Compound ester anti-foaming agent, application thereof and lubricating oil

Abstract

The invention provides a compound ester anti-foaming agent, application of the compound ester anti-foaming agent and lubricating oil, and belongs to the technical field of anti-foaming agents. The compound ester anti-foaming agent is prepared from the following components in parts by mass: 65 to 85 parts of a compound ester compound, 5 to 10 parts of a surfactant, 10 to 15 parts of a dispersing agent, 0.1 to 1 part of an antioxidant and 0.1 to 0.5 part of an anti-freezing agent. According to the invention, the addition of the compound ester compound, the surfactant and the dispersing agent can reduce the surface tension of liquid and destroy the elastic mode of a foam film, so that the foam is rapidly broken to recover the normal performance of the lubricating oil; the antioxidant can enhance the oxidation resistance of the lubricating oil, interrupt the oxidation chain reaction in the anti-foaming agent, decompose peroxide and protect the anti-foaming agent from being oxidized in the storage process, and the efficient defoaming performance of the anti-foaming agent in the whole service cycle can be kept; the anti-freezing agent can exert excellent foam inhibition / defoaming performance under a wider range of conditions, so that the adverse effect of foam generation on the lubricating oil is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of antifoaming agents, and particularly to a compound ester antifoaming agent, its application, and lubricating oil. Background Art

[0002] Lubricating oil plays a crucial role in lubricating, cooling, cleaning, and rust prevention during mechanical operation. However, during actual use, lubricating oil often generates a large amount of foam due to reasons such as equipment air leakage, poor sealing, air suction into the oil pipe, and air entrainment during mechanical operation. In addition, the components of lubricating oil itself, such as base oil and additives (such as antiwear agents, extruding agents, detergents and dispersants, etc.), also have a tendency to foam during use. The presence of foam will sharply reduce the lubrication effect of lubricating oil, increase mechanical wear, and in severe cases, can lead to equipment failure. Secondly, foam will occupy the space of the fuel tank, reduce the cooling efficiency of lubricating oil, and cause the equipment to overheat. In addition, foam may also increase the viscosity of lubricating oil, making it difficult to flow, hinder the circulation of lubricating oil, resulting in a decrease in equipment cleanliness, and further affecting the normal operation of the equipment.

[0003] With the continuous development of industrial production and the increasing requirements for equipment performance, the performance requirements for defoaming of lubricating oil in the production process are also getting higher and higher. To solve the foam problem in lubricating oil, antifoaming agents are widely used in industry. Antifoaming agents for lubricating oil are chemical additives designed specifically to eliminate and inhibit foam in lubricating oil. It can quickly spread to the surface of the foam and, by reducing the surface tension, destroying the elasticity of the foam film, etc., cause the foam to quickly break and restore the normal performance of the lubricating oil.

[0004] The commonly used antifoaming agents for existing lubricating oil are mainly polyether ester antifoaming agents and polysiloxane antifoaming agents. Polyether ester antifoaming agents have good water solubility, high temperature resistance, and strong alkali resistance, but their defoaming speed and foam suppression time are not very ideal; polysiloxane antifoaming agents have the characteristics of rapid defoaming, long foam suppression time, and safety and non-toxicity, but they are poorly soluble in oil and have poor high temperature and strong alkali resistance. Therefore, most antifoaming agents have problems such as large dosage, low defoaming efficiency, and short foam suppression time, and cannot meet the antifoaming requirements of lubricating oil under complex base oil systems. Therefore, it is very important to develop a special antifoaming agent for lubricating oil. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a compound ester antifoaming agent, its application, and lubricating oil. The compound ester antifoaming agent provided by the present invention has good oil solubility, excellent performance of good foam suppression effect, short defoaming time, and small usage amount, and can effectively solve the problem of abnormal foam characteristics under complex base oil systems.

[0006] To achieve the above invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a compound ester defoamer, which comprises the following components in parts by mass: 65-85 parts of a compound ester compound, 5-10 parts of a surfactant, 10-15 parts of a dispersant, 0.1-1 part of an antioxidant, and 0.1-0.5 part of an antifreeze agent, wherein the compound ester compound comprises two or more kinds of ester compounds.

[0008] Preferably, the compound ester defoamer comprises the following components in parts by mass: 75-80 parts of a compound ester compound, 6.5-8 parts of a surfactant, 11-13 parts of a dispersant, 0.25-0.5 part of an antioxidant, and 0.3-0.45 part of an antifreeze agent.

[0009] Preferably, the ester compound comprises a fatty acid ester compound and / or a phosphate ester compound. The fatty acid ester compound comprises one or more of ethyl stearate, butyl stearate, butyl acetate, ethyl acetate, and butyl butyrate. The phosphate ester compound comprises tributyl phosphate and / or diethyl phosphate.

[0010] Preferably, the surfactant comprises a non-ionic surfactant.

[0011] Preferably, the non-ionic surfactant comprises one or more of polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleate, and polyoxyethylene-polyoxypropylene diblock copolymer.

[0012] Preferably, the dispersant comprises succinimide.

[0013] Preferably, the antioxidant comprises one or more of dibutylhydroxytoluene, 2,6-di-tert-butyl-p-cresol, and 2,6-di-tert-butylphenol.

[0014] Preferably, the antifreeze agent comprises one or more of polyethylene glycol, propylene glycol, and propylene glycol methyl ether.

[0015] The present invention also provides an application of the compound ester defoamer according to the above technical solution in the lubrication field.

[0016] The present invention also provides a lubricating oil, which comprises the compound ester defoamer and a base oil.

[0017] The present invention provides a compound ester defoamer, which comprises the following components in parts by mass: 65-85 parts of a compound ester compound, 5-10 parts of a surfactant, 10-15 parts of a dispersant, 0.1-1 part of an antioxidant, and 0.1-0.5 part of an antifreeze agent, wherein the compound ester compound comprises two or more kinds of ester compounds.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] In the present invention, the addition of the compound ester, surfactant and dispersant can help reduce the surface tension of the liquid, break the elasticity of the foam film, cause the foam to rupture rapidly, and thus restore the normal performance of the lubricating oil. Moreover, the compound ester has a better anti-foaming effect than a single ester compound. The addition of the antioxidant can enhance the antioxidant capacity of the lubricating oil, interrupt the oxidation chain reaction in the anti-foaming agent, decompose peroxides, protect the anti-foaming agent from oxidation during storage, help maintain the high-efficiency defoaming performance of the anti-foaming agent throughout the service life, and ensure high-efficiency performance and high reliability in actual application scenarios. The addition of the antifreeze can exhibit excellent foam suppression / defoaming performance under a wider range of conditions and reduce the adverse effects of foam generation on the lubricating oil. The present invention defines the dosages of the compound ester, surfactant, dispersant, antioxidant and antifreeze, so that the compound ester-based anti-foaming agent has good oil solubility, excellent foam suppression effect, short defoaming time and small dosage, can effectively solve the problem of abnormal foam characteristics in a complex base oil system, still maintain excellent defoaming performance at a lower added mass fraction, and has higher cost performance and application flexibility.

[0020] The present invention also provides a preparation method of the compound ester-based anti-foaming agent according to the above technical solution. The production conditions of the compound ester-based anti-foaming agent of the present invention are mild, and the foam suppression / defoaming effect is remarkable. Specific Embodiments

[0021] The present invention provides a compound ester-based anti-foaming agent, which comprises the following components in parts by mass: 65-85 parts of a compound ester, 5-10 parts of a surfactant, 10-15 parts of a dispersant, 0.1-1 part of an antioxidant and 0.1-0.5 part of an antifreeze, wherein the compound ester comprises two or more ester compounds.

[0022] In the present invention, unless otherwise specified, the raw materials used are commercially available products in the art.

[0023] In the present invention, by mass parts, the compound ester type antifoaming agent comprises 65 - 85 parts of a compound ester compound, more preferably 75 - 80 parts, specifically 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84 or 85 parts; the ester compound preferably comprises a fatty acid ester compound and / or a phosphate ester compound, the fatty acid ester compound preferably comprises one or more of ethyl stearate, butyl stearate, butyl acetate, ethyl acetate and butyl butyrate, the phosphate ester compound preferably comprises tributyl phosphate and / or diethyl phosphate, when the compound ester compound preferably comprises two ester compounds, more preferably comprises ethyl stearate and tributyl phosphate, ethyl stearate and diethyl phosphate, butyl stearate and tributyl phosphate, butyl acetate and ethyl acetate, ethyl acetate and butyl butyrate, mixing two or more of the ester compounds can further improve the antifoaming performance; the compound ester compound can reduce the surface tension of the liquid, make the foam film thinner, and thus break more easily. During the defoaming process, the fatty acid ester compound can form a protective film on the foam film to prevent the foam from further expanding, the phosphate ester compound can form a stable protective film on the liquid surface to prevent air from entering the liquid, thereby preventing the re - formation of foam, and the ester compound has excellent thermal stability and can maintain a stable defoaming effect in a high - temperature environment, which makes them particularly suitable for applications under high - temperature and high - pressure environments and suitable for various working conditions.

[0024] Based on the mass parts of the compound ester compound, the compound ester type antifoaming agent comprises 5 - 10 parts of a surfactant, more preferably 6.5 - 8 parts, specifically 5, 6.5, 7, 7.5, 8 or 10 parts; the surfactant is preferably a non - ionic surfactant; the non - ionic surfactant preferably comprises one or more of polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleate and polyoxyethylene - polyoxypropylene diblock copolymer, the polyoxyethylene stearyl ether is more preferably Brij 78, the polyoxyethylene cetyl ether is more preferably Brij 97, the polyoxyethylene oleate is more preferably Simulsol 260, the polyoxyethylene - polyoxypropylene diblock copolymer is more preferably Pluronic L64 or Pluronic P123; the surfactant can be rapidly adsorbed at the gas - liquid interface, significantly reduce the surface tension of the liquid, destroy the stability of the foam film, and at the same time, by forming polymers or colloidal particles, adsorb on the bubble surface to prevent the aggregation and diffusion of bubbles.

[0025] Based on the mass parts of the compounded ester compounds, the compounded ester defoamer includes 10 to 15 parts of dispersant, more preferably 11 to 13 parts, and specifically can be 10, 11, 12, 13, 14 or 15 parts; the dispersant is preferably succinimide, and the dispersant can decompose larger particles (nanoscale, 1 to 100 nm) or droplets into smaller particles (micrometer scale, 1 to 100 μm), making it easier to suspend in the lubricating oil, avoiding precipitation or aggregation, and working synergistically with other components in the defoamer to further improve the defoaming effect.

[0026] Based on the mass parts of the compounded ester compounds, the compounded ester defoamer includes 0.1 to 1 part of antioxidant, more preferably 0.25 to 0.5 part, and specifically can be 0.1, 0.25, 0.35, 0.5 or 1 part; the antioxidant preferably includes one or more of dibutylhydroxytoluene, 2,6 - di - tert - butyl - p - cresol and 2,6 - di - tert - butylphenol; the antioxidant can interrupt the oxidation chain reaction in the defoamer, decompose peroxides, protect the defoamer from oxidation during storage, and help maintain the high - efficiency defoaming performance of the defoamer throughout the use cycle.

[0027] Based on the mass parts of the compounded ester compounds, the compounded ester defoamer includes 0.1 to 0.5 part of antifreeze, more preferably 0.3 to 0.5 part, and specifically can be 0.1, 0.25, 0.3, 0.45 or 0.5 part; the antifreeze preferably includes one or more of polyethylene glycol, propylene glycol and propylene glycol methyl ether; the antifreeze can effectively reduce the freezing point of the defoamer, ensure its fluidity at low temperatures, and ensure the normal use of the defoamer in cold environments.

[0028] In the present invention, the average molecular weight of the polyethylene glycol is preferably 2000 to 6000, and specifically can be 2000, 3000, 4000, 5000 or 6000.

[0029] The present invention also provides a preparation method of the compounded ester defoamer according to the above - mentioned technical solution, including the following steps:

[0030] Mix the compounded ester compounds, surfactant, dispersant, antioxidant and antifreeze to obtain the compounded ester defoamer.

[0031] In the present invention, the temperature of the mixing is preferably 40 to 60 °C, specifically can be 40, 45, 50, 55 or 60 °C, and the time is preferably 70 to 90 min; the mixing is preferably carried out under stirring conditions, and more preferably carried out in a stirring environment of a sealed container.

[0032] The present invention has no special limitation on the rotation speed of the stirring, and it can be mixed evenly by using a method well - known to those skilled in the art.

[0033] In a specific embodiment of the present invention, it is preferred to first mix a compound ester, a surfactant, and a dispersant to obtain a first mixture, and then secondarily mix the first mixture, an antioxidant, and an antifreeze to obtain the compound ester defoamer.

[0034] In the present invention, the stirring rate of the first mixing is preferably 300 - 500 r / min, and the time of the first mixing is preferably until there are no obvious immiscible liquid particles; the stirring rate of the second mixing is preferably 400 - 600 r / min, and the time of the second mixing is preferably 1 - 2 h.

[0035] The compound ester defoamer prepared by the present invention shows significant advantages in foam suppression / defoaming performance, with a fast defoaming speed and obvious effects; at the same time, it has good dispersibility, and the appearance of the lubricating oil remains unchanged before and after its addition.

[0036] The present invention also provides the application of the compound ester defoamer described in the above technical solution in the lubrication field.

[0037] In the present invention, it is preferred to mix the compound ester defoamer with a base oil and then use it for lubrication.

[0038] The present invention also provides a lubricating oil, which includes the compound ester defoamer and a base oil.

[0039] In the present invention, the mass ratio of the compound ester defoamer to the base oil is preferably 0.3 - 5:100, and specifically can be 0.3:100, 0.5:100, 1:100, 2:100, 3:100, 4:100, or 5:100.

[0040] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0041] In the embodiments of the present invention, the polyoxyethylene stearyl ether is Brij 78, the polyoxyethylene cetyl ether is Brij97, the polyoxyethylene oleate is Simulsol 260, the polyoxyethylene - polyoxypropylene diblock copolymer is Pluronic L64, and the average molecular weight of the polyethylene glycol is 2000.

[0042] Example 1

[0043] Prepare the compound ester defoamer according to the mass parts of each component:

[0044] Weigh 32 parts of ethyl stearate, 45 parts of tributyl phosphate, 12 parts of succinimide, 7 parts of polyoxyethylene cetyl ether, 0.5 part of dibutylhydroxytoluene, and 0.5 part of polyethylene glycol.

[0045] Add ethyl stearate, tributyl phosphate, succinimide, and polyoxyethylene cetyl ether into a container. Keep the hot stage temperature at 45 °C and stir until the components are evenly mixed without obvious immiscible liquid particles. The stirring rate is 300 r / min. Then add dibutylhydroxytoluene and polyethylene glycol, and continue to stir the mixture at a stirring rate of 400 r / min while keeping the temperature constant during the stirring process. After thorough mixing, continue to stir for 1 h to obtain a compound ester defoamer.

[0046] Example 2

[0047] Prepare a compound ester defoamer according to the mass parts of each component:

[0048] Weigh 25 parts of ethyl stearate, 55 parts of diethyl phosphate, 13 parts of succinimide, 7.5 parts of polyoxyethylene oleate, 0.35 part of dibutylhydroxytoluene, and 0.25 part of propylene glycol methyl ether.

[0049] Add ethyl stearate, diethyl phosphate, succinimide, and polyoxyethylene oleate into a container. Keep the hot stage temperature at 55 °C and stir until the components are evenly mixed without obvious immiscible liquid particles. The stirring rate is 500 r / min. Then add dibutylhydroxytoluene and propylene glycol methyl ether, and continue to stir the mixture at a stirring rate of 600 r / min while keeping the temperature constant during the stirring process. After thorough mixing, continue to stir for 1 h to obtain a compound ester defoamer.

[0050] Example 3

[0051] Prepare a compound ester defoamer according to the mass parts of each component:

[0052] Weigh 45 parts of butyl stearate, 30 parts of tributyl phosphate, 13 parts of succinimide, 7.5 parts of polyoxyethylene oleate, 0.35 part of dibutylhydroxytoluene, and 0.25 part of propylene glycol.

[0053] Add butyl stearate, tributyl phosphate, succinimide, and polyoxyethylene oleate into a container. Keep the hot stage temperature at 55 °C and stir until the components are evenly mixed without obvious immiscible liquid particles. The stirring rate is 500 r / min. Then add dibutylhydroxytoluene and propylene glycol, and continue to stir the mixture at a stirring rate of 600 r / min while keeping the temperature constant during the stirring process. After thorough mixing, continue to stir for 1 h to obtain a compound ester defoamer.

[0054] Example 4

[0055] Prepare a compound ester defoamer according to the mass parts of each component:

[0056] Weigh 42 parts of butyl acetate, 36 parts of ethyl acetate, 13 parts of succinimide, 6.5 parts of polyoxyethylene oleate, 0.25 parts of dibutylhydroxytoluene, and 0.45 parts of polyethylene glycol.

[0057] Add butyl acetate, ethyl acetate, succinimide, and polyoxyethylene oleate into a container. Keep the hot stage temperature at 55 °C and stir until the components are evenly mixed with no obvious immiscible liquid particles. The stirring rate is 500 r / min; then add dibutylhydroxytoluene and polyethylene glycol, and continue to stir the mixture at a stirring rate of 600 r / min. Keep the temperature constant during the stirring process. After thorough mixing, continue to stir for 2 h to obtain a compound ester defoamer.

[0058] Example 5

[0059] Prepare a compound ester defoamer according to the mass parts of each component:

[0060] Weigh 31 parts of ethyl acetate, 47 parts of butyl butyrate, 13 parts of succinimide, 8 parts of polyoxyethylene oleate, 0.5 parts of dibutylhydroxytoluene, and 0.5 parts of polyethylene glycol.

[0061] Add ethyl acetate, butyl butyrate, succinimide, and polyoxyethylene oleate into a container. Keep the hot stage temperature at 55 °C and stir until the components are evenly mixed with no obvious immiscible liquid particles. The stirring rate is 500 r / min; then add dibutylhydroxytoluene and polyethylene glycol, and continue to stir the mixture at a stirring rate of 600 r / min. Keep the temperature constant during the stirring process. After thorough mixing, continue to stir for 2 h to obtain a compound ester defoamer.

[0062] Comparative Example 1

[0063] Weigh 77 parts of ethyl stearate, 12 parts of succinimide, 7 parts of polyoxyethylene cetyl ether, 0.5 parts of dibutylhydroxytoluene, and 0.5 parts of polyethylene glycol.

[0064] Add ethyl stearate, succinimide, and polyoxyethylene cetyl ether into a container. Keep the hot stage temperature at 45 °C and stir until the components are evenly mixed with no obvious immiscible liquid particles. The stirring rate is 300 r / min; then add dibutylhydroxytoluene and polyethylene glycol, and continue to stir the mixture at a stirring rate of 400 r / min. Keep the temperature constant during the stirring process. After thorough mixing, continue to stir for 1 h to obtain an ester defoamer.

[0065] Testing Method

[0066] Test Example 1 designed experiments based on the national standard GB_T 12579-2002 to test the foam suppression / antifoaming performance of the compound ester antifoaming agent described in the present invention; Test Example 2 tested the dosage range of the compound ester antifoaming agent described in the present invention by changing the proportion of the compound ester antifoaming agent added to the lubricating oil. Antifoaming agents P1 and P2 were selected for comparative experiments with the compound ester antifoaming agent prepared in the examples of the present invention. Among them, P1, P2, and the base oil were commercially available. The 150N base oil with a kinematic viscosity of 150 cSt was selected for the experiment, and the addition amount of each antifoaming agent in Test Example 1 was 0.3% of the mass of the base oil. The foam suppression / antifoaming performance was studied using the above two groups of experiments, and the results are shown in Tables 1 and 2.

[0067] According to the data in Table 1, the foam behavior of the base oil 150N under different conditions was analyzed in detail. The results showed that: Without adding any antifoaming agent: At 24°C, the foam tendency of the base oil was 60 mL, and the defoaming time was 180 seconds. After heating to 93.5°C, the foam tendency decreased to 30 mL, and the defoaming time was shortened to 30 seconds. After adding the compound ester antifoaming agents of Examples 1-5 of the present invention: The foam suppression / antifoaming performance of the base oil was significantly improved. Whether at 24°C or 93.5°C, the foam tendency was greatly reduced. Especially in Examples 2 and 3, the foam tendency was only 5 mL, and the defoaming time was shortened to 10-15 seconds. Compared with Example 1, in Comparative Example 1, only a single type of ester compound was added to the antifoaming agent. According to the data in Table 1, it can be seen that the antifoaming agents obtained with single ester compounds lagged behind Example 1 in terms of foam suppression / antifoaming performance, indicating that the compound ester antifoaming agent described in the present invention exhibited excellent foam suppression and rapid defoaming capabilities at different temperatures; In contrast, although the commercially available antifoaming agents P1 and P2 could also reduce the foam tendency to a certain extent, the effect was not as good as that of the compound ester antifoaming agent of the present invention. Specifically, the defoaming time of P1 was longer than that of the base oil, indicating that its defoaming efficiency was lower. After high-temperature heating, the foam suppression / antifoaming performance of P2 decreased significantly, and it caused the oil product to become turbid, affecting the transparency and stability of the oil product. In summary, the compound ester antifoaming agent of the present invention is superior to the commercially available products P1 and P2 in terms of foam suppression and antifoaming performance.

[0068] Table 1 Results of the defoaming experiment

[0069]

[0070] Based on the data in Table 2, the following conclusions can be drawn: In the case of adding no components, the surface tension of base oil 150N is 37.52 mN / m. After adding the compound ester defoaming agents of Examples 1 - 5 of the present invention, the surface tension decreases significantly, dropping to 29.438 - 31.83 mN / m. As the addition ratio of the compound ester defoaming agent decreases, the surface tension continues to decrease. For example, in Example 1, it drops from 30.13 mN / m to 28.76 mN / m (when the addition ratio decreases from 5% to 0.3%, and the addition ratio refers to the mass ratio of the defoaming agent to the base oil). This indicates that at a relatively low addition ratio (such as 0.3%), the compound ester defoaming agent of the present invention can still effectively reduce the surface tension, thereby achieving a better defoaming effect. Examples 2 - 5 also show a similar trend, that is, as the addition ratio decreases, the surface tension gradually decreases, and excellent defoaming performance can still be maintained at a lower ratio; P1 and P2 can also reduce the surface tension in the initial stage (when the addition ratio is relatively high), but after the addition ratio drops to 2%, the surface tension starts to rise, indicating that their defoaming effect is poor at low concentrations; and compared with Example 1, the surface tension of Comparative Example 1 is higher. This further proves that the compound ester defoaming agent of the present invention can still maintain excellent defoaming performance at a relatively low addition ratio, and has higher cost performance and application flexibility.

[0071] Table 2 Experimental Results of Surface Tension at Different Addition Ratios of Defoaming Agents

[0072]

[0073] The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A composite ester antifoaming agent, characterized in that: The invention comprises the following components in parts by weight: 65-85 parts of a composite ester compound, 5-10 parts of a surfactant, 10-15 parts of a dispersant, 0.1-1 parts of an antioxidant and 0.1-0.5 parts of an antifreeze agent, wherein the composite ester compound comprises two or more ester compounds.

2. The composite ester antifoaming agent according to claim 1, characterized in that: The compound ester antifoaming agent comprises the following components in parts by weight: 75-80 parts of compound ester compound, 6.5-8 parts of surfactant, 11-13 parts of dispersant, 0.25-0.5 parts of antioxidant and 0.3-0.45 parts of antifreeze agent.

3. The composite ester antifoaming agent according to claim 1 or 2, characterized in that: The ester compounds include fatty acid ester compounds and / or phosphate compounds, the fatty acid ester compounds include one or more of ethyl stearate, butyl stearate, butyl acetate, ethyl acetate and butyl butyrate, and the phosphate compounds include tributyl phosphate and / or diethyl phosphate.

4. The composite ester antifoaming agent according to claim 1 or 2, characterized in that: The surfactant includes a nonionic surfactant.

5. The composite ester antifoaming agent according to claim 4, characterized in that: The nonionic surfactant includes one or more of polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleate and polyoxyethylene-polyoxypropylene diblock copolymer.

6. The composite ester antifoaming agent according to claim 1 or 2, characterized in that: The dispersant includes succinimide.

7. The composite ester antifoaming agent according to claim 1 or 2, characterized in that: The antioxidant includes one or more of butylated hydroxytoluene, 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butylphenol.

8. The composite ester antifoaming agent according to claim 1 or 2, characterized in that: The antifreeze agent includes one or more of polyethylene glycol, propylene glycol and propylene glycol methyl ether.

9. Use of the compound ester antifoaming agent according to any one of claims 1 to 8 in the field of lubrication.

10. A lubricating oil, characterized in that: The invention comprises the composite ester antifoaming agent and base oil.

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