Cleaning agent suitable for aluminum alloy anode after nickel-free hole sealing and use method of cleaning agent

Abstract

The invention relates to the technical field of cleaning agents, in particular to a cleaning agent suitable for aluminum alloy anodes after nickel-free hole sealing and a using method thereof.The cleaning agent is prepared from, by weight, 5%-10% of organic acid, 3%-5% of chelating agent, 2%-5% of corrosion inhibitor, 6%-12% of active agent, 2%-5% of wetting agent and the balance water. The cleaning agent provided by the invention can effectively remove processing residues on the surface of a product and ensure the surface integrity and color difference stability of the product obtained by a nickel-free hole sealing process, so that the high-standard requirement of modern electronic product manufacturing on aluminum alloy surface treatment is met.

Description

Technical Field

[0001] The present invention relates to the technical field of cleaning agents, and particularly relates to a cleaning agent suitable for use after nickel-free sealing of aluminum alloy anodes and a method for using the same. Background Art

[0002] Due to its advantages such as light weight, corrosion resistance, high ductility, excellent electrical and thermal conductivity, and easy machinability, aluminum alloy is favored by many electronic product designers. Especially after anodizing treatment, the oxidation resistance and corrosion resistance of aluminum alloy are greatly improved, making its application in electronic products more extensive.

[0003] However, after the anodizing treatment of aluminum alloy, a sealing treatment is required. Most of the currently widely used aluminum alloy anodic sealing agents contain heavy metal nickel, which not only poses a potential threat to the environment but also may have an adverse impact on human health. To eliminate these hidden dangers, some manufacturers have developed new sealing agents without heavy metals to replace the traditional nickel-containing sealing agents. However, at the same time, the supporting cleaning agents have not been improved in a timely manner, which has become an urgent problem to be solved.

[0004] In the nickel-free sealing process, the cleaning link is crucial. After the nickel-free sealing of the aluminum alloy anode, the chemical substances and impurities remaining on its surface must be thoroughly removed by cleaning. Otherwise, these residues will not only contaminate the sealing bath solution, reduce the sealing quality, but also may cause a decrease in the corrosion resistance and wear resistance of the oxide film, and even lead to surface defects. Therefore, cleaning can not only improve the product quality but also effectively extend the service life of the sealing bath solution and reduce the production cost.

[0005] Regarding the solution to the cleaning problem, relevant technologies have been disclosed. For example, CN116083917A discloses an acidic cleaning agent, a preparation method, and a cleaning method. The acidic cleaning agent includes: an acidic agent, a first auxiliary agent, a second auxiliary agent, a corrosion inhibitor, an ash remover, a surfactant, and a solvent. However, this acidic cleaning agent is mainly used to remove various contaminants such as cutting fluid, polishing wax, grinding ash, and polishing fluid generated during the processing of the surface of aluminum alloy workpieces. At the same time, it has the ability to clean the cutting fluid contaminants on the anodic oxidation film of aluminum alloy, but has a weak cleaning ability for the contaminants after the anodic nickel-free sealing of aluminum alloy. CN104313608A discloses an environmentally friendly aluminum material cleaning agent and its preparation method, which is prepared by compounding inorganic acids, organic acids, surfactants, penetrants, emulsifiers, defoamers, complexing agents, and water. It can well remove the oxide scale on the surface of aluminum parts and has good oil removal and rust removal abilities, but it cannot clean the contaminants after the anodic nickel-free sealing of aluminum alloy. In addition, most of the current cleaning agents on the market are only applicable to traditional nickel-sealing technologies. When cleaning aluminum alloy products with nickel-free sealing, these cleaning agents cannot thoroughly clean the residues on the surface of the workpieces, easily leading to problems such as sealing hole shedding, large color difference variation, and unqualified sealing hole testing, and cannot meet the cleaning requirements after nickel-free sealing. The existing cleaning agents have insufficient protective effects on aluminum alloy and its anodic film, are prone to causing damage to them; the cleaning time is long, and the cleaning efficiency is low. In short, the existing cleaning agents often cannot achieve ideal effects, the color difference variation is large, and it is difficult to pass the sealing hole test, and cannot meet the strict requirements of the nickel-free sealing process for cleaning technology.

[0006] In summary, it is urgent to develop a special cleaning agent that matches the cleaning after the anodic nickel-free sealing of aluminum alloy. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides a cleaning agent applicable to the anodic nickel-free sealing of aluminum alloy and its usage method. The cleaning agent provided by the present invention should be able to effectively remove the processing residues on the surface of the product while ensuring the integrity of the surface and the stability of the color difference of the product obtained by the nickel-free sealing process, so as to meet the high standards of modern electronic product manufacturing for the surface treatment of aluminum alloy. The cleaning agent of the present invention has thorough cleaning of the workpiece after nickel-free sealing, fast cleaning speed, and does not contain environmentally unfriendly and unsafe factors such as strong acids, strong alkalis, phosphorus, nitrates, heavy metal ions, and halogens, and will not corrode substrates such as aluminum alloy and its anodic film. The composition is simple, the preparation is easy, and it is suitable for industrial production.

[0008] It is achieved through the following technical solutions:

[0009] On the one hand, the present invention provides a cleaning agent applicable to the anodic nickel-free sealing of aluminum alloy, which, by weight percentage, includes: 5-10% of organic acid, 3-5% of chelating agent, 2-5% of corrosion inhibitor, 6-12% of active agent, 2-5% of wetting agent, and the balance is water.

[0010] Furthermore, the organic acid is at least one of citric acid, glycolic acid, tartaric acid, lactic acid, and dodecylbenzenesulfonic acid. The organic acid buffers and adjusts the pH range (5 - 7.0) of the agent to facilitate the control of the pH value in the cleaning tank; the organic acid dissociates the ash substances during the sealing process, and the organic acid root forms a water-soluble salt with the metal ions therein; the organic acid can effectively remove the "sealing white mist" after sealing; the pH values of the organic acids are relatively mild and will not affect the oxide film.

[0011] Furthermore, the chelating agent is at least one of potassium sodium tartrate, sodium citrate, EDTA-4Na, and sodium gluconate. The chelating agent has a certain chelating effect on the metal ions in the cleaning tank, avoiding excessive metal ions from reacting with other components and interfering with the cleaning effect, and adsorbing on the surface of the dirt particles to prevent the dirt particles from aggregating and redepositing on the cleaning surface. The chelating agent can enhance the performance of the cleaning agent during cleaning, prevent equipment corrosion, improve the cleaning rate, and help extend the service life of the equipment.

[0012] Furthermore, the corrosion inhibitor is at least one of organic amines, lignin-based substances, gluconates (such as sodium gluconate), imidazolines and their derivatives, and quaternary ammonium salts. The corrosion inhibitor has a protective effect on aluminum alloy and its anodic film, forming a protective film on the surface of the aluminum alloy workpiece and preventing the corrosive medium from contacting the metal of the aluminum alloy workpiece. During the cleaning process, it can adjust the pH, enhance the cleaning power, inhibit corrosion, and complex metal ions, etc., to improve the performance of the cleaning agent. The corrosion inhibitor is compounded with components such as surfactants and chelating agents to form a synergistic effect, improving the comprehensive performance of the cleaning agent, such as emulsification and dispersion ability, etc., and can effectively remove the oil stains and impurities on the surface of the aluminum alloy workpiece while protecting the metal surface from corrosion. Furthermore, the organic amine is selected from at least one of cyclohexylamine, polyethyleneimine (PEI), organic amine ester TPP, monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA). Furthermore, the lignin-based substances are selected from at least one of lignosulfonate, sulfate lignin, and alkali lignin. Furthermore, the imidazoline derivatives are selected from at least one of alkyl imidazoline quaternary ammonium salts, imidazoline oleates, and imidazoline sebacates. Furthermore, the quaternary ammonium salts are selected from at least one of triethanolamine stearate quaternary ammonium salt, polyquaternium, and coconut alkyl quaternary amine ethoxylate, which can effectively remove the oil stains and impurities on the surface of the aluminum alloy while protecting the metal surface from corrosion.

[0013] Furthermore, the active agent is at least one of AEO-9 (fatty alcohol polyoxyethylene ether), TO-6, TO-7, and TO-9 (isomeric tridecanol polyoxyethylene ether). The active agent can quickly dissolve the oil stains on the surface of the workpiece, and gently clean the surface of the aluminum alloy workpiece, avoiding metal corrosion. When cleaning the aluminum alloy workpiece, it emulsifies various oil stains covering the workpiece surface, disperses the oil stains into tiny oil droplets and suspends them in the cleaning tank, solubilizes the oil stains, wets and penetrates, prevents redeposition, gently cleans, synergistically enhances the effect, and improves the stability of the cleaning agent, significantly improving the cleaning efficiency and quality. The active agent can effectively reduce the surface tension of the cleaning solution, easily wet the aluminum alloy surface, penetrate into the tiny gaps on the surface of the aluminum alloy workpiece for cleaning, and will not corrode the workpiece substrate, can maintain the smoothness of the workpiece surface, and can also avoid surface scratching or redeposition after cleaning, thus ensuring the cleanliness after cleaning.

[0014] Furthermore, the wetting agent is at least one of glycerol, polyethylene glycol, random polyether, and block polyether. Further, the random polyether is selected from at least one of isomeric tridecanol random polyether, propylene glycol random polyether, glycerol random polyether, butanol random polyether, lauric acid random polyether, and dodecanol random polyether. Used as a low-foam detergent or defoaming agent, it has good surface activity and can reduce the surface tension of the liquid. Further, the block polyether is selected from at least one of PEO-PPO block polyether, L series block polyethers (L61, L62, L64), PD series block polyethers (PD720 or PD740), AEP series block polyethers (AEP53), polyoxyethylene-polyoxypropylene block polyether, and propylene glycol block polyether. The block polyether has good emulsification, dispersion, wetting, and defoaming functions, etc. The wetting agent plays a role in promoting oil removal and dirt removal, peeling the oil stains from the workpiece surface to promote the fusion of the oil stains and the active agent, and can also improve the smoothness of the surface of the aluminum alloy workpiece. During the cleaning process, through functions such as emulsifying oil stains, reducing surface tension, synergistically enhancing the effect, preventing ash hanging and redeposition, it significantly improves the cleaning efficiency and quality, and at the same time is gentle on the aluminum alloy surface, reducing the corrosion risk.

[0015] On the other hand, the present invention provides a method for using the cleaning agent after the anodic nickel-free sealing of the aluminum alloy, including the following steps:

[0016] Add the cleaning agent after the anodic nickel-free sealing of the aluminum alloy into the cleaning tank. After mixing evenly, put the aluminum alloy workpiece treated with the nickel-free sealing technology into the cleaning tank for ultrasonic soaking, rinsing, and drying to complete the cleaning.

[0017] Furthermore, when the cleaning solution in the tank decreases as the aluminum alloy workpiece is taken away, directly add the cleaning agent to the tank. Further, the amount of the cleaning agent added is 3-5% of the volume of water in the cleaning tank.

[0018] Further, the addition amount of the cleaning agent is 10-20% of the volume of water in the cleaning tank.

[0019] Further, the temperature of the ultrasonic wave is 55-65°C. Conventionally, the ultrasonic power density is 0.3-0.8 W / cm 2 , preferably 0.5 W / cm 2 .

[0020] Further, the soaking time is 3-5 min. The effective treatment of "sealing ash" can be achieved through the soaking of the cleaning agent.

[0021] The drying after rinsing can be carried out by conventional operations, such as natural drying, hot air drying, vacuum drying, air blowing with compressed air, etc.

[0022] On the other hand, the present invention provides an application for cleaning workpieces after anodizing aluminum alloy without nickel sealing, and the application includes: using the cleaning agent described in the present invention for cleaning during the process of anodizing aluminum alloy without nickel sealing.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The cleaning agent of the present invention is specially developed for workpieces after anodizing aluminum alloy without nickel sealing. Through scientific screening and formulation, it has a reasonable pH value, can completely clean and remove the dirt and deposits on the surface, gaps and around of the workpieces after anodizing aluminum alloy without nickel sealing, and has no adverse effects on the aluminum alloy surface, oxide film at the sealing hole, etc., and has excellent cleaning effects on "pretreatment ash", "sealing white mist" and "sealing ash"; can ensure the cleanliness and brightness of the product; will not damage the upper aluminum alloy anode layer, ensuring small color difference variation of the workpiece. During the cleaning process, a lower temperature is used, that is, used in ultrasonic waves with a cleaning temperature of 55-65°C, which can effectively improve production efficiency and reduce energy consumption.

[0025] Through reasonable screening of each component, the present invention adopts an efficient compounding of organic acids, chelating agents, corrosion inhibitors, surfactants, wetting agents and water. It has simple components and is easy to prepare, being suitable for industrial production. Among them, the organic acid buffers and adjusts the pH range of the agent; the chelating agent can not only form a buffer with the organic acid, but also chelate metal ions in the dirt, avoiding the aggregation and redeposition of dirt particles; the corrosion inhibitor can form a protective film on the surface of the cleaned workpiece, forming a synergistic effect with the surfactant and chelating agent, increasing the emulsification and dispersion ability, which can not only remove the oil stains and impurities on the surface, but also protect the workpiece surface from corrosion; the surfactant penetrates into the gaps of the ash on the surface of the aluminum alloy, disperses the stains into tiny suspensions, which are captured by the surfactant and chelating agent to complete the cleaning and avoid redeposition; the wetting agent cooperates with the surfactant to strip "sealed white fog" and the like from the workpiece surface, and cooperates with the chelating agent to prevent the workpiece from being re-dusted and redeposited. Combining with the protection of the corrosion inhibitor on the workpiece surface, it realizes the efficient cleaning of the dirt on the workpiece after the anodic oxidation sealing of the aluminum alloy, with thorough cleaning and fast cleaning speed.

[0026] The cleaning agent of the present invention has a short time, low damage to the anodic layer, small influence on color difference, and the cleaned workpiece has a long service life; the cleaning agent of the present invention does not contain environmentally unfriendly and unsafe factors such as strong acids, strong alkalis, phosphorus, nitrates, heavy metal ions, and halogens. The organic acid contained in the cleaning agent is not only weakly acidic but also easily degradable, which is beneficial to environmental protection while ensuring the cleaning cleanliness.

[0027] The cleaning agent of the present invention has a remarkable cleaning effect on the CNC reprocessing of workpieces with a nickel-free sealing technology for various aluminum alloy anodes, with thorough cleaning, no damage to the sealing, small color difference variation, no corrosion of the aluminum alloy substrate, no damage to the aluminum alloy anodic film, simple components, easy preparation, and is suitable for industrial production. Specific Embodiments

[0028] The cleaning agent for the aluminum alloy anode after nickel-free sealing is further described below through specific embodiments.

[0029] The cleaning agent for the aluminum alloy anode after nickel-free sealing prepared by the present invention is a composition with comprehensive properties, which is the result of the synergistic cooperation of various substances. Each composition forms a complete whole, making the cleaning agent have good cleaning effects, fast and thorough degreasing speed, can pass the 38 dynes pen test, does not damage the aluminum alloy anodic layer. After using the cleaning agent prepared by this scheme to clean the anode products with nickel-free sealing, the color difference variation of the workpiece does not exceed 10%, and it will not corrode the aluminum alloy substrate, with simple components, easy preparation, and is suitable for industrial production and other advantages.

[0030] Example 1

[0031] A cleaning agent for the aluminum alloy anode after nickel-free sealing, comprising:

[0032] 5% glycolic acid, 3% sodium citrate, 2% sodium gluconate, 3% organic amine ester TPP, 95% TO, 63% TO, 3% polyoxyethylene-polyoxypropylene block polyether, 76% water.

[0033] In water at 30 - 40°C, add organic acids and stir well. Then add the chelating agent, corrosion inhibitor, surfactant, and wetting agent in sequence. After the previous component is mixed evenly, add the next component and mix evenly to obtain the cleaning agent.

[0034] Application: Suspend the aluminum alloy workpiece to be cleaned with a fixture and place it in a 15% dilution of the above cleaning agent. The measured temperature is 60°C. Turn on the ultrasonic wave and sonicate for 4 minutes. Take out the workpiece, rinse and dry it. Neither the aluminum alloy nor the aluminum alloy anode layer is damaged.

[0035] Example 2

[0036] A cleaning agent for aluminum alloy anodic non-nickel sealing, comprising:

[0037] 8% tartaric acid, 3% potassium sodium tartrate, 3% organic amine ester TPP, 95% AEO, 74% TO, 3% random polyether of isomeric tridecanol, 74% water.

[0038] The preparation process is the same as that of Example 1.

[0039] Application: Suspend the aluminum alloy workpiece to be cleaned with a fixture and place it in a 10% dilution of the above cleaning agent. At room temperature, the measured bath temperature is 55°C. Turn on the ultrasonic wave and sonicate for 5 minutes. Take out the workpiece, rinse and dry it. Neither the aluminum alloy nor the aluminum alloy anode layer is damaged.

[0040] Example 3

[0041] A cleaning agent for aluminum alloy anodic non-nickel sealing, comprising: 6% citric acid, 4% sodium citrate, 2% sodium gluconate, 65% TO, 94% TO, 3% glycerol, 74% water.

[0042] The preparation process is the same as that of Example 1.

[0043] Application: Suspend the aluminum alloy workpiece to be cleaned with a fixture and place it in a 20% dilution of the above cleaning agent. At room temperature, the measured bath temperature is 65°C. Turn on the ultrasonic wave and sonicate for 4 minutes. Take out the workpiece, rinse and dry it. Neither the aluminum alloy nor the aluminum alloy anode layer is damaged.

[0044] Comparative Example 1

[0045] The difference from Example 1 is that there is no sodium citrate.

[0046] Comparative Example 2

[0047] It is different from Example 1 in that there is no sodium gluconate.

[0048] Comparative Example 3

[0049] It is different from Example 1 in that there is no organic amine ester TPP.

[0050] Comparative Example 4

[0051] It is different from Example 1 in that there is no TO-9 and TO-6.

[0052] Comparative Example 5

[0053] It is different from Example 1 in that there is no polyoxyethylene-polyoxypropylene block polyether.

[0054] Comparative Example 6

[0055] It is different from Example 1 in that TO-9 is replaced by TO-6.

[0056] Effect Verification Test 1

[0057] The cleaning process tests were carried out using the cleaning agents of Examples 1-3 and Comparative Examples 1-6. The volume of the chemicals in the cleaning tank was 500L. The specific process used the cleaning process of Example 1, and the continuous cleaning duration was set to 48 hours. The workpieces went through the whole inspection process such as appearance cleanliness test and functional test, and the number of qualified products during continuous cleaning was counted. The requirements for judging qualified products were as follows: there was no damage to the aluminum alloy and the aluminum alloy anode layer, and the surface was clean, bright, and observed under a 500-fold magnifying glass, there was no dust or stain. The specific comparison of the qualified rates is as follows in the table:

[0058] Table 1 Comparison Table of Qualified Rates

[0059] Cleaning agent Total number of cleanings in 48 hours Number of good products Yield rate Example 1 59800 59702 99.84％ Example 2 59790 59675 99.81％ Example 3 59805 59348 99.24％ Comparative example 1 57702 51005 88.39％ Comparative example 2 58739 50974 86.78％ Comparative example 3 56990 50707 88.98％ Comparative example 4 59902 50097 83.63％ Comparative example 5 59876 51009 85.19％ Comparative example 6 59797 56910 95.17％

[0060] It can be seen from the comparison data in the above table that when the cleaning agents of Examples 1 to 3 were continuously cleaned for 48 hours, the obtained qualified rates were all above 99.5%, which could meet the production requirements. From the comparison of Comparative Examples 1 to 5, it can be seen that the components of Example 1 of the present application worked synergistically, and the lack of a certain component had a great impact on the qualified rate of the cleaning products, and the qualified rate of continuous cleaning for 48 hours was lower than 90%. From the cleaning qualified rates of Comparative Example 6 and Example 1, it can be seen that the cleaning agent prepared with two surfactants had a better cleaning effect in dissolving the dirt on the surface of the workpiece.

[0061] Although some exemplary embodiments of the present invention have been shown above, those skilled in the art understand that changes can be made to these exemplary embodiments without departing from the principle or spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A cleaning agent suitable for aluminum alloy anodes after nickel-free sealing, characterized in that: Calculated by weight percentage, it includes: 5-10% organic acid, 3-5% chelating agent, 2-5% corrosion inhibitor, 6-12% activator, 2-5% wetting agent, and the balance is water.

2. The cleaning agent according to claim 1, characterized in that: The organic acid is at least one of citric acid, glycolic acid, tartaric acid, lactic acid and dodecylbenzenesulfonic acid.

3. The cleaning agent according to claim 1, characterized in that: The chelating agent is at least one of potassium sodium tartrate, sodium citrate, EDTA-4Na and sodium gluconate.

4. The cleaning agent according to claim 1, characterized in that: The corrosion inhibitor is at least one of organic amines, lignin, gluconate, imidazoline and its derivatives, and quaternary ammonium salts.

5. The cleaning agent according to claim 1, characterized in that: The active agent is at least one of AEO-9, TO-6, TO-7 and TO-9.

6. The cleaning agent according to claim 1, characterized in that: The wetting agent is at least one of glycerol, polyethylene glycol, random polyether and block polyether.

7. A method for using the cleaning agent according to any one of claims 1 to 6, characterized in that: The following steps are involved: The cleaning agent after nickel-free sealing of the aluminum alloy anode is added into the cleaning tank, and after being evenly mixed, the aluminum alloy workpiece treated by the nickel-free sealing technology is placed in the cleaning tank for ultrasonic immersion, rinsing and drying to complete the cleaning.

8. The method of use according to claim 7, characterized in that: When the cleaning liquid in the tank is reduced as the aluminum alloy workpiece is taken away, cleaning agent is directly added to the tank; further, the amount of cleaning agent added is 3-5% of the volume of water in the cleaning tank.

9. The method of use according to claim 7, characterized in that: The amount of detergent added is 10-20% of the volume of water in the cleaning tank; The temperature of the ultrasound is 55-65°C; The soaking time is 3 to 5 minutes.

10. An application of cleaning workpieces after nickel-free sealing of aluminum alloy anodes, characterized in that: The application includes: in the process of nickel-free sealing of aluminum alloy anodes, cleaning is performed by using the cleaning agent described in any one of claims 1 to 6.