Dispersive PMA viscosity index improver-containing lubricating oil additive for ammonia fuel engine and composition

Abstract

The invention provides a dispersing type PMA viscosity index agent-containing lubricating oil additive for an ammonia fuel engine and a composition. The preparation process of the composition comprises the following steps: mixing the viscosity index agent dry glue blocks with part of the base oil according to the formula proportion, heating to 100-130 DEG C, stirring, dissolving, and standing for 6-8 hours to obtain a product a; and putting the product a and the remaining base oil into a blending kettle, sequentially adding a clearing agent, an antioxidant, an anti-wear and anti-friction agent and a corrosion inhibitor according to the formula proportion, starting to stir, heating to 40-50 DEG C, keeping the temperature, and continuously stirring for 4-10 hours to obtain the lubricating oil composition containing the dispersing type PMA viscosity index improver for the ammonia fuel engine. Through specific additive combination, hydrolysis resistance and ammonia corrosion resistance are enhanced, oil-water emulsification is stabilized, sediment generation is inhibited, wear resistance is improved, and reliable operation of an ammonia fuel engine lubricating system is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of lubricating oil technology, and more specifically to a lubricating oil additive and composition for ammonia fuel engines containing a dispersible PMA viscosity index modifier. Background Technology

[0002] Ammonia-fueled engines use ammonia (NH3) as their core fuel. Their working principle involves the oxidation and combustion of NH3 in the combustion chamber, releasing energy and producing high-temperature, high-pressure gas that drives the piston to power the engine. However, the combustion characteristics of NH3 present several technical challenges: firstly, the relatively high combustion temperature easily triggers nitrogen oxides (NOx). x The formation of nitrogen oxides (NO) is a major pollutant that needs to be controlled by an after-treatment system. Secondly, and more importantly, the chemical properties and combustion products of ammonia fuel pose a severe challenge to the engine lubrication system, making it difficult for traditional lubricating oil systems to adapt.

[0003] From a chemical corrosion perspective, NH3 is strongly alkaline and significantly corrodes metallic materials, especially copper, zinc, tin, and their alloys. These materials are widely used in sliding bearings, seals, and hydraulic components of traditional engines. In an NH3 atmosphere, they are prone to alkaline corrosion, leading to decreased surface finish, increased clearances, and ultimately, leaks or failures. Simultaneously, NH3 readily neutralizes acidic additives in lubricating oils, disrupting their colloidal stability and causing them to lose their dispersing and cleaning functions, thus exacerbating sludge buildup.

[0004] The effects of combustion products are more complex and cascading: First, the chemical reaction of ammonia combustion is 4NH3 + 3O2 → 2N2 + 6H2O, producing three times the amount of H2O as a gasoline engine. Excessive water intrusion into the lubricating oil triggers additive hydrolysis. Traditional antioxidants such as zinc dialkyl dithiophosphate (ZDDP) easily decompose into corrosive phosphoric acid in the presence of water. Hindered phenols also lose their activity due to hydrolysis, leading to a sharp drop in oil film strength, boundary lubrication, or even dry friction in the friction pair, causing severe wear. Second, unburned escaped ammonia combines with water to form ammonium hydroxide (NH4OH), which not only disrupts the emulsification stability of the lubricating oil, causing oil-water separation, but also accelerates intergranular cracking of bearing alloys through stress corrosion mechanisms. This is particularly detrimental to brittle materials such as Babbitt metals.

[0005] In addition, NO produced by combustion xAt high temperatures, NH3 reacts with ammonium nitrate to form ammonium salt crystals. These substances pose a dual hazard: firstly, as strong oxidants, they catalyze the oxidation of lubricating oil, leading to abnormal viscosity increases and a surge in acid value; secondly, the crystal particles easily deposit at low temperatures, forming sludge that clogs filters and oil passages, affecting lubrication system circulation. Simultaneously, hydrogen atoms produced by the decomposition of NH3 at high temperatures can permeate into the metal lattice, triggering hydrogen embrittlement, which reduces the toughness of high-strength components such as valves and pistons, increasing the risk of breakage.

[0006] To address the aforementioned pain points, conventional lubricating oils, not designed specifically for ammonia fuel characteristics, suffer from three major deficiencies: first, the additive system lacks sufficient hydrolysis resistance, making it unable to cope with high-moisture environments; second, there is a lack of dedicated corrosion inhibitors against ammonia corrosion, resulting in weak metal protection; and third, poor emulsification stability, failing to form an effective lubricating film after oil-water separation. While the industry recognizes the need for an "emulsified oil-water non-separation" technology approach, there remains a technological gap in the development of key functional additives, and a mature solution has not yet been established. This has become a significant bottleneck restricting the industrial application of ammonia fuel engines. Summary of the Invention

[0007] The purpose of this invention is to provide a lubricating oil additive and composition for ammonia fuel engines containing a dispersible PMA viscosity index modifier, which overcomes the shortcomings of traditional lubricating oil compositions such as easy hydrolysis, weak resistance to ammonia corrosion, and unstable emulsification, and solves problems such as lubrication failure caused by high moisture content and strong alkaline corrosion in ammonia fuel engines, thus ensuring lubrication performance.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A lubricating oil additive for ammonia fuel engines containing a dispersible PMA viscosity index modifier includes the following raw materials: detergent, viscosity index modifier, antioxidant, anti-wear and friction reducing agent, and corrosion inhibitor, wherein the viscosity index modifier is a dispersible PMA viscosity index modifier.

[0010] A lubricating oil composition for ammonia fuel engines containing a dispersible PMA viscosity index modifier, comprising, by mass percentage: 1-10% detergent, 8-18% viscosity index modifier, 0.5-5% antioxidant, 0.5-10% anti-wear and friction reducing agent, 0.005-0.010% corrosion inhibitor, and the balance being base oil.

[0011] Preferably, the base oil is a high viscosity index Group III paraffinic synthetic oil, which is composed of 250N and 150N base oils.

[0012] A method for preparing a lubricating oil composition for ammonia fuel engines containing a dispersible PMA viscosity index modifier includes the following steps:

[0013] (1) Sol: Cut the dry gel of dispersible PMA adhesive into pieces according to the formula ratio and mix it with part of the base oil. Heat to 100~130℃ and stir to dissolve. Let stand for 6~8h to obtain product a;

[0014] (2) Blending: Place product a and the remaining base oil into a blending vessel, add detergent, antioxidant, anti-wear and friction reducer and corrosion inhibitor in sequence according to the formula ratio, start stirring and heat to 40~50℃ and keep warm, continue stirring for 4~10h to obtain a lubricating oil composition for ammonia fuel engine containing dispersible PMA viscosity index agent.

[0015] Preferably, in step (2), the detergent includes one or two of alkyl salicylate and sulfide alkylphenol salt; the antioxidant includes one or two of long-chain alkyl diphenylamine and long-chain alkyl thiohedral phenol; the corrosion inhibitor includes alkyl benzotriazole; and the anti-wear and friction reducing agent is one or two of nano molybdenum disulfide and graphene oxide.

[0016] Preferably, the structure of the alkyl salicylate is shown in Formula I:

[0017] ;

[0018] Formula I

[0019] Where R is an alkyl group containing 10 to 20 carbon atoms, M is Ca or Mg, and m and n are non-zero positive integers;

[0020] The structure of the sulfide alkylphenol salt is preferably shown in Formula II:

[0021] ;

[0022] Formula II

[0023] In the formula, R2 is an alkyl group containing 10 to 24 carbon atoms, M is Ca or Mg, and m2, n2, and x are non-zero positive integers.

[0024] Preferably, the dispersible PMA viscosity indexing agent is a copolymer of dodecyl methacrylate and N-vinylpyrrolidone. Dodecyl methacrylate, N-vinylpyrrolidone, solvent, and initiator are mixed and polymerized at 50-80°C for 5-9 hours. The resulting toluene solution of the polymerization product is subjected to vacuum distillation, followed by vacuum filtration, alcohol washing, and vacuum drying to obtain a white or pale yellow dispersible PMA viscosity indexing agent. The reaction formula is as follows:

[0025] .

[0026] Preferably, the weight ratio of dodecyl methacrylate to N-vinylpyrrolidone is (4~6):1.

[0027] Preferably, the initiator includes one or more of azobiscyanopentanoic acid, azobisisobutyronitrile, benzoyl peroxide, and azobisisoheptane, and the amount of initiator is 0.02 to 1.5% of the weight of dodecyl acrylate and N-vinylpyrrolidone.

[0028] Preferably, the solvent is toluene, and the amount used is 15~35 mL / mol.

[0029] The present invention has the following beneficial effects:

[0030] 1. The alkaline component of low-alkalinity calcium salts is mainly calcium hydroxide, while the alkaline component of high-alkalinity calcium salts is mainly calcium carbonate and a small amount of calcium hydroxide. Calcium hydroxide is more soluble in water than calcium carbonate; furthermore, ammonia fuel combustion produces more acidic substances. This invention preferentially uses a combination of high-alkalinity magnesium salicylate and alkylphenol calcium sulfide. The phenolic oxygen group in alkylphenol calcium sulfide reacts directly with NH3: RO - +NH3→ROH+NH- 2, and its high-temperature stability is superior to that of sulfonates, inhibiting nitration deposition; synergistic with phenolic / amine antioxidants: long-chain alkyl diphenylamine directly captures NO. x The acid generated by the neutralization of magnesium alkyl salicylate and high-base-value calcium alkylphenol sulfide creates an alkaline environment that enhances the activity of long-chain alkylthiohedral oxidants and inhibits nitration-induced oxidation reactions. Magnesium salts have a lower molecular weight than calcium salts, providing more total base number (TBN) per unit mass. They also have the advantage of high ash content and better base number retention compared to calcium salts. While calcium salts can rapidly neutralize acidic substances, magnesium salts excel in base number retention; therefore, the combination of high-base-value magnesium salicylate and high-base-value calcium alkylphenol sulfide offers synergistic advantages.

[0031] 2. Antioxidants are available in amine and shielded phenolic forms. Traditional lubricating oil compositions use zinc dialkyl dithiophosphate and zinc diaryl dithiophosphate as antioxidants. These additives are highly susceptible to hydrolysis upon contact with water, resulting in the loss of the lubricating oil's antioxidant and anti-corrosion functions. Therefore, hindered thiophenols and long-chain alkyl diphenylamine antioxidants are preferred. For temperatures below 150°C, phenolic antioxidants are most effective. Compared to amine antioxidants, phenolic antioxidants are more compatible with base oils, more resistant to ammonia-alkali environments, and their long alkyl chains (such as C12) form a hydrophobic barrier, preventing NH3 from contacting the phenolic hydroxyl groups and thus preventing precipitation. They also exhibit stronger activity at low temperatures. Due to the loss of naturally occurring sulfur-containing components in synthetic base oils caused by advanced processing techniques, and the high susceptibility of synthetic base oils to sulfur-containing antioxidants, hindered thiophenol antioxidants are preferred. Thio-hindered phenolic antioxidants containing a thioether group can terminate the chain oxidation reaction of hydrocarbon molecules through homolytic dehydrogenation of the phenolic hydroxyl group and reaction with ROO·, and can also decompose ROOH into ROH through the thioether group, thus generating a self-synergistic antioxidant effect. This gives thio-hindered phenolic antioxidants superior antioxidant activity compared to thiophenol-free types, and the dual functions of a low-to-medium temperature free radical scavenger and a hydroperoxide decomposer. For high temperatures above 150°C, long-chain alkyl diphenylamine is combined with thio-hindered phenolic antioxidants. This combination of high- and low-temperature antioxidants provides high-temperature stability, improving the oil's resistance to high-temperature oxidation. Diphenylamine excels at high-temperature protection. The long-chain alkyl diphenylamine and thio-hindered phenolic antioxidants, containing long-chain alkanes, are more easily dissolved in oil and have stable performance. Thio-hindered phenols excel at low-to-medium temperature and decompose hydroperoxides. The combined use of these two antioxidants provides effective antioxidant protection throughout the entire range from the crankcase (low to medium temperature) to the piston ring region (high temperature). The synergistic effect results in a significantly prolonged oxidation induction period for the oil, increased viscosity, higher acid value, and a substantial reduction in the rate of sludge and deposit formation. The selected thiohedral phenols and diphenylamines should possess excellent thermal and hydrolytic stability to withstand the high-temperature and high-moisture environment of ammonia-fueled engines. In synergistic effect with detergents, long-chain alkyl diphenylamines directly capture NO. x The detergent neutralizes the acid, forming a double defense.

[0032] 3. Alkylated benzotriazole acts as a metal corrosion inhibitor, reducing nitrate formation. The NH or N-CH3 groups of alkylated benzotriazole form a dense five-membered ring chelate with the metal surface, covering the active sites. The complex "locks" free metal ions in the passivation layer, preventing them from diffusing into the oil to catalyze the nitration reaction. Alkylated benzotriazole, grafted with C12-C18 alkyl chains, enhances oil solubility and prolongs the residence time on the metal surface. The synergistic effect with alkaline additives, high-alkalinity alkyl salicylate magnesium and high-alkalinity sulfurized alkylphenol calcium neutralize nitrifying acids, and alkylated benzotriazole blocks metal catalysis, thus doubly inhibiting the nitration chain reaction.

[0033] 4. The anti-wear and friction-reducing agent of this invention uses nano-molybdenum disulfide (MoS2) and graphene oxide as anti-wear and friction-reducing agents, which themselves possess excellent mechanical properties, thermal conductivity, and potential tribological properties. Their layered structure can also fill tiny surface pits, improving surface contact. Furthermore, MoS2 has catalytic conversion properties, capable of blocking the nitration reaction chain and catalyzing the reaction of ammonia with NO. x The reaction 4NH3 + 4NO + O2 → 4N2 + 6H2O reduces nitrate formation and prevents filter clogging. Traditional lubricating oil anti-wear agent zinc dialkyl dithiophosphate (ZDDP) is unstable and decomposes in water. Nano-molybdenum disulfide (MoS2) and graphene oxide, used as anti-wear and friction-reducing agents, exhibit excellent water resistance and stable performance, making them a viable alternative to zinc dialkyl dithiophosphate (ZDDP).

[0034] 5. Traditional dispersants, such as ashless dispersants and boronized polyisobutylene succinimide dispersants, contain amine bonds, imine bonds, and polar alcohol groups, which are highly susceptible to hydrolysis and loss of their dispersant properties. To address this issue, this invention employs a dispersible PMA viscosity indexing agent. Dispersible PMA viscosity indexing agents are highly amphoteric polymers with an amphiphilic molecular structure. Containing N-vinylpyrrolidone (NVP), these agents complex ammonia molecules (NH3), water, and amine combustion products through hydrogen bonding, reducing direct contact between alkaline substances and engine metal parts, thus mitigating alkaline corrosion. Through the interaction of hydroxyl bonds with water, they reduce interfacial tension, inhibit water droplet aggregation, and maintain oil phase continuity. This ensures the oil-water emulsion remains intact, allowing the lubricating oil to maintain a stable emulsion state even with high water content, guaranteeing normal cold starts at low temperatures. It also exhibits excellent dispersing effects on high-temperature deposits such as sludge and varnish produced during ammonia fuel engine combustion. Dispersible PMA viscosity index enhancers, with their polar groups acting like magnets, strongly adhere to the surfaces of metal friction pairs, forming a stable, adsorbed, and non-extrudable polymeric oil film. The dispersible PMA viscosity index enhances the base film thickness, while the nanoparticles fill and reinforce it, increasing the overall oil film thickness. This strengthens the oil film on the surfaces of friction components, reducing friction, wear, and pitting. It prevents deposition on high-temperature friction surfaces, keeps the friction pairs clean, avoids localized hot spots and abnormal wear, indirectly protecting the integrity of the oil film and protecting engine components during boundary friction. Dispersible PMA viscosity index enhancers also have a synergistic effect with MoS2 and graphene oxide, utilizing their amphiphilicity, steric hindrance, electrostatic repulsion, and ability to form a supporting network to solve the problems of dispersion stability and anti-settling of graphene oxide and MoS2 in lubricating oils. Attached Figure Description

[0035] Figure 1 This is a test result of the heat pipe after emulsification in Example 1;

[0036] Figure 2 This is a test result image of the heat pipe after emulsification in Example 2;

[0037] Figure 3 This is a test result image of the heat pipe after emulsification in Example 3;

[0038] Figure 4 This is a test result of the heat pipe after emulsification, as shown in Comparative Example 3.

[0039] Figure 5 Example 2: Trend chart of kinematic viscosity change rate of ammonia fuel engine lubricating oil during 250-hour bench test at 100°C;

[0040] Figure 6 Example 2: Trend chart of kinematic viscosity change of lubricating oil for ammonia fuel engine at 100°C after 250 hours bench test;

[0041] Figure 7 Example 2: Oxidation value trend of lubricating oil in ammonia fuel engine after 250 hours bench test;

[0042] Figure 8 This is a graph showing the trend of nitration value change in the lubricating oil of an ammonia fuel engine during a 250-hour bench test, as shown in Example 2.

[0043] Figure 9 Example 2: Base number variation trend of ammonia fuel engine lubricating oil after 250 hours bench test;

[0044] Figure 10 This is a graph showing the trend of acid value change in the lubricating oil of an ammonia fuel engine during a 250-hour bench test, as shown in Example 2. Detailed Implementation

[0045] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0046] In this invention, a method for preparing a lubricating oil composition for an ammonia fuel engine containing a dispersible PMA viscosity index modifier includes the following steps:

[0047] (1) Sol: Cut the dry adhesive of the adhesive indexing agent into pieces according to the formula ratio and mix with part of the base oil. Heat to 100~130℃ and stir to dissolve. Let stand for 6~8h to obtain product a;

[0048] (2) Blending: Place product a and the remaining base oil into a blending vessel, add detergent, antioxidant, anti-wear and friction reducer and corrosion inhibitor in sequence according to the formula ratio, start stirring and heat to 40~50℃ and keep warm, continue stirring for 4~10h to obtain a lubricating oil composition for ammonia fuel engine containing dispersible PMA viscosity index agent.

[0049] The working mechanism and principle of each preparation step:

[0050] Step 1 is a crucial step in achieving uniform integration of the dispersible PMA viscosity indexer with the base oil. By mixing the dry gel of the viscosity indexer with a portion of the base oil and stirring to dissolve it at a specific temperature, heat is used to promote the expansion of the polymer chains, breaking down intermolecular entanglement and aggregation. During this process, the base oil, acting as a dispersion medium, penetrates into the viscosity indexer molecules through solvation, allowing the amphiphilic PMA molecules (containing hydrophobic alkyl chains and hydrophilic pyrrolidone groups) to form a stable colloidal dispersion system. Static treatment further eliminates localized concentration differences, ensuring uniform distribution of the viscosity indexer molecules in the base oil and creating a homogeneous carrier environment for the synergistic effect of subsequent additives.

[0051] The core of this step lies in achieving complete dissolution and stable dispersion of the PMA viscosity index enhancer through temperature control and intermolecular force balance. The resulting colloidal structure not only provides basic viscosity support for the lubricating oil but also pre-builds adsorption sites through the polar groups of the PMA molecules, creating conditions for the interfacial bonding of subsequent anti-wear agents, detergents, and other components, thus avoiding localized lubrication failure caused by uneven dispersion of the viscosity index enhancer.

[0052] Step 2 is the core process for achieving the synergistic effect of various functional additives. By sequentially introducing antioxidants, detergents, anti-wear and friction reducers, and metal corrosion inhibitors, and controlling the temperature and stirring conditions, molecular-level interactions and functional complementarity are promoted.

[0053] First, the long-chain alkyl thiohedral phenols and long-chain alkyl diphenylamines in the antioxidant dissolve in the base oil through hydrophobic interactions. The phenolic hydroxyl groups of the thiohedral phenols form a synergistic antioxidant system with the thioether groups, which can capture free radicals in the medium and low temperature range and decompose hydrogen peroxides. The long-chain alkyl diphenylamines, on the other hand, are stable at high temperatures due to their aromatic amine structure and preferentially react with NO. x The reaction blocks the oxidation chain initiated by nitration; secondly, high-alkalinity alkyl salicylate magnesium and high-alkalinity sulfurized alkylphenol calcium act as detergents, adsorbing acidic substances produced by combustion through the double-layer structure of colloidal particles, whose metal ions (Mg... 2+ Ca 2+ The molybdenum disulfide combines with acid radicals to achieve neutralization, while the phenolic oxygen groups react with ammonia molecules to inhibit alkaline corrosion. Furthermore, the nano-molybdenum disulfide and graphene oxide maintain stable dispersion through the steric hindrance and electrostatic repulsion of the dispersible PMA viscosity index agent. The layered structure can fill the pits on the surface of the friction pair, and the adsorbed oil film formed with PMA synergistically enhances the strength of the lubricating film. Molybdenum disulfide can also catalyze the reaction of ammonia and NO. xThe process involves a harmless reaction that reduces nitrate deposition. Finally, alkylated benzotriazole forms a chelate passivation layer on the metal surface via NH groups, blocking the catalytic effect of metal ions on oxidation reactions, creating a dual protection mechanism with the acid neutralization function of the detergent. The entire blending process uses temperature control to ensure the additives are fully dissolved without thermal decomposition, and continuous stirring promotes intermolecular interactions, ultimately forming a lubricating oil system with anti-hydrolysis, anti-corrosion, anti-wear, and stable emulsification functions, suitable for the harsh operating conditions of ammonia fuel engines.

[0054] To make the present invention more fully disclosed, more specific embodiments are described below.

[0055] I. Examples and Comparative Examples

[0056] Example 1

[0057] (1) Sol: Cut the adhesive dry glue into pieces according to the formula ratio and mix with part of the base oil. Heat to 120°C and stir until completely dissolved. Let stand for 6 hours to obtain product a;

[0058] (2) Blending: Product a and the remaining base oil are placed in a blending vessel. Detergent, antioxidant, anti-wear and friction reducing agent and corrosion inhibitor are added in sequence according to the formula ratio. Stirring is started and the temperature is raised to 45°C and kept at that temperature. Stirring is continued for 4 hours to obtain a lubricating oil composition for ammonia fuel engines containing dispersible PMA viscosity index modifier. The heat pipe test results after emulsification using the lubricating oil composition produced in Example 1 are shown in the attached figure. Figure 1 As shown.

[0059] The lubricating oil composition for ammonia fuel engines in Example 1, calculated by mass percentage, shows the specific raw material composition and content as shown in Table 1.

[0060]

[0061] Example 2

[0062] (1) Sol: Cut the adhesive dry glue into pieces according to the formula ratio and mix with part of the base oil. Heat to 125°C and stir until completely dissolved. Let stand for 7 hours to obtain product a;

[0063] (2) Blending: Product a and the remaining base oil are placed in a blending vessel. Detergent, antioxidant, anti-wear and friction reducer and corrosion inhibitor are added in sequence according to the formula ratio. Stirring is started and the temperature is raised to 50°C and kept at that temperature. Stirring is continued for 6 hours to obtain a lubricating oil composition for ammonia fuel engines containing dispersible PMA viscosity index modifier. The heat pipe test results after emulsification of the lubricating oil composition produced in Example 2 are shown in the attached figure. Figure 2 As shown.

[0064] The lubricating oil composition for ammonia fuel engines in Example 2, calculated by mass percentage, shows the specific raw material composition and content as shown in Table 2.

[0065]

[0066] Example 3

[0067] (1) Sol: Cut the adhesive dry glue into pieces according to the formula ratio and mix with part of the base oil. Heat to 130°C and stir until completely dissolved. Let stand for 8 hours to obtain product a;

[0068] (2) Blending: Product a and the remaining base oil are placed in a blending vessel. Detergent, antioxidant, anti-wear and friction reducing agent and corrosion inhibitor are added in sequence according to the formula ratio. Stirring is started and the temperature is raised to 55°C and kept at that temperature. Stirring is continued for 8 hours to obtain a lubricating oil composition for ammonia fuel engines containing dispersible PMA viscosity index modifier. The heat pipe test results after emulsification using the lubricating oil composition produced in Example 3 are shown in the attached figure. Figure 3 As shown.

[0069] The lubricating oil composition for ammonia fuel engines in Example 3, calculated by mass percentage, shows the specific raw material composition and content as shown in Table 3.

[0070]

[0071] Comparative Example 1

[0072] The type of adhesive finger agent is OCP adhesive finger agent, and the other reaction conditions are the same as in Example 2.

[0073] The lubricating oil composition for ammonia fuel engines in Comparative Example 1, calculated by mass percentage, shows the specific raw material composition and content as shown in Table 4.

[0074]

[0075] Comparative Example 2

[0076] The detergent was a low-alkalinity detergent, and all other reaction conditions were the same as in Example 2.

[0077] The lubricating oil composition for ammonia fuel engines in Comparative Example 2, calculated by mass percentage, shows the specific raw material composition and content as shown in Table 5.

[0078]

[0079] Comparative Example 3

[0080] The anti-wear agent is zinc dialkyl dithiophosphate, which does not contain corrosion inhibitors. All other reaction conditions are the same as in Example 2. The heat pipe test results after emulsification using the lubricating oil composition produced in Comparative Example 3 are shown in the attached figure. Figure 4As shown.

[0081] The lubricating oil composition for ammonia fuel engines in Comparative Example 3, calculated by mass percentage, shows the specific raw material composition and content as shown in Table 6.

[0082]

[0083] II. Summary

[0084] The physicochemical test indicators of the embodiments and comparative examples of this invention are shown in Table 7. As can be seen from Table 7, each scheme belongs to the low-sulfur, low-phosphorus, and low-ash schemes, with a viscosity grade of 10W-40, which can reduce high-temperature deposits and protect the engine aftertreatment system. Examples 1-3, as well as Comparative Examples 2 and 3, contain dispersible PMA viscosity index enhancers, and therefore outperform Comparative Example 1 in high-temperature resistance tests such as heat pipe and crankcase simulation tests, and in diesel nozzle shear tests. Example 2 is the best among these. It can be seen that the dispersible PMA viscosity index enhancer has the functions of dispersion, high-temperature oxidation resistance, thickening, and shear resistance.

[0085]

[0086] Emulsification test experiment

[0087] 1. Emulsion stability test method: Take 100g of the lubricating oil composition of Examples 1-3 and Comparative Examples 1-3 and 10g of water and add them to a beaker, and stir at a speed of 10000r / min±2000r / min for 2min±2s. Observe the emulsification after storage at room temperature for 24 hours, 168 hours, 336 hours and at high temperature (150℃) for 168 hours, respectively. The analysis results are shown in Table 8.

[0088]

[0089] As can be seen from the test results in Table 8, the oil emulsions of Examples 1-3 of this invention are very stable. After using the emulsifier, the oil can be stored at both room temperature and high temperature for extended periods without oil-water separation, achieving the goal of preventing oil-water separation in lubricating oils for ammonia fuel engines. Comparative Example 1 does not contain a dispersing viscosity index agent, and the oil and water easily separate. Comparative Example 2, although containing a dispersing viscosity index agent, uses a low-alkalinity detergent. This type of detergent is easily hydrolyzed, resulting in a white precipitate at the bottom layer, indicating that the calcium salt micelle structure of the detergent has been damaged, and calcium hydroxide has precipitated. Comparative Example 3, although containing a dispersing viscosity index agent, uses traditional ZDDP, which hydrolyzes and produces precipitation in the presence of water.

[0090] 2. The high-temperature deposit properties of the engine oil before and after emulsification were tested using a coking test. The coking plate test conditions were: plate temperature reaction temperature 330℃, oil temperature 150℃, duration 6 hours. The more coke, the worse the oil's resistance to deposits. The coking plate test results of the engine lubricating oil compositions in Examples 1-3 and Comparative Examples 1-3 before and after emulsification are shown in Table 9.

[0091]

[0092] As can be seen from the test results in Table 9, the test results of the oil emulsions in Examples 1-3 against high-temperature deposit formation are consistent with those before emulsification, indicating that even under high water content conditions, the oils of the present invention can still maintain excellent antioxidant and anti-deposit performance control. From the coking test data before and after emulsification in Comparative Examples 1-3, it can be seen that the coke weight increased and the data deteriorated after emulsification, indicating that the oil in Comparative Example 1 experienced oil-water separation and reduced performance; the detergent in Comparative Example 2 and Comparative Example 3 experienced detergent hydrolysis and reduced performance.

[0093] 3. The anti-oxidation deposit performance of the engine oil before and after emulsification was tested using a heat pipe test. The heat pipe test conditions were: reaction temperature 280℃, oil speed 0.6ml / s, duration 16 hours. The worst result was 0 and the best result was 9. The heat pipe test results of the engine lubricating oil compositions of Examples 1-3 and Comparative Example 3 before and after emulsification are shown in Table 10.

[0094]

[0095] From Table 10, Figures 1-4 The test results show that the antioxidant and anti-deposit formation test results of the oil emulsions in Examples 1-3 are consistent with those before emulsification, indicating that even under high water content, the oils of the present invention can still maintain excellent antioxidant and anti-deposit performance control. From the heat pipe test data before and after emulsification of Comparative Example 3, it can be seen that the heat pipe data deteriorated after emulsification, indicating that the ZDDP anti-wear and friction-reducing agent in the oil of Comparative Example 3 underwent hydrolysis, resulting in reduced antioxidant performance.

[0096] 4. To test the wear scar diameter of the oil before emulsification, a four-ball mill was used. The test conditions were as follows: three steel balls with a diameter of 12.7 mm were clamped in an oil container and covered with test oil. Another steel ball of the same diameter was placed on top of the three balls, subjected to a force of 147 N (15 kgf) or 392 N (40 kgf), forming a "three-point contact". After the test oil reached a certain temperature (75℃ ± 20℃), the top ball rotated at a certain speed for 60 minutes. The wear resistance of the test oil was evaluated by the average wear scar diameter of the three balls. The results are shown in Table 11.

[0097]

[0098] As can be seen from the test results in Table 11, the wear scar diameters of the oils in Examples 1-3 of the present invention remained consistent before and after emulsification. This indicates that under high water content conditions, the anti-wear agent in the oils of the present invention did not hydrolyze, and the anti-wear performance of the oil was still maintained, providing sufficient anti-wear protection for the engine. However, the wear scar diameters of Comparative Example 3 before and after emulsification show that the anti-wear performance decreased significantly because ZDDP is easily decomposed when it comes into contact with water, causing the oil to lose its anti-wear performance.

[0099] 5. To test the rust prevention performance of the engine oil before and after emulsification, steel plates of standardized size and roughness were immersed in the lubricating oil composition and a certain amount of ammonia was added. The plates were then left to stand in an oven at 120°C for 5 days, and the rust spots on the steel plates were observed. The results are shown in Table 12.

[0100]

[0101] As can be seen from the test results in Table 12, the oil emulsions of Examples 1-3 of the present invention are stable, do not separate into oil and water, and contain corrosion inhibitors, thus maintaining the anti-corrosion performance of the engine oil. However, although Comparative Example 1 contains corrosion inhibitors, the steel sheets still rusted severely due to oil-water separation. Although Comparative Example 3 does not separate into oil and water, it does not contain corrosion inhibitors and still rusted. Therefore, it is necessary to add corrosion inhibitors to enhance the anti-corrosion performance of the ammonia fuel engine lubricating oil composition.

[0102] Reliability bench test verification

[0103] The optimal embodiment 2 was selected for reliability bench testing. This bench test lasted 250 hours. (See attached...) Figure 5 ~Appendix Figure 10 It can be seen that the kinematic viscosity change rate did not exceed the limit requirement of the oil change index, indicating that the oil has good kinematic viscosity retention and can well meet the lubrication requirements of the vehicle engine during the ultra-long oil change interval. The acid value of the oil gradually increases, but the change trend is stable, and the oil still has good detergency and base value reserve, which is higher than the standard requirement (≥1.0). The oxidation value and nitration value of the test oil gradually increase, but are lower than the standard requirement (not greater than 30A / cm). Therefore, the ammonia fuel engine lubricating oil composition of this invention passed the 250-hour reliability bench test.

[0104] The above description, in conjunction with preferred embodiments, provides a further detailed explanation of the present invention, but it should not be construed as limiting the specific implementation of the invention to these descriptions. For those skilled in the art, various substitutions or modifications can be made to the described embodiments without departing from the inventive concept, and all such substitutions or modifications should be considered to fall within the protection scope of the present invention.

[0105] Although the invention and its advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made without departing from the spirit and scope of the invention. Furthermore, the scope of the invention is not limited to the specific embodiments of the processes, manufactures, compositions of matter, methods, and steps described in the specification. From the disclosure of this invention, those skilled in the art will readily utilize existing or future processes, manufactures, compositions of matter, methods, or steps that substantially perform the same function or achieve the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to encompass such processes, manufactures, compositions of matter, methods, or steps.

Claims

1. A lubricating oil additive for ammonia fuel engines containing a dispersible PMA viscosity index modifier, characterized in that, It includes the following raw materials: detergent, viscous indexing agent, antioxidant, anti-wear and friction reducing agent, and corrosion inhibitor, wherein the viscous indexing agent is a dispersible PMA viscous indexing agent.

2. A lubricating oil composition for ammonia fuel engines containing a dispersible PMA viscosity index modifier according to claim 1, characterized in that, The composition, by weight percentage, includes the following raw materials: detergent 1-10%, viscosity index improver 8-18%, antioxidant 0.5-5%, anti-wear and friction reducer 0.5-10%, corrosion inhibitor 0.005-0.010%, and base oil balance.

3. The lubricating oil composition for ammonia fuel engines containing a dispersible PMA viscosity index modifier according to claim 2, characterized in that, The base oil is a high viscosity index Group III paraffinic synthetic oil, which is composed of 250N and 150N base oils.

4. A method for preparing a lubricating oil composition for an ammonia fuel engine containing a dispersible PMA viscosity index modifier according to claim 2 or 3, characterized in that, Includes the following steps: (1) Sol: Mix the dispersible PMA viscosity index agent with part of the base oil according to the formula ratio, heat to 100~130℃ and stir to dissolve, let stand for 6~8h to obtain product a; (2) Blending: Place product a and the remaining base oil into a blending vessel, add detergent, antioxidant, anti-wear and friction reducer and corrosion inhibitor in sequence according to the formula ratio, start stirring and heat to 40~50℃ and keep warm, continue stirring for 4~10h to obtain a lubricating oil composition for ammonia fuel engine containing dispersible PMA viscosity index agent.

5. The method for preparing a lubricating oil composition for ammonia fuel engines containing a dispersible PMA viscosity index modifier according to claim 4, characterized in that, In step (2), the cleaning agent includes one or two of alkyl salicylate and sulfide alkylphenol salt; the antioxidant includes one or two of long-chain alkyl diphenylamine and long-chain alkyl thiohed phenol; the corrosion inhibitor is alkyl benzotriazole; and the anti-wear and friction reducing agent includes one or two of nano molybdenum disulfide and graphene oxide.

6. The method for preparing a lubricating oil composition for an ammonia fuel engine containing a dispersible PMA viscosity index modifier according to claim 5, characterized in that, The structure of the alkyl salicylate is shown in Formula I: ； Formula I Where R is an alkyl group containing 10 to 20 carbon atoms, M is Ca or Mg, and m and n are non-zero positive integers; The structure of the sulfide alkylphenol salt is preferably shown in Formula II: ； Formula II In the formula, R2 is an alkyl group containing 10 to 24 carbon atoms, M is Ca or Mg, and m2, n2, and x are non-zero positive integers.

7. The method for preparing a lubricating oil composition for ammonia fuel engines containing a dispersible PMA viscosity index modifier according to claim 5, characterized in that, The dispersible PMA viscosity indexing agent is a copolymer of dodecyl methacrylate and N-vinylpyrrolidone. Dodecyl methacrylate, N-vinylpyrrolidone, solvent, and initiator are mixed and polymerized at 50-80°C for 5-9 hours. The resulting toluene solution of the polymerization product is subjected to vacuum distillation, followed by vacuum filtration, alcohol washing, and vacuum drying to obtain a white or pale yellow dispersible PMA viscosity indexing agent. The reaction formula is as follows: 。 8. The method for preparing a lubricating oil composition for ammonia fuel engines containing a dispersible PMA viscosity index modifier according to claim 7, characterized in that, The weight ratio of dodecyl methacrylate to N-vinylpyrrolidone is (4~6):

1.

9. The method for preparing a lubricating oil composition for an ammonia fuel engine containing a dispersible PMA viscosity index modifier according to claim 7, characterized in that, The initiator includes one or more of azobiscyanopentanoic acid, azobisisobutyronitrile, benzoyl peroxide, and azobisisoheptanecyanocyanate, and the amount of initiator used is 0.02 to 1.5% of the weight of dodecyl acrylate and N-vinylpyrrolidone.

10. The method for preparing a lubricating oil composition for an ammonia fuel engine containing a dispersible PMA viscosity index modifier according to claim 7, characterized in that, The solvent is toluene, and the amount used is 15~35 mL / mol.

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