Environment-friendly metal cutting fluid and preparation method thereof

Abstract

The present application belongs to the technical field of cutting fluid, and particularly relates to a green and environment-friendly metal cutting fluid and a preparation method thereof. According to mass fraction, the raw materials of the cutting fluid include: polyol ester 10-20%, high-molecular sugar polymer 0.2-2%, surfactant 20-45%, silicate 2-6%, antirust agent 0.5-4%, bactericide 0.1-1%, defoaming agent 0.1-1%, and water supplementing to 100%. The cutting fluid in the present application not only has excellent lubricity and antirust property, but also has excellent antifreezing property and hard water resistance.

Description

Technical Field

[0001] This invention belongs to the field of cutting fluid technology, specifically relating to a green and environmentally friendly metal cutting fluid and its preparation method. Background Technology

[0002] Metal cutting fluid is a liquid used for cooling and lubrication in metal processing. It plays a crucial role in metal cutting, grinding, drilling, and other machining processes, reducing friction between the tool and workpiece, extending tool life, improving machining accuracy and surface finish, and carrying away heat generated during cutting to prevent workpiece dimensional accuracy from being affected by thermal deformation. Metal cutting fluids typically consist of base oil, additives, and water (for water-soluble cutting fluids). Depending on their composition and application, they can be classified as oil-based cutting fluids, semi-synthetic cutting fluids, and fully synthetic cutting fluids. Proper selection and use of metal cutting fluids are essential for improving production efficiency and product quality. Compared to traditional cutting fluids, environmentally friendly cutting fluids place greater emphasis on environmental impact, typically containing little or no harmful chemicals, are easily biodegradable, and reduce potential harm to operator health and the environment.

[0003] Currently, research on environmentally friendly cutting fluids focuses primarily on enhancing their lubrication, cooling, and rust prevention capabilities. For example, CN118222350A is a water-based cutting fluid for aluminum alloys, made from organic amine compounds, organic acids, extreme pressure agents, surfactants, defoamers, corrosion inhibitors, bactericides, lubricants, and water. It is environmentally friendly, produces no smoke or odor during use, effectively improving the working environment and ensuring the health and safety of employees. Furthermore, this water-based cutting fluid combines the excellent lubricity of semi-synthetic cutting fluids with the cooling properties of fully synthetic cutting fluids, exhibiting stable performance and significantly extending tool life. However, cutting fluids may be exposed to low-temperature environments during transportation, and prolonged exposure to such environments can negatively impact their performance. Currently, there is almost no research on the antifreeze properties of cutting fluids. Summary of the Invention

[0004] The first aspect of this invention provides a green and environmentally friendly metal cutting fluid, wherein the raw materials of the cutting fluid, by mass fraction, include: 10-20% polyol ester, 0.2-2% high molecular weight sugar polymer, 20-45% surfactant, 2-6% silicate, 0.5-4% rust inhibitor, 0.1-1% bactericide, 0.1-1% defoamer, and water to 100%.

[0005] As a preferred embodiment of the present invention, the raw materials of the cutting fluid, by mass fraction, include: 15-18% polyol ester, 0.8-1.5% high molecular weight sugar polymer, 28-36% surfactant, 3-5% silicate, 1-3% rust inhibitor, 0.3-0.5% bactericide, 0.2-0.3% defoamer, and water to 100%.

[0006] As a preferred technical solution of the present invention, the raw materials of the cutting fluid, by mass fraction, include: 16% polyol ester, 1.2% high molecular weight sugar polymer, 33% surfactant, 4% silicate, 2% rust inhibitor, 0.4% bactericide, 0.25% defoamer, and water to 100%.

[0007] Polyol esters have certain lubricity and biodegradability. As a preferred technical solution of the present invention, the polyol ester is selected from at least one of pentaerythritol oleate, trimethylolpropane carboxylate and neopentyl glycol dioleate, preferably pentaerythritol oleate.

[0008] Existing metal cutting fluids have not been extensively studied for their antifreeze properties. However, the inventors of this invention discovered that metal cutting fluids may be exposed to cold environments before use, transportation, or application. Existing metal cutting fluids have poor antifreeze properties, which reduces their performance after exposure to cold environments. Existing antifreeze agents are generally small-molecule alcohols, which have low boiling points and are not suitable for use in metal cutting fluids. This may explain why existing cutting fluids cannot effectively overcome the antifreeze limitation. The inventors unexpectedly discovered that using high-molecular-weight sugar polymers in this invention can give the cutting fluid excellent antifreeze properties.

[0009] As a preferred embodiment of the present invention, the high molecular weight carbohydrate polymer is selected from at least one of sucrose, fructose, glucose, mannan and mannose, preferably mannan.

[0010] The mannan in this invention can be obtained commercially, preferably konjac mannan purchased from Jinan Shenghe Chemical Co., Ltd., with the model number XH52801QJCHP.

[0011] In particular, the use of mannan in this invention exhibits superior antifreeze properties. The reason for this is presumably that mannan interacts with water, exhibiting excellent flexibility at low temperatures. At the same time, mannan interacts with water through numerous hydrogen bonds, making the system structure more stable. The flexibility and stability at low temperatures reduce the formation of ice crystals. Even if ice crystals do form, the system's toughness provides excellent resilience when the cutting fluid returns to room temperature, thus having virtually no impact on the performance of the cutting fluid.

[0012] As a preferred embodiment of the present invention, the surfactant includes modified surfactants and cationic surfactants.

[0013] The method for preparing the modified surfactant includes:

[0014] (1) N-dodecylacrylamide and acrylonitrile are mixed to obtain a mixture. Then, chlorosulfonic acid is added dropwise to the mixture under dynamic mixing. After the addition is completed, the reaction continues for 4-7 hours to obtain reactant A.

[0015] (2) Add sodium hydroxide aqueous solution to reactant A to make the pH of the system 10-12 to obtain reactant B;

[0016] (3) The reactant B was vacuum evaporated to remove water, and then vacuum dried to obtain the modified surfactant.

[0017] The inventors discovered that using the modified surfactant in this invention can not only increase the lubricity of the cutting fluid, but also increase its resistance to hard water. This may be because the long alkyl chain in the modified surfactant can prevent the interaction of high molecular weight sugar polymers to form large molecules that affect the lubricity of the cutting fluid. At the same time, the imine group and the sulfonate at the tail end formed in the modified surfactant are less sensitive to metal ions, which is beneficial to improving the hard water resistance of the cutting fluid.

[0018] As a preferred embodiment of the present invention, the molar ratio of N-dodecylacrylamide to acrylonitrile is 1:(1-1.5).

[0019] As a preferred technical solution of the present invention, the conditions for dynamic mixing include: a temperature of 20-30℃ and a rotation speed of 200-400rpm.

[0020] As a preferred embodiment of the present invention, the dripping is completed within 1-1.5 hours.

[0021] As a preferred embodiment of the present invention, the concentration of the sodium hydroxide aqueous solution is 20-40 wt%.

[0022] As a preferred technical solution of the present invention, the temperature of the vacuum rotary evaporation for dehydration is 75-85℃.

[0023] As a preferred technical solution of the present invention, the vacuum drying conditions are: vacuum degree 0.06-0.085Mpa, temperature 70-80℃, and time 12-20h.

[0024] As a preferred embodiment of the present invention, the method for preparing the modified surfactant includes:

[0025] (1) N-dodecylacrylamide and acrylonitrile with a molar ratio of 1:(1-1.5) are mixed to obtain a mixture. Then, chlorosulfonic acid is added dropwise to the mixture at a temperature of 20-30℃ and a rotation speed of 200-400rpm. The chlorosulfonic acid is controlled to be added in 1-1.5 hours. After the chlorosulfonic acid is added, the reaction continues for 4-7 hours to obtain reactant A.

[0026] (2) Add a 20-40 wt% sodium hydroxide aqueous solution to reactant A to make the pH of the system 10-12 to obtain reactant B;

[0027] (3) The reactant B was vacuum evaporated at 75-85℃ to remove water, and then vacuum dried at 70-80℃ for 12-20h under vacuum conditions of 0.06-0.085Mpa and 70-80℃ to obtain the modified surfactant.

[0028] As a preferred embodiment of the present invention, the mass ratio of the modified surfactant to the cationic surfactant is 1:(0.5-1), preferably 1:(0.6-0.7).

[0029] As a preferred embodiment of the present invention, the surfactant is a modified surfactant and a cationic surfactant in a mass ratio of 1:(0.6-0.7).

[0030] The use of cationic surfactants in this invention, which interact with the specific modified surfactants of this invention, can better increase the lubricity of the cutting fluid. This may be because the modified surfactants are terminal anionic surfactants, which interact with the cationic surfactants to better form micelles in the system and can more quickly form a lubricating film on the substrate surface.

[0031] As a preferred embodiment of the present invention, the cationic surfactant is selected from imidazoline quaternary ammonium salts and / or long-chain quaternary ammonium salts, preferably imidazoline quaternary ammonium salts.

[0032] As a preferred embodiment of the present invention, the imidazoline quaternary ammonium salt is selected from tung oil acid imidazoline quaternary ammonium salt and / or castor oil rosin imidazoline quaternary ammonium salt, preferably tung oil acid imidazoline quaternary ammonium salt.

[0033] In this invention, the inventors unexpectedly discovered that the use of imidazoline quaternary ammonium salt cationic surfactants can further increase the rust prevention properties of cutting fluids, possibly because the imidazoline group can inhibit the formation of free radicals in high molecular weight sugar polymers, thus reducing the rust prevention properties of cutting fluids.

[0034] The addition of silicates in this invention can further increase the cutting fluid's resistance to hard water. It is speculated that this is because, under the synergistic effect of the modified surfactant, the Si-O- in silicates is not sensitive to the interaction with metal ions, and the cations in silicates can interact with the modified surfactant.

[0035] As a preferred embodiment of the present invention, the silicate is selected from inorganic silicates and / or organic silicates.

[0036] As a preferred embodiment of the present invention, the inorganic silicate is selected from at least one of sodium silicate, potassium silicate, sodium metasilicate, and potassium metasilicate.

[0037] As a preferred embodiment of the present invention, the organosilicon is selected from potassium propylsilicate and / or sodium propylsilicate.

[0038] Through experimental research, the inventors of this invention discovered that the use of organosilicon not only increases the hard water resistance of cutting fluid, but also improves the lubrication performance of cutting fluid to a certain extent due to the reduction caused by high molecular weight sugar polymers. This may be because the alkyl chains contained in organosilicon can prevent high molecular weight sugar polymers from forming gels in water. In addition, organosilicon also increases the rust prevention of cutting fluid to a certain extent.

[0039] As a preferred embodiment of the present invention, the rust inhibitor is selected from at least one of boric acid, sebacic acid, and benzotriazole, preferably benzotriazole.

[0040] As a preferred technical solution of the present invention, at least one of dicyclohexylamine, azole, thifluzamide and difenoconazole is used.

[0041] The defoamer in this invention can be a conventional polyether defoamer and / or silicone defoamer in the art, such as polyether defoamer PPG-1000.

[0042] The second aspect of this invention provides a method for preparing the green and environmentally friendly metal cutting fluid described in the first aspect of this invention, the method comprising:

[0043] Add 1 / 3 to 1 / 2 of the mass of surfactant and high molecular weight sugar polymer to polyol ester and heat to 50-60℃. After stirring for 20-40 minutes, stop heating. After reaching 20-30℃, add silicate, rust inhibitor, bactericide, defoamer and water and continue stirring for 20-30 minutes. Then add the remaining surfactant and stir for 20-40 minutes to obtain green and environmentally friendly metal cutting fluid.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] 1. The cutting fluid in this invention has excellent lubrication and wear resistance, which can reduce friction between the tool and the workpiece, extend tool life, and improve the surface finish of the machined surface. Furthermore, the cutting fluid can remove heat generated during machining, reducing the temperature of the workpiece and the tool, thereby improving machining efficiency and accuracy.

[0046] 2. The cutting fluid in this invention has excellent rust prevention properties, which can ensure the surface quality of the workpiece during the processing and storage period after processing, and avoid economic losses and scrapping of the workpiece caused by rust.

[0047] 3. The cutting fluid in this invention has excellent antifreeze properties and can be stored stably in cold environments;

[0048] 4. The cutting fluid in this invention has excellent resistance to hard water, ensuring that it can remain stable under hard water conditions and is not prone to reacting with minerals such as calcium and magnesium in the water to form precipitates, thereby ensuring the continuous effectiveness of its lubrication and cooling performance. Detailed Implementation

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] In the following embodiments:

[0051] The konjac glucomannan was purchased from Jinan Shenghe Chemical Co., Ltd., and its model number is XH52801QJCHP.

[0052] Example 1

[0053] Preparation of modified surfactants:

[0054] (1) N-dodecylacrylamide and acrylonitrile with a molar ratio of 1:1.2 were mixed to obtain a mixture. Then, chlorosulfonic acid was added dropwise to the mixture at a temperature of 25°C and a rotation speed of 300 rpm. The chlorosulfonic acid was controlled to be added in 1.2 hours. After the chlorosulfonic acid was completely added, the reaction continued for 5 hours to obtain reactant A.

[0055] (2) Add a 28wt% sodium hydroxide aqueous solution to reactant A to make the pH of the system 11.4 to obtain reactant B;

[0056] (3) The reactant B was dehydrated by vacuum rotary evaporation at 80°C, and then vacuum dried for 18 hours at a vacuum degree of 0.075 MPa and a temperature of 80°C to obtain the modified surfactant.

[0057] Preparation of cutting fluid raw materials: By mass fraction, prepare: pentaerythritol oleate 16%, konjac mannan 1.2%, surfactant 33% (a modified surfactant and tung oil acid imidazoline quaternary ammonium salt in a mass ratio of 1:0.65), potassium propylsilicate 4%, benzotriazole 2%.

[0058] Add 0.4% azole alcohol, 0.25% defoamer (polyether defoamer PPG-1000), and water to 100%.

[0059] Preparation of cutting fluid: Add 1 / 2 part by mass of surfactant and konjac mannan to pentaerythritol oleate and heat to 55°C. After stirring for 30 min, stop heating. At 25°C, add potassium propylsilicate, benzotriazole, azole alcohol, defoamer and water and continue stirring for 25 min. Then add the remaining surfactant and stir for 30 min to obtain green and environmentally friendly metal cutting fluid.

[0060] Example 2

[0061] Preparation of modified surfactants:

[0062] (1) N-dodecylacrylamide and acrylonitrile with a molar ratio of 1:1.5 were mixed to obtain a mixture. Then, chlorosulfonic acid was added dropwise to the mixture at a temperature of 25°C and a rotation speed of 300 rpm. The chlorosulfonic acid was controlled to be added in 1.5 hours. After the chlorosulfonic acid was added, the reaction continued for 4 hours to obtain reactant A.

[0063] (2) Add a 30wt% sodium hydroxide aqueous solution to reactant A to make the pH of the system 12 to obtain reactant B;

[0064] (3) The reactant B was dehydrated by vacuum rotary evaporation at 80°C, and then vacuum dried for 20 h at a vacuum degree of 0.75 MPa and a temperature of 72°C to obtain the modified surfactant.

[0065] Preparation of cutting fluid raw materials: By mass fraction, prepare: 12% pentaerythritol oleate, 0.5% konjac mannan, 35% surfactant (a modified surfactant and tung oil acid imidazoline quaternary ammonium salt in a mass ratio of 1:(0.6-0.7), 2% potassium propylsilicate, 1.5% benzotriazole, 0.2% azole alcohol, 0.3% defoamer (polyether defoamer PPG-1000), and water to 100%.

[0066] Preparation of cutting fluid: Add 1 / 2 part by mass of surfactant and konjac mannan to pentaerythritol oleate and heat to 60°C. After stirring for 20 minutes, stop heating. At 25°C, add potassium propylsilicate, benzotriazole, azole alcohol, defoamer and water and continue stirring for 30 minutes. Then add the remaining surfactant and stir for 30 minutes to obtain green and environmentally friendly metal cutting fluid.

[0067] Example 3

[0068] Preparation of modified surfactants:

[0069] (1) N-dodecylacrylamide and acrylonitrile with a molar ratio of 1:1.2 were mixed to obtain a mixture. Then, chlorosulfonic acid was added dropwise to the mixture at a temperature of 25°C and a rotation speed of 300 rpm. The chlorosulfonic acid was controlled to be added in 1.2 hours. After the chlorosulfonic acid was completely added, the reaction continued for 5 hours to obtain reactant A.

[0070] (2) Add a 28wt% sodium hydroxide aqueous solution to reactant A to make the pH of the system 11.4 to obtain reactant B;

[0071] (3) The reactant B was dehydrated by vacuum rotary evaporation at 80°C, and then vacuum dried for 18 hours at a vacuum degree of 0.075 MPa and a temperature of 80°C to obtain the modified surfactant.

[0072] Preparation of cutting fluid raw materials: By mass fraction, prepare: 20% pentaerythritol oleate, 2% konjac mannan, 35% surfactant (a modified surfactant and tung oil acid imidazoline quaternary ammonium salt in a mass ratio of 1:0.65), 6% potassium propylsilicate, 1% benzotriazole, 0.5% azole alcohol, 0.25% defoamer (polyether defoamer PPG-1000), and water to 100%.

[0073] Preparation of cutting fluid: Add 1 / 2 part by mass of surfactant and konjac mannan to pentaerythritol oleate and heat to 55°C. After stirring for 30 min, stop heating. At 25°C, add potassium propylsilicate, benzotriazole, azole alcohol, defoamer and water and continue stirring for 25 min. Then add the remaining surfactant and stir for 30 min to obtain green and environmentally friendly metal cutting fluid.

[0074] Comparative Example 1

[0075] The method according to Example 1 differs in that:

[0076] Use ethylene glycol to replace konjac mannan.

[0077] Comparative Example 2

[0078] The method according to Example 1 differs in that:

[0079] The surfactant is the modified surfactant from Example 1.

[0080] Comparative Example 3

[0081] The method according to Example 1 differs in that:

[0082] The surfactant is the tung oil acid imidazoline quaternary ammonium salt from Example 1.

[0083] Comparative Example 4

[0084] The method according to Example 1 differs in that:

[0085] Replace tung oil acid imidazoline quaternary ammonium salt with dodecyl dimethyl benzyl ammonium chloride.

[0086] Comparative Example 5

[0087] The method according to Example 1 differs in that:

[0088] Replace potassium propyl silicate with sodium silicate.

[0089] Performance testing

[0090] 1. Lubricity test:

[0091] The maximum non-seize load (P) of the cutting fluid in the examples and comparative examples was tested according to GB / T 3142-2019. B The higher the maximum non-seize load ( / N), the better the lubricity of the cutting fluid.

[0092] 2. Rust prevention

[0093] The cutting fluids in the examples and comparative examples were subjected to a first-level gray cast iron corrosion test and a copper corrosion test, in accordance with GB / T 6144-1985.

[0094] 3. Antifreeze properties

[0095] The cutting fluid was placed in an environment of -10±2℃ for 12 hours, then removed and allowed to return to room temperature before being shaken and tested for its maximum non-seize load (PB / N). The reduction rate of its maximum non-seize load (PB / N) was calculated compared with that of the cutting fluid before placement.

[0096] 4. Resistance to hard water

[0097] The cutting fluids in the examples and comparative examples were diluted with water with a hardness of 20 to a concentration of 5 wt% to obtain a diluted solution. The diluted solution was poured into a 100 mL graduated cylinder and allowed to stand for 1 hour at a temperature of 25℃±2℃. If there was no floating soap in the diluted solution, it was considered qualified; otherwise, it was considered unqualified.

[0098] The test results are shown in Table 1.

[0099]

[0100] As can be seen from the above performance test results, the cutting fluid in this invention not only has excellent lubricity and rust prevention, but also excellent antifreeze and hard water resistance.

[0101] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A green and environmentally friendly metal cutting fluid, characterized in that, The raw materials of this cutting fluid, by mass fraction, include: 10-20% polyol esters, 0.2-2% mannan, 20-45% surfactants, 2-6% silicates, 0.5-4% rust inhibitors, 0.1-1% bactericides, 0.1-1% defoamers, and water to 100%. The surfactants include modified surfactants and cationic surfactants; The silicate is selected from inorganic silicates and / or organic silicates; The organosilicon is selected from potassium propylsilicate and / or sodium propylsilicate; The method for preparing the modified surfactant includes: (1) N-dodecylacrylamide and acrylonitrile are mixed to obtain a mixture. Then, chlorosulfonic acid is added dropwise to the mixture under dynamic mixing. After the addition is completed, the reaction continues for 4-7 hours to obtain reactant A. (2) Add sodium hydroxide aqueous solution to reactant A to make the pH of the system 10-12 to obtain reactant B; (3) The reactant B was vacuum evaporated to remove water, and then vacuum dried to obtain the modified surfactant.

2. The green and environmentally friendly metal cutting fluid according to claim 1, characterized in that, The polyol ester is selected from at least one of pentaerythritol oleate, trimethylolpropane carboxylate, and neopentyl glycol dioleate.

3. The green and environmentally friendly metal cutting fluid according to claim 1, characterized in that, The molar ratio of N-dodecylacrylamide to acrylonitrile is 1:(1-1.5); the dynamic mixing conditions include: a temperature of 20-30℃ and a rotation speed of 200-400 rpm; the dropping is completed within 1-1.5 hours.

4. The green and environmentally friendly metal cutting fluid according to claim 1, characterized in that, The mass ratio of the modified surfactant to the cationic surfactant is 1:(0.5-1).

5. The green and environmentally friendly metal cutting fluid according to claim 4, characterized in that, The mass ratio of the modified surfactant to the cationic surfactant is 1:(0.6-0.7).

6. The green and environmentally friendly metal cutting fluid according to claim 1, characterized in that, The cationic surfactant is an imidazoline quaternary ammonium salt, which is selected from tung oil acid imidazoline quaternary ammonium salt and / or castor oil rosin imidazoline quaternary ammonium salt.

7. The green and environmentally friendly metal cutting fluid according to any one of claims 1-6, characterized in that, The rust inhibitor is selected from at least one of boric acid, sebacic acid, and benzotriazole.

8. A method for preparing a green and environmentally friendly metal cutting fluid according to any one of claims 1-7, characterized in that, Preparation methods include: Add 1 / 3 to 1 / 2 of the mass of surfactant and mannan to the polyol ester and heat to 50-60℃. Stir for 20-40 minutes and then stop heating. At 20-30℃, add silicate, rust inhibitor, bactericide, defoamer and water and continue stirring for 20-30 minutes. Then add the remaining surfactant and stir for 20-40 minutes to obtain a green and environmentally friendly metal cutting fluid.

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