A low-corrosion stripping agent for aluminum alloy anolyte films and its preparation method

Abstract

The present application relates to a kind of aluminium alloy anodic film low corrosion amount stripping agent, comprising: pure water, alkalinity providing agent and chelating dispersant;The alkalinity providing agent includes: one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate;The chelating dispersant includes: one or more of hydroxyethylidene diphosphonic acid tetrasodium, sodium gluconate, sodium polyacrylate, sodium polyepoxysuccinate;In the aluminium alloy anodic film low corrosion amount stripping agent, the weight fraction of each component: pure water 40-70 weight parts, alkalinity providing agent 15-35 weight parts, chelating dispersant 1-5 weight parts.The aluminium alloy anodic film low corrosion amount stripping agent of the present application, formula is screened and is deployed scientifically, with wide material application surface, and use energy consumption is low, and it is not easy to produce aluminium scale;The anodic oxide film of each type of aluminium material can be efficiently and completely removed, the corrosion amount of base material aluminum is low, and problems such as poor stripping effect, such as mottling, crystal spot, air mark, flow mark, etc.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy surface treatment technology, and in particular to a low-corrosion-substance stripping agent for aluminum alloy anodic films and its preparation method. Background Technology

[0002] Currently, there are many aluminum alloy anodized film stripping agents on the market, which can be divided into two technical directions: acid and alkali, but each has some defects.

[0003] The main advantage of acidic aluminum alloy anodized film stripping agents is their relatively low corrosiveness to the aluminum alloy substrate. However, because the acidic chemical components have relatively low corrosiveness to the aluminum alloy substrate, their corrosiveness to the aluminum alloy anodized film is also relatively low. Therefore, it is often necessary to increase the concentration, temperature, and time to accelerate the corrosion of the anodized film and remove it completely. This leads to disadvantages such as the large amount of agent used, generally requiring a usage ratio of more than 50% (by mass), and sometimes even using the undiluted solution; at the same time, the operating temperature is relatively high, resulting in high energy consumption, generally requiring 70-100℃; and the stripping time is also relatively long, generally 10-30 minutes.

[0004] Alkaline aluminum alloy anodized film stripping agents typically contain strongly alkaline substances in their formulations, making them highly corrosive to both the aluminum alloy substrate and its anodized film. Therefore, their main advantages are relatively low usage (generally 10-30% by mass), low operating temperature (generally 40-60℃), and fast stripping speed (generally 0.5-4 minutes). However, precisely because of their strong corrosiveness, they cause significant corrosion, easily affecting product dimensions, resulting in fewer rework cycles and lower rework yield. Furthermore, they easily generate aluminum scale, which, when suspended or deposited in the tank, affects the stripping effect and increases the difficulty of tank maintenance.

[0005] A common drawback of acidic and alkaline stripping agents is their poor versatility in stripping anodized films from various types of aluminum. Commonly used aluminum alloys for anodizing include the 1-series, 5-series, 6-series, and 7-series. Due to differences in trace elements and processing techniques, these different series of aluminum alloys exhibit variations in corrosion resistance and reactivity. These differences result in varying applicability of stripping agents, making it difficult to apply a single stripping agent to all series of aluminum alloys. This can easily lead to problems such as mottled spots, crystal spots, air marks, flow marks, and poor stripping results.

[0006] Therefore, it is necessary in this technical field to develop an aluminum alloy oxide film stripping agent that has a wide range of applications, reduced corrosivity, and less aluminum scale formation. Summary of the Invention

[0007] This invention provides a low-corrosion stripping agent for aluminum alloy anode films, which can solve at least one of the technical problems of existing aluminum alloy anode stripping agents, such as narrow applicability, high corrosivity to substrates, and easy formation of aluminum scale.

[0008] To achieve the above objectives, the present invention provides a low-corrosion stripping agent for aluminum alloy anode films, comprising: pure water, an alkalinity provider, and a chelating dispersant; the alkalinity provider comprises one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; the chelating dispersant comprises one or more of tetrasodium hydroxyethylidene diphosphonate, sodium gluconate, sodium polyacrylate, and sodium polyepoxysuccinate; in the low-corrosion stripping agent for aluminum alloy anode films, the weight parts of each component are: pure water 40-70 parts by weight, alkalinity provider 10-35 parts by weight, and chelating dispersant 1-5 parts by weight.

[0009] In the low-corrosion-rate stripping agent for aluminum alloy anode films according to the present invention, preferably, the low-corrosion-rate stripping agent for aluminum alloy anode films further includes one or more of the following: alkali stabilizer, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent; the alkali stabilizer includes one or more of the following: monoethanolamine, diethanolamine, diethylene glycolamine, 2-amino-2-methyl-1-propanol, and monoisopropanolamine; the scale inhibitor includes one or more of the following: glucose, sorbitol, sodium sulfate, and sodium phosphate; the corrosion inhibitor includes two or more of the following: thiourea, thiourea dioxide, dimethylthiourea, borax, and benzotriazole; the anti-marking wetting agent includes one or more of the following: glycerin, polyethylene glycol 200, polyethylene glycol 400, and propylene glycol; in the low-corrosion-rate stripping agent for aluminum alloy anode films, the weight parts of each component are: alkali stabilizer 5-10 parts by weight, scale inhibitor 1-5 parts by weight, corrosion inhibitor 1-5 parts by weight, and anti-marking wetting agent 5-10 parts by weight.

[0010] In the low-corrosion stripping agent for aluminum alloy anode films described in this invention, preferably, the alkalinity provider is one or more of sodium hydroxide and potassium hydroxide; and the chelating dispersant is one or more of sodium gluconate, sodium polyacrylate, and sodium polyepoxysuccinate.

[0011] In the low-corrosion stripping agent for aluminum alloy anode films of the present invention, preferably, the alkali stabilizer is one or more of monoethanolamine, diethylene glycolamine, and 2-amino-2-methyl-1-propanol; the scale inhibitor is one or more of glucose, sorbitol, and sodium phosphate; the corrosion inhibitor is two or more of thiourea, thiourea dioxide, dimethylthiourea, and borax; and the anti-marking wetting agent is one or more of polyethylene glycol 200, polyethylene glycol 400, and propylene glycol.

[0012] In the low corrosion stripping agent for aluminum alloy anode films described in this invention, preferably, the pure water comprises 50-60 parts by weight, the alkalinity provider comprises 10-30 parts by weight, and the chelating dispersant comprises 1-2 parts by weight.

[0013] In the low corrosion stripping agent for aluminum alloy anode films described in this invention, preferably, the alkali stabilizer is 5-8 parts by weight, the scale inhibitor is 2-5 parts by weight, the corrosion inhibitor is 2-5 parts by weight, and the anti-marking wetting agent is 5-10 parts by weight.

[0014] This invention also provides a method for preparing a low-corrosion stripping agent for aluminum alloy anode films. The preparation method includes the following steps: Step 1: Add pure water, and slowly add an alkalinity provider in batches to prevent violent exothermic boiling. After all the water has been added, cool it to 50-70°C. Step 2: Add a chelating dispersant while stirring, and stir until completely dissolved.

[0015] In the preparation method of the low corrosion removal agent for aluminum alloy anode film according to the present invention, preferably, in step 2, an alkali stabilizer, a scale inhibitor, a corrosion inhibitor, and an anti-marking wetting agent are added sequentially while stirring, and stirred until completely dissolved.

[0016] In the preparation method of the low corrosion stripping agent for aluminum alloy anode films according to the present invention, preferably, the alkalinity provider includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; the chelating dispersant includes one or more of tetrasodium hydroxyethylidene diphosphonate, sodium gluconate, sodium polyacrylate, and sodium polyepoxysuccinate; in the low corrosion stripping agent for aluminum alloy anode films, the weight parts of each component are: 40-60 parts by weight of pure water, 15-35 parts by weight of alkalinity provider, and 1-5 parts by weight of chelating dispersant.

[0017] In the preparation method of the low-corrosion stripping agent for aluminum alloy anode films according to the present invention, preferably, the alkali stabilizer includes one or more of monoethanolamine, diethanolamine, diethylene glycolamine, 2-amino-2-methyl-1-propanol, and monoisopropanolamine; the scale inhibitor includes one or more of glucose, sorbitol, sodium sulfate, and sodium phosphate; the corrosion inhibitor includes two or more of thiourea, thiourea dioxide, dimethylthiourea, borax, and benzotriazole; the anti-marking wetting agent includes one or more of glycerin, polyethylene glycol 200, polyethylene glycol 400, and propylene glycol; in the low-corrosion stripping agent for aluminum alloy anode films, the weight parts of each component are: alkali stabilizer 5-10 parts by weight, scale inhibitor 1-5 parts by weight, corrosion inhibitor 1-5 parts by weight, and anti-marking wetting agent 5-10 parts by weight.

[0018] The low-corrosion stripping agent for aluminum alloy anode films of this invention has been scientifically formulated and has the following beneficial effects:

[0019] I. The material has a wide range of applications and is highly versatile for anodizing film removal from various types of aluminum materials. It can efficiently and thoroughly remove anodized films from various types of aluminum materials, such as 1-series, 5-series, 6-series, and 7-series aluminum materials, without causing problems such as mottling, crystal spots, gas marks, flow marks, or poor film removal effect;

[0020] Second, it has low energy consumption and can effectively and quickly remove the anode film under medium and low temperature conditions (40-60℃);

[0021] Third, it has a low corrosion rate on the aluminum substrate, which can effectively reduce product size changes, significantly increase the number of rework cycles, reduce or avoid product scrap, and greatly improve the economic benefits of manufacturing enterprises.

[0022] Fourth, it is less likely to produce aluminum scale, avoiding aluminum scale from being suspended or deposited in the tank, which would affect the stripping effect and increase the difficulty of tank maintenance. Detailed Implementation

[0023] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0024] This invention discloses a low-corrosion-rate stripping agent for aluminum alloy anode films. The low-corrosion-rate stripping agent for aluminum alloy anode films comprises: pure water, an alkalinity provider, and a chelating dispersant; the alkalinity provider comprises one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; the chelating dispersant comprises one or more of tetrasodium hydroxyethylidene diphosphonate, sodium gluconate, sodium polyacrylate, and sodium polyepoxysuccinate; in the low-corrosion-rate stripping agent for aluminum alloy anode films, the weight parts of each component are: pure water 40-70 parts by weight, alkalinity provider 15-35 parts by weight, and chelating dispersant 1-5 parts by weight.

[0025] In a preferred embodiment of the present invention, the low-corrosion stripping agent for aluminum alloy anode films further includes one or more of the following: an alkali stabilizer, a scale inhibitor, a corrosion inhibitor, and an anti-marking wetting agent; the alkali stabilizer includes one or more of the following: monoethanolamine, diethanolamine, diethylene glycolamine, 2-amino-2-methyl-1-propanol, and monoisopropanolamine; the scale inhibitor includes one or more of the following: glucose, sorbitol, sodium sulfate, and sodium phosphate; the corrosion inhibitor includes two or more of the following: thiourea, thiourea dioxide, dimethylthiourea, borax, and benzotriazole; the anti-marking wetting agent includes one or more of the following: glycerin, polyethylene glycol 200, polyethylene glycol 400, and propylene glycol; in the low-corrosion stripping agent for aluminum alloy anode films, the weight parts of each component are: alkali stabilizer 5-10 parts by weight, scale inhibitor 1-5 parts by weight, corrosion inhibitor 1-5 parts by weight, and anti-marking wetting agent 5-10 parts by weight.

[0026] The low-corrosion stripping agent system for aluminum alloy anode films of the present invention scientifically combines pure water, an alkalinity provider, and a chelating dispersant, and selectively incorporates an alkali stabilizer, a scale inhibitor, a corrosion inhibitor, and an anti-marking wetting agent. The roles of each component in the low-corrosion stripping agent for aluminum alloy anode films of the present invention are as follows:

[0027] Alkalinity provider: The alkalinity provider is an essential component, its function is to provide alkalinity, mainly used to corrode the anodic oxide film, thus achieving a film stripping effect. Preferably, the alkalinity provider is sodium hydroxide and / or potassium hydroxide, which provides better film stripping effect. Higher amounts of alkalinity provider result in higher pH values, increasing the film stripping speed, but also slightly increasing the corrosion amount and dimensional change. Preferably, 15-30 parts by weight of alkalinity provider in the system provides a better film stripping speed without significantly increasing the corrosion amount and dimensional change. In the system of this invention, with the same amount of sodium hydroxide and potassium hydroxide, sodium hydroxide has a higher alkalinity and pH, meaning that under the same dosage conditions, sodium hydroxide has a better aging test life than potassium hydroxide, but the corresponding corrosion amount and dimensional change are also greater. Adding sodium hydroxide and potassium hydroxide in a 1:1 mass ratio provides a better synergistic effect.

[0028] Alkali stabilizer: used to maintain the pH value of the film stripping agent, so that the pH value can be better stabilized within a certain range during continuous mass production film stripping, thereby improving its service life; in a preferred embodiment, the alkali stabilizer is selected from one or more of monoethanolamine, diethylene glycolamine, and 2-amino-2-methyl-1-propanol, and the amount of alkali stabilizer added is preferably 5-8 parts by weight, which can ensure the film stripping effect and prevent the rapid drop in pH value from causing a deterioration in the film stripping effect.

[0029] Chelating dispersant: This agent has a strong chelating and removal ability for aluminum ions and other metal ions in aluminum alloys and their anolyte films, preventing these impurity metal ions from accumulating in the stripping agent working solution and affecting the stripping effect. It also has good dispersing power for large amounts of aluminum scale. Compared to existing technologies, in the basic system of this invention, a chelating dispersant is added simultaneously with an alkalinity provider. The chelating dispersant is preferably one or more of sodium gluconate, sodium polyacrylate, and sodium polyepoxysuccinate, preferably at a content of 1-2 parts by weight. This results in a better stripping effect and superior dispersing power. In the preferred stripping agent system, the combined use of a scale inhibitor and a chelating dispersant effectively prevents the aggregation of large particles that deposit on the tank, thus reducing the difficulty of tank maintenance.

[0030] Corrosion inhibitor: Used to protect the aluminum alloy substrate. After the anolyte film is removed and the aluminum alloy substrate is exposed, it greatly slows down the corrosive effect of the strong alkaline substances in the stripping agent on the aluminum alloy substrate, thus ensuring low corrosion and low dimensional change even with extended treatment time. Simultaneously, the scientifically formulated corrosion inhibitor uses a composite corrosion inhibitor, consisting of two or more of thiourea, thiourea dioxide, dimethylthiourea, borax, and benzotriazole; preferably, two or more of thiourea, thiourea dioxide, dimethylthiourea, and borax are used, and more preferably, the mass ratio of the two selected composite corrosion inhibitors is 1:1. This ensures better compatibility and protective effects for different types of aluminum materials, preventing the appearance of spots and crystalline deposits.

[0031] Scale inhibitor enhancer: When used in combination with chelating dispersants and corrosion inhibitors, it significantly enhances scale inhibition, preventing aluminum scale particles from agglomerating into large particles and depositing on the tank, thus increasing the difficulty of tank maintenance. The scale inhibitor enhancer is preferably one or more of glucose, sorbitol, and sodium phosphate, with an optimal addition amount of 2-5 parts by weight for better film removal and better dispersing power against aluminum scale.

[0032] Anti-marking wetting agent: This facilitates the rapid wetting and spreading of the stripping agent on the anolyte surface, while simultaneously penetrating into the micropores of the film layer. This improves the reaction speed and uniformity between the stripping agent and the anolyte, and, when combined with a corrosion inhibitor, effectively mitigates uneven reaction leading to spots, crystal spots, gas marks, and flow marks on the aluminum alloy substrate. In a preferred embodiment, the anti-marking wetting agent is selected from one or more of polyethylene glycol 200, polyethylene glycol 400, and propylene glycol, added in an amount of 5-10 parts by weight, resulting in even better reaction speed and uniformity between the stripping agent and the anolyte. More preferably, 2-amino-2-methyl-1-propanol is used as an alkali stabilizer, and polyethylene glycol 200 as an anti-marking wetting agent; their combined use has a synergistic effect, ensuring the stripping effect and further improving the reaction speed and uniformity between the stripping agent and the anolyte.

[0033] This invention also provides a method for preparing a low-corrosion stripping agent for aluminum alloy anolyte films. The preparation method includes the following steps: Step 1: Add pure water, and slowly add an alkalinity provider in batches to prevent violent exothermic boiling. After all the water has been added, cool to 40-60°C; Step 2: Add a chelating dispersant sequentially while stirring until completely dissolved. In Step 2, preferably, an alkali stabilizer, a chelating dispersant, a scale inhibitor, a corrosion inhibitor, and an anti-marking wetting agent are added sequentially while stirring until completely dissolved.

[0034] The low-corrosion stripping agent for aluminum alloy anolyte films of this invention is scientifically formulated with appropriate alkalinity providers, alkali stabilizers, chelating dispersants, scale inhibitors, corrosion inhibitors, and anti-marking wetting agents. Through extensive testing, the synergistic effect between the components maximizes the effectiveness of the stripping agent, achieving the following performance results:

[0035] I. Wide applicability: Compared to existing acidic and alkaline anodizing film stripping agents, this material is highly versatile for stripping anodized films from various aluminum materials. For example, it can quickly and thoroughly remove anodized films from 1-series, 5-series, 6-series, and 7-series aluminum alloys without adverse effects on the substrate, and does not cause defects such as mottled spots, crystal spots, air marks, or flow marks.

[0036] Second, compared with existing alkaline anodizing film stripping agents, it has a lower corrosion rate on the substrate, a wider tolerance for time during mass production, and the corrosion rate does not increase significantly with extended time, thus avoiding large dimensional changes, significantly increasing the number of rework cycles, and greatly reducing the scrap rate.

[0037] Third, compared with existing acidic anodizing film stripping agents, this stripping agent has low energy consumption, low dosage, and high economic efficiency; at medium and low temperatures (40-60℃), a concentration range of 10-30% (mass ratio) can effectively remove the anodized film.

[0038] Fourth, compared with existing alkaline anodizing film stripping agents, it is less likely to produce aluminum scale, avoiding aluminum scale from being suspended or deposited in the tank, affecting the stripping effect, and thus increasing the difficulty of tank maintenance.

[0039] The present invention will be described in detail below with reference to specific embodiments 1 to 12.

[0040] Examples 1-5 illustrate the effects of adding different types and amounts of alkalinity providers and chelating dispersants on the performance of low-corrosion stripping agents for aluminum alloy anode films.

[0041] Example 1

[0042] The low-corrosion stripping agent for aluminum alloy anolyte films in Example 1 comprises: pure water, 65 parts by weight; alkalinity provider: sodium hydroxide, 15 parts by weight; alkali stabilizer: 2-amino-2-methyl-1-propanol, 5 parts by weight; chelating dispersant: sodium gluconate, 1 part by weight; scale inhibitor: sorbitol, 2 parts by weight; corrosion inhibitor: thiourea, 1 part by weight; borax, 1 part by weight; and anti-marking wetting agent: polyethylene glycol 200, 10 parts by weight.

[0043] The preparation method includes the following steps: Step 1: First add water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the water has been added, the mixture must be cooled to 60°C before adding the remaining material to avoid the high temperature and high concentration of alkali causing other raw materials to deteriorate and affect the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0044] Example 2:

[0045] The low-corrosion stripping agent for aluminum alloy anolyte films in Example 2 comprises: pure water, 60 parts by weight; alkalinity provider: potassium hydroxide, 20 parts by weight; alkali stabilizer: 2-amino-2-methyl-1-propanol, 5 parts by weight; chelating dispersant: sodium polyacrylate, 1 part by weight; scale inhibitor: sorbitol, 2 parts by weight; corrosion inhibitor: thiourea, 1 part by weight; borax, 1 part by weight; and anti-marking wetting agent: polyethylene glycol 200, 10 parts by weight.

[0046] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, cool to 50°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing deterioration of other raw materials and affecting the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0047] Example 3

[0048] The low-corrosion stripping agent for aluminum alloy anolyte films in Example 3 comprises: pure water, 50 parts by weight; alkalinity provider: sodium carbonate, 30 parts by weight; alkali stabilizer: 2-amino-2-methyl-1-propanol, 5 parts by weight; chelating dispersant: sodium polyepoxysuccinate, 1 part by weight; scale inhibitor: sorbitol, 2 parts by weight; corrosion inhibitor: thiourea, 1 part by weight; borax, 1 part by weight; and anti-marking wetting agent: polyethylene glycol 200, 10 parts by weight.

[0049] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, the mixture must be cooled to 60°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing other raw materials to deteriorate and affect the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0050] Example 4

[0051] The low-corrosion stripping agent for aluminum alloy anolyte film in Example 4 comprises: pure water, 50 parts by weight; alkalinity provider: potassium hydroxide, 30 parts by weight; alkali stabilizer: 2-amino-2-methyl-1-propanol, 5 parts by weight; chelating dispersant: tetrasodium hydroxyethylidene diphosphonate, 1 part by weight; scale inhibitor: sorbitol, 2 parts by weight; corrosion inhibitor: thiourea, 1 part by weight; borax, 1 part by weight; and anti-marking wetting agent: polyethylene glycol 200, 10 parts by weight.

[0052] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, the mixture must be cooled to 55°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing deterioration of other raw materials and affecting the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0053] Example 5:

[0054] Example 5 describes a low-corrosion stripping agent for aluminum alloy anolyte films, comprising: pure water, 50 parts by weight; alkalinity providers: sodium hydroxide, 15 parts by weight, potassium hydroxide, 15 parts by weight; alkali stabilizer: 2-amino-2-methyl-1-propanol, 5 parts by weight; chelating dispersant: sodium gluconate, 1 part by weight; scale inhibitor: sorbitol, 2 parts by weight; corrosion inhibitor: thiourea, 1 part by weight, borax, 1 part by weight; and anti-marking wetting agent: polyethylene glycol 200, 10 parts by weight.

[0055] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, the mixture must be cooled to 60°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing other raw materials to deteriorate and affect the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0056] Example 6

[0057] The difference between Example 6 and Example 2 is that no corrosion inhibitor was added in Example 6.

[0058] The low-corrosion stripping agent for aluminum alloy anode films in Example 6 comprises: pure water, 62 parts by weight; alkalinity provider: sodium hydroxide, 20 parts by weight; alkali stabilizer: 2-amino-2-methyl-1-propanol, 5 parts by weight; chelating dispersant: sodium polyacrylate, 1 part by weight; scale inhibitor: sorbitol, 2 parts by weight; and anti-marking wetting agent: polyethylene glycol 200, 10 parts by weight.

[0059] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, cool to 50°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing deterioration of other raw materials and affecting the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0060] Example 7

[0061] The difference between Example 7 and Example 4 is that no scale inhibitor was added in Example 7.

[0062] The low-corrosion stripping agent for aluminum alloy anolyte film in Example 7 comprises: pure water, 52 parts by weight; alkalinity provider: potassium hydroxide, 30 parts by weight; alkali stabilizer: 2-amino-2-methyl-1-propanol, 5 parts by weight; chelating dispersant: tetrasodium hydroxyethylidene diphosphonate, 1 part by weight; corrosion inhibitor: thiourea, 1 part by weight; borax, 1 part by weight; and anti-marking wetting agent: polyethylene glycol 200, 10 parts by weight.

[0063] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, the mixture must be cooled to 60°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing other raw materials to deteriorate and affect the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0064] Example 8

[0065] The difference between Example 8 and Example 4 is that no alkali stabilizer was added in Example 8.

[0066] The low-corrosion stripping agent for aluminum alloy anode films in Example 8 comprises: pure water, 55 parts by weight; alkalinity provider: potassium hydroxide, 30 parts by weight; chelating dispersant: sodium gluconate, 1 part by weight; scale inhibitor: sorbitol, 2 parts by weight; corrosion inhibitor: thiourea, 1 part by weight; borax, 1 part by weight; and anti-marking wetting agent: polyethylene glycol 200, 10 parts by weight.

[0067] The preparation method includes the following steps: Step 1: First add water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the water has been added, the mixture must be cooled to 60°C before adding the remaining material to avoid the high temperature and high concentration of alkali causing other raw materials to deteriorate and affect the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0068] Example 9

[0069] The difference between Example 9 and Example 4 is that no anti-mark wetting agent was added in Example 9.

[0070] Example 4 describes a low-corrosion stripping agent for aluminum alloy anode films, comprising: pure water, 59 parts by weight; alkalinity provider: potassium hydroxide, 30 parts by weight; alkali stabilizer: 2-amino-2-methyl-1-propanol, 5 parts by weight; chelating dispersant: sodium polyacrylate, 2 parts by weight; scale inhibitor: sodium phosphate, 2 parts by weight; corrosion inhibitor: thiourea, 1 part by weight; and borax, 1 part by weight.

[0071] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, the mixture must be cooled to 60°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing other raw materials to deteriorate and affect the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0072] Example 10

[0073] In Example 10, the composition and weight of the raw materials were changed.

[0074] Example 10's low-corrosion stripping agent for aluminum alloy anolyte films comprises: pure water, 52.5 parts by weight; alkalinity provider: potassium hydroxide, 25 parts by weight; alkali stabilizer: monoethanolamine, 8 parts by weight; chelating dispersant: sodium gluconate, 1 part by weight, sodium polyoxysuccinate, 1 part by weight; scale inhibitor: sorbitol, 1 part by weight, sodium phosphate, 1 part by weight; corrosion inhibitor: thiourea, 1.5 parts by weight, benzotriazole, 1 part by weight; and anti-marking wetting agent: propylene glycol, 8 parts by weight.

[0075] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, the mixture must be cooled to 60°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing other raw materials to deteriorate and affect the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0076] Example 11

[0077] The difference from Example 10 is that no corrosion inhibitor and scale inhibitor were added in Example 11.

[0078] The low-corrosion stripping agent for aluminum alloy anolyte film in Example 11 comprises: pure water, 57 parts by weight; alkalinity provider: potassium hydroxide, 25 parts by weight; alkali stabilizer: monoethanolamine, 8 parts by weight; chelating dispersant: sodium gluconate, 1 part by weight, sodium polyepoxysuccinate, 1 part by weight; and anti-mark wetting agent: propylene glycol, 8 parts by weight.

[0079] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, the mixture must be cooled to 60°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing other raw materials to deteriorate and affect the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0080] Example 12

[0081] The difference from Example 10 is that in Example 12, 2-amino-2-methyl-1-propanol is used as an alkali stabilizer and polyethylene glycol 200 is used as an anti-stain wetting agent.

[0082] The low-corrosion stripping agent for aluminum alloy anolyte films in Example 12 comprises: pure water, 52.5 parts by weight; alkalinity provider: potassium hydroxide, 25 parts by weight; alkali stabilizer: 2-amino-2-methyl-1-propanol, 8 parts by weight; chelating dispersant: sodium gluconate, 1 part by weight, sodium polyoxysuccinate, 1 part by weight; scale inhibitor: sorbitol, 1 part by weight, sodium phosphate, 1 part by weight; corrosion inhibitor: thiourea, 1.5 parts by weight, benzotriazole, 1 part by weight; anti-marking wetting agent: polyethylene glycol 200, 8 parts by weight.

[0083] The preparation method includes the following steps: Step 1: First, add pure water, then slowly add the alkalinity provider in batches to prevent violent exothermic boiling. After all the materials are added, the mixture must be cooled to 60°C before adding the remaining materials to avoid the high temperature and high concentration of alkali causing other raw materials to deteriorate and affect the effect. Step 2: Add the alkali stabilizer, chelating dispersant, scale inhibitor, corrosion inhibitor, and anti-marking wetting agent in sequence while stirring, until completely dissolved.

[0084] Performance Tests and Results

[0085] The low-corrosion stripping agents for aluminum alloy anodic films obtained in Examples 1-12 were subjected to comprehensive performance tests. All aluminum alloys and their anodic oxide materials used in the comprehensive performance tests were cut to 6cm*5cm*2cm size to ensure consistent comparison results. For the same type of aluminum alloy anodic material, uniform anodizing parameters were used for preparation to ensure consistent comparison results. Specifically, performance tests were performed on each type of aluminum alloy and its anodic oxide film material, including corrosion rate testing, dimensional change testing, stripping testing, aging testing, and aluminum scale testing. The test methods are described below:

[0086] Test 1, Corrosion Test: Weigh the aluminum sheet without anodized film to its initial weight m1 (accurate to 5 decimal places). Then, immerse it in 1 kg of 20% (mass ratio) stripping agent at 55℃ for 90 seconds. After rinsing with water, immerse it in a 25% (mass ratio) nitric acid (30% content) solution for 30 seconds to remove dust. Then, rinse it clean with water and dry it. Record the mass m2 of the dried aluminum sheet (accurate to 5 decimal places) and calculate the mass change value Δm.

[0087] Test 2, Dimensional Change Test: First, measure the initial thickness h1 of the aluminum sheet without anodized film. Then, immerse it in 1 kg of 20% (mass ratio) stripping agent at 55℃ for 90 seconds. After washing with water, immerse it in a 25% (mass ratio) nitric acid (30% content) solution for 30 seconds to remove dust. Then, wash it clean with water, dry it, and measure the thickness h2 of the dried aluminum sheet. Calculate the dimensional change value Δh.

[0088] Test 3, Film Removal Test: The test piece with the anodized film was immersed in 1 kg of 20% (mass ratio) film removal agent at 55℃ for film removal treatment. After the film was removed cleanly, it was immersed in a 25% (mass ratio) nitric acid solution (30% content) for 30 seconds for dust removal treatment, then washed clean with water and dried. During this process, the time required for the film to be completely removed and the condition of the material surface (mottling, crystal spots, air marks, flow marks) were observed.

[0089] Test 4, Aging Test: At 55℃, 1 kg of 20% (mass ratio) of the tested stripping agent was used to dissolve the corresponding series of aluminum materials (without anodic oxide film) to make the aluminum content in the working solution 5 g / Kg and 10 g / Kg respectively. The pH value change and stripping effect of the stripping agent working solution were tested in sequence.

[0090] Test 5, Scaling Test: At 55℃, 50g / Kg of each aluminum alloy was dissolved in 1kg of 20% (mass ratio) of the tested film stripping agent, and the scaling was observed. Then the scale precipitate was filtered, dried, and weighed.

[0091] The following list of test results was obtained through the above tests.

[0092] Test results of Example 1

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[0095] Test results of Example 2

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[0097] Test results of Example 3

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[0100] Test results of Example 4

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[0103] Test results of Example 5

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[0105] Test results of Example 6

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[0107] Test results of Example 7

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[0110] Test results of Example 8

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[0113] Test results of Example 9

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[0116] Test results of Example 10

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[0118] Test results of Example 11

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[0121] Test results of Example 12

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[0123]

[0124] The above test results show that, in the embodiments of the present invention:

[0125] 1. In Examples 1-5, a higher dosage of alkalinity provider results in a higher pH value, which increases the film removal speed. However, it also slightly increases the corrosion rate and dimensional changes. Aging tests show that a higher dosage of alkalinity provider is more conducive to pH stability, with a slower downward trend and a slower decrease in film removal speed. In the system of this invention, for the same dosage of sodium hydroxide and potassium hydroxide, potassium hydroxide has a higher alkalinity and pH. That is, under the same dosage conditions, potassium hydroxide has a better aging test life than sodium hydroxide, but the corresponding corrosion rate and dimensional changes are also greater. Adding a certain proportion of sodium hydroxide and potassium hydroxide may further enhance the synergistic effect.

[0126] 2. A comparison between Example 2 and Example 6 shows that the corrosion inhibitor can effectively protect different types of aluminum materials, reducing corrosion and dimensional changes. The comparison table shows that with 20 parts by weight of sodium hydroxide as the alkalinity provider, the corrosion and dimensional changes are 5 times greater if no corrosion inhibitor is added to the system; furthermore, adding the corrosion inhibitor can prevent the formation of gas marks, mottling, and crystal spots.

[0127] 3. A comparison between Examples 4 and 7 shows that the scale inhibitor can significantly enhance the scale inhibition effect, preventing aluminum scale particles from agglomerating into large particles and depositing on the tank. Furthermore, a comparison of corrosion amount and size change data indicates that the scale inhibitor helps reduce both corrosion amount and size change.

[0128] 4. As can be seen from the comparison between Example 4 and Example 8, during the continuous material production process (aging), the alkali stabilizer can effectively stabilize the pH value, slow down the rate of pH value decrease, improve the service life of the film stripping agent, and ensure the film stripping effect.

[0129] 5. As can be seen from the comparison between Example 4 and Example 9, the anti-mark wetting agent can effectively improve the appearance of spots, crystal spots, air marks and flow marks on aluminum alloy substrates caused by uneven reaction.

[0130] 6. A comparison between Example 10 and Example 11 shows that the system does not contain corrosion inhibitors and scale inhibitors, resulting in significant variations in corrosion amount and size, as well as obvious gas marks, mottling, and crystal spots; and significant scale deposits are also present on the tank.

[0131] 7. A comparison between Example 10 and Example 12 shows that the system using 2-amino-2-methyl-1-propanol as an alkali stabilizer and polyethylene glycol 200 as an anti-marking wetting agent results in better corrosion reduction, dimensional changes, and stability.

[0132] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. 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 spirit and scope of the technical solutions of the present invention.

Claims

1. An aluminum alloy anodized film low-corrosion amount stripping agent, characterized by comprising: The aluminum alloy anodic film low corrosion amount stripping agent comprises pure water, alkalinity providing agent and chelating dispersant; The alkalinity providing agent comprises one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate; The chelating dispersant comprises one or more of tetrasodium hydroxyethyldiphosphonate, sodium gluconate, sodium polyacrylate and sodium polyepoxysuccinate; In the aluminum alloy anodic film low corrosion amount stripping agent, the weight fractions of the components are: 40-70 parts by weight of pure water, 10-35 parts by weight of alkalinity providing agent and 1-5 parts by weight of chelating dispersant; The aluminum alloy anodic film low corrosion amount stripping agent further comprises alkali stabilizer, scale inhibition enhancer, corrosion inhibitor and trace mark wetting agent; The alkali stabilizer comprises one or more of monoethanolamine, diethanolamine, diglycolamine and 2-amino-2-methyl-1-propanol; The scale inhibition enhancer comprises one or more of glucose, sorbitol, sodium sulfate and sodium phosphate; The corrosion inhibitor comprises two or more of thiourea, sulfur dioxide, dimethyl thiourea, borax and benzotriazole; The trace mark wetting agent comprises one or more of glycerol, polyethylene glycol 200, polyethylene glycol 400 and propylene glycol; In the aluminum alloy anodic film low corrosion amount stripping agent, the weight fractions of the components are: 5-10 parts by weight of alkali stabilizer, 1-5 parts by weight of scale inhibition enhancer, 1-5 parts by weight of corrosion inhibitor and 5-10 parts by weight of trace mark wetting agent.

2. The low-corrosion amount anodizing film stripping agent for aluminum alloy as claimed in claim 1, characterized by The alkalinity providing agent is one or more of sodium hydroxide and potassium hydroxide; The chelating dispersant is one or more of sodium gluconate, sodium polyacrylate and sodium polyepoxysuccinate.

3. The low-corrosion amount anodizing film stripping agent for aluminum alloy according to claim 1, characterized by The alkali stabilizer is one or more of monoethanolamine, diglycolamine and 2-amino-2-methyl-1-propanol; The scale inhibition enhancer is one or more of glucose, sorbitol and sodium phosphate; The corrosion inhibitor is two or more of thiourea, sulfur dioxide, dimethyl thiourea and borax; The trace mark wetting agent is one or more of polyethylene glycol 200, polyethylene glycol 400 and propylene glycol.

4. The low-corrosion amount anodizing film stripping agent for aluminum alloy according to Claim 1, characterized by comprising: The pure water is 50-60 parts by weight, the alkalinity providing agent is 10-30 parts by weight and the chelating dispersant is 1-2 parts by weight.

5. The low-corrosion amount anodizing film stripping agent for aluminum alloy as claimed in claim 1, characterized by The alkali stabilizer is 5-8 parts by weight, the scale inhibition enhancer is 2-5 parts by weight, the corrosion inhibitor is 2-5 parts by weight and the trace mark wetting agent is 5-10 parts by weight.

6. A method for producing an aluminum alloy anodized film low-corrosion stripping agent, for producing the aluminum alloy anodized film low-corrosion stripping agent according to any one of claims 1 to 5, characterized by, The preparation method comprises the following steps: step 1, adding pure water, slowly adding alkalinity providing agent in batches to prevent violent heat release and violent boiling, and cooling to 50-70℃ after all the alkalinity providing agent is added; Step 2, sequentially adding chelating dispersant while stirring until completely dissolved.

7. The method of claim 6, wherein the method is characterized by: In step 2, sequentially adding alkali stabilizer, scale inhibition enhancer, corrosion inhibitor and trace mark wetting agent while stirring until completely dissolved.

8. The preparation method of the aluminum alloy anodic film low corrosion amount stripping agent according to claim 6, wherein In the aluminum alloy anodic film low corrosion amount stripping agent, the weight fractions of the components are: 40-60 parts by weight of pure water, 15-35 parts by weight of alkalinity providing agent and 1-5 parts by weight of chelating dispersant.

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