Flame-retardant and wear-resistant hydraulic oil and preparation method thereof

Abstract

The present invention relates to a flame-retardant and wear-resistant hydraulic oil and a preparation method thereof, and to the technical field of lubricating materials, wherein the flame-retardant and wear-resistant hydraulic oil comprises, according to the weight percentage of the composition: 1.6-2.4% of a modified molybdenum amine complex, 2.0-4.0% of a high-temperature antioxidant, 0.5-1.0% of a low-temperature antioxidant, 0.002-0.005% of a defoaming agent, and the balance is a synthetic ester base oil, and the modified molybdenum amine complex is a reactant of graphene oxide, isocyanate and molybdenum amine complex, and the isocyanate includes diisocyanate and / or polyisocyanate; and the preparation method thereof comprises an initial mixing step and a final mixing step. The hydraulic oil protected by the present application does not contain elements such as sulfur, phosphorus, and chlorine, so that the friction pair is not prone to rust; and the hydraulic oil is ash-free and is suitable for mechanical equipment with high cleanliness; compared with the hydraulic oil mixed with the molybdenum amine complex and graphene oxide, the wear resistance of the hydraulic oil can be maintained more durable under high temperature conditions.

Description

Technical Field

[0001] The invention relates to the technical field of lubricating materials, in particular to a flame-retardant and wear-resistant hydraulic oil and a preparation method thereof. Background Art

[0002] Hydraulic oil is the hydraulic medium used in hydraulic systems. It plays the role of energy transmission, anti-wear, system lubrication, corrosion prevention, rust prevention, cooling, etc. In order to improve the anti-friction and wear resistance of hydraulic oil, molybdenum-containing additives are common additives in hydraulic oil, which have good anti-oxidation, anti-wear and friction reduction properties.

[0003] The first generation of molybdenum additives is molybdenum sulfide, which has excellent anti-friction and anti-wear properties because of its layered structure similar to that of graphite and weak van der Waals forces between its layers. However, since molybdenum disulfide is insoluble in base oil, it can only be used in the field of solid lubrication, which greatly limits its application.

[0004] The second generation of molybdenum additives are molybdenum dialkyl dithiophosphate (MoDDP) and molybdenum dialkyl dithiocarbamate (MoDTC). These two additives generate reaction films of molybdenum disulfide (MoS2), molybdenum dioxide (MoO2), ferrous sulfide (FeS) and deposition films of iron phosphate (FePO4) and ferrous molybdenum oxide (FeMo2O4) under high temperature and extreme pressure conditions, which make these two organic molybdenums have excellent anti-friction and anti-wear properties, and can reduce friction coefficient and wear. However, since this additive contains sulfur, it is corrosive to hydraulic equipment, which ultimately limits the scope of use of this additive.

[0005] The third generation of molybdenum lubricants are non-sulfur and non-phosphorus organic molybdenum, and its typical representative products are molybdenum amine complexes and organic molybdenum acid esters. Since this additive does not contain phosphorus and sulfur elements, its anti-wear and wear-reducing mechanism is to generate molybdenum trioxide (MoO3) and molybdenum-iron alloy under extreme pressure conditions to fill the grooves on the friction surface, thereby playing an anti-wear and wear-reducing role; at the same time, since it does not contain sulfur elements, this additive is not easy to cause corrosion to hydraulic equipment when used.

[0006] However, non-sulfur-phosphorus organic molybdenum also has many problems.

[0007] 1. The solubility of non-sulfur-phosphorus organic molybdenum is poor. After adding it into the hydraulic oil, the viscosity of the hydraulic oil is high, it is difficult to form a lubricating film on the surface of the friction pair, and the friction reduction effect is not obvious.

[0008] 2. The melting point of molybdenum-iron alloy is low. After filling the grooves on the surface of the friction pair under high temperature conditions, continued friction will cause the molybdenum-iron alloy on the surface of the friction pair to move again, which will lead to the inability to maintain the anti-wear performance for a long time under high temperature conditions.

[0009] 3. Since it does not contain sulfur and phosphorus elements, it is more difficult to form an "anti-friction film" under extreme pressure conditions, making its anti-wear effect inferior to that of organic molybdenum additives containing sulfur and phosphorus. The diameter of the long wear spot is large and does not meet the national standard.

[0010] 4. In order to improve the anti-wear effect of non-sulfur-phosphorus organic molybdenum, T203 anti-wear additive (zinc dialkyl dithiosulfate) is usually added to the hydraulic oil. Although this can improve the anti-wear effect, T203 anti-wear additive is an ash-containing additive and cannot be used on mechanical equipment with high cleanliness requirements; and the addition of zinc dialkyl dithiosulfate also introduces sulfur, which will still cause corrosion to the equipment.

[0011] Therefore, there is an urgent need for an additive that can have good anti-wear effect under extreme pressure conditions and reduce the corrosion effect on equipment. Summary of the invention

[0012] In order to exert good anti-wear effect under extreme pressure conditions and reduce the probability of equipment being affected by corrosion, the present invention provides a flame retardant and anti-wear hydraulic oil and a preparation method thereof.

[0013] In the first aspect, the present invention provides a flame retardant and anti-wear hydraulic oil, which adopts the following technical solution:

[0014] A flame retardant and anti-wear hydraulic oil comprises, by weight percentage, 1.6-2.4% of a modified molybdenum amine complex, 2.0-4.0% of a high-temperature antioxidant, 0.5-1.0% of a low-temperature antioxidant, 0.002-0.005% of a defoaming agent, and the remainder is a synthetic ester base oil. The modified molybdenum amine complex is a reactant of graphene oxide, isocyanate and the molybdenum amine complex, and the isocyanate comprises diisocyanate and / or polyisocyanate.

[0015] By adopting the above technical solution, the hydraulic oil does not contain sulfur, phosphorus, chlorine and other elements, making it difficult for the friction pair to rust; and the hydraulic oil is ash-free and suitable for mechanical equipment with high cleanliness. Synthetic ester base oil and various additives in the hydraulic oil are flame-retardant substances, which makes the hydraulic oil have a high flash point, is not easy to catch fire, and has high safety.

[0016] The modified molybdenum amine complex, one of the -NCO groups of the diisocyanate and / or polyisocyanate is connected to the graphene oxide, and the other -NCO groups are connected to the molybdenum amine complex, so that the molybdenum amine complex is loaded on the graphene oxide.

[0017] Under extreme pressure conditions, the modified molybdenum amine complex can adhere to the surface of the friction pair to form a lubricating film; since graphene oxide has a layered structure, it can have a good anti-wear effect compared to hydraulic oil that only adds pure molybdenum amine complex.

[0018] As the friction progresses, the temperature of the friction pair surface gradually increases, and the molybdenum complex forms molybdenum trioxide (MoO3) and molybdenum-iron alloy under physical and chemical reactions, which fully fills the grooves on the friction pair surface to reduce the friction coefficient of the friction pair, thereby achieving the effect of reducing wear.

[0019] Since the molybdenum-amine complex is loaded on graphene oxide, the lubricating film layer in the grooves of the friction pair is a circulating layer structure of graphene oxide-molybdenum-iron alloy-graphene oxide, so that the molybdenum-iron alloy that has been formed and filled in the grooves can dissipate heat quickly, reducing the probability of the molybdenum-iron alloy melting again. Compared with the hydraulic oil mixed with molybdenum-amine complex and graphene oxide, the wear resistance of the hydraulic oil can be maintained longer under high temperature conditions.

[0020] Optionally, the isocyanate further comprises monoisocyanate.

[0021] By adopting the above technical solution, when monoisocyanate is loaded on graphene oxide, the R group (non-polar group) on the monoisocyanate can be combined with the synthetic ester base oil to further improve the solubility of the modified molybdenum amine complex in the hydraulic oil.

[0022] Optionally, the invention also includes 1.6-4.0% nitrogen-containing boronized fat.

[0023] By adopting the above technical solution, the addition of nitrogen-containing boronized grease makes it easier to form a lubricating film on the friction pair surface; and under extreme pressure and high temperature conditions, the nitrogen-containing boronized grease can precipitate a cubic boron nitride structure, which can react with the graphene oxide attached to the surface of the friction pair, and when the temperature of the friction pair has not risen to the point where the molybdenum-iron complex fully exerts its effect, it can compensate for the anti-wear and friction-reducing effect of the friction pair. As the friction progresses, the temperature of the friction pair surface gradually increases, and the boron nitride structure can adhere to the surface of molybdenum trioxide (MoO3) and molybdenum-iron alloy, further improving the anti-wear and friction-reducing effect.

[0024] Optionally, the composition further comprises 0.3-0.4% dialkyl zinc dithiosulfate and 0.1-0.3% benzotriazole.

[0025] By adopting the above technical scheme, in some hydraulic equipment with low requirements for cleanliness, dialkyl zinc dithiosulfate can be added to the hydraulic oil for auxiliary friction reduction and anti-wear. Under extreme pressure conditions, the modified molybdenum amine complex can still form a deposited film of molybdenum disulfide (MoS2) with the sulfur element in dialkyl zinc dithiosulfate. The composite effect of molybdenum disulfide (MoS2), graphene oxide and boron carbide further improves the anti-wear and friction reduction effect of the hydraulic oil.

[0026] In a second aspect, the present invention provides a method for preparing a flame retardant and anti-wear hydraulic oil, which adopts the following technical solution:

[0027] A method for preparing a flame-retardant and wear-resistant hydraulic oil comprises the following steps:

[0028] Initial mixing: according to the proportion of each substance in the first aspect, the high-temperature antioxidant, the low-temperature antioxidant, and the synthetic ester base oil are mixed, heated to 60-80° C., and then stirred until the high-temperature antioxidant and the low-temperature antioxidant are evenly dispersed in the synthetic ester base oil;

[0029] Final mixing: according to the proportion of each substance in the first aspect, the modified molybdenum amine complex and the defoaming agent are added to the product obtained by the initial mixing, and the temperature is maintained and stirring is continued until the modified molybdenum amine complex is completely dissolved in the synthetic ester base oil to obtain a flame retardant and anti-wear hydraulic oil.

[0030] By adopting the above technical solution, when preparing hydraulic oil, the high-temperature antioxidant and the low-temperature antioxidant are first evenly mixed in the synthetic ester base oil, and then the modified molybdenum amine complex and the defoaming agent are added to the synthetic ester base oil, thereby reducing the probability of the modified molybdenum oxide being oxidized prematurely.

[0031] Optionally, in the initial mixing step, the nitrogen-containing boronized fat is added to the synthetic ester base oil according to the proportion of the nitrogen-containing boronized fat described in the first aspect.

[0032] Optionally, in the initial mixing step, benzotriazole is also added to the synthetic ester base oil according to the proportion of benzotriazole described in the first aspect;

[0033] In the final mixing step, zinc dialkyl dithiosulfate is added to the product obtained in the initial mixing according to the ratio of zinc dialkyl dithiosulfate described in the first aspect.

[0034] Optionally, the preparation method of the modified molybdenum amine complex is as follows:

[0035] Modifying graphene oxide: putting graphene oxide into anhydrous dimethyl amide, using ultrasound to disperse the graphene oxide for 30 to 40 minutes, then adding an excess of isocyanate as described in the first aspect, stirring and reacting at 50 to 60° C. for 18 to 24 hours, and filtering to obtain alkyl-modified graphene oxide;

[0036] Grafting molybdenum amine complex: put alkyl-modified graphene oxide and anhydrous methanol into anhydrous dimethylamide, stir until mixed evenly, then put the molybdenum amine complex into anhydrous dimethylamide, stir and react at room temperature for 4 to 5 hours, and filter to obtain a modified molybdenum amine complex; the mass ratio of the alkyl-modified graphene oxide to the molybdenum amine complex is 1.2 to 1.5:1.

[0037] By adopting the above technical solution, the graphene oxide is first dispersed uniformly, which can be beneficial to the subsequent reaction. When using an excess of isocyanate, the graphene oxide can be fully reacted to obtain an alkyl-modified graphene oxide product. The unreacted isocyanate is filtered out by filtering to obtain an alkyl-modified graphene oxide. Since the isocyanate includes diisocyanate and polyisocyanate, the other -NCO groups on the alkyl-modified graphene oxide can react with the amine or secondary amine on the molybdenum amine complex, and then the molybdenum amine complex is grafted onto the alkyl-modified graphene oxide. In this way, the connection between the graphene oxide and the molybdenum amine complex is more stable. Under extreme pressure and high temperature conditions, the modified molybdenum amine complex appears in the grooves of the friction pair with a uniform layer structure. Under high temperature conditions, the urea group breaks, releases the molybdenum complex and forms molybdenum trioxide and molybdenum iron alloy. The graphene oxide layer and the molybdenum iron alloy layer are evenly distributed, which facilitates the heat conduction of the molybdenum iron alloy and reduces the probability of the molybdenum iron alloy melting again, so that the wear resistance of the hydraulic oil can be maintained more durable under high temperature conditions.

[0038] Optionally, the isocyanate is a mixture of monoisocyanate and non-monoisocyanate, wherein the ratio of non-monoisocyanate to monoisocyanate is 2 to 3:1.

[0039] By adopting the above technical solution, monoisocyanate provides alkyl groups for graphene oxide, thereby enhancing the solubility of graphene oxide in synthetic ester base oil and reducing the viscosity and polymerization of hydraulic oil; non-monoisocyanate (diisocyanate and polyisocyanate) is used to connect graphene oxide and molybdenum amine complex. When the ratio of non-monoisocyanate to monoisocyanate is 2 to 3:1, more molybdenum amine complex can be loaded while maintaining the solubility of graphene oxide, thereby improving the wear resistance of hydraulic oil.

[0040] Optionally, in the step of modifying graphene oxide, the filtered alkyl-modified graphene oxide is washed with dichloromethane.

[0041] By adopting the above technical scheme and washing the alkyl-modified graphene oxide with dichloromethane, the isocyanate adhering to the alkyl-modified graphene oxide can be removed, so that the molybdenum amine complex can be better linked to the -NCO group of the alkyl-modified graphene oxide, thereby improving the uniformity of the dispersion of the molybdenum amine complex and graphene oxide in the hydraulic oil.

[0042] In summary, the present invention includes at least one of the following beneficial technical effects:

[0043] 1. By using modified molybdenum amine complexes, the hydraulic oil does not contain sulfur, phosphorus, chlorine and other elements, making it difficult for the friction pair to rust; and the hydraulic oil is ash-free and suitable for mechanical equipment with high cleanliness. And because the molybdenum amine complex is loaded on graphene oxide, the lubricating film layer in the grooves of the friction pair is a circulation layer structure of graphene oxide-molybdenum iron alloy-graphene oxide, so that the molybdenum iron alloy that has been formed in the grooves can quickly dissipate heat, reducing the probability of the molybdenum iron alloy melting again. Compared with the hydraulic oil mixed with molybdenum amine complex and graphene oxide, the wear resistance of the hydraulic oil can be maintained longer under high temperature conditions.

[0044] 2. By using isocyanate to link graphene oxide and molybdenum amine complex, graphene oxide can be fully dissolved in synthetic ester base oil, and the combination of graphene oxide and molybdenum amine complex can be more stably and dispersed more evenly. Under extreme pressure and high temperature conditions, it is easier to form a circulation layer structure of graphene oxide-molybdenum iron alloy-graphene oxide in the friction pair grooves, which improves the heat dissipation efficiency of molybdenum iron alloy and reduces the probability of molybdenum iron alloy melting again. Under high temperature conditions, the wear resistance of hydraulic oil can be maintained for a longer time.

[0045] 3. By using an excess of isocyanate when modifying graphene oxide, more -NCO groups can be linked to graphene oxide, making it easier to link the molybdenum amine complex to graphene oxide. Excess isocyanate can be reused without causing waste.

[0046] 4. By washing the filtered alkyl-modified graphene oxide with dichloromethane in the step of modifying graphene oxide, the isocyanate adhering to the alkyl-modified graphene oxide can be removed, so that the molybdenum amine complex can be better linked to the -NCO group of the alkyl-modified graphene oxide instead of the free -NCO group, thereby improving the uniformity of the dispersion of the molybdenum amine complex and graphene oxide in the hydraulic oil, thereby also improving the utilization rate of the molybdenum amine complex. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below with reference to the embodiments.

[0048] In the following embodiments, the configuration of the hydraulic oil is configured according to the standard of HM46, so as to facilitate the comparison of various data indicators. The materials used in the following embodiments can all be obtained through commercial purchase.

[0049] Example 1: This example discloses a flame retardant and wear-resistant hydraulic oil and a preparation method thereof.

[0050] A flame-retardant and wear-resistant hydraulic oil comprises, by weight percentage, 2.0% of a modified molybdenum amine complex, 3.0% of a high-temperature antioxidant, 0.8% of a low-temperature antioxidant, 0.003% of a defoaming agent, and the remainder being a synthetic ester base oil.

[0051] In the embodiment of the present application, butyl diphenylamine is selected as the high temperature antioxidant, and in other embodiments, octyl diphenylamine can also be selected as the high temperature antioxidant; 2,6-di-tert-butyl-p-cresol is selected as the low temperature antioxidant, and methyl silicone oil is selected as the defoaming agent. Pentaerythritol oleate is selected as the synthetic ester base oil, and in other embodiments, trimethylolpropane oleate, fatty acid monoester, fatty acid diester, fatty acid polyol ester, animal and vegetable oil modified ester or other polyacid monoester is selected as the synthetic ester base oil.

[0052] The preparation method is as follows:

[0053] Modification of graphene oxide: Put graphene oxide into anhydrous dimethyl amide, the mass ratio of graphene oxide to anhydrous dimethyl amide is 1:80; use ultrasound (50W) to disperse graphene oxide for 30 to 40 minutes. Then add excess isocyanate, which includes monoisocyanate and diisocyanate. Then stir the reaction at 50 to 60°C for 18 to 24 hours, filter to obtain a solid product (the isocyanate in the filtrate can be reused in the next step of modifying graphene oxide); use dichloromethane to wash the filtered solid product to obtain alkyl-modified graphene oxide.

[0054] In the embodiments of the present application, the monoisocyanate is dodecyl isocyanate, the diisocyanate is diphenylmethane-4,4'-diisocyanate (MDI), and the mass ratio of diphenylmethane-4,4'-diisocyanate to dodecyl isocyanate is 2.5:1.

[0055] Grafting molybdenum amine complex: put alkyl-modified graphene oxide and anhydrous methanol into anhydrous dimethylamide and stir until mixed evenly. The mass ratio of alkyl-modified graphene oxide, anhydrous methanol and anhydrous dimethylamide is 1:25:75. Then put the molybdenum amine complex into anhydrous dimethylamide, stir and react at room temperature for 4 to 5 hours, and filter to obtain a modified molybdenum amine complex. The mass ratio of alkyl-modified graphene oxide to the molybdenum amine complex is 1.3:1. The molybdenum amine complex uses MO-LYVAN855.

[0056] Initial mixing: According to the proportion of each substance in the flame retardant and anti-wear hydraulic oil of this embodiment, the high-temperature antioxidant, the low-temperature antioxidant and the synthetic ester base oil are mixed, heated to 60-80° C., and then stirred until the high-temperature antioxidant and the low-temperature antioxidant are evenly dispersed in the synthetic ester base oil.

[0057] Final mixing: according to the proportion of each substance in the flame retardant and anti-wear hydraulic oil of this embodiment, the modified molybdenum amine complex and the defoaming agent are added to the product obtained by the initial mixing, and the temperature is maintained and stirring is continued until the modified molybdenum amine complex is completely dissolved in the synthetic ester base oil to obtain the flame retardant and anti-wear hydraulic oil.

[0058] Example 2: This example discloses a flame retardant and wear-resistant hydraulic oil and a preparation method thereof.

[0059] A flame-retardant and anti-wear hydraulic oil, the weight percentage of which includes: 2.0% of modified molybdenum amine complex, 3.0% of high-temperature antioxidant, 0.8% of low-temperature antioxidant, 0.003% of defoamer, 3.0% of nitrogen-containing boronized fat, and the balance is synthetic ester base oil. Except that the nitrogen-containing boronized fat is boronized fatty amine ester, the selection of the above other substances is exactly the same as that of Example 1.

[0060] The preparation method is exactly the same as that of Example 1, except that in the initial mixing step, the nitrogen-containing boronized fat is added to the synthetic ester base oil according to the above-mentioned ratio of the nitrogen-containing boronized fat.

[0061] Example 3: This example discloses a flame retardant and wear-resistant hydraulic oil and a preparation method thereof.

[0062] A flame-retardant and anti-wear hydraulic oil, the composition of which includes by weight: 2.0% of a modified molybdenum amine complex, 3.0% of a high-temperature antioxidant, 0.8% of a low-temperature antioxidant, 0.003% of a defoamer, 0.3-0.4% of dialkyl zinc dithiosulfate, 0.1-0.3% of benzotriazole, and the balance is a synthetic ester base oil. Except for the dialkyl zinc dithiosulfate, the selection of the other substances is exactly the same as in Example 1.

[0063] The preparation method is exactly the same as Example 1 except that in the initial mixing step, benzotriazole is added to the synthetic ester base oil according to the above-mentioned proportion of benzotriazole; in the final mixing step, dialkyl zinc dithiosulfate is added to the product obtained by the initial mixing according to the above-mentioned proportion of dialkyl zinc dithiosulfate.

[0064] Example 4: A flame-retardant and anti-wear hydraulic oil, the weight percentage of which includes: 2.0% modified molybdenum amine complex, 3.0% high-temperature antioxidant, 0.8% low-temperature antioxidant, 0.003% defoamer, 3.0% nitrogen-containing boronized fat, 0.3-0.4% dialkyl zinc dithiosulfate, 0.1-0.3% benzotriazole, and the balance is synthetic ester base oil. Except that the nitrogen-containing boronized fat is boronized fatty amine ester, the selection of the other substances is exactly the same as that of Example 3.

[0065] The preparation method is exactly the same as Example 3 except that in the initial mixing step, benzotriazole is added to the synthetic ester base oil according to the above-mentioned proportion of benzotriazole; in the final mixing step, dialkyl zinc dithiosulfate is added to the product obtained by the initial mixing according to the above-mentioned proportion of dialkyl zinc dithiosulfate.

[0066] Example 5: In this example, the weight percentage of the flame retardant and anti-wear hydraulic oil is exactly the same as that in Example 1. The preparation method is exactly the same as that in Example 1, except that in the step of modifying graphene oxide, dichloromethane is not used to wash the filtered alkyl-modified graphene oxide.

[0067] Example 6: In this example, the weight percentage of the flame retardant and anti-wear hydraulic oil is exactly the same as that in Example 1. The preparation method is exactly the same as that in Example 1 except that in the step of modifying graphene oxide, all the isocyanates used are diphenylmethane-4,4'-diisocyanate.

[0068] Comparative Example 1: This comparative example provides a flame-retardant and anti-wear hydraulic oil, the weight percentage of which includes: 2.0% molybdenum amine complex, 3.0% high-temperature antioxidant, 0.8% low-temperature antioxidant, 0.003% defoaming agent; the balance is synthetic ester base oil. The selection of the above other substances is exactly the same as in Example 1.

[0069] Comparative Example 2: This comparative example provides a flame retardant and anti-wear hydraulic oil, the weight percentage of which includes: 1.0% molybdenum amine complex, 1.3% dodecyl modified graphene oxide, 3.0% high temperature antioxidant, 0.8% low temperature antioxidant, 0.003% defoaming agent, and the balance is synthetic ester base oil. The selection of the above other substances is exactly the same as that of Example 1.

[0070] Comparative Example 3: This comparative example provides a flame-retardant and anti-wear hydraulic oil, the weight percentage of which includes: 1.6-4.0% nitrogen-containing boronized fat, 3.0% high-temperature antioxidant, 0.8% low-temperature antioxidant, 0.003% defoamer, 0.3-0.4% dialkyl zinc dithiosulfate, 0.1-0.3% benzotriazole, and the balance is synthetic ester base oil. The selection of the above other substances is exactly the same as that of Example 3.

[0071]

[0072] It can be seen from the data of Example 1 that the hydraulic oil using the modified molybdenum amine complex additive has the appearance of a uniform transparent fluid, and its color is brown-red. When the hydraulic oil is oxidized or contaminated, the color changes significantly, which is convenient for users to promptly discover the quality changes of the hydraulic oil, and thus facilitates maintenance by users.

[0073] By comparing Example 1 with Comparative Example 1, it can be seen that the kinematic viscosity of the hydraulic oil in Example 1 is 46.1 mm at 40°C. 2 / s, in line with national standards, the kinematic viscosity of the hydraulic oil in Example 1 is 51.5mm at 40°C 2 / s, the kinematic viscosity of the hydraulic oil in Example 1 is much lower than that in Comparative Example 1. It can be seen that adding a modified molybdenum amine complex to the base oil is more advantageous than adding a molybdenum amine complex. By comparing Example 1 with Comparative Example 2, it can be seen that only after the molybdenum amine complex is modified, its dissolution in the base oil will be more sufficient. Simply mixing the molybdenum amine complex with the alkyl-modified graphene by physical means cannot significantly reduce the kinematic viscosity of the hydraulic oil. By comparing Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3, it can be seen that the molybdenum amine complex is one of the most important factors that increase the viscosity of the hydraulic oil. By adding a modified molybdenum amine complex, the viscosity of the hydraulic oil will still increase, but it is within an acceptable range.

[0074] By comparing Example 1 with Comparative Example 1, it can be seen that the maximum no-seizure load of the hydraulic oil in Example 1 can reach 725N, the wear spot diameter is 0.45mm, and the wear reduction effect is obvious, while the maximum no-seizure load of the hydraulic oil in Comparative Example 1 is 685N, the wear spot diameter is 0.58mm, the maximum no-seizure load of the hydraulic oil in Example 1 is significantly higher than that in Comparative Example 1, and the wear spot diameter of the hydraulic oil in Example 1 is significantly lower than that in Comparative Example 1. It can be seen that compared with adding molybdenum amine complex to hydraulic oil, adding modified molybdenum amine complex to hydraulic oil has more obvious anti-wear and wear reduction effect, and the modified molybdenum amine complex overcomes the defect of poor wear reduction effect of non-sulfur-phosphorus organic molybdenum.

[0075] By comparing Example 1 with Example 2, it can be seen that adding nitrogen-containing boronized grease to the hydraulic oil in Example 1 can further enhance the anti-wear and friction-reducing ability of the hydraulic oil without almost affecting the kinematic viscosity of the hydraulic oil; and by comparing Example 1 with Example 3, it can be seen that adding dialkyl zinc dithiosulfate to the hydraulic oil in Example 1 can further enhance the anti-wear and friction-reducing ability of the hydraulic oil without almost affecting the kinematic viscosity of the hydraulic oil; however, after adding dialkyl zinc dithiosulfate to the hydraulic oil, the corrosion resistance of the hydraulic oil will be significantly reduced, and the hydraulic oil is no longer ash-free, and the use conditions of the hydraulic oil will be subject to certain restrictions.

[0076] By comparing Example 3 with Example 4, it can be seen that the nitrogen-containing boronized fat and dialkyl zinc dithiosulfate can work synergistically. Adding nitrogen-containing boronized fat and dialkyl zinc dithiosulfate to the hydraulic oil in Example 1 can greatly improve the anti-wear and friction-reducing ability of the hydraulic oil. By comparing Example 4, Comparative Example 1 with Comparative Example 3, it can be seen that the modified molybdenum amine complex is the main substance that greatly improves the anti-wear and friction-reducing ability of the hydraulic oil. The nitrogen-containing boronized fat and dialkyl zinc dithiosulfate mainly play a synergistic role in the anti-wear and friction-reducing ability of the hydraulic oil, rather than a decisive role.

[0077] By comparing Example 1 with Example 5, it can be seen that in Example 5, in the step of modifying graphene oxide, dichloromethane is not used to wash the filtered alkyl-modified graphene oxide, so that the kinematic viscosity of the hydraulic oil described in Example 5 is reduced compared with Example 1, but the anti-wear and friction reduction ability is significantly reduced. This is mainly because the alkyl-modified graphene oxide is not washed, so that free isocyanate will adhere to the alkyl-modified graphene oxide, and this part of the isocyanate will also react with the molybdenum amine complex; the molybdenum amine complex that reacts with isocyanate has a smaller molecular weight and is more easily soluble in the base oil, so that the kinematic viscosity of the hydraulic oil is reduced. However, under extreme pressure conditions, the uniformity of the circulation layer structure of graphene oxide-molybdenum iron alloy-graphene oxide in the grooves of the friction pair is poor, and it is difficult for the hydraulic oil to maximize its anti-wear and friction reduction ability, so the maximum no-seizure load is reduced, and the wear spot diameter is increased, but it is still within the national standard range.

[0078] By comparing Example 1 with Example 5, it can be seen that in Example 6, in the step of modifying graphene oxide, all the isocyanates used are diphenylmethane-4,4'-diisocyanate; so that the kinematic viscosity of the hydraulic oil described in Example 6 is significantly reduced, but the anti-wear and friction reduction ability is basically unchanged from that in Example 1. This is mainly because after one end of diphenylmethane-4,4'-diisocyanate is connected to graphene oxide, the other end is more easily connected to the molybdenum amine complex, so that the modified molybdenum amine complex lacks a lipophilic group, which leads to a larger kinematic viscosity of the hydraulic oil.

[0079] Since the hydraulic oil in Examples 1, 2, 5 and 6 does not contain elements such as sulfur, phosphorus and chlorine, the hydraulic oil has good corrosion resistance and can meet the 1a standard, reducing the environmental restrictions on the use of the hydraulic oil. In addition, the hydraulic oil in Examples 1 to 6 does not contain flammable substances, so that the hydraulic oil has good flame retardancy and is relatively safe.

[0080] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A flame retardant and anti-wear hydraulic oil, characterized in that: The composition comprises by weight: 1.6-2.4% of modified molybdenum amine complex, 2.0-4.0% of high temperature antioxidant, 0.5-1.0% of low temperature antioxidant, 0.002-0.005% of defoamer, and the balance is synthetic ester base oil. The modified molybdenum amine complex is a reactant of graphene oxide, isocyanate and molybdenum amine complex. The preparation method of the modified molybdenum amine complex is as follows: Modifying graphene oxide: putting graphene oxide into anhydrous dimethyl amide, using ultrasound to disperse the graphene oxide for 30 to 40 minutes, then adding an excess of isocyanate, stirring and reacting at 50 to 60°C for 18 to 24 hours, and filtering to obtain alkyl-modified graphene oxide; Grafting molybdenum amine complex: putting alkyl-modified graphene oxide and anhydrous methanol into anhydrous dimethylamide, stirring until uniformly mixed, then putting the molybdenum amine complex into anhydrous dimethylamide, stirring and reacting at room temperature for 4 to 5 hours, and filtering to obtain a modified molybdenum amine complex; the mass ratio of the alkyl-modified graphene oxide to the molybdenum amine complex is 1.2 to 1.5:1; The isocyanate includes diisocyanate and / or polyisocyanate.

2. The flame retardant and anti-wear hydraulic oil according to claim 1, characterized in that: Isocyanates also include monoisocyanates.

3. The flame retardant and anti-wear hydraulic oil according to claim 1, characterized in that: It also includes 1.6-4.0% of nitrogen-containing boronated ester, wherein the nitrogen-containing boronated ester is a boronated fatty amine ester.

4. The flame retardant and anti-wear hydraulic oil according to claim 1, characterized in that: It also includes 0.3-0.4% dialkyl zinc dithiosulfate and 0.1-0.3% benzotriazole.

5. A method for preparing the flame retardant and anti-wear hydraulic oil according to any one of claims 1 to 4, characterized in that: The following steps are involved: Initial mixing: according to the proportion of each substance, mix the high-temperature antioxidant, low-temperature antioxidant and synthetic ester base oil, heat to 60-80°C, and then stir until the high-temperature antioxidant and low-temperature antioxidant are evenly dispersed in the synthetic ester base oil; Final mixing: Add the modified molybdenum amine complex and the defoamer into the product obtained by the initial mixing according to the proportion of each substance, maintain the temperature and continue stirring until the modified molybdenum amine complex is completely dissolved in the synthetic ester base oil to obtain a flame retardant and anti-wear hydraulic oil.

6. The method for preparing a flame retardant and anti-wear hydraulic oil according to claim 5, characterized in that: In the initial mixing step, the nitrogen-containing boronated ester is also added to the synthetic ester base oil according to the proportion of the nitrogen-containing boronated ester.

7. The method for preparing a flame retardant and anti-wear hydraulic oil according to claim 5, characterized in that: In the initial mixing step, benzotriazole is also added to the synthetic ester base oil according to the proportion of benzotriazole; In the final mixing step, zinc dialkyl dithiosulfate is added to the product obtained in the initial mixing according to the proportion of zinc dialkyl dithiosulfate.

8. The method for preparing a flame retardant and anti-wear hydraulic oil according to claim 7, characterized in that: The isocyanate is a mixture of monoisocyanate and non-monoisocyanate, wherein the ratio of non-monoisocyanate to monoisocyanate is 2-3:

1.

9. The method for preparing a flame retardant and anti-wear hydraulic oil according to claim 7, characterized in that: In the step of modifying graphene oxide, the filtered alkyl-modified graphene oxide is washed with dichloromethane.

Images