A highly freeze-resistant liquid lubricant and a method for preparing the same

Abstract

This invention discloses a high-freeze-resistant liquid lubricating oil and its preparation method, comprising the following ingredients by weight percentage: 70-82 wt% synthetic base oil, 5-10 wt% modified mineral oil, 8-15 wt% composite low-temperature resistant additive, and 3-7 wt% auxiliary functional additive; wherein the synthetic base oil is a compound of polyalphaolefin (PAO-4), pentaerythritol ester, and polyether polyol; the composite low-temperature resistant additive is composed of a modified pour point depressant, a novel viscosity index improver, and a low-temperature flow promoter; and the auxiliary functional additive is composed of an anti-wear agent, an antioxidant, a dispersant, and a defoamer. Through innovative ingredient compounding design, the technical pain points of limited antifreeze effect and poor ingredient synergy in existing low-temperature resistant lubricating oils are solved. By using ternary synthetic base oil, graphene-modified mineral oil, and ternary composite low-temperature resistant additive, a synergistic balance of ultra-low pour point, high compatibility, strong dispersibility, and low cost is achieved.

Description

Technical Field

[0001] This invention relates to the field of lubricating oil technology, and in particular to a high antifreeze liquid lubricating oil and its preparation method. Background Technology

[0002] Liquid lubricating oil is a core lubricating medium in industrial production, transportation, and other fields. Its low-temperature resistance is crucial for its proper functioning in lubrication, heat dissipation, and sealing under cold and low-temperature conditions. Existing low-temperature lubricating oils on the market have significant limitations in their antifreeze effect: ordinary mineral oil-based lubricating oils have high pour points and are prone to wax crystal precipitation at low temperatures, leading to loss of fluidity; ordinary synthetic lubricating oils experience a sharp increase in viscosity and insufficient oil film stability in extreme low-temperature environments below -40°C, and the compatibility of additives with base oils is poor; high-end extreme cold-weather-specific lubricating oils suffer from excessive cost, cumbersome preparation, and difficulty in large-scale commercialization. Considering the current state of formulation and preparation processes for low-temperature lubricating oils, the core technical challenges include unreasonable base oil ratios, poor synergy of low-temperature additives, and interference with antifreeze effects by auxiliary additives. Therefore, this application provides a high-freeze-resistant liquid lubricating oil and its preparation method to meet the demand. Summary of the Invention

[0003] The purpose of this application is to provide a high-freeze-resistant liquid lubricating oil and its preparation method, in order to solve the technical problems of limited antifreeze effect and poor ingredient synergy of existing low-temperature lubricating oils.

[0004] To achieve the above objectives, this application provides the following technical solution: a high antifreeze liquid lubricating oil, composed of the following ingredients by weight percentage:

[0005] Synthetic base oil 70-82wt%, modified mineral oil 5-10wt%, composite low-temperature additives 8-15wt%, auxiliary functional additives 3-7wt%;

[0006] The synthetic base oil is composed of polyalphaolefin (PAO-4), pentaerythritol ester, and polyether polyol in a weight ratio of 5:3:2. After blending, the pour point of the synthetic base oil can be reduced to below -55℃. Compared with PAO-4 alone (pour point ≤ -60℃ but poor compatibility), it has more stable low-temperature fluidity. Compared with pentaerythritol ester alone (pour point ≤ -55℃ but insufficient antifreeze properties), it can meet the requirements of extreme low temperatures of -45℃. Compared with polyether polyol alone (pour point ≤ -50℃), the antifreeze effect is significantly improved, and the viscosity change at low temperatures is more gradual, avoiding lubrication failure caused by a sudden increase in viscosity.

[0007] The 5:3:2 ratio allows the antifreeze function of the three components to have a synergistic effect. PAO-4 provides core antifreeze, pentaerythritol ester avoids low-temperature stratification, and polyether polyol promotes the dispersion of antifreeze additives. The synergistic effect of the three can extend the fluidity retention time of the finished lubricating oil at -45℃ to more than 72 hours, which is far superior to a single base oil. At the same time, it can prevent oil film rupture at low temperatures and ensure the continuous lubrication effect.

[0008] The 5:3:2 ratio allows the three components to form a stable homogeneous system, while improving the compatibility of synthetic base oil with modified mineral oil, composite low-temperature additives, and auxiliary functional additives. This prevents stratification and precipitation at low temperatures, ensuring the stable performance of the lubricating oil during long-term use and preventing a decrease in antifreeze and lubrication performance due to compatibility issues.

[0009] This ratio allows the three base oil molecules to form stable hydrogen bonds, avoiding microscopic stratification. It also improves the compatibility of base oils with graphene, preventing graphene agglomeration. In synergy with various additives, it can reduce the adsorption loss of additives and ensure their long-term effectiveness. In addition, it can prevent chemical reactions between base oils and additives at high temperatures, which would generate ineffective products and affect the overall performance of the lubricating oil.

[0010] The 5:3:2 ratio can improve the stability of the dispersion system by more than 50%, and prevent the additives from agglomerating during storage and use. At the same time, it can promote the uniform distribution of graphene in the base oil, so that the reinforcing effect of graphene can be evenly covered across the entire lubrication surface. In addition, it can ensure the uniform dispersion of the low-temperature additives, avoid local concentrations that are too high or too low, and ensure the uniformity of the antifreeze effect.

[0011] The modified mineral oil is a graphene-modified, deeply dewaxed mineral oil. The modification method is as follows: the deeply dewaxed mineral oil is heated to 60-70℃, 0.1-0.3wt% of graphene powder is added, the mixture is stirred and dispersed for 30-40 minutes, ultrasonically treated for 15-20 minutes, cooled to room temperature, and then filtered to obtain the modified mineral oil.

[0012] Deeply dewaxed mineral oils are preferred to reduce the content of wax crystals in the mineral oil and prevent the precipitation of wax crystals at low temperatures, which would affect the antifreeze performance of the lubricating oil. After deep dewaxing, the low-temperature fluidity of the mineral oil is improved, which lays the foundation for graphene modification. At the same time, its oil film strength is high, which can reinforce the synthetic base oil.

[0013] Heating temperature 60-70℃: Suitable for graphene dispersion and mineral oil viscosity requirements. Specifically: 1. Reduces the viscosity of deeply dewaxed mineral oil, making graphene easier to disperse in the mineral oil and avoiding graphene agglomeration due to excessive viscosity; 2. Prevents excessively high temperatures (above 70℃) from causing mineral oil oxidation and degradation, while also preventing graphene oxidation (graphene is easily oxidized at high temperatures, losing its reinforcing effect); 3. Prevents excessively low temperatures (below 60℃), resulting in high mineral oil viscosity, uneven graphene dispersion, and inability to form a stable dispersion system; 4. A temperature of 60-70℃ can promote the interaction between the active groups on the graphene surface and mineral oil molecules, improving the dispersion stability of graphene and preventing graphene sedimentation during subsequent use. Additional information: A temperature range of 60-70℃ can reduce the viscosity of mineral oil to 15-20 mm² / s (at 40℃), which perfectly matches the dispersion requirements of graphene. This avoids graphene sedimentation due to excessively low viscosity, and also prevents dispersion difficulties due to excessively high viscosity. This temperature range prevents the loss of active groups on the graphene surface, ensuring the binding force between graphene and mineral oil molecules and improving dispersion stability. Simultaneously, it accelerates the wetting rate of graphene in mineral oil, shortens dispersion time, and improves modification efficiency. Furthermore, this temperature range prevents the volatilization of light components in the mineral oil, ensuring the stability of the modified mineral oil components and not affecting subsequent blending effects with synthetic base oils.

[0014] Adding graphene at a concentration of 0.1-0.3 wt% (relative to deeply dewaxed mineral oil) ensures that graphene can fully exert its reinforcing effect, avoiding insufficient addition which would fail to improve the oil film strength, low-temperature fluidity, and thermal conductivity of the mineral oil. If the addition is below 0.1 wt%, the graphene dispersion concentration is insufficient, the reinforcing effect is negligible, and the modified mineral oil is no different from ordinary deeply dewaxed mineral oil. If the addition is above 0.3 wt%, it leads to graphene agglomeration—graphene has a large specific surface area and easily adsorbs to form agglomerates. Agglomeration not only fails to exert its reinforcing effect but also increases the viscosity of the mineral oil, affecting low-temperature fluidity; it also affects the compatibility of the modified mineral oil with synthetic base oil, leading to stratification and precipitation.

[0015] Within the range of 0.1-0.3wt%, a balance of "reinforcement + cost + dispersion" can be achieved. Within this range, graphene can be uniformly dispersed in mineral oil, which can improve the oil film strength of modified mineral oil by more than 30%, the low temperature fluidity by more than 15%, and the thermal conductivity by more than 25%, while keeping the cost under control and making it suitable for large-scale production.

[0016] The composite low-temperature additive is composed of a modified pour point depressant, a novel viscosity index improver, and a low-temperature flow promoter in a weight ratio of 4:3:3.

[0017] The modified pour point depressant accounts for 40%, the highest among the three components. Its advantages are as follows: the modified pour point depressant is the core component for inhibiting wax crystal growth and lowering the pour point of lubricating oil. Its core function is to disrupt the crystallization morphology of wax crystals, preventing wax crystal aggregation at low temperatures that leads to decreased lubricating oil fluidity. The 40% proportion ensures its effective concentration, fully leveraging its "pour point depressant core" role—inhibiting the growth of residual wax crystals in synthetic base oils and modified mineral oils, while also matching the overall formulation's 8-15wt% total proportion of composite low-temperature additives. Even when the total proportion of composite low-temperature additives is at the lower limit of 8wt%, the effective concentration of the modified pour point depressant can still reach 3.2wt%, stably lowering the pour point of the finished lubricating oil to below -50℃, avoiding a decrease in antifreeze effect due to insufficient core component proportion. Simultaneously, the 40% proportion avoids performance redundancy caused by excessive amounts (such as exceeding 50%), preventing excessive adsorption of the modified pour point depressant on the wax crystal surface, which could negatively impact the performance of other low-temperature additives, thus balancing core function and synergy.

[0018] The novel viscosity index improver and low temperature flow promoter each account for 30% (weight ratio 3:3), which is a balanced proportion. The advantage of this is that both are antifreeze auxiliary components, which are complementary and indispensable. The balanced proportion can ensure that the auxiliary effects of the two are fully exerted and avoid the functional loss caused by the low proportion of a single auxiliary component. The core function of the novel viscosity index improver is to regulate the viscosity-temperature properties of lubricating oil, preventing a sudden increase in viscosity at low temperatures and a low viscosity at high temperatures. A 30% proportion ensures that it effectively regulates the viscosity-temperature curve, making the viscosity of the lubricating oil change smoothly over a wide temperature range of -45℃ to 100℃. This ensures both pumping performance and fluidity at low temperatures, as well as oil film strength at high temperatures. The core function of the low-temperature flow promoter is to improve the low-temperature flow performance of lubricating oil, reduce the kinematic viscosity at low temperatures, and reduce the flow resistance of lubricating oil in pipelines. A 30% proportion ensures that it works synergistically with the modified pour point depressant to further improve low-temperature fluidity. The modified pour point depressant "inhibits wax crystal aggregation," while the low-temperature flow promoter "improves flow resistance." The balanced proportion of the two can form a synergistic effect, improving the flow performance of lubricating oil at -45℃ by more than 40%, which is far superior to the effect of a single component.

[0019] The auxiliary functional additive is composed of anti-wear agent, antioxidant, dispersant and defoamer in a weight ratio of 3:2:2:1;

[0020] The anti-wear agent accounts for 30% (by weight), the highest among the four components. Its advantages are as follows: the core requirement of auxiliary functional additives is to "ensure lubrication reliability," while the core function of the anti-wear agent is to form a protective film on the surface of mechanical parts, reducing friction and wear between metals and preventing metal debris from wear from affecting the antifreeze performance of the lubricating oil and clogging lubrication lines. The 30% proportion ensures its effective concentration, fully leveraging its core anti-wear function—adapting to the heavy-load and low-temperature operating conditions required in the overall formulation, compensating for the insufficient oil film strength of synthetic base oils and modified mineral oils under heavy loads, and synergizing with the physical reinforcing effect of graphene in modified mineral oils to form a dual protection system of "chemical anti-wear + physical reinforcement," improving the anti-wear performance of the lubricating oil by more than 25%, extending the service life of mechanical parts and the lubricating oil replacement cycle. At the same time, the 30% proportion avoids the negative effects of excessive amounts (such as exceeding 40%), preventing excessive anti-wear agent from antagonizing the low-temperature additives and affecting the antifreeze effect, and avoiding excessive adsorption leading to abnormal oil film thickness, which affects the operating precision of mechanical parts.

[0021] Antioxidants and dispersants each account for 20% (by weight, 2:2), a balanced proportion. This balance is beneficial because both are key components ensuring the long-term stability of lubricating oil, with complementary functions and equal priority. A balanced proportion ensures that both functions are fully utilized, avoiding insufficient stability due to the low proportion of any single component. The core function of the antioxidant is to inhibit oxidative degradation of lubricating oil during high-temperature, long-term use, reducing the formation of oxidation products (such as carbon deposits and sludge). A 20% proportion ensures its effective concentration, suitable for the oxidative stability requirements of synthetic base oils and modified mineral oils. It synergizes with the antioxidant effect of pentaerythritol esters in synthetic base oils, extending the oxidation induction period of lubricating oil (to over 600 hours at 120℃), preventing increased viscosity and reduced antifreeze performance caused by oxidative degradation. The core function of the dispersant is to promote the growth of composite low-temperature additives and graphite. The uniform dispersion of graphene prevents component agglomeration and disperses metal debris and oxidation products generated by wear. A 20% proportion ensures its dispersion effect and adapts to the dispersion requirements of each component in the overall formulation. It promotes the uniform dispersion of composite low-temperature additives to ensure uniform antifreeze effect, and also promotes the stable dispersion of graphene in modified mineral oils and synthetic base oils to ensure uniform physical reinforcement covering the lubrication surface and avoid increased flow resistance and lubrication failure caused by agglomerates. At the same time, a 20% proportion can avoid the decrease in oil film strength caused by excessive dispersant, thus balancing dispersibility and lubrication. 3. The defoamer accounts for 10% (by weight), the lowest among the four components. Its advantages are as follows: The defoamer's function is to eliminate bubbles generated during the stirring and pumping of lubricating oil, preventing bubbles from freezing at low temperatures and affecting lubrication. However, its function requires "on-demand supply"—a defoaming effect can be achieved without a high proportion. A 10% proportion ensures its effective concentration, quickly eliminating generated bubbles while avoiding uneven lubrication and equipment vibration caused by residual bubbles. The low 10% proportion avoids the negative effects of excessive amounts, preventing abnormal surface tension of the lubricating oil due to excessive defoamer, which could affect the sealing performance of the lubrication system. It also avoids excessive reactions with other components, generating ineffective products, thus balancing defoaming function and system compatibility. Furthermore, a 10% proportion controls costs. Defoamer is relatively expensive; a low proportion reduces the overall cost of auxiliary functional additives while achieving the defoaming function.

[0022] In a preferred embodiment of this invention, the synthetic base oil contains: polyalphaolefin (PAO-4) with a kinematic viscosity of 4.0-4.5 mm² / s at 40°C, ensuring excellent low-temperature fluidity and smooth pumping, meeting the core requirements for antifreeze; a pour point ≤-60°C; and a purity ≥99%, laying the foundation for the system's ultra-low antifreeze properties and preventing low-temperature crystallization; the combination of the two components allows for full utilization of their dominant antifreeze role, and their viscosity is compatible with other components, preventing stratification after compounding;

[0023] Pentaerythritol ester has a kinematic viscosity of 6.0-7.0 mm² / s at 40℃, which compensates for the shortcomings of PAO-4, such as low viscosity and insufficient oil film strength, and improves lubrication durability; its pour point is ≤-55℃, which meets the overall antifreeze requirements of the system and does not drag down the pour point after compounding; its acid value is ≤0.1 mgKOH / g; its viscosity is compatible with PAO-4 and polyether polyols, taking into account both compatibility and lubricity, and its acid value meets the requirements to improve oxidation stability.

[0024] The polyether polyol has a kinematic viscosity of 5.0-5.5 mm² / s at 40℃. As an intermediate viscosity component, it connects PAO-4 and pentaerythritol ester to ensure uniform viscosity after the three are compounded, avoiding stratification and agglomeration. The pour point is ≤-50℃, which helps to enhance the antifreeze properties of the system. It matches the pour points of the previous two components to ensure that the pour point of the compounded product is stable at ≤-55℃. At the same time, it meets the dispersion requirements and helps the additives to be uniformly dispersed.

[0025] As a preferred embodiment of this example, the deeply dewaxed mineral oil is made from paraffin-based crude oil through a three-stage dewaxing process, with the first stage crystallization temperature at -10℃, the second stage at -25℃, and the third stage at -35℃. After dewaxing, the wax content is ≤0.5wt% and the pour point is ≤-35℃. The graphene powder is graphene oxide with a particle size of 50-100nm.

[0026] Three-stage gradient dewaxing ensures a more thorough process, prevents wax crystal aggregation, and improves dewaxing efficiency.

[0027] Initially remove high-melting-point wax at -10℃, remove medium-melting-point wax at -25℃, and remove low-melting-point wax at -35℃. This process is carried out gradually to avoid clogging the equipment and ensure thorough dewaxing.

[0028] Wax content ≤0.5wt%: This prevents the precipitation and aggregation of wax crystals at low temperatures, without affecting the overall freeze resistance and flowability;

[0029] Pour point ≤ -35℃: Adapts to the antifreeze requirements of the system without lowering the overall pour point after compounding;

[0030] 50-100nm graphene oxide: with moderate particle size and good dispersibility, it is easy to combine with mineral oil to strengthen the oil film strength. At the same time, it has high activity and improves lubrication and thermal conductivity.

[0031] In a preferred embodiment of this invention, the modified pour point depressant in the composite low-temperature additive is made from polymethyl methacrylate (PMA) as the base material and modified with Mannich base.

[0032] Compared to traditional PMA pour point depressants, its low-temperature adsorption efficiency is improved by more than 30%, and its compatibility with base oils is significantly improved. Its core function is to adsorb onto the surface of wax crystals at low temperatures, inhibiting the growth and aggregation of wax crystals and preventing wax crystal agglomeration from causing loss of lubricating oil fluidity.

[0033] The novel viscosity index improver is a polymethyl methacrylate-siloxane copolymer (PMA-Si) with a number average molecular weight of 50,000-80,000.

[0034] Its number-average molecular weight is controlled between 50,000 and 80,000. The beneficial effects of this molecular weight range are: it can enhance the viscosity-temperature properties of lubricating oil, ensuring that the viscosity does not increase sharply at low temperatures and does not decrease excessively at high temperatures, and it can also improve the shear resistance of lubricating oil, avoiding the failure of additives due to shearing during mechanical operation. If the molecular weight is lower than 50,000, the shear resistance is insufficient; if it is higher than 80,000, it will lead to increased viscosity at low temperatures, affecting the flow performance.

[0035] The low-temperature flow promoter is a compound of isodecylbenzenesulfonate and polyethylene glycol monomethyl ether in a weight ratio of 2:1.

[0036] Its core function is to reduce the low-temperature flow resistance of lubricating oil and promote the dispersion of wax crystals. In synergy with modified pour point depressants, it can further improve the antifreeze effect. Isodecylbenzenesulfonate can reduce the surface tension of wax crystals, and polyethylene glycol monomethyl ether can improve the dispersibility of wax crystals. The 2:1 compound ratio of the two can achieve synergistic effect. Compared with the single component, the low-temperature flow promotion effect can be improved by 20%.

[0037] In a preferred embodiment of this invention, the anti-wear agent in the auxiliary functional additive is a compound of organic molybdenum and zinc dialkyl dithiophosphate in a weight ratio of 1:2.

[0038] The antioxidant is a compound of hindered phenolic antioxidants and amine antioxidants in a weight ratio of 3:2;

[0039] The dispersant is boronized succinimide;

[0040] The defoamer is polyether-modified silicone oil.

[0041] A method for preparing a high-antifreeze liquid lubricating oil.

[0042] S1. Preparation and pretreatment: Weigh each component according to the ratio, and pretreat the synthetic base oil, composite low-temperature additive, and auxiliary functional additive to obtain pretreated synthetic base oil, pretreated composite low-temperature additive, and pretreated auxiliary functional additive.

[0043] S2. Base oil compounding: Pretreated synthetic base oil is added to a reaction vessel, modified mineral oil is slowly added under nitrogen protection, the temperature is raised to 55-65℃, stirred and ultrasonically dispersed to obtain compound base oil;

[0044] Advantages of a temperature of 55-65℃: It avoids graphene agglomeration caused by sudden temperature changes, ensuring that the reinforcing effect of graphene in modified mineral oil is fully utilized; at this temperature, the viscosity of the composite base oil is moderate, which is conducive to ultrasonic dispersion and will not cause the light components of the base oil to volatilize due to excessive temperature, ensuring the stability of the ratio of 70-82wt% synthetic base oil to 5-10wt% modified mineral oil in the formulation.

[0045] S3. Adding and synergistic mixing of additives in stages: Add pretreatment composite low-temperature resistant additive, pretreatment auxiliary functional additive and defoamer to the composite base oil in sequence, keep the temperature at 55-65℃, stir in stages to achieve full mixing;

[0046] The benefits of adding in stages: First, add the composite low-temperature additive to ensure it is fully mixed with the composite base oil. The modified pour point depressant can be adsorbed onto the surface of residual wax crystals in the base oil in advance. PMA-Si simultaneously regulates viscosity-temperature performance and matches the 4:3:3 ratio in the formula. Then, add auxiliary functional additives to avoid interference from anti-wear agents, antioxidants, etc., with the role of the low-temperature component, ensuring that the 3:2:2:1 ratio in the formula is precisely utilized.

[0047] The benefits of maintaining a temperature of 55-65℃ are: it maintains the base oil compounding temperature, avoids viscosity increase due to cooling, and ensures rapid and uniform diffusion of additives; at the same time, this temperature will not damage the additive structure, ensuring the stability of antifreeze, anti-wear and other functions.

[0048] S4. Low-temperature co-processing: Cool the material to -10 to -15℃ for low-temperature maturation, then heat it to 25-30℃, filter to remove impurities, and degas it a second time to obtain the finished product.

[0049] S5. Testing and Packaging: Conduct performance testing on the finished products, and repackage them after they pass the test.

[0050] As a preferred embodiment of this example, the synthetic base oil is pretreated by adding PAO-4, pentaerythritol ester, and polyether polyol to a pretreatment vessel, with a nitrogen flow rate of 0.5-1.0 L / min, heating to 40-50°C, stirring at 300-400 r / min for 15-20 min, and cooling to 25-30°C.

[0051] Benefits of a temperature of 40-50℃: Higher than room temperature but lower than the component oxidation temperature, it reduces the viscosity of PAO-4, pentaerythritol ester, and polyether polyol, promoting the rapid formation of a homogeneous system in a 5:3:2 ratio, thus strengthening the synergistic effect of "ultra-low pour point + high compatibility"; it avoids component oxidation and degradation due to excessively high temperatures, while excessively low temperatures result in high viscosity and uneven mixing. Benefits of nitrogen protection: It isolates the synthetic base oil components from air, preventing oxidation and ensuring the stability of its core antifreeze indicators such as pour point and viscosity.

[0052] Pretreatment of composite low-temperature additive: Add each component of the composite low-temperature additive to the pretreatment kettle, add 5-8% of the total weight of the pretreatment synthetic base oil, heat to 35-45℃, rotate at 500-600 r / min, stir for 10-15 min, and ultrasonically treat for 5-8 min.

[0053] Benefits of using a temperature range of 35-45℃: The mild temperature range is suitable for the properties of the modified pour point depressant, PMA-Si, and the compound flow promoter, avoiding high-temperature damage to the molecular structure of PMA-Si and ensuring its viscosity index regulating function; it also promotes the pre-dissolution of additives with a small amount of synthetic base oil, improving subsequent compatibility with the main base oil. Benefits of adding a small amount of synthetic base oil: As a dilution carrier, it solves the problem of easy agglomeration when the three low-temperature additives are directly mixed, ensuring the functional synergy of the 4:3:3 ratio. Benefits of ultrasonic treatment: It further breaks down micro-agglomerates, ensuring uniform dispersion of the modified pour point depressant and laying the foundation for subsequent inhibition of wax crystal growth.

[0054] Pretreatment of auxiliary functional additives: Mix anti-wear agent, antioxidant and dispersant, heat to 30-40℃ and stir for 8-10 minutes.

[0055] Benefits of a temperature of 30-40℃: It adapts to the compounding requirements of anti-wear agents, antioxidants, and dispersants, avoids the decomposition of organic molybdenum and the failure of hindered phenolic antioxidants caused by high temperatures; promotes the initial mixing of the three components in a 3:2:2 ratio, and improves the subsequent fusion efficiency with the base oil.

[0056] As a preferred embodiment of this example, in step S2: nitrogen flow rate is 0.3-0.8 L / min, heating rate is 1-2℃ / min, rotation speed is 450-550 r / min, stirring is 25-35 min, ultrasonic dispersion power is 300-400 W, and ultrasonic time is 10-15 min;

[0057] Advantages of a heating rate of 1-2℃ / min: slow heating avoids local overheating, prevents base oil oxidation, and allows the two base oil molecules to gradually penetrate and fuse, forming stable hydrogen bonds and improving the low-temperature stability of the composite base oil.

[0058] Benefits of nitrogen protection + ultrasonic dispersion: Nitrogen isolates the air to prevent oxidation; ultrasonic vibration breaks up any possible micro-agglomerates of graphene, ensuring its uniform dispersion in the composite base oil, enhancing oil film strength and thermal conductivity; the combined effect of stirring and ultrasound improves mixing efficiency and avoids stratification.

[0059] In a preferred embodiment of this example, in step S4: during low-temperature curing, the cooling rate is 0.5-1℃ / min, the rotation speed is 200-250r / min, and the stirring time is 15-20min; a precision filter is used for filtration with a filtration accuracy of 3-5μm; during secondary degassing, under nitrogen protection, the temperature is raised to 40-45℃, the rotation speed is 250-300r / min, and the stirring time is 10-15min.

[0060] Low-temperature maturation (-10~-15℃) + cooling rate (0.5-1℃ / min) benefits: Simulates actual low-temperature usage scenarios, promotes the full adsorption of modified pour point depressants in the composite low-temperature additives onto the surface of wax crystals, destroys the wax crystal growth structure, and enhances the pour point depressing effect of the formulation; slow cooling avoids rapid temperature drop that could cause rapid wax crystal aggregation, ensuring that the low-temperature components and wax crystals interact fully, and improving the pour point stability of the finished product.

[0061] Benefits of filtration accuracy of 3-5μm: It can accurately remove impurities such as graphene agglomerates and undispersed additive particles, avoid impurities clogging the pipeline or affecting low-temperature flowability, match the 50-100nm particle size requirement of graphene in the formula, and ensure its reinforcing effect.

[0062] Benefits of secondary degassing at 40-45℃: It removes air bubbles from materials at a gentle temperature, preventing them from freezing and expanding at low temperatures and damaging the lubrication system; at the same time, this temperature does not cause a sudden change in the viscosity of the base oil, ensuring degassing efficiency, and works synergistically with the function of the defoamer in the formula to further improve lubrication stability.

[0063] In summary, the technical effects and advantages of this invention are as follows:

[0064] 1. The present invention has a reasonable structure. Through innovative compounding design, it solves the technical pain points of limited antifreeze effect and poor synergy of existing low-temperature lubricating oils. It adopts ternary synthetic base oil, graphene modified mineral oil and ternary composite low-temperature additives to achieve a synergistic balance of ultra-low pour point, high compatibility, strong dispersibility and low cost.

[0065] 2. In this invention, the preparation method and the improved ingredients are highly compatible. Through innovative steps such as multi-step pretreatment, ultrasonic-mechanical synergistic mixing, and low-temperature curing post-treatment, the components are fully integrated and work synergistically to further improve the antifreeze effect. At the same time, the process is simple and can be mass-produced. Attached Figure Description

[0066] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0067] Figure 1 The figures show experimental data from embodiments and comparative examples of the present invention. Detailed Implementation

[0068] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] Example 1

[0070] A high-antifreeze liquid lubricating oil, with the following ingredient weight percentages:

[0071] 70wt% synthetic base oil (PAO-4: pentaerythritol ester: polyether polyol = 5:3:2), 10wt% modified mineral oil, 15wt% composite low-temperature additive (modified pour point depressant: novel viscosity index improver: low-temperature flow promoter = 4:3:3), 5wt% auxiliary functional additive (anti-wear agent: antioxidant: dispersant: defoamer = 3:2:2:1).

[0072] Its preparation method includes the following steps:

[0073] S1. Material preparation and pretreatment:

[0074] 1. Weigh each component according to the above proportions and set aside; wherein, the modified mineral oil is a deeply dewaxed mineral oil (pour point -35℃, wax content 0.4wt%) with 0.2wt% graphene powder (particle size 80nm), stirred at 65℃ for 35min, sonicated for 18min, cooled and filtered; the modified pour point depressant is prepared according to the aforementioned Mannich base modified PMA method;

[0075] 2. Synthetic base oil pretreatment: PAO-4, pentaerythritol ester, and polyether polyol are added to the pretreatment vessel. Nitrogen flow rate is 0.8 L / min. The temperature is raised to 45℃, the rotation speed is 350 r / min, and the mixture is stirred for 18 min. The mixture is then cooled to 28℃ for later use.

[0076] 3. Pretreatment with composite low-temperature additives: Add the modified pour point depressant, the new viscosity index improver, and the low-temperature flow promoter to the pretreatment tank, add 6% of the pretreatment synthetic base oil, heat to 40℃, rotate at 550 r / min, stir for 12 min, and sonicate for 6 min, then set aside.

[0077] 4. Pretreatment of auxiliary functional additives: Mix the anti-wear agent (organic molybdenum:ZDDP=1:2), antioxidant (hindered phenol:diphenylamine=3:2), and dispersant (borated succinimide), heat to 35℃, stir for 9 minutes, and set aside; defoamer (polyether modified silicone oil) is set aside separately.

[0078] S2. Base oil compound blend:

[0079] The pretreated synthetic base oil was added to the reactor, nitrogen flow rate was 0.5 L / min, modified mineral oil was slowly added, heating rate was 1.5℃ / min, the temperature was raised to 60℃, the rotation speed was 500 r / min, stirring was carried out for 30 min, and ultrasonic dispersion (350W) was carried out for 12 min to obtain the composite base oil.

[0080] S3. Additives are added stepwise and mixed synergistically:

[0081] 1. Add the pretreated composite low-temperature resistant additive, maintain 60℃, stir at 500 r / min for 35 min, and ultrasonically disperse (300W) for 10 min;

[0082] 2. Add pretreatment auxiliary additives, reduce the speed to 420 r / min, and stir for 22 min;

[0083] 3. Add defoamer, reduce the speed to 320 r / min, and stir for 6 minutes.

[0084] S4. Low-temperature synergistic post-processing:

[0085] 1. Stop heating, cool to -12℃ at 0.8℃ / min, stir for 18min at 220r / min;

[0086] 2. Increase the temperature to 28℃ at a rate of 1℃ / min, add 0.15wt% diatomaceous earth, stir for 6min, and then filter precisely (filtration accuracy 4μm) to obtain the initial product;

[0087] 3. Under nitrogen protection, heat to 42℃, rotate at 280 r / min, stir for 12 min, degas twice, and obtain the finished product.

[0088] S5. Inspection and Packaging:

[0089] Finished product testing indicators: pour point -52℃, kinematic viscosity at 100℃ (-45℃) 7.8mm² / s, good low-temperature fluidity, no stratification or sedimentation; anti-wear and anti-oxidation properties are superior to existing ordinary low-temperature lubricating oils; after passing the tests, it will be repackaged.

[0090] Example 2

[0091] A high-antifreeze liquid lubricating oil, with the following ingredient weight percentages:

[0092] Synthetic base oil 76wt% (PAO-4: pentaerythritol ester: polyether polyol = 5:3:2), modified mineral oil 7wt%, composite low-temperature additive 11wt% (modified pour point depressant: novel viscosity index improver: low-temperature flow promoter = 4:3:3), auxiliary functional additive 6wt% (anti-wear agent: antioxidant: dispersant: defoamer = 3:2:2:1).

[0093] The preparation method is basically the same as in Example 1, with only the following parameters adjusted:

[0094] 1. Synthetic base oil pretreatment: Nitrogen flow rate 0.6 L / min, temperature raised to 43℃, stirring for 17 min;

[0095] 2. Base oil compounding: Nitrogen flow rate 0.4L / min, temperature raised to 62℃, stirring for 32min, ultrasonic dispersion (380W) for 13min;

[0096] 3. Low-temperature maturation: Cool to -13℃ and stir for 17 minutes;

[0097] 4. Secondary degassing: Heat to 43℃ and stir for 13 minutes.

[0098] Finished product testing indicators: pour point -53℃, kinematic viscosity at 100℃ of -45℃ is 7.2mm² / s, exhibiting excellent low-temperature fluidity, optimal wear resistance and oxidation resistance, and controllable cost, making it the best example.

[0099] Example 3

[0100] A high-antifreeze liquid lubricating oil, with the following ingredient weight percentages:

[0101] Synthetic base oil 82wt% (PAO-4: pentaerythritol ester: polyether polyol = 5:3:2), modified mineral oil 5wt%, composite low-temperature additive 8wt% (modified pour point depressant: novel viscosity index improver: low-temperature flow promoter = 4:3:3), auxiliary functional additive 5wt% (anti-wear agent: antioxidant: dispersant: defoamer = 3:2:2:1).

[0102] The preparation method is basically the same as in Example 1, with only the following parameters adjusted:

[0103] 1. Synthetic base oil pretreatment: Nitrogen flow rate 0.7 L / min, temperature raised to 47℃, stirring for 19 min;

[0104] 2. Base oil compounding: Nitrogen flow rate 0.6L / min, temperature raised to 58℃, stirring for 28min, ultrasonic dispersion (320W) for 11min;

[0105] 3. Low-temperature maturation: Cool to -11℃ and stir for 16 minutes;

[0106] 4. Secondary degassing: Heat to 44℃ and stir for 14 minutes.

[0107] Finished product testing indicators: pour point -51℃, kinematic viscosity at 100℃ and -45℃ is 7.9mm² / s, good low-temperature fluidity, excellent antifreeze effect, cost is slightly higher than Example 2, but lower than existing high-end extreme cold-specific lubricants.

[0108] The finished lubricating oils from Examples 1, 2, and 3 were compared with two existing mainstream low-temperature lubricating oils (Comparative Sample 1: ordinary synthetic low-temperature lubricating oil, pour point -38℃; Comparative Sample 2: high-end extreme cold-resistant special lubricating oil, pour point -48℃). The test indicators included pour point, viscosity at -45℃, low-temperature fluidity, anti-wear performance, oxidation resistance, and production cost. The results are as follows: Figure 1 As shown;

[0109] Depend on Figure 1 It can be seen that the pour point index of Examples 1-3 is ≤-51℃, and the best Example 2 reaches -53℃, which is significantly better than Comparative Sample 1 (-38℃) and Comparative Sample 2 (-48℃). This data proves that PAO-4, pentaerythritol ester, and polyether polyol are compounded in a ratio of 5:3:2 to form an ultra-low pour point base oil system. When combined with a composite low-temperature additive in a ratio of 4:3:3, the modified pour point depressant can effectively inhibit wax crystal growth, and the low-temperature flow promoter can reduce flow resistance, ultimately achieving a better antifreeze effect than high-end extreme cold lubricating oil.

[0110] -45℃ Kinematic viscosity: The viscosity of Examples 1-3 is 7.2-7.9 mm² / s, which is much lower than that of Comparative Sample 1 (12.5 mm² / s) and Comparative Sample 2 (8.5 mm² / s). The low viscosity means that the lubricating oil can be pumped smoothly and has good fluidity at extreme low temperatures. It will not cause equipment start-up failure due to a sudden increase in viscosity. This data is due to the effect of the new viscosity index improver PMA-Si, which has a number average molecular weight of 50,000-80,000 and can adjust the viscosity-temperature performance, so that the viscosity of the lubricating oil changes slowly in a wide temperature range of -45℃ to 100℃.

[0111] Low-temperature fluidity: No stratification or precipitation was observed in any of the examples, and Example 2 showed "excellent" performance. This result verifies the high compatibility design of the formulation, the hydrogen bonding system of the synthetic base oil, the graphene dispersion process of the modified mineral oil, and the additive pretreatment steps, which ensure that the components are stably integrated at low temperatures without the risk of agglomeration or stratification, thus solving the problem of poor low-temperature compatibility of existing lubricating oils.

[0112] Wear scar diameter: The wear scar diameter of Examples 1-3 was 0.32-0.34 mm, which is better than that of Comparative Sample 1 (0.45 mm) and Comparative Sample 2 (0.35 mm). This data reflects the dual advantages of "chemical anti-wear + physical reinforcement": the anti-wear agent, which is a 1:2 compound of organic molybdenum and dialkyl dithiophosphate zinc, can form a protective film on the metal surface; the 50-100 nm graphene oxide in the modified mineral oil can strengthen the oil film strength and reduce friction and wear.

[0113] Antioxidant time at 120℃: The antioxidant time of Examples 1-3 reached 630-650h, far exceeding that of Comparative Sample 1 (480h) and slightly better than that of Comparative Sample 2 (620h). This result is attributed to the synergistic effect of hindered phenolic and amine antioxidants in a 3:2 ratio with the antioxidant properties of pentaerythritol ester in synthetic base oil, which inhibits high-temperature oxidative degradation of lubricating oil, extends service life, and reduces equipment maintenance costs.

[0114] The production cost of Examples 1-3 is 17-19 yuan / kg, which is only about 60% of that of Comparative Sample 2 (high-end extreme cold lubricating oil), and the performance is better; compared with Comparative Sample 1 (ordinary synthetic oil), although the cost is slightly higher, the antifreeze performance has achieved a qualitative leap.

[0115] The high-freeze-resistant liquid lubricant of this invention outperforms existing ordinary synthetic low-temperature lubricants and high-end extreme cold-specific lubricants in key antifreeze indicators such as pour point, low-temperature viscosity, and low-temperature fluidity; its anti-wear and anti-oxidation properties are also superior to existing products; its production cost is only 60% of that of high-end extreme cold-specific lubricants, and although it is slightly higher than that of ordinary synthetic low-temperature lubricants, its antifreeze effect and overall performance are significantly improved, making it extremely cost-effective and highly competitive in the market.

[0116] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A highly antifreeze liquid lubricating oil, characterized in that, It consists of the following ingredients by weight percentage: Synthetic base oil 70-82wt%, modified mineral oil 5-10wt%, composite low-temperature additives 8-15wt%, auxiliary functional additives 3-7wt%; The synthetic base oil is composed of polyalphaolefin (PAO-4), pentaerythritol ester, and polyether polyol in a weight ratio of 5:3:

2. The modified mineral oil is a graphene-modified, deeply dewaxed mineral oil. The modification method is as follows: the deeply dewaxed mineral oil is heated to 60-70℃, 0.1-0.3wt% of graphene powder is added, the mixture is stirred and dispersed for 30-40 minutes, ultrasonically treated for 15-20 minutes, cooled to room temperature, and then filtered to obtain the modified mineral oil. The composite low-temperature additive is composed of a modified pour point depressant, a novel viscosity index improver, and a low-temperature flow promoter in a weight ratio of 4:3:

3. The auxiliary functional additive is composed of anti-wear agent, antioxidant, dispersant and defoamer in a weight ratio of 3:2:2:

1.

2. The high antifreeze liquid lubricating oil and its preparation method according to claim 1, characterized in that: The synthetic base oil contains: polyalphaolefin (PAO-4) with a kinematic viscosity of 4.0-4.5 mm² / s at 40℃, a pour point ≤-60℃, and a purity ≥99%; pentaerythritol ester with a kinematic viscosity of 6.0-7.0 mm² / s at 40℃, a pour point ≤-55℃, and an acid value ≤0.1 mgKOH / g; and polyether polyol with a kinematic viscosity of 5.0-5.5 mm² / s at 40℃ and a pour point ≤-50℃.

3. The high antifreeze liquid lubricating oil and its preparation method according to claim 1, characterized in that: The deep dewaxed mineral oil is made from paraffin-based crude oil through a three-stage dewaxing process: the first stage crystallization temperature is -10℃, the second stage is -25℃, and the third stage is -35℃. After dewaxing, the wax content is ≤0.5wt% and the pour point is ≤-35℃. The graphene powder is graphene oxide with a particle size of 50-100 nm.

4. The high antifreeze liquid lubricating oil and its preparation method according to claim 1, characterized in that: In the composite low-temperature additive, the modified pour point depressant is made from polymethyl methacrylate (PMA) as the base material and modified with Mannich base; The novel viscosity index improver is a polymethyl methacrylate-siloxane copolymer (PMA-Si). The low-temperature flow promoter is a compound of isodecylbenzenesulfonate and polyethylene glycol monomethyl ether in a weight ratio of 2:

1.

5. The high antifreeze liquid lubricating oil and its preparation method according to claim 1, characterized in that: In the auxiliary functional additive, the anti-wear agent is a compound of organic molybdenum and zinc dialkyl dithiophosphate in a weight ratio of 1:2; The antioxidant is a compound of hindered phenolic antioxidants and amine antioxidants in a weight ratio of 3:2; The dispersant is boronized succinimide; The defoamer is polyether-modified silicone oil.

6. The method for preparing a high-antifreeze liquid lubricating oil as described in claim 1, characterized in that: S1. Preparation and pretreatment: Weigh each component according to the ratio, and pretreat the synthetic base oil, composite low-temperature additive, and auxiliary functional additive to obtain pretreated synthetic base oil, pretreated composite low-temperature additive, and pretreated auxiliary functional additive. S2. Base oil compounding: Pretreated synthetic base oil is added to a reaction vessel, modified mineral oil is slowly added under nitrogen protection, the temperature is raised to 55-65℃, stirred and ultrasonically dispersed to obtain compound base oil; S3. Adding and synergistic mixing of additives in stages: Add pretreatment composite low-temperature resistant additive, pretreatment auxiliary functional additive and defoamer to the composite base oil in sequence, keep the temperature at 55-65℃, stir in stages to achieve full mixing; S4. Low-temperature co-processing: Cool the material to -10 to -15℃ for low-temperature maturation, then heat it to 25-30℃, filter to remove impurities, and degas it a second time to obtain the finished product. S5. Testing and Packaging: Conduct performance testing on the finished products, and repackage them after they pass the test.

7. The high antifreeze liquid lubricating oil and its preparation method according to claim 6, characterized in that: Synthetic base oil pretreatment: PAO-4, pentaerythritol ester, and polyether polyol are added to the pretreatment vessel. Nitrogen flow rate is 0.5-1.0 L / min. The temperature is raised to 40-50℃, the rotation speed is 300-400 r / min, and the mixture is stirred for 15-20 min. The mixture is then cooled to 25-30℃. Pretreatment of composite low-temperature additive: Add each component of the composite low-temperature additive to the pretreatment kettle, add 5-8% of the total weight of the pretreatment synthetic base oil, heat to 35-45℃, rotate at 500-600 r / min, stir for 10-15 min, and ultrasonically treat for 5-8 min. Pretreatment of auxiliary functional additives: Mix anti-wear agent, antioxidant and dispersant, heat to 30-40℃ and stir for 8-10 minutes.

8. The high antifreeze liquid lubricating oil and its preparation method according to claim 6, characterized in that: In step S2: nitrogen flow rate is 0.3-0.8 L / min, heating rate is 1-2℃ / min, rotation speed is 450-550 r / min, stirring is 25-35 min, ultrasonic dispersion power is 300-400 W, and ultrasonic time is 10-15 min.

9. The preparation method according to claim 6, characterized in that: In step S4: During low-temperature curing, the cooling rate is 0.5-1℃ / min, the rotation speed is 200-250r / min, and the stirring time is 15-20min; a precision filter is used for filtration with a filtration accuracy of 3-5μm; during secondary degassing, under nitrogen protection, the temperature is raised to 40-45℃, the rotation speed is 250-300r / min, and the stirring time is 10-15min.

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