidity or precipitation. The absence of precipitation or flocculation in the sample indicates that the two formed a stable blend system. This result demonstrates that the Nano-C prepared in this embodiment of the invention... 14 MA / MMT pour point depressants have good solubility and dispersibility.

[0120] (2) FTIR and XPS measurements

[0121] Nano-C prepared by XPS Example 1 was analyzed using FTIR. 14 Structural analysis of MA / MMT pour point depressant, Nano-C 14 The infrared spectrum of MA / MMT pour point depressant is shown below. Figure 2 The C1S and O1S spectra of XPS are shown below. Figure 3 , Figure 4 ,Depend on Figure 2 It can be seen that C 14 MA at 1640cm -1 The C=C stretching vibration peak completely disappeared after the in-situ free radical polymerization reaction, resulting in a peak at 1250 cm⁻¹. -1 The COC stretching vibration peak at this location indicates the successful conduction of the free radical polymerization reaction. Nano-C 14 The alkyl group of MA / MMT pour point depressant is at 2926 cm⁻¹ -1 and 2854cm -1 The characteristic -CH3 and -CH2 absorption peaks at 1730 cm⁻¹ -1 The weakening of the C=O stretching vibration peak at 1250 cm⁻¹ and the 1250 cm⁻¹ peak -1 1098cm -1 The appearance of the CO stretching vibration peak at 3400 cm⁻¹ -1 The weakening of the -OH stretching vibration peak at C indicates that... 14 MA polymers underwent chemical adsorption or cross-linking reactions with the MMT surface, C 14 The COC of MA and the -OH of MMT generate new C=O and CO, which also proves that C 14 MA successfully adhered to the surface of OMMT, combining with the CC, C=O, CO, and COC peaks of XPS, such as Figure 3 and Figure 4 As shown, this proves Nano-C 14 Successful preparation of MA / MMT pour point depressant.

[0122] (3) FTIR and TG-DSC tests of XSBO-based lubricants

[0123] The modified XSBO-based lubricants (0.25 wt% Nano-C) prepared in Example 5 were analyzed by FTIR. 14 The structure of MA / MMT was characterized by TG-DSC for 0.25 wt% Nano-C. 14 The thermal stability and thermal oxidation stability of MA / MMT were tested and analyzed using 0.25wt% Nano-C. 14 The infrared spectrum of MA / MMT is shown below. Figure 5 The TG-DSC curve is shown below. Figure 6 (where (a) is the TG analysis result of Xanthoceras sorbifolium oil and lubricating oil under nitrogen (N2) atmosphere, (b) is the TG analysis result of Xanthoceras sorbifolium oil and lubricating oil under air atmosphere, (c) is the DSC analysis result of Xanthoceras sorbifolium oil and lubricating oil under N2 atmosphere, and (d) is the DSC analysis result of Xanthoceras sorbifolium oil and lubricating oil under air atmosphere).

[0124] Nano-C prepared by this invention 14 The process by which MA / MMT pour point depressants lower the pour point of lubricating oil mainly involves physical processes, rather than the breaking of chemical bonds. The mechanism is as follows: Adsorption: Nano-C 14 MA / MMT pour point depressants adsorb onto the surface of wax crystals, altering their growth pattern and preventing the formation of bulk structures; Crystal modification: Nano-C 14 MA / MMT pour point depressants modify the morphology of wax crystals, making them smaller, more dispersed, and less prone to forming a three-dimensional network structure; Dispersing effect: Nano-C 14 MA / MMT pour point depressants help wax crystals disperse evenly in the oil, preventing them from agglomerating. These effects are achieved physically, without involving the breaking or formation of chemical bonds, and therefore do not alter the chemical properties of the lubricating oil. Figure 5 It can be seen that XSBO-based lubricants (0.25wt% Nano-C) 14 MA / MMT basically retains the group properties of XSBO, but XSBO-based lubricants (0.25wt% Nano-C) 14 MA / MMT) at 966cm -1 The trans C=C expression occurs because the montmorillonite matrix contains acidic sites, which may cause some of the 1667 cm⁻¹ soil to react. -1The cis C=C was converted to trans C=C; furthermore, no peaks were found in the FTIR spectrum indicating CH bonds connected to unsaturated C=C or other heteroatoms. Therefore, the tribological properties and thermal stability of the lubricating oil were not significantly affected. Figure 6 The TG-DSC curve shows that XSBO-based lubricants (0.25wt% Nano-C) 14 MA / MMT exhibits good thermal stability within the range of 0-300℃.

[0125] (4) Low-temperature flowability and rheological testing of XSBO-based lubricants

[0126] The modified Xanthoceras sorbifolium oil-based lubricants prepared in the examples and comparative examples were tested for low-temperature fluidity (low-temperature fluidity is expressed as pour point, and the test method is GB / T 510-2018) and rheological properties using instruments such as polarizing microscope and rheometer. The rheological properties of the modified Xanthoceras sorbifolium oil-based lubricants (XSBO-based lubricants) in Examples 1-6 are shown in Table 1, and the rheological properties of the Xanthoceras sorbifolium oil-based lubricants in Comparative Examples 1-4 are shown in Table 2.

[0127] Table 1. Rheological performance test results of XSBO-based lubricants in the embodiments.

[0128]

[0129] Table 2. Rheological property test results of comparative example *Sapindus mukorossi* oil-based lubricating oils

[0130]

[0131] Nano-C 14 MA / MMT pour point depressants act as nucleation points, promoting the formation of wax crystals in lubricating oil, resulting in finer and more uniformly distributed wax crystals, thereby delaying the formation of large wax crystal networks; additionally, Nano-C 14 MA / MMT pour point depressants not only disperse in lubricating oil, increasing the distance between wax crystals and hindering their interconnection, thus delaying the formation of wax crystal networks, but they can also adsorb onto the surface of wax crystals, inhibiting their growth and aggregation, preventing the formation of large wax crystal networks, and further lowering the pour point. Nano-C 14 MA / MMT pour point depressant is a nanomaterial with high surface energy. To maintain the energy stability of the solid-liquid system and release the encapsulated crystalline liquid from the three-dimensional network structure, small particulate crystals must be arranged to reduce energy inequality and form a stable solid-liquid surface. Table 1 shows that adding 0.25 wt% Nano-C... 14The MA / MMT pour point depressant exhibited the best lubricating oil performance, with the pour point of the lubricating oil dropping as low as -37℃, a decrease of 19℃ compared to *Xanthoceras sorbifolium* oil. In Comparative Examples 3 and 4, the room temperature or 80℃ water bath conditions primarily accelerated the dispersion of the additives in *Xanthoceras sorbifolium* oil and reduced preparation time, having little impact on the performance of the lubricating oil.

[0132] Using a polarizing microscope (e.g.) Figure 7 As shown in the image, 2 μL of sample was titrated onto a glass slide and covered with a glass coverslip. The slide was then placed in a cold storage room and rapidly frozen to -50°C at a cooling rate of 20°C / min, and held for 1 minute. The sample temperature was then raised to a specified temperature (10°C / min) and held for 5 minutes. Ice crystal photographs were recorded. Photographs of the crystals precipitated at different low temperatures for the *Sapindus mukorossi* oil of Comparative Example 1 and the modified lubricating oil of Example 5 are shown in the image. Figures 8-18 O1-O4 represent Comparative Example 1, and B1-B7 represent Example 5 (the scale bars on the figure are all 50 μm).

[0133] It was observed that, after Nano-C 14 The MA / MMT-modified lubricating oil has a pour point that can be lowered to -37°C, a decrease of 19°C compared to Xanthoceras sorbifolium crude oil (Comparative Example 1, XSBO). When the temperature drops from -5°C to -37°C, the number of wax crystals increases. At the same temperature, compared to XSBO, the lubricating oil has significantly fewer crystals, and the crystals exhibit a smaller, spherical structure. (Addition of Nano-C...) 14 MA / MMT can make the arrangement and distribution of point crystals more orderly, while transforming needle-like crystals into tiny, uniform, near-spherical crystals. Furthermore, the crystal size gradually increases as the temperature decreases from -5℃ to -37℃. Therefore, Nano-C 14 MA / MMT pour point depressants can exhibit pour point depressing effects on Xanthoceras sorbifolium oil.

[0134] The shear stress-shear rate curves (a), shear stress-viscosity curves (b), and viscosity-temperature curves (c) of the XSBO-based lubricants of Example 5 and the XSBO of Comparative Example 1 are shown in Figure 5. Figure 19 ,like Figure 19 As shown in (a) and (b), the shear stress-shear rate curves at different temperatures exhibit a linear relationship, indicating that their viscosity is only affected by temperature, making them standard Newtonian fluids; according to Figure 19As shown in the viscosity-temperature curves (c), compared to XSBO, the viscosity of XSBO-based lubricants increases with further decrease in temperature, indicating improved viscosity-temperature properties and low-temperature fluidity of the lubricant. With decreasing temperature, the viscosity of XSBO increases significantly, and continues to increase with further decreases in temperature, indicating that this lubricant thickens at low temperatures. Similarly, the viscosity of XSBO-based lubricants increases with decreasing temperature, but at -37℃, it is slightly higher than that of XSBO at the same temperature. This is because nano-montmorillonite forms a spatial network through interlayer adsorption, inhibiting the decrease in viscosity at high temperatures, while tetradecyl methacrylate interferes with wax crystal growth, reducing viscosity at low temperatures. Both work synergistically to optimize the viscosity-temperature properties of the lubricant. This indicates that XSBO-based lubricants maintain good fluidity at lower temperatures and are suitable for use over a wider temperature range. On the other hand, in the range of 0-30℃, the viscosity changes of both XSBO and XSBO-based lubricants are small and tend to be stable, indicating good stability at high temperatures.

[0135] (5) Friction reduction and wear resistance

[0136] The friction-reducing and anti-wear properties of lubricating oil are parameters used to visually indicate its lubrication performance. They are typically evaluated using a four-ball friction and wear tester, which measures the average wear scar diameter (AWSD) and coefficient of friction (COF) under these conditions. Specific parameters are shown in Table 3.

[0137] Friction and wear tests were conducted on the samples using an MRS-1J four-ball friction and wear tester. Precision bearing steel balls with a diameter of 12.7 mm were selected as friction balls. The samples were ground for 30 minutes at a speed of 1200 r / min under a load of 392 N to determine the lubricating performance of the lubricating oil. First, 2 mL of the oil sample to be tested was injected into the oil tank to ensure that the contact surfaces of the steel ball and the gasket were completely immersed in the oil sample. A balance bar was installed on the upper fixed device, and a load was applied by suspending a weight. After the test, a centralized computer control box was used to monitor data such as the coefficient of friction (COF), test temperature, and test humidity in real time. At the end of the test, the test steel balls were removed, and the grease on their surface was cleaned with methanol. Then, the average wear scar diameter was calculated using formula (1).

[0138]

[0139] In formula (1), X represents the transverse length (mm) of the steel ball wear scar, and Y represents the longitudinal length (mm) of the steel ball wear scar.

[0140] Table 3. Specific values ​​of lubricating oil in terms of friction coefficient and wear scar diameter.

[0141]

[0142] 1) Friction Reduction Performance Analysis

[0143] The friction reduction performance of the lubricating oils obtained in Example 5 and Comparative Example 1 was analyzed, and the friction coefficient results are shown in Table 4.

[0144] Table 4. Coefficient of friction of *Sapindus mukorossi* oil-based lubricants

[0145]

[0146] As can be seen from Table 4, when Nano-C 14 When the addition amount of MA / MMT is 0.25wt%, the friction coefficient of the prepared lubricating oil is significantly lower than that of Xanthoceras sorbifolium oil, decreasing to 0.010, and the friction type is mixed friction. This indicates that Nano-C... 14 The addition of MA / MMT allows nanoparticles to form a lubricating film on the friction surface, reducing direct contact. Simultaneously, the excellent dispersibility of montmorillonite nanoparticles in lubricating oil contributes to performance improvement, enhancing not only XSBO-based lubricants (0.25wt% Nano-C) but also... 14 While increasing the kinematic viscosity (MA / MMT), it also enhances the adhesion between the oil film and the metal surface, allowing a thicker protective oil film to form on the friction surface. Additionally, C... 14 The ester group (-COO-) at the end of the MA molecular chain combines with the oxide layer or hydroxyl group on the metal surface through polar bonds (such as hydrogen bonds, dipole-dipole interactions) to form a strong adsorption layer, reducing direct contact under boundary lubrication and thus reducing the coefficient of friction.

[0147] 2) Anti-wear performance analysis

[0148] The anti-wear properties of the lubricating oils obtained in Example 5 and Comparative Example 1 were analyzed, and the results are shown in Table 5.

[0149] Table 5 Average wear scar diameter of lubricating oil

[0150]

[0151] Table 5 shows that XSBO-based lubricants (0.25wt% Nano-C) 14 The wear scar diameter (AWSD) of MA / MMT is 0.50 mm, lower than that of XSBO. This is because nanoparticles can fill surface microcracks, repair damage, and form a protective layer on the surface, reducing wear. Meanwhile, Nano-C...14 MA / MMT nanoparticles can improve the strength of lubricating oil films and enhance their stability under high loads. The extreme pressure and anti-wear properties of the nanoparticles help reduce wear under extreme conditions, and C 14 The polar adsorption of ester groups in MA inhibits catalytic oxidation on metal surfaces, while the physical barrier effect of montmorillonite reduces oxygen diffusion. Together, they delay the viscosity decrease and wear failure caused by oil degradation. In addition, they can improve the thermal stability of lubricating oil and reduce performance loss at high temperatures, thus improving anti-wear ability.

[0152] (6) Contact angle

[0153] The contact angle diagrams of the lubricating oils obtained in Example 5 and Comparative Example 1 are shown below. Figure 20 In Comparative Example 1 (a) and Example 5 (b), it can be seen that the contact angle of the *Xanthoceras sorbifolium* oil in Comparative Example 1 is 34.5°, while that of the *Xanthoceras sorbifolium* oil-based lubricant prepared in Example 1 is 20.6°. This is because of the difference in contact angle between Nano-C and the surface temperature. 14 MA / MMT is composed of nanoparticles that can alter the surface tension of lubricating oil. Changes in surface tension directly affect the wettability of the lubricating oil on solid surfaces, thus altering the contact angle and enhancing its wettability. Similarly, Nano-C... 14 MA / MMT can improve the dispersibility of wax crystals in lubricating oils, preventing them from agglomerating into large particles. This dispersing effect allows the lubricating oil to spread more evenly on solid surfaces, thereby reducing the contact angle. The above describes XSBO-based lubricants (0.25wt% Nano-C) 14 MA / MMT has better wettability and surface compatibility than XSBO.

[0154] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a montmorillonite-tetradecyl methacrylate nano-pouring depressant, characterized in that, Using tetradecyl methacrylate as a monomer, and with the participation of an initiator, it is grafted onto the surface of modified montmorillonite via free radical polymerization to obtain the nano-montmorillonite-tetradecyl methacrylate nano-pour depressant.

2. The preparation method of the montmorillonite-tetradecyl methacrylate nano-pouring depressant according to claim 1, characterized in that, The modified montmorillonite is obtained by modifying montmorillonite with hexadecyltrimethylammonium bromide. And / or, the initiator is benzoyl peroxide.

3. The preparation method of the montmorillonite-tetradecyl methacrylate nano-pouring depressant according to claim 1, characterized in that, The ratio of the modified montmorillonite, tetradecyl methacrylate, and initiator is 1 g: 0.2 mol: 0.6 mmol.

4. The preparation method of the montmorillonite-tetradecyl methacrylate nano-pouring depressant according to claim 1, characterized in that, The free radical polymerization reaction was carried out at a temperature of 80°C for 4 hours.

5. A montmorillonite-tetradecyl methacrylate nano-pouring depressant, characterized in that, It is prepared by the preparation method according to any one of claims 1-4.

6. The application of the montmorillonite-tetradecyl methacrylate nanoparticle pour point depressant as described in claim 5 in improving the low-temperature flow properties of Xanthoceras sorbifolium oil-based lubricating oil.

7. A modified *Sapindus mukorossi* oil-based lubricant, characterized in that, The raw materials include *Sapindus mukorossi* oil and the montmorillonite-tetradecyl methacrylate nanoparticle depressant as described in claim 5.

8. The modified *Sapindus mukorossi* oil-based lubricating oil according to claim 7, characterized in that, The amount of the montmorillonite-tetradecyl methacrylate nano-pour-depressant added to the *Sapindus mukorossi* oil is 0.05-0.30 wt%.

9. A method for preparing a modified *Sapindus mukorossi* oil-based lubricating oil as described in any one of claims 7-8, characterized in that, Montmorillonite-tetradecyl methacrylate nanoparticle pour point depressant was added to Xanthoceras sorbifolium oil and stirred evenly to obtain the modified Xanthoceras sorbifolium oil-based lubricating oil.

10. The method for preparing the modified *Sapindus mukorossi* oil-based lubricating oil according to claim 9, characterized in that, The stirring temperature is 60°C, and the mixture is cooled to room temperature after being stirred evenly.

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