Preparation method of an environment-friendly paint stripper for aluminum production

Abstract

The present invention provides a preparation method of an environment-friendly paint stripper for aluminum production, belonging to the technical field of paint stripper preparation; its preparation process includes the following steps: preparation of formic acid microcapsules; preparation of imidazole-based ionic liquids; preparation of molecular sieves loaded with alkaline metal oxides; preparation of paint strippers. In the paint stripper of the present invention, formic acid is added. Under the action of formic acid, the intermolecular force of the paint film is weakened, and formic acid molecules can penetrate into the interior of the paint film, interact with polymer molecules in the paint film, and destroy the structural integrity of the paint film. The paint stripper containing formic acid can soften and dissolve the paint film in a shorter time, thereby improving the efficiency of paint stripping operation.

Description

Technical Field

[0001] The present invention relates to the technical field of paint stripper preparation, and specifically relates to a preparation method of an environment-friendly paint stripper for aluminum production. Background Art

[0002] With the wide application of aluminum in various fields, the surface treatment technology of aluminum has attracted increasing attention. In the production and processing of aluminum, it is often necessary to remove the paint on its surface to meet subsequent processing requirements or achieve recycling. Traditional paint strippers often have problems such as serious environmental pollution and corrosion to aluminum.

[0003] Traditional paint strippers usually contain a large amount of organic solvents, such as benzene, toluene, xylene, dichloromethane, etc. These organic solvents volatilize into the air, causing serious pollution to the atmospheric environment and also harming the health of operators. The waste residues generated after the use of some traditional paint strippers are difficult to treat. If discharged randomly, they will pollute the soil and water bodies. At the same time, some traditional paint strippers have strong corrosiveness, which will corrode the aluminum itself while removing the paint on the aluminum surface, affecting the quality and performance of the aluminum.

[0004] Therefore, we propose a preparation method of an environment-friendly paint stripper for aluminum production with low corrosiveness. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a preparation method of an environment-friendly paint stripper for aluminum production.

[0006] A preparation method of an environment-friendly paint stripper for aluminum production includes the following steps:

[0007] S1: Preparation of formic acid microcapsules

[0008] Using sodium alginate, earthworm powder, astaxanthin, and chitosan as wall materials, prepare formic acid microcapsules;

[0009] S2: Preparation of imidazole-based ionic liquid

[0010] Using N-methylimidazole and n-butyl chloride as raw materials, react in a reactor to prepare imidazole-based ionic liquid;

[0011] S3: Preparation of molecular sieve loaded with basic metal oxide

[0012] Using sodium silicate, sodium aluminate, calcium chloride, aluminum sulfate octadecahydrate, and sodium hydroxide as raw materials, mix and react, then add imidazole-based ionic liquid, stir and mix, and then carry out crystallization and calcination to obtain a molecular sieve. Impregnate the molecular sieve with a mixed solution of calcium chloride and barium chloride, and then calcine to obtain the preparation of the molecular sieve loaded with basic metal oxide;

[0013] S4: Preparation of paint stripper

[0014] Add molecular sieve loaded with basic metal oxide, formic acid microcapsules, sodium citrate, wetting agent and surfactant to sodium hydroxide solution, and mix them to obtain the paint stripper.

[0015] Furthermore, the preparation of formic acid microcapsules in step S2 specifically includes the following steps:

[0016] S1.1: Add 1.5 - 2 parts by weight of sodium alginate, 0.01 - 0.02 parts by weight of earthworm powder and 0.01 - 0.015 parts by weight of astaxanthin to 100 - 120 parts by weight of deionized water, and stir until completely dissolved to form wall material A solution;

[0017] S1.2: Add 6 - 7 parts by weight of chitosan to 50 - 60 parts by weight of deionized water, stir and dissolve to obtain wall material B solution, and mix wall material A solution and wall material B solution evenly to obtain wall material solution;

[0018] S1.3: Add 2 - 3 parts by weight of formic acid to 18 - 20 parts by weight of wall material solution, stir and mix evenly, and use electrospray technology to prepare formic acid microcapsules at 20 - 25 kV and 0.5 - 2 mL / min.

[0019] Furthermore, the preparation of imidazole ionic liquid in step S2 specifically includes the following steps:

[0020] S2.1: Add 23 - 25 parts by weight of N - methylimidazole and 29 - 30 parts by weight of n - butyl chloride to a three - necked flask, place the three - necked flask in a reactor, and react at 100 - 110 °C and a power of 600 - 650 W for 50 - 60 min to obtain a reactant;

[0021] S2.2: Cool the reactant and wash it with ethyl acetate 2 - 3 times to obtain a crude reactant, and carry out vacuum evaporation of the crude reactant with a rotary evaporator at 50 - 55 °C and 60 - 70 r / min for 20 - 30 min to obtain imidazole ionic liquid.

[0022] Furthermore, the preparation of molecular sieve loaded with basic metal oxide in step S3 specifically includes the following steps:

[0023] S3.1: Dissolve 1 - 2 parts by weight of sodium silicate and 0.01 - 0.02 parts by weight of sodium meta - aluminate in 20 - 30 parts by weight of deionized water, then add 0.1 - 0.2 parts by weight of calcium chloride, stir and mix for 1 - 2 h to obtain a mixed solution, and dissolve 1 - 2 parts by weight of aluminum sulfate octadecahydrate in 10 - 12 parts by weight of deionized water to obtain aluminum sulfate octadecahydrate solution;

[0024] S3.2: Add 1-2 parts by weight of sodium silicate to 15-18 parts by weight of deionized water, then slowly add 1-2 parts by weight of aluminum sulfate octadecahydrate solution. After stirring evenly, add 0.1-0.2 parts by weight of sodium hydroxide, stir and mix for 1-2 h, then heat to 35-38 °C, add the above mixed solution, stir for 1-2 h, and then add 10-12 parts by weight of imidazole-based ionic liquid, stir for 3-5 h to obtain a mixture;

[0025] S3.3: Transfer the mixture to a hydrothermal crystallization kettle, crystallize at 200-230 °C for 1-2 h, then wash with deionized water, dry, and calcine in a muffle furnace. Place the calcined product in 10-12 parts by weight of a mixed solution of calcium chloride and barium chloride with a molar concentration of 0.14 mol / L, stir magnetically for 50-60 min, then centrifuge, wash until neutral, dry, and calcine again in a muffle furnace to obtain a molecular sieve loaded with basic metal oxides.

[0026] Furthermore, the preparation of the paint stripper in step S4 specifically includes the following steps:

[0027] S4.1: Add 15-20 parts by weight of sodium hydroxide to 150-200 parts by weight of deionized water, stir and mix evenly at 65-75 °C and 300-500 r / min to obtain a sodium hydroxide solution;

[0028] S4.2: Add 15-20 parts by weight of the molecular sieve loaded with basic metal oxides, 5-8 parts by weight of formic acid microcapsules, 3-5 parts by weight of sodium citrate, 2-3 parts by weight of wetting agent, and 3-5 parts by weight of surfactant to the sodium hydroxide solution, and stir evenly to obtain a paint stripper.

[0029] Furthermore, the reactor in step S2.1 is a solid / liquid phase microwave reactor.

[0030] Furthermore, the molar ratio of calcium chloride to barium chloride in step S3.3 is 1:1.

[0031] Furthermore, the temperature of the muffle furnace in step S3.3 is 550-560 °C, the first calcination time is 8-9 h, and the second calcination time is 2-3 h.

[0032] Furthermore, the wetting agent in step S4.2 is obtained by mixing ethanol, propylene glycol, and glycerol in a mass ratio of 1:2-3:1.

[0033] Furthermore, the surfactant in step S4.2 includes one of AEO-9, cetyltrimethylammonium bromide, and Tween-60.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] 1. The molecular sieve loaded with alkaline metal oxides prepared by the present invention has alkaline sites. These alkaline sites can interact with organic compounds such as esters and ethers in the paint, promoting the breakage of the macromolecular structure of the paint, thereby accelerating the dissolution and peeling of the paint layer. Moreover, the molecular sieve has a large specific surface area and an ordered pore structure, which can load a large amount of alkaline metal oxides, improving their dispersibility and activity, and enhancing the degradation rate of the paint film. At the same time, the molecular sieve can also act as a catalyst to promote the chemical reaction between the paint remover and the paint layer, improving the paint removal efficiency.

[0036] 2. Formic acid is added to the paint remover of the present invention. Under the action of formic acid, the intermolecular force in the paint film is weakened. Formic acid molecules can penetrate into the interior of the paint film and interact with the polymer molecules in the paint film, destroying the structural integrity of the paint film. The paint remover containing formic acid can soften and dissolve the paint film in a shorter time, thereby improving the efficiency of the paint removal operation.

[0037] 3. Formic acid microcapsules are prepared in the present invention. Formic acid is encapsulated in the microcapsules, and the microcapsules can achieve controlled release of formic acid, enabling it to be slowly released during the paint removal process, prolonging the action time of formic acid. For some relatively thick or structurally complex paint films, it can continuously dissolve and damage them, improving the thoroughness of paint removal. Moreover, the formic acid microcapsules can reduce the chance of direct contact between formic acid and the substrate by controlling the release amount and release position of formic acid, thereby reducing the corrosion risk to the substrate.

[0038] 4. Sodium alginate, earthworm powder, astaxanthin, and chitosan are used as the wall materials in the present invention. Sodium alginate has good film-forming properties and can form a uniform and stable wall film to encapsulate formic acid, effectively isolating the core material. Earthworm powder contains rich components such as proteins and cellulose, which can enhance the strength and stability of the microcapsule wall material. Astaxanthin has strong antioxidant properties and can inhibit the oxidation of formic acid into products such as carbon dioxide, thus ensuring that the active ingredient of the formic acid microcapsule does not deteriorate during storage and prolonging the service life of the microcapsule. The amino and hydroxyl functional groups in the chitosan molecule can chemically adsorb on the metal surface to form a uniform and dense protective film on the metal surface, thereby improving the corrosion inhibition effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings incorporated herein and constituting a part of the specification illustrate embodiments of the present disclosure and, together with the specification, are further used to explain the principles of the present disclosure and enable those skilled in the relevant art to implement and use the present disclosure.

[0040] Figure 1 It is a flowchart of a preparation method of an environment-friendly paint remover for aluminum material production adopted in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The following is a detailed description of a preparation method of an environmentally friendly paint stripper for aluminum production provided by the present invention in combination with the accompanying drawings and specific embodiments. At the same time, it should be noted here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments. For some well-known technologies, those skilled in the art can also adopt other alternative methods for implementation; moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0042] Example 1

[0043] A preparation method of an environmentally friendly paint stripper for aluminum production is as Figure 1 shown, and includes the following steps:

[0044] S1: Preparation of formic acid microcapsules

[0045] S1.1: Add 1.5 parts by weight of sodium alginate, 0.01 part by weight of earthworm powder, and 0.01 part by weight of astaxanthin to 100 parts by weight of deionized water and stir until completely dissolved to form a wall material A solution;

[0046] S1.2: Add 6 parts by weight of chitosan to 50 parts by weight of deionized water, stir and dissolve to obtain a wall material B solution, and mix the wall material A solution and the wall material B solution evenly to obtain a wall material solution;

[0047] S1.3: Add 2 parts by weight of formic acid to 18 parts by weight of the wall material solution, stir and mix evenly, and then use the electrostatic spraying technique to prepare formic acid microcapsules at 20 kV and 0.5 mL / min;

[0048] S2: Preparation of imidazole-based ionic liquid

[0049] S2.1: Add 23 parts by weight of N-methylimidazole and 29 parts by weight of n-butyl chloride to a three-necked flask, place the three-necked flask in a solid / liquid phase microwave reactor, and react at 100 °C and a power of 600 W for 50 min to obtain a reactant;

[0050] S2.2: After cooling the reactant, wash it twice with ethyl acetate to obtain a crude reactant, and carry out vacuum evaporation of the crude reactant with a rotary evaporator at 50 °C and 60 r / min for 20 min to obtain an imidazole-based ionic liquid;

[0051] S3: Preparation of molecular sieve loaded with basic metal oxide

[0052] S3.1: Dissolve 1 part by weight of sodium silicate and 0.01 part by weight of sodium aluminate in 20 parts by weight of deionized water, then add 0.1 part by weight of calcium chloride, stir and mix for 1 h to obtain a mixed solution. Dissolve 1 part by weight of aluminum sulfate octadecahydrate in 10 parts by weight of deionized water to obtain an aluminum sulfate octadecahydrate solution;

[0053] S3.2: Add 1 part by weight of sodium silicate to 15 parts by weight of deionized water, slowly add 1 part by weight of the aluminum sulfate octadecahydrate solution, stir evenly, then add 0.1 part by weight of sodium hydroxide, stir and mix for 1 h, then heat to 35 °C, add the above mixed solution, stir for 1 h, then add 10 parts by weight of an imidazole-based ionic liquid, stir for 3 h to obtain a mixture;

[0054] S3.3: Transfer the mixture to a hydrothermal crystallization kettle, crystallize at 200 °C for 1 h, then wash with deionized water, dry, and place in a muffle furnace at 550 °C for calcination for 8 h. Place the calcined product in 10 parts by weight of a mixed solution of calcium chloride and barium chloride with a molar concentration of 0.14 mol / L, and the molar ratio of calcium chloride to barium chloride is 1:1. Magnetically stir for 50 min, then centrifuge, wash until neutral, dry, and place in a muffle furnace at 550 °C for calcination for 2 h to obtain a molecular sieve loaded with alkaline metal oxides;

[0055] S4: Preparation of paint stripper

[0056] S4.1: Add 15 parts by weight of sodium hydroxide to 150 parts by weight of deionized water, stir and mix evenly at 65 °C and 300 r / min to obtain a sodium hydroxide solution;

[0057] S4.2: Add 15 parts by weight of the molecular sieve loaded with alkaline metal oxides, 5 parts by weight of formic acid microcapsules, 3 parts by weight of sodium citrate, 2 parts by weight of wetting agent, and 3 parts by weight of cetyltrimethylammonium bromide to the sodium hydroxide solution, stir evenly to obtain the SW-1046 paint stripper.

[0058] The wetting agent is obtained by mixing ethanol, propylene glycol, and glycerol in a mass ratio of 1:2:1.

[0059] Example 2

[0060] A preparation method of an environment-friendly paint stripper for aluminum material production, as Figure 1 shown, includes the following steps:

[0061] S1: Preparation of formic acid microcapsules

[0062] S1.1: Add 2 parts by weight of sodium alginate, 0.02 part by weight of earthworm powder, and 0.015 part by weight of astaxanthin to 120 parts by weight of deionized water, stir until completely dissolved to form a wall material A solution;

[0063] S1.2: Add 7 parts by weight of chitosan to 60 parts by weight of deionized water, stir and dissolve to obtain the wall material B solution, and mix the wall material A solution and the wall material B solution evenly to obtain the wall material solution;

[0064] S1.3: Add 3 parts by weight of formic acid to 20 parts by weight of the wall material solution, stir and mix evenly, and then use the electrostatic spraying technique to prepare formic acid microcapsules at 20 kV and 0.5 mL / min;

[0065] S2: Preparation of imidazole-based ionic liquid

[0066] S2.1: Add 25 parts by weight of N-methylimidazole and 30 parts by weight of n-butyl chloride to a three-necked flask, place the three-necked flask in a solid / liquid phase microwave reactor, and react at 100 °C and a power of 600 W for 50 min to obtain a reactant;

[0067] S2.2: Cool the reactant and wash it twice with ethyl acetate to obtain a crude reactant. Use a rotary evaporator to perform vacuum evaporation on the crude reactant at 50 °C and 60 r / min for 20 min to obtain the imidazole-based ionic liquid;

[0068] S3: Preparation of molecular sieve loaded with alkaline metal oxide

[0069] S3.1: Dissolve 2 parts by weight of sodium silicate and 0.02 parts by weight of sodium meta-aluminate in 30 parts by weight of deionized water, then add 0.2 parts by weight of calcium chloride, stir and mix for 1 h to obtain a mixed solution. Dissolve 2 parts by weight of aluminum sulfate octadecahydrate in 12 parts by weight of deionized water to obtain an aluminum sulfate octadecahydrate solution;

[0070] S3.2: Add 2 parts by weight of sodium silicate to 18 parts by weight of deionized water, slowly add 2 parts by weight of the aluminum sulfate octadecahydrate solution, stir evenly, add 0.2 parts by weight of sodium hydroxide, stir and mix for 1 h, then heat to 35 °C, add the above mixed solution, stir for 1 h, and then add 12 parts by weight of the imidazole-based ionic liquid, stir for 3 h to obtain a mixture;

[0071] S3.3: Transfer the mixture to a hydrothermal crystallization kettle, crystallize at 200 °C for 1 h, then wash with deionized water, dry, place in a muffle furnace at 550 °C and calcine for 8 h. Place the calcined product in 12 parts by weight of a mixed solution of calcium chloride and barium chloride with a molar concentration of 0.14 mol / L, the molar ratio of calcium chloride to barium chloride is 1:1, stir magnetically for 50 min, then centrifuge, wash until neutral and dry, and place in a muffle furnace at 550 °C and calcine for 2 h to obtain the molecular sieve loaded with alkaline metal oxide;

[0072] S4: Preparation of paint remover

[0073] S4.1: Add 20 parts by weight of sodium hydroxide to 200 parts by weight of deionized water. After stirring and mixing evenly at 65 °C and 300 r / min, a sodium hydroxide solution is obtained.

[0074] S4.2: Add 20 parts by weight of molecular sieve loaded with alkaline metal oxide, 8 parts by weight of formic acid microcapsules, 5 parts by weight of sodium citrate, 3 parts by weight of wetting agent, and 5 parts by weight of AEO-9 to the sodium hydroxide solution, and stir evenly to obtain the SW-1046 paint stripper.

[0075] The wetting agent is obtained by mixing ethanol, propylene glycol, and glycerol in a mass ratio of 1:3:1.

[0076] Example 3

[0077] A preparation method of an environment-friendly paint stripper for aluminum production, as Figure 1 shown, includes the following steps:

[0078] S1: Preparation of formic acid microcapsules

[0079] S1.1: Add 1.5 parts by weight of sodium alginate, 0.01 parts by weight of earthworm powder, and 0.01 parts by weight of astaxanthin to 100 parts by weight of deionized water, and stir until completely dissolved to form the wall material A solution.

[0080] S1.2: Add 6 parts by weight of chitosan to 50 parts by weight of deionized water, stir and dissolve to obtain the wall material B solution, and mix the wall material A solution and the wall material B solution evenly to obtain the wall material solution.

[0081] S1.3: Add 2 parts by weight of formic acid to 18 parts by weight of the wall material solution, stir and mix evenly, and use the electrostatic spraying technology to prepare formic acid microcapsules at 25 kV and 2 mL / min.

[0082] S2: Preparation of imidazole-based ionic liquid

[0083] S2.1: Add 23 parts by weight of N-methylimidazole and 29 parts by weight of n-butyl chloride to a three-necked flask, place the three-necked flask in a solid / liquid phase microwave reactor, and react at 110 °C and a power of 650 W for 60 min to obtain the reactant.

[0084] S2.2: After cooling the reactant, wash it 3 times with ethyl acetate to obtain the crude reactant, and carry out vacuum evaporation of the crude reactant at 55 °C and 70 r / min for 30 min using a rotary evaporator to obtain the imidazole-based ionic liquid.

[0085] S3: Preparation of molecular sieve loaded with alkaline metal oxide

[0086] S3.1: Dissolve 1 part by weight of sodium silicate and 0.01 part by weight of sodium aluminate in 20 parts by weight of deionized water, then add 0.1 part by weight of calcium chloride and stir and mix for 2 h to obtain a mixed solution. Dissolve 1 part by weight of aluminum sulfate octadecahydrate in 10 parts by weight of deionized water to obtain an aluminum sulfate octadecahydrate solution;

[0087] S3.2: Add 1 part by weight of sodium silicate to 15 parts by weight of deionized water, slowly add 1 part by weight of the aluminum sulfate octadecahydrate solution, stir evenly, then add 0.1 part by weight of sodium hydroxide, stir and mix for 2 h, then heat to 38 °C, add the above mixed solution, stir for 2 h, then add 10 parts by weight of an imidazole-based ionic liquid and stir for 5 h to obtain a mixture;

[0088] S3.3: Transfer the mixture to a hydrothermal crystallization kettle, crystallize at 230 °C for 2 h, then wash with deionized water, dry, and place in a muffle furnace at 560 °C for calcination for 9 h. Place the calcined product in 10 parts by weight of a mixed solution of calcium chloride and barium chloride with a molar concentration of 0.14 mol / L, and the molar ratio of calcium chloride to barium chloride is 1:1. Stir magnetically for 60 min, then centrifuge, wash until neutral, and dry. Place in a muffle furnace at 560 °C again for calcination for 3 h to obtain a molecular sieve loaded with basic metal oxides;

[0089] S4: Preparation of paint remover

[0090] S4.1: Add 15 parts by weight of sodium hydroxide to 150 parts by weight of deionized water, stir and mix evenly at 75 °C and 500 r / min to obtain a sodium hydroxide solution;

[0091] S4.2: Add 15 parts by weight of the molecular sieve loaded with basic metal oxides, 5 parts by weight of formic acid microcapsules, 3 parts by weight of sodium citrate, 2 parts by weight of wetting agent, and 3 parts by weight of Tween-60 to the sodium hydroxide solution, stir evenly to obtain the SW-1046 paint remover.

[0092] The wetting agent is obtained by mixing ethanol, propylene glycol, and glycerol in a mass ratio of 1:2:1.

[0093] Comparative Example 1

[0094] Compared with Example 1, the difference in Comparative Example 1 is that Comparative Example 1 is the paint remover prepared in Example 1 of Patent CN110845905B, denoted as Comparative Example 1.

[0095] Comparative Example 2

[0096] Compared with Example 1, the difference in Comparative Example 2 is that Comparative Example 2 is the paint remover prepared by removing the molecular sieve loaded with basic metal oxides in Steps S2 - S3 and S4.2, and the remaining steps remain unchanged, denoted as Comparative Example 2.

[0097] Comparative Example 3

[0098] Compared with Example 1, the difference in Comparative Example 3 is that in Comparative Example 3, the formic acid microcapsules in steps S1 and S4.2 were removed, and the other steps remained unchanged to prepare a paint stripper, denoted as Comparative Example 3.

[0099] Comparative Example 4

[0100] Compared with Example 1, the difference in Comparative Example 4 is that in Comparative Example 4, step S1 was removed, and the formic acid microcapsules in S4.2 were replaced with an equal weight portion of formic acid, and the other steps remained unchanged to prepare a paint stripper, denoted as Comparative Example 4.

[0101] Determination of paint stripping time:

[0102] The aluminum sheets were cleaned, polished, and dried, and then uniformly sprayed with paint (paint materials: polyurethane paint and epoxy paint) on one side of the metal aluminum sheet. The thickness of the paint film was consistent, and the painted aluminum sheets were cut into aluminum sheets of equal area.

[0103] Five painted aluminum sheets were respectively placed in the paint strippers obtained in Examples 1 - 3 and Comparative Examples 1 - 2, and a paint stripping experiment was carried out under the condition of a 70°C water bath. The time when the paint film of each group was completely detached was recorded as the paint stripping time, and the measurement results are shown in Table 1.

[0104] Table 1. Paint stripping times of Examples 1 - 3 and Comparative Examples 1 - 2

[0105] Polyurethane paint stripping time Epoxy paint stripping time Example 1 10min 20min Example 2 11min 21min Example 3 10min 21min Comparative Example 1 12min 23min Comparative Example 2 27min 58min

[0106] It can be seen from Table 1 that the data of the examples are slightly better than those of Comparative Example 1, indicating that the paint stripper prepared by the present invention has a better paint stripping effect. Moreover, compared with Comparative Example 1, the components of the present invention are more environmentally friendly and will not cause environmental pollution. It can be seen from the data of Comparative Example 2 that after adding the molecular sieve loaded with basic metal oxides in the present invention, the dissolution and peeling of the paint layer are accelerated, effectively improving the paint stripping efficiency.

[0107] Determination of corrosion rate:

[0108] Five identically painted aluminum sheets were respectively immersed in the paint strippers obtained in Examples 1 - 3 and Comparative Examples 3 - 4, and a paint stripping experiment was carried out under the condition of a 70°C water bath. The mass of the aluminum sheet after the paint film of each group was completely detached was recorded as the mass after paint stripping. The mass of the same aluminum material with the same area of aluminum sheet after being cleaned by the same process was used as the mass before paint stripping. The measurement results are shown in Table 2, and the corrosion rate was calculated using the following formula:

[0109] Corrosion rate = (mass before paint stripping - mass after paint stripping) / mass before paint stripping × 100%.

[0110] Table 2. Corrosion rate results of Examples 1 - 3 and Comparative Examples 3 - 4

[0111] Corrosion rate (%) Example 1 0.3 Example 2 0.4 Example 3 0.4 Comparative Example 3 2.1 Comparative Example 4 4.5

[0112] As can be seen from the data in Table 2, the corrosion rate of the examples is lower than that of Comparative Examples 3-4, and the corrosion rate of Comparative Example 4 is higher than that of Comparative Example 3, indicating that directly adding formic acid is likely to cause corrosion to aluminum materials. The formic acid microcapsules improve the stability of formic acid, and the microcapsules can achieve controlled release of formic acid, enabling it to be slowly released during the paint stripping process, thereby reducing the corrosion risk to aluminum materials. At the same time, the added chitosan can achieve a long-term corrosion inhibition effect. Subsequently, the corrosion inhibition effect of the paint stripper is better after adding the formic acid microcapsules.

[0113] The above examples merely illustrate the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above examples without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A preparation method of an environment-friendly paint stripper for aluminum production, characterized in that, It includes the following steps: S1: Preparation of formic acid microcapsules S1.1: Add 1.5 - 2 parts by weight of sodium alginate, 0.01 - 0.02 parts by weight of earthworm powder, and 0.01 - 0.015 parts by weight of astaxanthin to 100 - 120 parts by weight of deionized water, and stir until completely dissolved to form wall material A solution; S1.2: Add 6 - 7 parts by weight of chitosan to 50 - 60 parts by weight of deionized water, stir and dissolve to obtain wall material B solution. Mix wall material A solution and wall material B solution evenly to obtain wall material solution; S1.3: Add 2 - 3 parts by weight of formic acid to 18 - 20 parts by weight of wall material solution, stir and mix evenly, and then use electrostatic spraying technology to prepare formic acid microcapsules at 20 - 25 kV and 0.5 - 2 mL / min; S2: Preparation of imidazole ionic liquid S2.1: Add 23 - 25 parts by weight of N - methylimidazole and 29 - 30 parts by weight of n - butyl chloride to a three - necked flask. Place the three - necked flask in a reactor and react at 100 - 110 °C and a power of 600 - 650 W for 50 - 60 min to obtain a reactant; S2.2: After cooling the reactant, wash it with ethyl acetate 2 - 3 times to obtain a crude reactant. Use a rotary evaporator to perform vacuum evaporation on the crude reactant at 50 - 55 °C and 60 - 70 r / min for 20 - 30 min to obtain imidazole ionic liquid; S3: Preparation of molecular sieve loaded with alkaline metal oxide S3.1: Dissolve 1 - 2 parts by weight of sodium silicate and 0.01 - 0.02 parts by weight of sodium meta - aluminate in 20 - 30 parts by weight of deionized water, then add 0.1 - 0.2 parts by weight of calcium chloride, stir and mix for 1 - 2 h to obtain a mixed solution. Dissolve 1 - 2 parts by weight of aluminum sulfate octadecahydrate in 10 - 12 parts by weight of deionized water to obtain aluminum sulfate octadecahydrate solution; S3.2: Add 1 - 2 parts by weight of sodium silicate to 15 - 18 parts by weight of deionized water, slowly add 1 - 2 parts by weight of aluminum sulfate octadecahydrate solution, stir evenly, add 0.1 - 0.2 parts by weight of sodium hydroxide, stir and mix for 1 - 2 h, then heat to 35 - 38 °C, add the above - mentioned mixed solution, stir for 1 - 2 h, and then add 10 - 12 parts by weight of imidazole ionic liquid, stir for 3 - 5 h to obtain a mixture; S3.3: Transfer the mixture to a hydrothermal crystallization kettle, crystallize at 200 - 230 °C for 1 - 2 h, then wash with deionized water, dry, and place in a muffle furnace for calcination. Place the calcined product in 10 - 12 parts by weight of a mixed solution of calcium chloride and barium chloride with a molar concentration of 0.14 mol / L, stir magnetically for 50 - 60 min, then centrifuge, wash until neutral, dry, and place in a muffle furnace for calcination again to obtain a molecular sieve loaded with alkaline metal oxide; S4: Preparation of paint remover S4.1: Add 15 - 20 parts by weight of sodium hydroxide to 150 - 200 parts by weight of deionized water, stir and mix evenly at 65 - 75 °C and 300 - 500 r / min to obtain sodium hydroxide solution; S4.2: Add 15 - 20 parts by weight of molecular sieve loaded with alkaline metal oxide, 5 - 8 parts by weight of formic acid microcapsule, 3 - 5 parts by weight of sodium citrate, 2 - 3 parts by weight of wetting agent, and 3 - 5 parts by weight of surfactant to the sodium hydroxide solution, and stir evenly to obtain the paint stripper.

2. The preparation method of an environment-friendly paint stripper for aluminum production according to claim 1, characterized in that, The reactor in step S2.1 is a solid / liquid phase microwave reactor.

3. The preparation method of an environment-friendly paint stripper for aluminum production according to claim 1, characterized in that, In step S3.3, the molar ratio of calcium chloride to barium chloride is 1:

1.

4. The preparation method of an environment-friendly paint stripper for aluminum production according to claim 1, characterized in that, In step S3.3, the temperature of the muffle furnace is 550 - 560 °C, the first calcination time is 8 - 9 h, and the second calcination time is 2 - 3 h.

5. The preparation method of an environment-friendly paint stripper for aluminum production according to claim 1, characterized in that, In step S4.2, the wetting agent is obtained by mixing ethanol, propylene glycol, and glycerol in a mass ratio of 1:2 - 3:

1.

6. The preparation method of an environment-friendly paint stripper for aluminum material production according to claim 1, characterized in that, In step S4.2, the surfactant includes one of AEO - 9, cetyltrimethylammonium bromide, and Tween - 60.

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