A low-foaming cleaning agent for oil stains on mechanical parts

Abstract

This invention proposes a low-foaming cleaning agent for oil stains on mechanical parts, belonging to the field of cleaning agent technology. The components of this invention include glycine monoglycolipids, sodium hydroxide, a low-foaming surfactant, an antifoaming agent, a chelating agent, and a corrosion inhibitor. This invention, through the preparation of glycine monoglycolipids combined with a low-foaming surfactant and enzyme catalysis process, offers advantages in terms of cleaning efficiency, environmental friendliness, and material compatibility. It aligns closely with the industry trend towards low toxicity, low foaming, and high efficiency, and exhibits excellent oil stain removal performance.

Description

Technical Field

[0001] This invention belongs to the field of cleaning agent technology, and in particular relates to a low-foaming cleaning agent for oil stains on mechanical parts. Background Technology

[0002] During the production, use, and maintenance of metal parts, it is necessary to clean various contaminants adhering to their surfaces to ensure the smooth progress of processing procedures, prevent rust and wear, guarantee the internal and surface quality of the products, and extend their service life.

[0003] The low-foaming properties of cleaning agents can prevent liquid from overflowing from the tank due to excessive foam during high-pressure spraying, ultrasonic cleaning, or mechanical agitation, thus reducing raw material waste and site pollution. For example, excessive foam during high-pressure cleaning may carry oil stains that spill onto the ground, polluting the environment and increasing the difficulty of cleaning.

[0004] At the same time, low-foaming cleaning agents reduce the number of rinsing cycles and water consumption, thus lowering water and electricity consumption. For example, traditional high-foaming cleaning agents require multiple rinsing cycles to remove residual foam, while low-foaming formulas can achieve a cleaning effect with just one rinsing, making them particularly suitable for continuous operations in large-scale industrial production.

[0005] CN114561125A discloses a heavy oil stain cleaning agent that uses active bacteria (Aeromonas hydrophila and Pseudomonas aeruginosa / Bacillus) to degrade mineral oil, reducing oil residue in washing wastewater. It exhibits strong biodegradability and is environmentally friendly. However, the active bacteria require multiple steps such as sterilization, cultivation, and gel encapsulation, making the process cumbersome and costly. Furthermore, the active bacteria may become inactive during long-term storage, necessitating strict temperature control, which limits its practical application.

[0006] CN117737743A discloses a high-efficiency, low-foaming, rust-preventing water-based cleaning agent for ferrous metals. This agent combines an organic alkali (diethylene glycolamine / AMP95 / dicyclohexylamine) with a rust inhibitor (sebacic acid / neodecanic acid / tribasic acid) to achieve both low-foaming and rust-preventing functions, eliminating the need for additional defoamers. However, this formula requires strict adherence to the specified ratios (e.g., 1:2:1 and 3:2:3) for the organic alkali and rust inhibitor to prevent rust failure or precipitation. It is designed only for ferrous metals and may corrode non-ferrous metals (such as aluminum and copper); compatibility has not been verified. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides a low-foaming cleaning agent for oil stains on mechanical parts, comprising the following components by weight:

[0008]

[0009]

[0010] The preparation method of the glycine-monoglycolipid includes the following steps:

[0011] S1: Glycine and hydroxy fatty acids are heated in an ionic liquid and lipase is added to carry out a condensation reaction to obtain glycine-hydroxy fatty acid monoester.

[0012] S2: Glycine-hydroxy fatty acid monoester and N-hydroxysuccinimide are dissolved in an organic solvent, activated by adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and then papain is added to react to obtain amide bond modified glycine-hydroxy fatty acid monoester.

[0013] S3: Glycine-hydroxy fatty acid monoester and monosaccharide are dissolved in buffer solution, and glycosyltransferase is added to react to obtain glycine-monosaccharide-hydroxy fatty acid monoester complex.

[0014] S4: The glycine-monosaccharide-hydroxy fatty acid monoester complex was heated in a hydroxy fatty acid ionic liquid, and lipase was added to connect the remaining hydroxyl sites of the monosaccharide to hydroxy fatty acids; then purified to obtain glycine-monosaccharide ester.

[0015] Preferably, the monosaccharide is at least one of the following components:

[0016] Galactose, mannose, and glucose;

[0017] The hydroxy fatty acid contains at least one of the following:

[0018] 3-Hydroxyoctanoic acid, 3-Hydroxydecanoic acid, 3-Hydroxydodecanoic acid.

[0019] Preferably, in step S1 of the method for preparing glycine-monoglycolipid, the molar ratio of glycine to hydroxy fatty acid is at least 1:4; the amount of lipase used is at least 10 wt% of the mass of glycine; the reaction time is at least 60°C and the reaction time is at least 24 h.

[0020] Preferably, in step S2 of the method for preparing glycine-monoglycolipid, the molar ratio of glycine-hydroxy fatty acid monoester, N-hydroxysuccinimide, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:at least 1.2:at least 1.2;

[0021] The amount of papain used is at least 5 wt% of glycine-hydroxy fatty acid monoester; the reaction time is at least 12 h.

[0022] Preferably, in step S3 of the method for preparing glycine-monoglycolipid, the molar ratio of glycine-hydroxy fatty acid monoester to monosaccharide is at least 1:1.2; and the amount of glycosyltransferase used is at least 5 wt% of the mass of glycine-hydroxy fatty acid monoester.

[0023] The reaction temperature is 36-38℃; the reaction time is at least 48 hours.

[0024] Preferably, in step S4 of the method for preparing glycine-monoglycolipid, the molar ratio of glycine-monoglycolipid-hydroxy fatty acid monoester complex to hydroxy fatty acid is at least 1:4; the amount of lipase used is at least 10 wt% of glycine-monoglycolipid-hydroxy fatty acid monoester complex; the reaction time is at least 60°C and the reaction time is at least 24 h.

[0025] Preferably, the low-foaming surfactant is at least one of the following components:

[0026] Polyether-type nonionic surfactants, lauryl alcohol polyoxyethylene ether phosphate, and isooctyl alcohol polyoxyethylene ether phosphate.

[0027] Preferably, the defoamer is polyoxypropylene polyoxyethylene ether.

[0028] The chelating agent is sodium pyrophosphate and / or sodium metasilicate.

[0029] The corrosion inhibitor is sodium benzoate and / or sodium nitrite.

[0030] The glycine-monoglycolipid prepared in this invention is composed of monosaccharides, glycine, and multiple hydrophobic chains of hydroxyl fatty acids. Its molecular structure exhibits both hydrophilic and lipophilic properties, significantly reducing the surface tension at the oil-water interface and effectively lowering solution surface tension, thus enhancing its emulsification and dispersion capabilities for oil stains. Simultaneously, the introduction of monosaccharides regulates foam stability through hydrogen bonding of hydroxyl groups. Combined with low-foaming surfactants and defoamers in the formulation, it achieves efficient detergency while inhibiting foam formation, making it suitable for high-pressure spray or circulating cleaning systems. The amino and carboxylic acid groups of glycine can form a protective film on metal surfaces, synergistically reducing the risk of corrosion from strong alkalis (sodium hydroxide) with corrosion inhibitors (such as sodium benzoate) in the formulation. The hydroxyl groups of monosaccharides (such as glucose and galactose) and the amino acid structure of glycine possess natural antibacterial properties, reducing skin irritation to operators and inhibiting microbial growth during the cleaning process.

[0031] In addition to glycine, different monosaccharides and hydroxy fatty acids can be selected to adjust the hydrophilic-hydrophobic balance of the product. Furthermore, in the final hydrophobic chain amplification, 1-4 hydroxy fatty acids can be introduced as needed to adapt to the cleaning requirements of different types of oil stains.

[0032] The sodium hydroxide in this invention is highly alkaline and can quickly saponify animal and vegetable oils to generate soluble sodium fatty acids, thereby improving cleaning efficiency; when combined with chelating agents, it softens water and reduces the interference of hard water on cleaning agents.

[0033] Low-foaming surfactants are used in combination with glycine-monoglycolipids to inhibit foam formation while enhancing the wetting and penetration of oil stains.

[0034] The defoamer further breaks bubbles quickly by reducing surface tension, making it suitable for dynamic cleaning environments (such as ultrasonic cleaning). Since silicone is easily hydrolyzed and degraded in strong alkalis, this invention chooses to use polyoxypropylene polyoxyethylene ether.

[0035] Chelating agents (detergent builders) and slow-release agents improve the effectiveness of oil stain cleaners through different mechanisms. Chelating agents prevent dirt redeposition through colloidal suspension or steric hindrance effects; corrosion inhibitors protect metals by physically adsorbing and covering the metal surface. Although some chelating agents also have corrosion inhibition functions, they mainly serve the decontamination system; therefore, neither can completely replace the other.

[0036] This invention, through the preparation of glycine-monoglycolipids, combined with low-foaming surfactants and enzyme catalysis, has advantages in terms of decontamination efficiency, environmental friendliness, and material compatibility. It is highly consistent with the industry's trend towards low toxicity, low foaming, and high efficiency, and has excellent oil removal effect. Detailed Implementation

[0037] To better understand the present invention, the present invention will be further described below with reference to specific serial numbers. The terminology used in the serial numbers is for describing specific embodiments and does not constitute a limitation on the scope of protection of the present invention.

[0038] In this invention, some of the raw materials used in specific embodiments are shown below:

[0039] Lipases: CAL-B, Novozym 435;

[0040] Glycosyltransferase: BtGT

[0041] Buffer solution: Tris-HCl buffer (pH 8.0)

[0042] Organic solvent: N,N-dimethylformamide (DMF)

[0043] Ionic liquid: 1-Butyl-3-methylimidazolium tetrafluoroborate

[0044] Example 1: Preparation of Oil Stain Cleaning Agent

[0045] Step S1: Preparation of glycine-monoglycolipid, including the following steps:

[0046] A1: Glycine and 3-hydroxyoctanoic acid are heated in an ionic liquid and lipase CAL-B is added to carry out a condensation reaction to obtain glycine-3-hydroxyoctanoic acid monoester.

[0047] The molar ratio of glycine to 3-hydroxyoctanoic acid is 1:4; the amount of lipase CAL-B used is 10 wt% of the mass of glycine; the reaction time is 60℃ for 24 h; and the lipase is inactivated at 80℃ after the reaction is completed.

[0048] A2: Glycine-3-hydroxyoctanoic acid monoester and N-hydroxysuccinimide are dissolved in an organic solvent, activated by adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and then papain is added to react to obtain amide bond modified glycine-3-hydroxyoctanoic acid monoester.

[0049] The molar ratio of glycine-3-hydroxyoctanoic acid monoester, N-hydroxysuccinimide, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:1.2:1.2;

[0050] The amount of papain used was 5 wt% of glycine-3-hydroxyoctanoic acid monoester; the reaction time was 12 h; after the reaction was completed, the reaction solution was dialyzed (molecular weight cutoff 1 kDa) to remove small molecule impurities.

[0051] A3: Glycine-3-hydroxyoctanoic acid monoester and galactose were dissolved in buffer solution, and glycosyltransferase BtGT was added to react to obtain glycine-galactose-3-hydroxyoctanoic acid monoester complex; after the reaction, the enzyme was inactivated by heating to 95℃, the precipitate was removed by centrifugation, and the supernatant was purified by HPLC (C18 column, acetonitrile-water gradient elution).

[0052] The molar ratio of glycine-3-hydroxyoctanoic acid monoester to galactose is 1:1.2; the amount of glycosyltransferase used is 5 wt% of the mass of glycine-3-hydroxyoctanoic acid monoester; the reaction temperature is maintained at 36-38℃; and the reaction time is 48 h.

[0053] A4: The glycine-galactose-3-hydroxyoctanoic acid monoester complex was heated with 3-hydroxyoctanoic acid ionic liquid, and lipase CAL-B was added to connect 3-hydroxyoctanoic acid to the remaining hydroxyl sites of the monosaccharide; then purified to obtain glycine-monosaccharide ester.

[0054] The molar ratio of glycine-galactose-3-hydroxyoctanoic acid monoester complex to 3-hydroxyoctanoic acid is 1:4; the amount of lipase CAL-B used is 10 wt% of the mass of glycine-galactose-3-hydroxyoctanoic acid monoester complex; the reaction time is 60℃ for 24 h; after the reaction, the mixture is purified (silica gel column chromatography, petroleum ether-ethyl acetate 3:1); this step is repeated 3 times.

[0055] Step S2: Weigh the raw materials according to the mass fraction, stir them evenly and set aside.

[0056]

[0057] Example 2: Preparation of oil stain cleaning agent

[0058] Step S1: Preparation of glycine-monoglycolipid, including the following steps:

[0059] A1: Glycine and 3-hydroxydecanoic acid are heated in an ionic liquid and lipase CAL-B is added to carry out a condensation reaction to obtain glycine-3-hydroxydecanoic acid monoester.

[0060] The molar ratio of glycine to 3-hydroxydecanoic acid is 1:4; the amount of lipase CAL-B used is 10wt% of the mass of glycine; the reaction time is 60℃ for 24h; and the lipase is inactivated at 80℃ after the reaction is completed.

[0061] A2: Glycine-3-hydroxydecanoic acid monoester and N-hydroxysuccinimide are dissolved in an organic solvent, activated by adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and then papain is added to react to obtain amide bond modified glycine-3-hydroxydecanoic acid monoester.

[0062] The molar ratio of glycine-3-hydroxydecanoic acid monoester, N-hydroxysuccinimide, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:1.2:1.2;

[0063] The amount of papain used was 5 wt% of glycine-3-hydroxydecanoic acid monoester; the reaction time was 12 h; after the reaction was completed, the reaction solution was dialyzed (molecular weight cutoff 1 kDa) to remove small molecule impurities.

[0064] A3: Glycine-3-hydroxydecanoic acid monoester and mannose were dissolved in buffer solution, and glycosyltransferase BtGT was added to react to obtain glycine-mannose-3-hydroxydecanoic acid monoester complex; after the reaction, the enzyme was inactivated by heating to 95℃, the precipitate was removed by centrifugation, and the supernatant was purified by HPLC (C18 column, acetonitrile-water gradient elution).

[0065] The molar ratio of glycine-3-hydroxydecanoic acid monoester to mannose is 1:1.2; the amount of glycosyltransferase used is 5 wt% of the mass of glycine-3-hydroxydecanoic acid monoester; the reaction temperature is maintained at 36-38℃; and the reaction time is 48 h.

[0066] A4: The glycine-mannose-3-hydroxydecanoic acid monoester complex was heated with 3-hydroxydecanoic acid ionic liquid, and lipase CAL-B was added to connect the remaining hydroxyl sites of the monosaccharide to 3-hydroxydecanoic acid; then purified to obtain glycine-monosaccharide ester.

[0067] The molar ratio of glycine-mannose-3-hydroxydecanoic acid monoester complex to 3-hydroxydecanoic acid is 1:4; the amount of lipase CAL-B used is 10 wt% of the mass of glycine-mannose-3-hydroxydecanoic acid monoester complex; the reaction time is 60℃ for 24 h; after the reaction, the mixture is purified (silica gel column chromatography, petroleum ether-ethyl acetate 3:1); this step is repeated 3 times.

[0068] Step S2: Weigh the raw materials according to the mass fraction, stir them evenly and set aside.

[0069]

[0070] Example 3: Preparation of Oil Stain Cleaning Agent

[0071] Step S1: Preparation of glycine-monoglycolipid, including the following steps:

[0072] A1: Glycine and 3-hydroxydodecanoic acid are heated in an ionic liquid and lipase NOVOZYM 435 is added to carry out a condensation reaction to obtain glycine-3-hydroxydodecanoic acid monoester.

[0073] The molar ratio of glycine to 3-hydroxydodecanoate was 1:4; the amount of the lipase NOVOZYM 435 was 10 wt% of the mass of glycine; the reaction time was 60°C for 24 h; and the lipase was inactivated at 80°C after the reaction was completed.

[0074] A2: Glycine-3-hydroxydodecanoate monoester and N-hydroxysuccinimide are dissolved in an organic solvent, activated by adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and then papain is added to react to obtain amide bond modified glycine-3-hydroxydodecanoate monoester.

[0075] The molar ratio of glycine-3-hydroxydodecanoate monoester, N-hydroxysuccinimide, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1:1.2:1.2;

[0076] The amount of papain used was 5 wt% of glycine-3-hydroxydodecanoate monoester; the reaction time was 12 h; after the reaction was completed, the reaction solution was dialyzed (molecular weight cutoff 1 kDa) to remove small molecule impurities.

[0077] A3: Glycine-3-hydroxydodecanoate monoester and glucose were dissolved in buffer solution, and glycosyltransferase BtGT was added to react to obtain glycine-glucose-3-hydroxydodecanoate monoester complex; after the reaction was completed, the enzyme was inactivated by heating to 95℃, the precipitate was removed by centrifugation, and the supernatant was purified by HPLC (C18 column, acetonitrile-water gradient elution).

[0078] The molar ratio of glycine-3-hydroxydodecanoate monoester to glucose is 1:1.2; the amount of glycosyltransferase used is 5 wt% of the mass of glycine-3-hydroxydodecanoate monoester; the reaction temperature is maintained at 36-38℃; and the reaction time is 48 h.

[0079] A4: The glycine-glucose-3-hydroxydodecanoic acid monoester complex was heated in a 3-hydroxydodecanoic acid ionic liquid, and lipase NOVOZYM 435 was added to attach 3-hydroxydodecanoic acid to the remaining hydroxyl sites of the monosaccharide; then purified to obtain glycine-monosaccharide ester.

[0080] The molar ratio of glycine-glucose-3-hydroxydodecanoate monoester complex to 3-hydroxydodecanoate is 1:4; the amount of lipase NOVOZYM 435 used is 10wt% of the mass of glycine-glucose-3-hydroxydodecanoate monoester complex; the reaction time is 60℃ for 24h; after the reaction, the mixture is purified (silica gel column chromatography, petroleum ether-ethyl acetate 3:1); this step is repeated 3 times.

[0081] Step S2: Weigh the raw materials according to the mass fraction, stir them evenly and set aside.

[0082]

[0083]

[0084] Example 4: Preparation of Oil Stain Cleaning Agent

[0085] Weigh the raw materials according to the mass fraction, stir them evenly and set aside.

[0086]

[0087] Example 5: Preparation of Oil Stain Cleaning Agent

[0088] The difference from Example 1 is that step A4 is not performed in step S1, the preparation of glycine-monoglycolipid.

[0089] Example 6: Preparation of Oil Stain Cleaning Agent

[0090] The difference from Example 1 is that in step S1, the preparation of glycine-monoglycolipid, step A4 is performed only once.

[0091] Example 7: Preparation of Oil Stain Cleaning Agent

[0092] The difference from Example 1 is that step S2 is modified to: weigh the raw materials according to the mass parts, stir them evenly and set aside.

[0093]

[0094] The performance of the oil stain cleaning agent prepared in the above embodiments was tested:

[0095] The cleaning power, corrosiveness, and rinsing performance were tested according to GB / T 35759-2017 Metal Cleaning Agents.

[0096] Five times the mass of water was added to each of the aforementioned embodiments, and the mixture was thoroughly mixed to serve as the test sample.

[0097] The results are shown in Table 1 below.

[0098] Table 1. Cleaning results of metal cleaning agent

[0099]

[0100] In Table 1, corrosion level 0 is the best, indicating that the surface is rust-free and has no obvious changes; level 3 is the worst, indicating that the surface is severely discolored or corroded.

[0101] As shown in Table 1, the selection of different monosaccharides and hydroxy fatty acids with different hydrophobic chain lengths has a significant impact on cleaning ability. The effect of the hydrophobic chain length of hydroxy fatty acids is more significant. Since galactose, mannose and glucose are all hexose aldoses with similar structures, their effects are not significant.

[0102] In Example 4, no glycine-monoglycolipids were added; relying solely on low-foaming surfactants and strong alkalis as the main detergency components, its cleaning power was clearly insufficient.

[0103] Examples 5 and 6 are comparisons of no hydrophobic chain amplification and only one hydrophobic chain amplification, respectively. It can be seen that as the number of hydrophobic chains increases, the cleaning power also increases. This means that different glycine-monoglycolipid molecules can be customized according to different cleaning scenarios.

[0104] Example 7 uses only strong alkali and glycine-monoglycolipids as the main detergency components, lacking low-foaming surfactants. The experimental results show that its cleaning power is somewhat reduced, and the rinsing performance test shows that there is some residue. This indicates that glycine-monoglycolipids need to be combined with low-foaming surfactants to achieve better results.

[0105] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of this invention. In practical applications, those skilled in the art can select some or all of the workflow to achieve the purpose of this embodiment according to actual needs, and no restrictions are imposed here.

[0106] In addition, for technical details not described in detail in this embodiment, please refer to the parameter operation method provided in any embodiment of the present invention, which will not be repeated here.

[0107] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0108] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0109] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A low-foaming cleaning agent for oil stains on mechanical parts, characterized in that, The following components are included in parts by weight: Glycine-monoglycolipid 10-15 Sodium hydroxide 20-30 Low-foaming surfactant 2-4 Defoamer 0.5-2 Chelating agent 2-6 Corrosion inhibitor 0.5-1.5 The preparation method of the glycine-monoglycolipid includes the following steps: S1: Glycine and hydroxy fatty acids are heated in an ionic liquid and lipase is added to carry out a condensation reaction to obtain glycine-hydroxy fatty acid monoester. S2: Glycine-hydroxy fatty acid monoester and N-hydroxysuccinimide are dissolved in an organic solvent, activated by adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and then papain is added to react to obtain amide bond modified glycine-hydroxy fatty acid monoester. S3: Glycine-hydroxy fatty acid monoester and monosaccharide are dissolved in buffer solution, and glycosyltransferase is added to react to obtain glycine-monosaccharide-hydroxy fatty acid monoester complex. S4: The glycine-monosaccharide-hydroxy fatty acid monoester complex was heated in a hydroxy fatty acid ionic liquid, and lipase was added to connect the remaining hydroxyl sites of the monosaccharide to hydroxy fatty acids; then purified to obtain glycine-monosaccharide ester.

2. The low-foaming oil stain cleaner for mechanical parts according to claim 1, characterized in that, The monosaccharide is at least one of the following components: Galactose, mannose, and glucose; The hydroxy fatty acid contains at least one of the following: 3-Hydroxyoctanoic acid, 3-Hydroxydecanoic acid, 3-Hydroxydodecanoic acid.

3. The low-foaming oil stain cleaner for mechanical parts according to claim 1, characterized in that, In step S1 of the method for preparing glycine-monoglycolipid, the molar ratio of glycine to hydroxy fatty acid is at least 1:4; the amount of lipase used is at least 10 wt% of the mass of glycine; the reaction time is at least 60°C and at least 24 h.

4. The low-foaming oil stain cleaner for mechanical parts according to claim 1, characterized in that, In step S2 of the method for preparing glycine-monosaccharide lipoester, the molar ratio of glycine-hydroxy fatty acid monoester, N-hydroxysuccinimide, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1: at least 1.2: at least 1.2; The amount of papain used is at least 5 wt% of glycine-hydroxy fatty acid monoester; the reaction time is at least 12 h.

5. The low-foaming oil stain cleaner for mechanical parts according to claim 1, characterized in that, In step S3 of the method for preparing the glycine-monoglycolipid, the molar ratio of glycine-hydroxy fatty acid monoester to monosaccharide is at least 1:1.2; the amount of glycosyltransferase used is at least 5 wt% of the mass of glycine-hydroxy fatty acid monoester. The reaction temperature is 36-38℃; the reaction time is at least 48 hours.

6. The low-foaming oil stain cleaner for mechanical parts according to claim 1, characterized in that, In step S4 of the method for preparing glycine-monoglycolipid, the molar ratio of glycine-monoglycolipid-hydroxy fatty acid monoester complex to hydroxy fatty acid is at least 1:4; the amount of lipase used is at least 10 wt% of the mass of glycine-monoglycolipid-hydroxy fatty acid monoester complex; the reaction time is at least 60°C and at least 24 h.

7. The low-foaming oil stain cleaner for mechanical parts according to claim 1, characterized in that, The low-foaming surfactant is at least one of the following components: Polyether-type nonionic surfactants, lauryl alcohol polyoxyethylene ether phosphate, and isooctyl alcohol polyoxyethylene ether phosphate.

8. The low-foaming oil stain cleaner for mechanical parts according to claim 1, characterized in that, The defoamer is polyoxypropylene polyoxyethylene ether.

9. The low-foaming oil stain cleaner for mechanical parts according to claim 1, characterized in that, The chelating agent is sodium pyrophosphate and / or sodium metasilicate.

10. The low-foaming oil stain cleaner for mechanical parts according to claim 1, characterized in that, The corrosion inhibitor is sodium benzoate and / or sodium nitrite.

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