A fully synthetic easy-to-clean copper cutting fluid and a method for preparing the same

Abstract

The present application relates to a kind of full synthesis easy-to-clean copper cutting fluid and its preparation method.The raw material of the full synthesis copper cutting fluid includes composite rust inhibitor, chelating agent, special amine, aluminum copper corrosion inhibitor, lubricant, defoaming agent and solvent, and the composite rust inhibitor is composed of sebacic acid and dodecanedioic acid.The composite rust inhibitor can overcome discoloration corrosion well, has obvious cost advantage, and will not produce obvious color residue, can meet the existing user demand.Sebacic acid and dodecanedioic acid are not long carbon chain (C10 / C12) can be embedded in the gap of lubricating film, improve boundary lubrication performance, make friction coefficient reduce 5~8%, adapt to medium-low speed heavy load processing, not easy to break in long-term cyclic use (>6 months), especially suitable for the processing of nickel-containing copper alloy, can reduce the risk of pitting.

Description

Technical Field

[0001] This invention relates to the field of lubricating composition technology, and in particular to a fully synthetic easy-to-clean copper cutting fluid and its preparation method. Background Technology

[0002] In the field of precision cutting of copper and copper alloys (such as beryllium copper, cobalt copper, brass, etc.) (including milling, drilling, turning, etc.), fully synthetic water-based cutting fluids have gradually replaced emulsions and semi-synthetic cutting fluids and become the mainstream choice for high-end copper processing scenarios due to their advantages such as good environmental protection, high cooling efficiency, long service life and less sludge generation.

[0003] If the fully synthetic cutting fluid in contact with copper and copper alloy workpieces has insufficient rust prevention after machining, oxidation corrosion and discoloration will easily occur on the workpiece surface. This will cause the workpiece surface to gradually change from its original metallic luster to dark red, brown or even black spots. In severe cases, a continuous corrosion layer will form, and the corrosion area will be concentrated in the cutting edge, workpiece groove and other areas where cutting fluid is likely to remain.

[0004] For cobalt-containing copper alloys, existing fully synthetic cutting fluids still exhibit the unique problem of copper and cobalt ion precipitation. After a period of use, the cutting fluid gradually changes color from transparent or pale yellow to bluish-green, and in some scenarios, flocculent precipitation occurs. Ion detection reveals the presence of Cu ions in the cutting fluid. 2+ Concentrations can reach 50~200 ppm, Co 2+ The concentration can reach 10-50 ppm, and continues to increase with prolonged use. Firstly, the precipitated copper and cobalt ions contaminate the cutting fluid, reacting with carboxylic acid-based rust inhibitors and polyether-based lubricants in the formula to form water-insoluble complexes. This significantly reduces the lubricity and rust prevention properties of the cutting fluid, thereby exacerbating tool wear. Secondly, high concentrations of metal ions clog the cutting fluid's filtration system (such as filter elements and screens), increasing equipment maintenance frequency and costs. Finally, the presence of heavy metal ions (Co...)... 2+ Improper handling of cutting fluid can increase the difficulty of wastewater treatment and fail to meet environmental emission standards.

[0005] To address these issues, the industry has proposed several solutions. For example, some solutions increase the amount of rust inhibitors (such as BTA) to overcome discoloration corrosion, but this increases the cost of cutting fluid. Excessive BTA can also leave white residue on the workpiece surface, affecting subsequent electroplating and welding processes. To inhibit copper and cobalt precipitation, some solutions lower the pH of the cutting fluid to 8.0-8.5, but this accelerates microbial growth and shortens the lifespan of the cutting fluid from 6-12 months to 3-6 months, thus increasing replacement costs. Summary of the Invention

[0006] The purpose of this invention is to disclose a fully synthetic easy-to-clean copper cutting fluid and its preparation method, so as to solve one or more technical problems existing in the prior art and provide at least one beneficial option or create conditions.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention is to provide a fully synthetic copper cutting fluid. The raw materials of the fully synthetic copper cutting fluid include a composite rust inhibitor, a chelating agent, a special amine, an aluminum-copper corrosion inhibitor, a lubricant, a defoamer, and a solvent. The composite rust inhibitor is composed of sebacic acid and dodecanoic acid. This composite rust inhibitor effectively overcomes discoloration corrosion, has a significant cost advantage, and does not produce noticeable color residue, thus meeting the needs of existing users. Both sebacic acid and dodecanoic acid have short carbon chains (C10 / C12) that can embed into the gaps in the lubricating film, improving boundary lubrication performance and reducing the coefficient of friction by 5-8%. It is suitable for medium-to-low speed, heavy-load machining and is not prone to cracking during long-term cyclic use (>6 months), making it particularly suitable for machining nickel-containing copper alloys and reducing the risk of pitting corrosion.

[0008] In some embodiments of the first aspect of the present invention, the chelating agent is an EDTA salt; preferably, the chelating agent is EDTA-2Na. EDTA-2Na strongly chelates copper and cobalt ions (complexation stability constant > 16), thereby removing free Cu from the cutting fluid. 2+ The concentration was reduced to below 5 ppm and the CoEDTA-2Na concentration was reduced to below 3 ppm to avoid the reaction of metal ions with other additives to form flocculent substances.

[0009] In some embodiments of the first aspect of the present invention, the special amine is selected from at least one of diethylene glycolamine, 2-amino-2-methyl-1-propanol, Clariant CH020, and n-butyldiethanolamine. The primary amine structure of the diethylene glycolamine (DGA) can stabilize the pH of the cutting fluid in the range of 8.5 to 10.0, neutralize microbial metabolic acids and carbon dioxide, and prevent system acidification leading to the failure of the corrosion inhibitor film. Simultaneously, the hydroxyl and amino groups in the molecule synergistically adsorb onto the metal surface, forming a protective film and reducing Co in the machining of cobalt-containing copper alloys. 2+ The leaching of copper ions (concentration <10ppm) enhances the adsorption stability of azole corrosion inhibitors. The DGA reacts with sebacic acid to form a fatty acid amine salt, creating a dense hydrophobic film on the copper surface. This blocks the contact between water, oxygen, and copper, controlling the copper ion leaching to below 8ppm and preventing dark red oxide spots from appearing on the workpiece surface. The steric hindrance effect of the tertiary amine structure of Clariant CH020 reduces the complexation of amine groups with metal ions, and, combined with the hydrophobic segments, enhances the density of the protective film, allowing Cu... 2+ Concentration <20ppm, Co 2+Concentration <15ppm; it can also reduce the interfacial tension between oil and water, allowing lubricants and corrosion inhibitors to be evenly dispersed in hard water, avoiding stratification, and extending the life of cutting fluid from 6 months to more than 9 months.

[0010] In some embodiments of the first aspect of the present invention, the aluminum-copper corrosion inhibitor is selected from at least one of octyl phosphate corrosion inhibitors, phosphate ester derivative corrosion inhibitors, and methyltriazole derivative corrosion inhibitors. Preferably, the octyl phosphate corrosion inhibitor is Clariant OPS75, which can disperse polyether and fatty acid to form a uniform lubrication system; the phosphate ester groups adsorb onto the metal surface, helping to reduce the coefficient of friction to below 0.08; the surface tension is reduced to below 28 mN / m, improving the spreadability of the cutting fluid, while the foam height is <5 mm under high-pressure spraying (>20 MPa); it chelates calcium and magnesium ions, making it suitable for hard water formulations. The phosphate ester derivative corrosion inhibitor is selected from Solvay AS010, whose phosphate ester groups undergo a tribochemical reaction with the tool surface to generate a FePO4 low-shear film, reducing tool wear by 50%, suitable for high-speed milling of cobalt-containing copper alloys, and can also synergize with nitrogen heterocyclic structures to both inhibit copper ion dissolution (<10 ppm) and chelate Co. 2+ It is a core component with dual functions of lubrication and corrosion inhibition. The methyltriazole derivative corrosion inhibitor is selected from BASF 42. It forms coordination bonds with the active sites on the copper surface to build a monolayer protective film, which specifically inhibits the oxidation and discoloration of copper and copper alloys. It is especially suitable for precision electronic copper parts, with low dosage and no risk of residue.

[0011] In some embodiments of the first aspect of the invention, the lubricant comprises a block copolymer, an unsaturated fatty acid, and a polyol; preferably, the block copolymer is selected from at least one of BASF 1720, BASF 1740, Clariant Emulsogen LRO, and Dow UCON LB-625. The block copolymer contains EO segments with a trans-polyether structure that provide hydrophilicity, and PO segments that form a lubricating film with a friction coefficient as low as 0.07, suitable for high-speed cutting scenarios using fully synthetic cutting fluids; its low-foaming properties (foam height < 5 mm) prevent foam overflow from the circulating system. The unsaturated fatty acid is palmitoleic acid, whose long C16 carbon chain can be embedded in the gaps of the polyether lubricating film, enhancing the film's density through chemical adsorption, reducing torque fluctuation by 40% under low-speed, heavy-load conditions; the fatty acid amine salt generated by the reaction with DGA can further enhance the corrosion inhibition effect. The polyol is selected from at least one of glycerol, tetraglycerol and sorbitol. Its hydroxyl groups form hydrogen bonds with fatty acids and polyethers, which improves the miscibility of the lubricating components and avoids stratification. At the same time, it helps to reduce the coefficient of friction, especially at low temperatures (<5°C) to prevent the lubricating film from becoming embrittled.

[0012] In some embodiments of the first aspect of the present invention, the defoamer includes a modified silicone defoamer and a polyether-modified silicone defoamer; preferably, the modified silicone defoamer is Dow Corning 3168; preferably, the polyether-modified silicone defoamer is Mengqingxin 575. The combination of the defoamers can achieve three core functions—rapid defoaming, long-lasting foam suppression, and wide-range adaptability—through molecular-level synergy.

[0013] In some embodiments of the first aspect of the present invention, the mass percentage of the raw materials is as follows: solvent 60-65%, composite rust inhibitor 5-8%, chelating agent 1-3%, special amine 5-8%, aluminum-copper corrosion inhibitor 4-6%, lubricant 23-30%, and defoamer 0.1-0.2%.

[0014] The preparation method provided by the second aspect of the present invention includes the following steps: 1) Add solvent to the container, then add the composite rust inhibitor, chelating agent, and special amine and stir until homogeneous; 2) Add aluminum-copper corrosion inhibitor to the container and stir well; 3) Add lubricant and stir well; 4) Add defoamer and stir well to obtain the final product.

[0015] Compared with existing similar products, the present invention has the following advantages: (1) All performance indicators meet or exceed the relevant indicators of GB / T 6144-2010, and can completely replace similar products at home and abroad; (2) It has good lubricity and can be used in various processes such as CNC, machining lathe, milling machine, and sawing machine. It can also be used for tapping and thread tapping, which can improve the machining accuracy of the workpiece while effectively reducing tool wear and increasing the tool life. (3) This product has a good cleaning function and an effective refraction of 40±1%. While keeping the workpiece surface clean and bright, it has a good cleaning effect and can effectively protect the machine tool. (4) It has good antioxidant properties, which can extend the service life of the oil and protect the machine. It contains special additives that can effectively prevent cobalt precipitation and prevent the working fluid from turning blue during processing. (5) It can adapt to the processing of non-ferrous metal workpieces such as aluminum and copper without changing the color of the workpiece, especially providing good protection for the surface of copper workpieces. (6) It has excellent flushing and cooling performance, which can reduce the amount of coolant carried out, while keeping the tool and workpiece clean; (7) This product can be used for a long time. The working fluid can be reused and can be used for a long time without replacing the new fluid. Just monitor and maintain the product, replenish the new fluid in time, and keep it at a certain concentration for long-term use. (8) It has good anti-rust performance for machine tools, does not damage the paint, and is compatible with commonly used machine tool seals; (9) The formula does not contain chlorine, sulfur, boron, phenols and nitrites, nor does it contain toxic and harmful substances such as sulfur. It is harmless to the human body and has no impact on the environment. It is an environmentally friendly product. Attached Figure Description

[0016] Figure 1 These are photos of immersion experiments with copper and brass. Detailed Implementation

[0017] Example 1: Preparation of No. 1 fully synthetic copper cutting fluid This embodiment provides a preparation process for a fully synthetic copper cutting fluid. The materials are prepared according to the following mass ratios: deionized water 47.9%, sebacic acid 2.5%, dodecanoic acid 2.5%, ETDA-2Na 1%, diethylene glycolamine 2.5%, Clariant CHO2O 2.5%, Clariant OPS75 2%, Solvay AS010 2%, BASF 42 2%, BASF 1720 5%, BASF 1740 15%, polyether ester 5%, palmitoleic acid 5%, glycerin 5%, and defoamer 0.1%.

[0018] The specific steps include: 1) Add solvent to the container, then add the composite rust inhibitor, chelating agent, and special amine and stir until homogeneous; 2) Add aluminum-copper corrosion inhibitor to the container and stir well; 3) Add lubricant and stir well; 4) Add defoamer and stir well to obtain a clear and transparent finished product concentrate.

[0019] The above concentrate can be diluted 20 times before use.

[0020] Example 2: Preparation of No. 2 fully synthetic copper cutting fluid This embodiment provides a preparation process for a fully synthetic copper cutting fluid. The materials are prepared according to the following mass ratios: deionized water 47.9%, sebacic acid 2.5%, dodecanoic acid 2.5%, ETDA-2Na 1%, diethylene glycolamine 2.5%, Clariant CHO2O 2.5%, Clariant OPS75 2%, Solvay AS010 2%, BASF 42 2%, BASF 1720 8%, BASF 1740 12%, polyether ester 5%, palmitoleic acid 5%, glycerin 5%, and defoamer 0.1%.

[0021] Example 3: Preparation of No. 3 fully synthetic copper cutting fluid This embodiment provides a preparation process for a fully synthetic copper cutting fluid. The materials are prepared according to the following mass ratios: deionized water 47.8%, sebacic acid 2.5%, dodecanoic acid 2.5%, ETDA-2Na 1%, diethylene glycolamine 2.5%, Clariant CHO2O 2.5%, Clariant OPS75 2%, Solvay AS010 2%, BASF 42 2%, BASF 1720 13%, BASF 1740 7%, polyether ester 5%, palmitoleic acid 5%, glycerin 5%, and defoamer 0.2%.

[0022] Example 4: Preparation of No. 4 fully synthetic copper cutting fluid This embodiment provides a preparation process for a fully synthetic copper cutting fluid. The materials are prepared according to the following mass ratios: deionized water 47.8%, sebacic acid 2.5%, dodecanoic acid 2.5%, ETDA-2Na 1%, diethylene glycolamine 2.5%, Clariant CHO2O 2.5%, Clariant OPS75 2%, Solvay AS010 2%, BASF 42 2%, BASF 1720 15%, BASF 1740 5%, polyether ester 5%, palmitoleic acid 5%, glycerin 5%, and defoamer 0.2%.

[0023] Example 5: Preparation of No. 5 fully synthetic copper cutting fluid This embodiment provides a preparation process for a fully synthetic copper cutting fluid. The materials are prepared according to the following mass ratios: deionized water 49.9%, sebacic acid 2.5%, dodecanoic acid 2.5%, ETDA-2Na 1%, diethylene glycolamine 2.5%, Clariant CHO2O 2.5%, Clariant OPS75 2%, Solvay AS010 2%, BASF 4 2%, BASF 1720 23%, palmitoleic acid 5%, glycerin 5%, and defoamer 0.1%.

[0024] Immersion experiments were conducted on common copper and brass to verify the performance of the fully synthetic copper cutting fluid. Results are as follows: Figure 1 As shown, neither of the two copper sheets exhibited any adverse reactions such as corrosion or discoloration after being immersed in the fully synthetic copper cutting fluid of Example 1. The formulation contains two polyethers, BASF 1720 and BASF 1740. 1720, due to its lower EO (ethylene oxide) number, is slightly oleophilic and more lubricating, while 1740, with its higher EO number, is more hydrophilic and has better cleaning properties. Therefore, through experiments with different components, a 50% addition of each was found to be optimal, achieving both lubrication and better cleaning performance when combined with the polyether grease.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A fully synthetic copper cutting fluid, characterized in that, The raw materials include a composite rust inhibitor, a chelating agent, a special amine, an aluminum-copper corrosion inhibitor, a lubricant, a defoamer, and a solvent. The composite rust inhibitor is composed of sebacic acid and dodecanoic acid.

2. The fully synthetic copper cutting fluid according to claim 1, characterized in that, The chelating agent is an EDTA salt; preferably, the chelating agent is EDTA-2Na.

3. The fully synthetic copper cutting fluid according to claim 1, characterized in that, The special amine is selected from at least one of diethylene glycolamine, 2-amino-2-methyl-1-propanol, Clariant CH020, and n-butyldiethanolamine.

4. The fully synthetic copper cutting fluid according to claim 1, characterized in that, The aluminum-copper corrosion inhibitor is selected from at least one of octyl phosphate corrosion inhibitors, phosphate ester derivative corrosion inhibitors, and methyltriazole derivative corrosion inhibitors.

5. The fully synthetic copper cutting fluid according to claim 1, characterized in that, The lubricant comprises block copolymers, unsaturated fatty acids, and polyols; preferably, the block copolymer is selected from at least one of BASF 1720, BASF 1740, Clariant Emulsogen LRO, and Dow UCON LB-625.

6. The fully synthetic copper cutting fluid according to claim 5, characterized in that, The unsaturated fatty acid is palmitoleic acid.

7. The fully synthetic copper cutting fluid according to claim 5 or 6, characterized in that, The polyol is selected from at least one of glycerol, tetraglycerol and sorbitol.

8. The fully synthetic copper cutting fluid according to claim 1, characterized in that, The defoamer includes a modified silicone defoamer and a polyether modified silicone defoamer; preferably, the modified silicone defoamer is Dow Corning 3168; preferably, the polyether modified silicone defoamer is Mengqingxin 575.

9. The fully synthetic copper cutting fluid according to claim 1, characterized in that, The raw materials are as follows by weight percentage: solvent 60-65%, composite rust inhibitor 5-8%, chelating agent 1-3%, special amine 5-8%, aluminum and copper corrosion inhibitor 4-6%, lubricant 23-30%, and defoamer 0.1-0.2%.

10. A method for preparing the fully synthetic copper cutting fluid according to any one of claims 1 to 9, characterized in that, Including the following steps: 1) Add solvent to the container, then add the composite rust inhibitor, chelating agent, and special amine and stir until homogeneous; 2) Add aluminum-copper corrosion inhibitor to the container and stir well; 3) Add lubricant and stir well; 4) Add defoamer and stir well to obtain the final product.

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