Green degreaser based on alkyl glycoside and fatty alcohol ether sulphate and its use in the pretreatment of rolled aluminium foil before coating

Abstract

This invention discloses a green alkaline degreasing agent composition based on alkyl glycoside (APG1214) and sodium fatty alcohol ether sulfate (AES) and its application in the pretreatment of rolled aluminum foil before coating. The composition consists of the following components by weight percentage: APG1214 (40% to 60% active ingredient) 1.5% to 3.0%, AES (60% to 72% active ingredient) 2.0% to 3.5%, Iso-AEO 0.3% to 1.0%, potassium sodium tartrate 0.3% to 0.8%, triethanolamine 0.5% to 1.0%, polyether defoamer 0.2% to 0.4%, with the balance being deionized water. The working solution pH is 9.0 to 9.8. This invention uses APG1214 and AES as the core surfactant system, is completely free of endocrine disruptors such as nonylphenol polyoxyethylene ether, and has a biodegradability rate greater than 95%. Operating at 50 to 55 degrees Celsius, combined with ultrasonic dual-frequency degreasing and electrochemical strengthening treatment, the overall degreasing rate of rolling oil on rolled aluminum foil reaches over 99.5%, with surface residue less than 5 mg / m², and coating peel strength not less than 2.5 N / mm. It is suitable for precision surface treatment before coating of aluminum current collectors for lithium-ion batteries, meeting the environmental compliance requirements of major global markets.

Description

Technical Field

[0001] This invention belongs to the field of green surfactant application and precision metal material cleaning technology, specifically involving an environmentally friendly alkaline degreasing agent composition with alkyl glycosides (APG) and fatty alcohol ether sulfates (AES) as core surfactants, and a method for applying this composition in the pretreatment of rolled aluminum foil (especially aluminum current collectors for batteries) before coating. Background Technology

[0002] In high-end applications such as lithium-ion batteries and aluminum electrolytic capacitors, the surface cleanliness of aluminum foil directly determines the performance of downstream products. Residual rolling oils (including mineral oil, fatty acid esters, extreme pressure anti-wear agents, and metal soaps) on the surface of rolled aluminum foil must be thoroughly removed before applying the coating slurry.

[0003] Currently, commercially available aluminum foil degreasers mainly rely on the following types of surfactant systems: (1) Nonylphenol polyoxyethylene ether (OP-10 / NPEO) system: The oil removal effect is acceptable, but it contains endocrine disruptors, and the EU has listed it as an SVHC for control. (2) Traditional AEO-9 system: It has better biodegradability than NPEO, but it contains polyoxyethylene ether structure, which is prone to flocculation under hard water and high temperature conditions, and the oil removal efficiency is unstable. (3) Single AES system: high foam, often foam overflow problem when used online, and insufficient penetration ability to thick oil film.

[0004] Alkyl glycosides (APGs), as a novel nonionic surfactant derived from renewable plant resources, have attracted industry attention due to their excellent ecotoxicological properties (biodegradability >98%) and good low-temperature water solubility. However, in existing technologies, APGs are mostly used as auxiliary surfactants, and alkaline degreasing agent formulations with APG as the main surfactant alone cannot meet the stringent requirement of >99.5% degreasing efficiency when dealing with high-speed cleaning of battery aluminum foil.

[0005] This invention creatively combines APG1214 with AES in a scientific compound, supplemented with Iso-AEO as a penetration enhancer, and combined with a triethanolamine buffer system, successfully resolving the technical contradiction between green environmental protection and efficient oil removal, and realizing the industrial application of APG-based degreasing agents in high-speed cleaning scenarios. Summary of the Invention

[0006] (a) The technical problem solved by the present invention The technical problem solved by this invention is to provide a green alkaline degreasing agent composition with APG1214 and AES as the core surfactants. Under the premise of meeting environmental compliance (zero APEO, biodegradability >95%), this composition has excellent emulsification penetration and saponification removal capabilities for rolling oil of rolled aluminum foil, with a comprehensive degreasing rate of over 99.5%. It is particularly suitable for precision surface treatment before coating of rolled aluminum foil, and does not corrode or damage the aluminum foil substrate.

[0007] (II) Technical Solution This invention provides the following technical solutions:

[0008] Option A – Core Composition A green alkaline degreasing agent composition, characterized in that it uses alkyl glycoside (APG1214) and sodium fatty alcohol ether sulfate (AES) as the main surfactant system, supplemented by isomeric alcohol polyoxyethylene ether (Iso-AEO) as a penetration enhancer, potassium sodium tartrate as a chelating agent, triethanolamine as a pH buffer and aluminum corrosion inhibitor, and polyether defoamer to control foam. The weight percentage range of each component is as follows: APG1214 (40% to 60% active ingredient): 1.5% to 3.0%; AES (60% to 72% active ingredient): 2.0% to 3.5%; ISO-AEO: 0.3% to 1.0%; Sodium potassium tartrate: 0.3% to 0.8%; Triethanolamine (85%): 0.5% to 1.0%; Polyether defoamer: 0.2% to 0.4%; The remainder is deionized water; Working solution pH range: 9.0 to 9.8.

[0009] Option B – Pretreatment method for rolled aluminum foil before coating A method for pretreatment of rolled aluminum foil using the degreasing agent described in Scheme A includes the following steps: (1) Pre-softening: The aluminum foil is fed into the steam softening section at a speed of 100 to 300 m / min, and the surface of the aluminum foil is sprayed with saturated steam at 100 to 120 degrees Celsius for 0.2 to 0.5 seconds to reduce the viscosity of the rolling oil by 40% to 60%; (2) Main degreasing: The aluminum foil is sent into the ultrasonic alkaline water degreasing tank. The working solution is a diluted solution of the above degreasing agent composition (dilution ratio 1:20 to 1:50), pH 9.3 to 9.5, temperature 50 to 55 degrees Celsius, ultrasonic frequency 28 kHz plus 40 kHz dual frequency, power density not less than 3 W / cm², and action time 0.3 to 0.6 seconds; (3) Electrochemical enhancement: The aluminum foil is fed into the electrochemical degreasing tank, the cathode current density is 5 to 15 A / dm square, and the residual stubborn oil film is peeled off by hydrogen microbubbles generated by electrolysis for 0.3 to 0.6 seconds; (4) High-pressure rinsing and two-stage pure water rinsing; (5) Drying: The aluminum foil is passed through an air knife (not less than 4 bar), a condensation drying section and a low-temperature hot air drying section of 60 to 80 degrees Celsius in sequence, so that the surface moisture of the aluminum foil is not higher than 30 mg / m². (6) Quality inspection: The cleanliness of the aluminum foil after cleaning is tested. The residual oil on the surface is required to be less than 5 mg / m², and the peel strength between the coating slurry and the aluminum foil is not less than 2.5 N / mm.

[0010] (III) Innovations and Beneficial Effects of the Invention Replacing traditional APEO surfactants with APG1214 Completely eliminates the risk of endocrine disruptors, with a biodegradability rate of over 95%, meeting EU REACH and Chinese clean production standards. AES and APG1214 are scientifically combined AES provides strong emulsifying ability (HLB approximately 40), while APG1214 offers low-temperature penetration and gentleness; together, they achieve an oil removal efficiency greater than 99.5%. Iso-AEO as a penetration enhancer This enhances the penetration capabilities of AES and APG under high oil loading conditions, making it particularly suitable for the rapid removal of thick rolled oil films (greater than 500 mg / m²). Triethanolamine buffer corrosion inhibitor system The pH was kept stable between 9.0 and 9.8, balancing saponification efficiency and aluminum foil protection, with an aluminum corrosion rate of less than 0.01 mm per year. Polyether defoamer as a substitute for silicone Eliminate the environmental risks of D4 / D5 / D6 cyclic siloxanes while meeting foam control requirements under high-speed spraying (200 to 250 m / min). Attached Figure Description

[0011] Figure 1 This diagram illustrates the synergistic degreasing mechanism of the APG1214 and AES compound system, showcasing the synergistic emulsification, penetration, and stripping process of rolling oil molecules on the aluminum foil surface by APG1214 and AES, as well as the arrangement and interaction mechanism of the two surfactant molecules at the oil / water interface.

[0012] Figure 2 The graph shows the biodegradability test curve of the formulation of this invention and the comparison with the NPEO system. The vertical axis represents the biodegradability rate (%) and the horizontal axis represents time (days). The graph shows the degradation curves of the APG+AES system of this invention and the traditional NPEO system, respectively, which intuitively reflects the biodegradability performance advantages of the formulation of this invention.

[0013] Figure 3 shows the oil removal efficiency curves of the formulation of the present invention under different pH and temperature conditions, including two sub-figures: Figure 3a The curve shows the oil removal efficiency as a function of the working fluid pH (pH range 8.5 to 10.5). Figure 3b The curves show the oil removal efficiency as a function of temperature (temperature range 30 to 65 degrees Celsius). Both graphs use oil removal efficiency (%) as the vertical axis to reflect the optimal operating parameter range of the formulation of this invention.

[0014] Figure 4 The flowchart shows the pretreatment process for rolled aluminum foil before coating, from left to right: pre-softening section, ultrasonic alkaline degreasing tank, electrochemical degreasing tank, high-pressure rinsing section, two-stage pure water rinsing section, air knife drying section, low-temperature hot air drying section, and quality inspection and discharge section. The key process parameters of each section are marked.

[0015] Figure 5This is a comparison chart of the peel strength test results of the aluminum foil coating after cleaning. The vertical axis represents the peel strength (N / mm), and the horizontal axis represents the cleaning process type. The peel strength values ​​of the coating under three process conditions—the method of this invention, the existing NPEO system, and the single AEO system—are compared to verify the beneficial effect of the method of this invention on improving the adhesion of aluminum foil coating.

Claims

1. A green alkaline degreasing agent composition based on alkyl glycosides and fatty alcohol ether sulfates, characterized in that, The surfactant is mainly composed of alkyl glycosides and sodium salts of fatty alcohol ether sulfates, and consists of the following components by weight percentage: (a) Alkyl glycoside (APG1214), with an active ingredient content of 40% to 60%, used in an amount of 1.5% to 3.0% of the total weight of the composition; (b) Sodium fatty alcohol ether sulfate (AES), with an active ingredient content of 60% to 72%, used in an amount of 2.0% to 3.5% of the total weight of the composition; (c) Iso-AEO, used in an amount of 0.3% to 1.0% of the total weight of the composition; (d) Sodium potassium tartrate, used in an amount of 0.3% to 0.8% of the total weight of the composition; (e) Triethanolamine, used in an amount of 0.5% to 1.0% of the total weight of the composition; (f) Polyether defoamer, used in an amount of 0.2% to 0.4% of the total weight of the composition; (g) The remainder is deionized water with a conductivity of less than 5 μS / cm; (h) The working solution of the composition has a pH of 9.0 to 9.8 and is free of nonylphenol polyoxyethylene ether and nonylphenol.

2. The application of the green alkaline degreasing agent composition according to claim 1 in the pretreatment of rolled aluminum foil before coating, characterized in that, Includes the following steps: (1) Pre-softening: The surface of the rolled aluminum foil is sprayed with saturated steam at 100 to 120 degrees Celsius for 0.2 to 0.5 seconds to reduce the viscosity of the rolling oil; (2) Ultrasonic alkaline water degreasing: The aluminum foil is passed through an ultrasonic degreasing tank containing the degreasing agent dilution solution of claim 1 (dilution ratio 1:20 to 1:50). The working solution pH is 9.3 to 9.5, the temperature is 50 to 55 degrees Celsius, the frequency is 28 kHz and 40 kHz dual frequency superposition, the power density is not less than 3 W / cm², and the action time is 0.3 to 0.6 seconds. (3) Electrochemical degreasing: Aluminum foil is passed through an electrochemical degreasing tank with a cathode current density of 5 to 15 A / dm², and hydrogen microbubbles are used to peel off the residual oil film for 0.3 to 0.6 seconds. (4) High-pressure rinsing and two-stage pure water rinsing; (5) Drying: sequentially passing through an air knife (not less than 4 bar), condensation drying, and low-temperature hot air drying; (6) Quality inspection: The residual oil content on the aluminum foil surface after cleaning is less than 5 mg / m², and the peel strength is not less than 2.5 N / mm.

3. The composition according to claim 1, characterized in that: The alkyl carbon chain length of the APG1214 is C12 to C14, the average degree of polymerization is 1.3 to 1.5, and the HLB value is in the range of 12 to 14.

4. The composition according to claim 1, characterized in that: The AES uses C12 to C16 fatty alcohols as raw materials, and its foam height (Roche method) does not exceed 120 mm.

5. The composition according to claim 1, characterized in that: The Iso-AEO has a carbon chain length of C13 to C15, an HLB value in the range of 11 to 13, and is used in an amount of 0.4% to 0.7%.

6. The composition according to any one of claims 1 to 5, characterized in that: The mass ratio of potassium sodium tartrate to triethanolamine is 1:1.2 to 1.5, and the two work together to achieve the dual functions of metal ion chelation and pH buffering.

7. The composition according to claim 1, characterized in that: The polyether defoamer is an ethylene oxide to propylene oxide block copolymer with a molecular weight in the range of 2000 to 6000 and an alkali resistance temperature of up to 80 degrees Celsius.

8. The application method as described in claim 2, characterized in that: The working fluid temperature is preferably 50 to 55 degrees Celsius. Within this temperature range, APG1214 is not close to its cloud point, and the emulsifying activity of AES is in its optimal range.

9. The application method as described in claim 2, characterized in that: In step (2), the length of the ultrasonic degreasing tank is 1.5 to 2.0 m. When the linear speed is 200 to 250 m / min, the effective ultrasonic treatment time of the aluminum foil reaches 0.43 to 0.54 seconds.

10. The application method as described in claim 2, characterized in that: In step (3), the length of the electrochemical degreasing tank is also 1.5 to 2.0 m, and the diameter of the hydrogen microbubbles generated by electrolysis is 10 to 50 micrometers, which has a highly efficient physical stripping effect on the residual oil film.

11. The composition according to any one of claims 1 to 5, characterized in that: The composition does not contain D4, D5, or D6 cyclic siloxanes, perfluorinated compounds, or heavy metal catalyst residues.

12. A method for preparing the composition according to any one of claims 1 to 5, characterized in that, include: Mix APG1214, AES, and Iso-AEO in deionized water at 40 to 50 degrees Celsius and stir for 30 to 40 minutes. Then add potassium sodium tartrate, triethanolamine, and polyether defoamer in sequence. Finally, adjust the pH to 9.3 to 9.5 with dilute NaOH solution and let it age for 12 to 24 hours before use.

13. The application method as described in claim 2, characterized in that: The object to be cleaned is an aluminum current collector for lithium-ion batteries with a thickness of 8 to 20 micrometers. After cleaning, the surface cleanliness of the aluminum foil meets the requirements for coating, and the amount of residual oil on the surface is no more than 3 mg / m².

Images