Aluminum alloy battery shell drawing oil and preparation method thereof

Abstract

The present application relates to the technical field of drawing oil, and particularly relates to a kind of aluminum alloy battery shell drawing oil and its preparation method, the present application takes refined mineral oil, antioxidant, low viscosity synthetic ester, extreme pressure agent, surface penetrant as raw material, under the low viscosity of 100-115cSt, through the chemical film forming mode of three components cooperation of high activity extreme pressure agent, low viscosity synthetic ester and surface penetrant, effectively prevent the problems of sticking die and drawing injury.The present application through the synergistic effect of low viscosity of 100-115cSt and surface penetrant, cleaning time is shortened to less than one fourth of traditional high viscosity product, greatly reduces the energy consumption, material consumption and waste liquid treatment cost of subsequent process.The present application has excellent antioxidant property, low viscosity environment is conducive to the rapid settlement and filtration purification of pollutants such as aluminum powder, the long service life and easy purification characteristics of oil product are mutually synergistic, and effective cycle number is increased by more than two times compared with traditional product.

Description

Technical Field

[0001] This invention relates to the field of stretching oil technology, specifically to a stretching oil for aluminum alloy battery casings and its preparation method. Background Technology

[0002] Aluminum alloys are the preferred material for power battery casings due to their low density, high specific strength, and excellent thermal conductivity. However, aluminum alloys are soft and chemically reactive. During stretching and forming, the nascent metal surface comes into close contact with the mold under high pressure and high temperature, which can easily lead to serious defects such as sticking to the mold, tearing, or even breakage.

[0003] To overcome the sticking problem, existing drawing oils generally employ a strategy of increasing viscosity, preventing direct metal-to-metal contact by creating a thicker physical barrier film between the die and the workpiece. These products typically have a kinematic viscosity as high as 150-170 cSt at 40°C. While this alleviates sticking to some extent, it presents the following problems: Cleaning is extremely difficult: the high viscosity causes a large amount of grease to adhere firmly to the complex surface and micropores of the molded parts. Subsequent cleaning processes require high concentrations, high temperatures, and long durations, resulting in extremely high energy consumption and cleaning agent costs, and generating a large amount of oily wastewater.

[0004] Poor recyclability: To reduce costs and waste, drawing oils are typically recycled after sedimentation and filtration. However, high-viscosity oils have a strong encapsulating effect on the fine aluminum powder generated during drawing, resulting in extremely slow settling. After simple filtration and regeneration, the suspended hard particles in the oil can actually act as abrasives, exacerbating stringing and die sticking. Furthermore, after repeated thermal cycling and shearing, the viscous sludge generated by oxidation of high-viscosity oil combines with the aluminum powder to form a stubborn scale layer, further complicating cleaning and worsening recyclability.

[0005] It is evident that in order to prevent sticking to the mold, one must bear the high cost of difficult cleaning and short cycle life, and there is currently no effective way to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a low-viscosity aluminum alloy battery casing stretching oil that is non-stick, easy to clean, and has good cycle performance, as well as its preparation method, thereby solving the technical problems mentioned in the background art.

[0007] The objective of this invention is achieved through the following technical solution: an aluminum alloy battery casing stretching oil, composed of the following components in parts by weight: 70-88 parts refined mineral oil Antioxidant 1-5 parts 5-10 parts of low viscosity synthetic ester 5-10 parts of extreme pressure agent 1-5 parts of surface penetrant.

[0008] Preferably, the refined mineral oil is a paraffinic base oil with a kinematic viscosity of 80-100 cSt at 40°C, which provides a basis for formulating a low-viscosity product of 100-115 cSt.

[0009] Preferably, the antioxidant is an amine antioxidant, specifically an alkylated diphenylamine or N-phenyl-α-naphthylamine.

[0010] Preferably, the low-viscosity synthetic ester has a kinematic viscosity of 10-40 cSt at 40°C.

[0011] Preferably, the low-viscosity synthetic ester is one or more selected from diisooctyl adipate, trimethylolpropane oleate, and neopentyl glycol dioleate. This type of ester possesses excellent lubricity, good solubility for extreme pressure agents, and easy cleaning properties.

[0012] Preferably, the extreme pressure agent is a mixture of methyl oleate and triglyceride in a mass ratio of (2-4):1. During stretching, methyl oleate reacts the fastest, rapidly forming a hard extreme pressure film to prevent welding; while triglyceride provides long-lasting lubrication, its soft oil film filling the gaps in the hard film, making sliding smoother, and simultaneously suppressing the corrosion risk of highly reactive sulfur.

[0013] Preferably, the surface penetrant is a C12-15 branched carbonyl synthetic alcohol. The unique branched structure of the C12-15 branched carbonyl synthetic alcohol endows it with an extremely low pour point and excellent penetrating power. In low-viscosity stretching oil systems, it can spread instantly on nascent metal surfaces, effectively reducing interfacial tension and facilitating rapid film formation of extreme pressure agents, thus solving the problem of difficult cleaning with traditional high-viscosity oils.

[0014] More preferably, the hydroxyl value of the C12-15 branched carbonyl synthetic alcohol is 250-280 mg KOH / g, and ExxonMobil Exxal™ 13 can be used.

[0015] A method for preparing a stretching oil for aluminum alloy battery casings, comprising the following process steps: Step (1) Add the refined mineral oil to the mixing vessel according to the formula amount and heat to 50-60℃; Step (2) While stirring, add the extreme pressure agent, low viscosity synthetic ester and antioxidant in sequence, and continue stirring for 25-35 minutes; In step (3), add the surface penetrant and continue stirring and dispersing for 15-25 minutes to obtain an aluminum alloy battery casing stretching oil.

[0016] Preferably, step (3) yields an aluminum alloy battery casing stretching oil with a viscosity of 100-115 cSt.

[0017] The mechanism of action of this invention is as follows: First, this invention abandons the traditional anti-sticking method of drawing oils that relies on high-viscosity physical thick films. Instead, it adopts a chemical film-forming mechanism with the synergistic action of three components: a highly active extreme pressure agent, a low-viscosity synthetic ester, and a surface penetrant. The surface penetrant, with its ultra-low surface tension and strong spreading ability, first penetrates and opens the chemical channels in the nanoscale micro-gap between the mold and the workpiece. The low-viscosity synthetic ester, as a highly efficient carrier, carries the extreme pressure agent along these channels to rapidly penetrate deep into the plastic deformation zone, forming a physical lubrication pre-film before the extreme pressure agent reacts. The sulfurized methyl oleate in the extreme pressure agent preferentially reacts with the newly formed aluminum alloy surface under instantaneous high temperature and pressure, generating a dense sulfurized extreme pressure chemical film. The sulfurized triglyceride continues to form a soft lubricating film to fill the defects in the hard film. These three components form a progressive synergy of opening channels, transporting components, and generating film layers, resulting in rapid and complete film formation. This allows the invention to achieve superior anti-sticking reliability even at a kinematic viscosity of only 100-115 cSt at 40℃ (approximately 35% lower than traditional products).

[0018] Secondly, the low viscosity (100-115 cSt) of this invention significantly reduces the amount of drawing oil residue on the workpiece, greatly decreasing its cohesive energy and physical adhesion to the metal. Based on this, the surface penetrant can rapidly migrate to the oil-water interface during the cleaning process, producing efficient emulsification, entrainment, and dispersion of residual oil. This synergistic effect of low viscosity physical weight reduction and active stripping by the surface penetrant enables a clean surface to be obtained under low temperature, low concentration, and short cleaning time conditions, completely solving the shortcomings of traditional high-viscosity oil cleaning, which is time-consuming and costly.

[0019] Third, the carefully selected paraffinic base oil and amine antioxidants of this invention endow the oil with excellent antioxidant stability, inhibiting the formation of gums and sludge at high temperatures from the source. Simultaneously, the low viscosity environment of 100-115 cSt facilitates the rapid settling and filtration of solid contaminants such as aluminum powder mixed in during recycling. The purified recycled oil has a purity close to that of new oil, greatly mitigating secondary wear and catalytic oxidation induced by contaminant particles. The oil's long lifespan and easy-to-maintain cleanliness physical properties work together to create a significantly extended cycle life, with more than twice the number of cycles compared to traditional products.

[0020] The beneficial effects of this invention are as follows: Using refined mineral oil, antioxidants, low-viscosity synthetic esters, extreme pressure agents, and surface penetrants as raw materials, this invention effectively prevents sticking and tearing by employing a synergistic chemical film-forming mechanism involving a highly active extreme pressure agent, low-viscosity synthetic ester, and surface penetrant at a low viscosity of 100-115 cSt. Through the synergistic effect of the low viscosity (100-115 cSt) and the surface penetrant, the cleaning time is reduced to less than one-quarter of that of traditional high-viscosity products, significantly reducing energy consumption, material consumption, and wastewater treatment costs in subsequent processes. This invention exhibits excellent antioxidant properties; the low viscosity environment facilitates the rapid sedimentation and filtration purification of contaminants such as aluminum powder; and the oil's long lifespan and easy purification characteristics work synergistically, increasing the effective cycle count by more than two times compared to traditional products. Detailed Implementation

[0021] The present invention will be further described in conjunction with the following embodiments.

[0022] Example 1

[0023] An aluminum alloy battery casing stretching oil, comprising the following components in parts by weight: 70 parts refined mineral oil 1 part antioxidant 5 parts of low viscosity synthetic ester 5 parts extreme pressure agent 1 part surface penetrant.

[0024] The refined mineral oil is a paraffinic base oil with a kinematic viscosity of 100 cSt at 40°C.

[0025] The antioxidant is an amine antioxidant, and the amine antioxidant is alkylated diphenylamine.

[0026] The low-viscosity synthetic ester has a kinematic viscosity of 10 cSt at 40°C.

[0027] The low-viscosity synthetic ester is diisooctyl adipate.

[0028] The extreme pressure agent is a mixture of methyl oleate and triglyceride in a mass ratio of 2:1.

[0029] The surface penetrant is a C12-15 branched carbonyl synthetic alcohol. The hydroxyl value of the C12-15 branched carbonyl synthetic alcohol is 250-280 mg KOH / g, specifically ExxonMobil Exxal™ 13.

[0030] A method for preparing a stretching oil for aluminum alloy battery casings, comprising the following process steps: Step (1) Add the refined mineral oil to the mixing vessel according to the formula amount and heat to 50°C; Step (2) While stirring, add the extreme pressure agent, low viscosity synthetic ester and antioxidant in sequence, and continue stirring for 25 minutes; In step (3), the surface penetrant is added and the mixture is stirred and dispersed for 15 minutes to obtain an aluminum alloy battery casing stretching oil.

[0031] In step (3), the viscosity of the stretching oil for aluminum alloy battery casing is 102 cSt.

[0032] Example 2

[0033] An aluminum alloy battery casing stretching oil, comprising the following components in parts by weight: 80 parts refined mineral oil 3 parts antioxidant 7 parts of low viscosity synthetic ester 7 parts extreme pressure agent 3 parts surface penetrant.

[0034] The refined mineral oil is a paraffinic base oil with a kinematic viscosity of 90 cSt at 40°C.

[0035] The antioxidant is an amine antioxidant, specifically N-phenyl-α-naphthylamine.

[0036] The low-viscosity synthetic ester has a kinematic viscosity of 30 cSt at 40°C.

[0037] The low-viscosity synthetic ester is trimethylolpropane oleate.

[0038] The extreme pressure agent is a mixture of methyl oleate and triglyceride in a mass ratio of 3:1.

[0039] The surface penetrant is a C12-15 branched carbonyl synthetic alcohol. The hydroxyl value of the C12-15 branched carbonyl synthetic alcohol is 250-280 mg KOH / g, specifically ExxonMobil Exxal™ 13.

[0040] A method for preparing a stretching oil for aluminum alloy battery casings, comprising the following process steps: Step (1) Add the refined mineral oil to the mixing vessel according to the formula amount and heat to 55°C; Step (2) While stirring, add the extreme pressure agent, low viscosity synthetic ester and antioxidant in sequence, and continue stirring for 30 minutes; In step (3), a surface penetrant is added and the mixture is stirred and dispersed for 20 minutes to obtain an aluminum alloy battery casing stretching oil.

[0041] In step (3), the viscosity of the stretching oil for aluminum alloy battery casing is 108 cSt.

[0042] Example 3

[0043] An aluminum alloy battery casing stretching oil, comprising the following components in parts by weight: 88 parts refined mineral oil 5 parts antioxidant 10 parts of low viscosity synthetic ester 10 parts of extreme pressure agent 5 parts surface penetrant.

[0044] The refined mineral oil is a paraffinic base oil with a kinematic viscosity of 80 cSt at 40°C.

[0045] The antioxidant is an amine antioxidant, and the amine antioxidant is alkylated diphenylamine.

[0046] The low-viscosity synthetic ester has a kinematic viscosity of 10 cSt at 40°C.

[0047] The low-viscosity synthetic ester is neopentyl glycol dioleate.

[0048] The extreme pressure agent is a mixture of methyl oleate and triglyceride in a mass ratio of 4:1.

[0049] The surface penetrant is a C12-15 branched carbonyl synthetic alcohol. The hydroxyl value of the C12-15 branched carbonyl synthetic alcohol is 250-280 mg KOH / g, specifically ExxonMobil Exxal™ 13.

[0050] A method for preparing a stretching oil for aluminum alloy battery casings, comprising the following process steps: Step (1) Add the refined mineral oil to the mixing vessel according to the formula amount and heat to 60°C; Step (2) While stirring, add the extreme pressure agent, low viscosity synthetic ester and antioxidant in sequence, and continue stirring for 35 minutes; In step (3), a surface penetrant is added and the mixture is stirred and dispersed for 25 minutes to obtain an aluminum alloy battery casing stretching oil.

[0051] In step (3), the viscosity of the stretching oil for aluminum alloy battery casing is 114 cSt.

[0052] Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that the refined mineral oil in Example 2 was replaced with a paraffinic base oil with a viscosity of 120 cSt at 40°C, and the weight of the refined mineral oil was increased to 84 parts. The 3 parts of surface penetrant were adjusted to 5 parts of surface penetrant, and the kinematic viscosity of the finished stretching oil at 40°C was 160 cSt.

[0053] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that this Comparative Example does not contain a surface penetrant.

[0054] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that the extreme pressure agent in this comparative example is replaced with 5 parts of active sulfurized olefin (LZ5340) and 2 parts of phosphate ester, and does not contain surface penetrant.

[0055] The experimental data for Examples 1-3 and Comparative Examples 1-3 of this invention are shown in Table 1. Kinematic viscosity was determined according to GB / T265. Anti-sticking / tear-resistance properties were tested using an 80-ton punch press, stretching aluminum alloy discs into square shells to simulate the stretching process of battery casings. Twenty workpieces were continuously stamped and observed. Extreme pressure properties were determined according to GB / T3142. Cleanability was assessed by immersing oiled test pieces in a 3% (w / w) commercially available metal cleaning agent solution at 60°C and ultrasonically recording the time required for a continuous water film to form on the test piece surface. Cycle life was determined by mixing stretching oil and aluminum alloy powder at a mass ratio of 100:0.1 (simulating contamination), filtering with 5μm filter paper, and then reusing the mixture for stretching aluminum alloy discs → square shells. Sticking and tearing on the workpiece surface were observed. Oxidation stability was determined according to SH / T0193 at a test temperature of 150°C. Odor was assessed using sensory evaluation.

[0056] Table 1 Kinematic viscosity at 40°C (cSt) 102 108 114 160 107 108 Anti-sticking / anti-tear properties 20 pieces without adhesive residue or tearing 20 pieces without adhesive residue or tearing 20 pieces without adhesive residue or tearing The 8th piece slightly stuck to the mold and occasionally had some stringiness. 20 pieces without adhesive residue or tearing 16 pieces were not stuck to the mold; the 17th piece had slight stringing. Extreme pressure performance (PB value, N) 882 902 918 836 885 895 Ease of cleaning (seconds) 31 37 42 98 86 84 Cycle life No sticking to the mold after 5 cycles, very little sludge. No sticking to the mold after 5 cycles, very little sludge. No sticking to the mold after 5 cycles, minimal sludge. Increased sludge after 3 cycles, and tearing occurred after the 4th cycle. Increased sludge after 3 cycles, and tearing occurred after the 4th cycle. Increased sludge after two cycles, and tearing occurred after the third cycle. Antioxidant stability (rotating oxygen bomb, min) 378 388 395 300 382 308 odor Low odor Low odor Low odor Low odor Low odor It has a distinctly pungent odor. Experimental data analysis showed that Comparative Example 1 significantly increased the viscosity from 108 cSt in Example 2 to 160 cSt, returning to the technical route relying on physical thick film isolation. Despite increasing the amount of surface penetrant, the high viscosity environment severely limited its effectiveness, leading to a comprehensive deterioration in overall performance. Anti-sticking performance was poor, with sticking occurring as early as the 8th piece, mainly due to the poor fluidity of the high-viscosity oil. During high-speed stretching, the viscous oil could not quickly flow into the microscopic gaps between the mold and the nascent aluminum surface to replenish the material. This is completely opposite to the rapid film-forming mechanism of this invention, which promotes spreading with low viscosity and opens channels with penetrants, resulting in localized oil shortages and interruption of physical isolation, thus causing sticking and stringing. Cleaning was extremely difficult; the high viscosity resulted in enormous cohesive energy and physical adhesion, leading to a thick and stubborn residual oil film. The cleaning fluid struggled to remove and emulsify the high-viscosity oil film from the complex surface and micropores of the workpiece, directly confirming the extreme difficulty of cleaning traditional high-viscosity oils in the background technology of this invention. The short cycle life, with problems occurring after the fourth cycle, can be attributed to three reasons: 1) The high viscosity exerts a strong encapsulating force on the fine aluminum powder generated during stretching, making it difficult for the powder to settle and rendering it ineffective with simple filtration, thus acting as an abrasive during circulation; 2) The rotating oxygen bomb test data (300 min) is significantly lower than the example (388 min), demonstrating its poor oxidation stability and making it more prone to generating viscous sludge during repeated thermal cycling; 3) The sludge combines with the aluminum powder to form a stubborn scale layer, further exacerbating wear and oil degradation. This systematically demonstrates the inherent disadvantages of high-viscosity systems in cyclic use.

[0057] Comparative Example 2 fully retained the extreme pressure agent and low viscosity base oil system of this invention, but removed the key component, the surface penetrant. The fresh oil performance was acceptable, indicating that the basic lubrication framework of the system remained effective even without the penetrant. Cleaning performance significantly deteriorated; due to the lack of penetrant, residual oil adhered firmly to the metal surface, preventing the cleaning fluid from effectively penetrating to the oil-metal interface for displacement and stripping. The cleaning time (86 seconds) was 2.3 times that of Example 2 (37 seconds), demonstrating the active stripping effect of the penetrant during the cleaning process. Cycle life was short, with problems occurring in the fourth cycle. The lack of a penetrant's rapid opening effect slightly reduced the film formation rate and integrity of the extreme pressure agent during dynamic stretching, leading to increased micro-adhesive wear and the generation of more aluminum powder. Simultaneously, the lack of penetrant also weakened the oil's ability to disperse contaminants. The combined effect of aluminum powder accumulation and slight oil degradation resulted in a shortened cycle life. Its rotating bomb oxidation data (382 min) was good, indicating that basic oxidation resistance remained, with physical contamination being the primary cause.

[0058] Comparative Example 3 uses reactive sulfurized olefins combined with classic phosphate esters to form a powerful extreme pressure anti-wear combination. However, this simple stacking, detached from material properties and system synergy, not only failed to deliver high performance but also caused chemical mismatch and systemic failure. It has a distinctly pungent odor, a natural defect of reactive sulfurized olefins (dialkyl pentasulfides). The reaction of reactive sulfurized olefins is violent and uncontrollable, resulting in a thick, brittle, and poorly bonded sulfurized film on the aluminum alloy surface. Under continuous tensile mechanical stress, this brittle film easily breaks and peels off, forming hard abrasive debris. This debris gets trapped between the mold and the workpiece, scratching the surface of subsequent workpieces, accumulating to the point of scoring by the 17th piece; it also severely contaminates the oil, accelerating base oil oxidation, causing the oil to fail after only two cycles. Comparative Example 3 lacks a surface penetrant, missing the pre-opening effect of a penetrant to open microscopic gaps and facilitate the rapid spread of the extreme pressure agent. Although the reaction of reactive sulfurized olefins is fast, the pathway to the reaction interface is obstructed and the spreading is uneven, resulting in both excessively thick local films and insufficient overall coverage, which further amplifies the negative effects of chemical mismatch. At the same time, the lack of active stripping action of penetrants in the cleaning process is also a direct cause of its poor cleaning performance (85 seconds).

[0059] In summary, only by organically combining a specific extreme pressure agent system consisting of a low-viscosity base oil of 100-115cSt, methyl oleate, and triglyceride, along with a specific surface penetrant, can we simultaneously achieve the unity of anti-sticking, easy cleaning, and long cycle life.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A stretching oil for aluminum alloy battery casings, characterized in that: It consists of the following components in parts by weight: 70-88 parts refined mineral oil Antioxidant 1-5 parts 5-10 parts of low viscosity synthetic ester 5-10 parts of extreme pressure agent 1-5 parts of surface penetrant.

2. The aluminum alloy battery casing stretching oil according to claim 1, characterized in that: The refined mineral oil is a paraffinic base oil with a kinematic viscosity of 80-100 cSt at 40°C.

3. The aluminum alloy battery casing stretching oil according to claim 1, characterized in that: The antioxidant is an amine antioxidant, specifically an alkylated diphenylamine or N-phenyl-α-naphthylamine.

4. The aluminum alloy battery casing stretching oil according to claim 1, characterized in that: The low-viscosity synthetic ester has a kinematic viscosity of 10-40 cSt at 40°C.

5. The aluminum alloy battery casing stretching oil according to claim 1, characterized in that: The low-viscosity synthetic ester is one or more of diisooctyl adipate, trimethylolpropane oleate, or neopentyl glycol dioleate.

6. The aluminum alloy battery casing stretching oil according to claim 1, characterized in that: The extreme pressure agent is methyl oleate and triglyceride sulfide in a mass ratio of (2-4):

1.

7. The aluminum alloy battery casing stretching oil according to claim 1, characterized in that: The surface penetrant is a C12-15 branched carbonyl synthetic alcohol.

8. The aluminum alloy battery casing stretching oil according to claim 7, characterized in that: The hydroxyl value of the C12-15 branched carbonyl synthetic alcohol is 250-280 mg KOH / g.

9. A method for preparing an aluminum alloy battery casing stretching oil according to any one of claims 1-8, characterized in that: It includes the following process steps: Step (1) Add the refined mineral oil to the mixing vessel according to the formula amount and heat to 50-60℃; In step (2), while stirring, add the extreme pressure agent, low viscosity synthetic ester and antioxidant in sequence, and continue stirring until homogeneous; In step (3), the surface penetrant is added and stirred until evenly dispersed to obtain an aluminum alloy battery casing stretching oil.

10. The method for preparing an aluminum alloy battery casing stretching oil according to claim 9, characterized in that: Step (3) yields an aluminum alloy battery casing stretching oil with a viscosity of 100-115 cSt.