Preparation method of environment-friendly paint remover for aluminum product production

Abstract

The invention provides a preparation method of an environment-friendly paint remover for aluminum product production, and belongs to the technical field of paint remover preparation. The preparation process comprises the following steps: preparing formic acid microcapsules; preparing an imidazolium ionic liquid; preparing a molecular sieve loaded with an alkaline metal oxide; and preparing the paint remover. The formic acid is added into the paint remover, under the action of the formic acid, the acting force between paint film molecules is weakened, the formic acid molecules can permeate into the paint film and interact with polymer molecules in the paint film, the structural integrity of the paint film is destroyed, and the paint remover containing the formic acid can soften and dissolve the paint film in a shorter time; therefore, the efficiency of paint removal operation is improved.

Description

Technical Field

[0001] The invention relates to the technical field of paint stripper preparation, and in particular to a method for preparing an environmentally friendly paint stripper for aluminum material production. Background Art

[0002] With the wide application of aluminum in various fields, aluminum surface treatment technology has also received increasing attention. In the production and processing of aluminum, it is often necessary to remove the paint on its surface to meet subsequent processing needs or achieve recycling. Traditional paint strippers often have 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 evaporate into the air, causing serious pollution to the atmospheric environment and also harmful to the health of operators. The waste residues generated by some traditional paint strippers after use are difficult to handle. If discharged at will, they will cause pollution to the soil and water bodies. At the same time, some traditional paint strippers are highly corrosive. While removing the paint on the surface of aluminum, they will also corrode the aluminum itself, affecting the quality and performance of the aluminum.

[0004] Therefore, we propose a method for preparing an environmentally friendly paint stripper for aluminum production with low corrosiveness. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing an environmentally friendly paint stripper for aluminum production.

[0006] A method for preparing an environmentally friendly paint stripper for aluminum production comprises the following steps:

[0007] S1: Preparation of formic acid microcapsules

[0008] Formic acid microcapsules were prepared using sodium alginate, earthworm powder, astaxanthin and chitosan as wall materials;

[0009] S2: Preparation of Imidazole Ionic Liquids

[0010] N-methylimidazole and n-butyl chloride are used as raw materials to react in a reactor to prepare an imidazole ionic liquid;

[0011] S3: Preparation of molecular sieves loaded with basic metal oxides

[0012] Sodium silicate, sodium aluminate, calcium chloride, aluminum sulfate 18hydrate and sodium hydroxide are mixed and reacted as raw materials, and then imidazole ionic liquid is added, stirred and mixed, and then crystallized and calcined to obtain a molecular sieve, and the molecular sieve is impregnated with a mixed solution of calcium chloride and barium chloride, and then calcined to obtain a molecular sieve loaded with alkaline metal oxides;

[0013] S4: Preparation of paint stripper

[0014] A molecular sieve loaded with alkaline metal oxide, formic acid microcapsules, sodium citrate, a wetting agent and a surfactant are added into a sodium hydroxide solution and mixed to obtain a paint stripping agent.

[0015] Furthermore, step S2 of preparing formic acid microcapsules specifically comprises 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 to completely dissolve to form a 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 a wall material B solution, and mix the wall material A solution and the wall material B solution to obtain a wall material solution;

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

[0019] Furthermore, step S2 of preparing the imidazole ionic liquid specifically comprises 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 into a three-necked flask, place the three-necked flask in a reactor, and react at 100-110° C. and 600-650 W for 50-60 min to obtain a reactant;

[0021] S2.2: After cooling the reactant, wash it with ethyl acetate 2-3 times to obtain a crude reactant, and evaporate the crude reactant under reduced pressure using a rotary evaporator at 50-55° C. and 60-70 r / min for 20-30 min to obtain an imidazole ionic liquid.

[0022] Furthermore, step S3 of preparing the molecular sieve loaded with alkaline metal oxide specifically comprises 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 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 hours to obtain a mixed solution, and dissolve 1-2 parts by weight of aluminum sulfate 18hydrate in 10-12 parts by weight of deionized water to obtain an aluminum sulfate 18hydrate solution;

[0024] S3.2: 1-2 parts by weight of sodium silicate are added to 15-18 parts by weight of deionized water, and then 1-2 parts by weight of aluminum sulfate 18hydrate solution are slowly added, and after stirring evenly, 0.1-0.2 parts by weight of sodium hydroxide are added, and the mixture is stirred for 1-2 hours, and then heated to 35-38° C., and then the above mixed solution is added, and after stirring for 1-2 hours, 10-12 parts by weight of imidazole ionic liquid are added, and the mixture is stirred for 3-5 hours to obtain a mixture;

[0025] S3.3: The mixture is transferred to a hydrothermal crystallization reactor, and then crystallized at 200-230°C for 1-2 hours. After that, it is washed with deionized water, dried, and calcined in a muffle furnace. The calcined product is placed 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, and magnetically stirred for 50-60 minutes. After that, it is centrifuged, washed to neutrality, and dried. It is then placed in a muffle furnace and calcined again to obtain a molecular sieve loaded with alkaline metal oxides.

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

[0027] S4.1: Add 15-20 parts by weight of sodium hydroxide to 150-200 parts by weight of deionized water, and stir and mix 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 molecular sieve loaded with alkaline metal oxide, 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, in step S3.3, the molar ratio of calcium chloride to barium chloride is 1:1.

[0031] Furthermore, 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.

[0032] Furthermore, 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.

[0033] Furthermore, in step S4.2, the surfactant 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, which can interact with organic compounds such as esters and ethers in the paint to promote the breakage of the macromolecular structure of the paint, thereby accelerating the dissolution and shedding of the paint layer. In addition, the molecular sieve has a large specific surface area and an ordered pore structure, and can load a large amount of alkaline metal oxides, thereby improving its dispersibility and activity and increasing the degradation rate of the paint film. At the same time, the molecular sieve can also serve as a catalyst to promote the chemical reaction between the paint stripper and the paint layer and improve the paint stripping efficiency.

[0036] 2. The present invention adds formic acid to the paint stripper. Under the action of formic acid, the interaction between the molecules of the paint film is weakened, and the formic acid molecules can penetrate into the paint film and interact with the polymer molecules in the paint film to 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 the paint stripping operation.

[0037] 3. The present invention prepares formic acid microcapsules, in which formic acid is encapsulated. The microcapsules can realize the controlled release of formic acid, so that the formic acid is slowly released during the paint stripping process, thereby extending the action time of formic acid. For some thicker or complex paint films, the microcapsules can continuously dissolve and destroy them, thereby improving the thoroughness of paint stripping. In addition, the formic acid microcapsules can reduce the chance of formic acid directly contacting the substrate by controlling the release amount and release position of formic acid, thereby reducing the risk of corrosion to the substrate.

[0038] 4. The present invention adopts sodium alginate, earthworm powder, astaxanthin and chitosan as wall materials. Sodium alginate has good film-forming properties and can form a uniform and stable wall film to wrap formic acid therein and effectively isolate the core material. Earthworm powder is rich in protein, cellulose and other ingredients, which can enhance the strength and stability of the microcapsule wall material. Astaxanthin has strong antioxidant properties and can inhibit formic acid from being oxidized to products such as carbon dioxide, thereby ensuring that the effective ingredients of formic acid microcapsules will not deteriorate during storage and extending the service life of the microcapsules. Functional groups such as amino and hydroxyl groups in chitosan molecules can chemically adsorb to 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 accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure.

[0040] Figure 1 The present invention is a flow chart of a method for preparing an environmentally friendly paint stripper for aluminum production used in an embodiment of the present invention. DETAILED DESCRIPTION

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

[0042] Example 1

[0043] A method for preparing an environmentally friendly paint stripper for aluminum production, such as Figure 1 As shown, the following steps are included:

[0044] S1: Preparation of formic acid microcapsules

[0045] 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 to completely dissolve 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 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 electrostatic spray technology at 20 kV and 0.5 mL / min to prepare formic acid microcapsules;

[0048] S2: Preparation of Imidazole Ionic Liquids

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

[0050] S2.2: Cool the reactant and wash it twice with ethyl acetate to obtain a crude reactant, and evaporate the crude reactant under reduced pressure at 50° C. and 60 r / min for 20 min using a rotary evaporator to obtain an imidazole ionic liquid;

[0051] S3: Preparation of molecular sieves loaded with basic metal oxides

[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 hour to obtain a mixed solution, and dissolve 1 part by weight of aluminum sulfate 18hydrate in 10 parts by weight of deionized water to obtain an aluminum sulfate 18hydrate solution;

[0053] S3.2: 1 part by weight of sodium silicate is added to 15 parts by weight of deionized water, and then 1 part by weight of aluminum sulfate 18hydrate solution is slowly added, and after stirring evenly, 0.1 part by weight of sodium hydroxide is added, and the mixture is stirred for 1 hour, and then heated to 35° C., and the above mixed solution is added, and after stirring for 1 hour, 10 parts by weight of imidazole ionic liquid is added, and the mixture is stirred for 3 hours to obtain a mixture;

[0054] S3.3: The mixture is transferred to a hydrothermal crystallization reactor, and then crystallized at 200°C for 1 hour, and then washed with deionized water, dried, and calcined in a muffle furnace at 550°C for 8 hours, and the calcined product is placed 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, and magnetically stirred for 50 minutes, and then centrifuged, washed to neutrality, and dried, and then placed in a muffle furnace at 550°C for calcination for 2 hours to obtain a molecular sieve loaded with alkaline metal oxides;

[0055] S4: Preparation of paint stripper

[0056] S4.1: 15 parts by weight of sodium hydroxide are added to 150 parts by weight of deionized water, and the mixture is stirred at 65° C. and 300 r / min to obtain a sodium hydroxide solution;

[0057] S4.2: Add 15 parts by weight of molecular sieve loaded with alkaline metal oxide, 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, and stir evenly to obtain SW-1046 paint stripper.

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

[0059] Example 2

[0060] A method for preparing an environmentally friendly paint stripper for aluminum production, such as Figure 1 As shown, the following steps are included:

[0061] S1: Preparation of formic acid microcapsules

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

[0063] S1.2: adding 7 parts by weight of chitosan to 60 parts by weight of deionized water, stirring to dissolve, to obtain a wall material B solution, and mixing the wall material A solution and the wall material B solution evenly to obtain a 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 electrostatic spray technology at 20 kV and 0.5 mL / min to prepare formic acid microcapsules;

[0065] S2: Preparation of Imidazole Ionic Liquids

[0066] S2.1: 25 parts by weight of N-methylimidazole and 30 parts by weight of n-butyl chloride are added to a three-necked flask, and the three-necked flask is placed in a solid / liquid phase microwave reactor, and reacted at 100° C. and 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, and evaporate the crude reactant under reduced pressure at 50° C. and 60 r / min for 20 min using a rotary evaporator to obtain an imidazole ionic liquid;

[0068] S3: Preparation of molecular sieves loaded with basic metal oxides

[0069] S3.1: 2 parts by weight of sodium silicate and 0.02 parts by weight of sodium aluminate are dissolved in 30 parts by weight of deionized water, and then 0.2 parts by weight of calcium chloride are added, and the mixture is stirred for 1 hour to obtain a mixed solution, and 2 parts by weight of aluminum sulfate 18hydrate is dissolved in 12 parts by weight of deionized water to obtain an aluminum sulfate 18hydrate solution;

[0070] S3.2: 2 parts by weight of sodium silicate are added to 18 parts by weight of deionized water, and then 2 parts by weight of aluminum sulfate 18hydrate solution are slowly added, and after stirring evenly, 0.2 parts by weight of sodium hydroxide are added, and the mixture is stirred for 1 hour, and then heated to 35° C., and the above mixed solution is added, and after stirring for 1 hour, 12 parts by weight of imidazole ionic liquid are added, and the mixture is stirred for 3 hours to obtain a mixture;

[0071] S3.3: The mixture is transferred to a hydrothermal crystallization reactor, and then crystallized at 200°C for 1 hour, and then washed with deionized water, dried, and calcined in a muffle furnace at 550°C for 8 hours, and the calcined product is placed in 12 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, and magnetically stirred for 50 minutes, and then centrifuged, washed to neutrality, and dried, and then placed in a muffle furnace at 550°C for calcination for 2 hours to obtain a molecular sieve loaded with alkaline metal oxides;

[0072] S4: Preparation of paint stripper

[0073] S4.1: Add 20 parts by weight of sodium hydroxide to 200 parts by weight of deionized water, and stir and mix them at 65° C. and 300 r / min to obtain a sodium hydroxide solution;

[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 a sodium hydroxide solution, stir well to obtain SW-1046 paint stripper.

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

[0076] Example 3

[0077] A method for preparing an environmentally friendly paint stripper for aluminum production, such as Figure 1 As shown, the following steps are included:

[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 to completely dissolve to form a 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 a wall material B solution, and mix the wall material A solution and the wall material B solution to obtain a 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 then use electrostatic spray technology at 25 kV and 2 mL / min to prepare formic acid microcapsules;

[0082] S2: Preparation of Imidazole Ionic Liquids

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

[0084] S2.2: Cool the reactant and wash it with ethyl acetate three times to obtain a crude reactant, and evaporate the crude reactant under reduced pressure at 55° C. and 70 r / min for 30 min using a rotary evaporator to obtain an imidazole ionic liquid;

[0085] S3: Preparation of molecular sieves loaded with basic metal oxides

[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, stir and mix for 2 hours to obtain a mixed solution, and dissolve 1 part by weight of aluminum sulfate 18hydrate in 10 parts by weight of deionized water to obtain an aluminum sulfate 18hydrate solution;

[0087] S3.2: 1 part by weight of sodium silicate is added to 15 parts by weight of deionized water, and then 1 part by weight of aluminum sulfate 18hydrate solution is slowly added, and after stirring evenly, 0.1 part by weight of sodium hydroxide is added, and the mixture is stirred for 2 hours, and then heated to 38° C., and then the above mixed solution is added, and after stirring for 2 hours, 10 parts by weight of imidazole ionic liquid is added, and the mixture is stirred for 5 hours to obtain a mixture;

[0088] S3.3: The mixture is transferred to a hydrothermal crystallization reactor, and then crystallized at 230°C for 2h, and then washed with deionized water, dried, and calcined in a muffle furnace at 560°C for 9h, and the calcined product is placed 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, and magnetically stirred for 60min, and then centrifuged, washed to neutrality, and dried, and then placed in a muffle furnace at 560°C for calcination for 3h to obtain a molecular sieve loaded with alkaline metal oxides;

[0089] S4: Preparation of paint stripper

[0090] S4.1: 15 parts by weight of sodium hydroxide are added to 150 parts by weight of deionized water, and the mixture is stirred at 75° C. and 500 r / min to obtain a sodium hydroxide solution;

[0091] S4.2: Add 15 parts by weight of molecular sieve loaded with alkaline metal oxide, 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 a sodium hydroxide solution, and stir evenly to obtain SW-1046 paint stripper.

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

[0093] Comparative Example 1

[0094] Compared with Example 1, the difference of Comparative Example 1 is that Comparative Example 1 is a paint stripper prepared in Example 1 of patent CN110845905B, and is recorded as Comparative Example 1.

[0095] Comparative Example 2

[0096] Compared with Example 1, the difference of Comparative Example 2 is that Comparative Example 2 removes the molecular sieve loaded with alkaline metal oxide in steps S2-S3 and S4.2, and the remaining steps remain unchanged to prepare the paint stripper, which is recorded as Comparative Example 2.

[0097] Comparative Example 3

[0098] Compared with Example 1, the difference of Comparative Example 3 is that, in Comparative Example 3, the formic acid microcapsules in steps S1 and S4.2 are removed, and the remaining steps remain unchanged to prepare the paint stripper, which is recorded as Comparative Example 3.

[0099] Comparative Example 4

[0100] Compared with Example 1, the difference of Comparative Example 4 is that step S1 is removed in Comparative Example 4, the formic acid microcapsules in S4.2 are replaced with an equal weight portion of formic acid, and the remaining steps are unchanged to prepare the paint stripper, which is recorded as Comparative Example 4.

[0101] Determination of paint stripping time:

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

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

[0104] Table 1. Paint stripping time 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 embodiment is slightly better than that of the comparative example 1, indicating that the paint stripper prepared by the present invention has a better paint stripping effect, and the present invention is more environmentally friendly and will not cause environmental pollution compared with the comparative example 1. It can be seen from the data of the comparative example 2 that the addition of the molecular sieve loaded with alkaline metal oxides in the present invention accelerates the dissolution and shedding of the paint layer, and effectively improves the paint stripping efficiency.

[0107] Corrosion rate determination:

[0108] Take five aluminum sheets with the same paint spraying and immerse them in the paint strippers obtained in Examples 1-3 and Comparative Examples 3-4, respectively, and carry out paint stripping experiments in a water bath at 70°C. Take the mass of the aluminum sheet after each group of paint films are completely detached, and record it as the mass after paint stripping. Take the mass of aluminum sheets with the same area of ​​the same aluminum material and the same cleaning process as the mass before paint stripping. Refer to Table 2 for the measurement results, and calculate the corrosion rate by 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] From the data in Table 2, it can be seen that the corrosion rate of the embodiment 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 corrode the aluminum material, while the formic acid microcapsules improve the stability of formic acid. The microcapsules can achieve controlled release of formic acid, so that it is slowly released during the paint stripping process, thereby reducing the risk of corrosion to the aluminum material. At the same time, the added chitosan can achieve a long-term corrosion inhibition effect, and then the corrosion inhibition effect of the paint stripper is better after the formic acid microcapsules are added.

[0113] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing an environmentally friendly paint stripper for aluminum production, It is characterized in that The steps include: S1: Preparation of formic acid microcapsules Formic acid microcapsules were prepared using sodium alginate, earthworm powder, astaxanthin and chitosan as wall materials; S2: Preparation of Imidazolium Ionic Liquids N-methylimidazole and n-butyl chloride are used as raw materials to react in a reactor to prepare an imidazole ionic liquid; S3: Preparation of molecular sieves loaded with basic metal oxides Sodium silicate, sodium aluminate, calcium chloride, aluminum sulfate 18hydrate and sodium hydroxide are mixed and reacted as raw materials, and then imidazole ionic liquid is added, stirred and mixed, and then crystallized and calcined to obtain a molecular sieve, and the molecular sieve is impregnated with a mixed solution of calcium chloride and barium chloride, and then calcined to obtain a molecular sieve loaded with alkaline metal oxides; S4: Preparation of paint stripper A molecular sieve loaded with alkaline metal oxide, formic acid microcapsules, sodium citrate, a wetting agent and a surfactant are added into a sodium hydroxide solution and mixed to obtain a paint stripping agent.

2. A method for preparing an environmentally friendly paint stripper for aluminum production according to claim 1, It is characterized in that Step S1: Preparation of formic acid microcapsules, specifically comprising the following steps: 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, stir and completely dissolve to form a 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 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; S1.3: Add 2-3 parts by weight of formic acid to 18-20 parts by weight of the wall material solution, stir and mix evenly, and then use electrostatic spray technology at 20-25 kV and 0.5-2 mL / min to prepare formic acid microcapsules.

3. A method for preparing an environmentally friendly paint stripper for aluminum production according to claim 2, It is characterized in that Step S2: Preparation of imidazole ionic liquid, specifically comprising the following steps: S2.1: Add 23-25 ​​parts by weight of N-methylimidazole and 29-30 parts by weight of n-butyl chloride into a three-necked flask, place the three-necked flask in a reactor, and react at 100-110° C. and 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, and evaporate the crude reactant under reduced pressure using a rotary evaporator at 50-55° C. and 60-70 r / min for 20-30 min to obtain an imidazole ionic liquid.

4. A method for preparing an environmentally friendly paint stripper for aluminum production according to claim 3, It is characterized in that Step S3: Preparation of molecular sieve loaded with basic metal oxide, specifically comprising the following steps: S3.1: Dissolve 1-2 parts by weight of sodium silicate and 0.01-0.02 parts by weight of sodium 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 hours to obtain a mixed solution, and dissolve 1-2 parts by weight of aluminum sulfate 18hydrate in 10-12 parts by weight of deionized water to obtain an aluminum sulfate 18hydrate solution; S3.2: 1-2 parts by weight of sodium silicate are added to 15-18 parts by weight of deionized water, and then 1-2 parts by weight of aluminum sulfate 18hydrate solution are slowly added, and after stirring evenly, 0.1-0.2 parts by weight of sodium hydroxide are added, and the mixture is stirred for 1-2 hours, and then heated to 35-38° C., and then the above mixed solution is added, and after stirring for 1-2 hours, 10-12 parts by weight of imidazole ionic liquid are added, and the mixture is stirred for 3-5 hours to obtain a mixture; S3.3: The mixture is transferred to a hydrothermal crystallization reactor, and then crystallized at 200-230°C for 1-2 hours. After that, it is washed with deionized water, dried, and calcined in a muffle furnace. The calcined product is placed 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, and magnetically stirred for 50-60 minutes. After that, it is centrifuged, washed to neutrality, and dried. It is then placed in a muffle furnace and calcined again to obtain a molecular sieve loaded with alkaline metal oxides.

5. A method for preparing an environmentally friendly paint stripper for aluminum production according to claim 4, It is characterized in that Step S4: preparing a paint stripper, specifically comprising the following steps: S4.1: Add 15-20 parts by weight of sodium hydroxide to 150-200 parts by weight of deionized water, and stir and mix at 65-75° C. and 300-500 r / min to obtain a 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 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.

6. A method for preparing an environmentally friendly paint stripper for aluminum production according to claim 3, It is characterized in that The reactor in step S2.1 is a solid / liquid phase microwave reactor.

7. A method for preparing an environmentally friendly paint stripper for aluminum production according to claim 4, It is characterized in that In step S3.3, the molar ratio of calcium chloride to barium chloride is 1:

1.

8. A method for preparing an environmentally friendly paint stripper for aluminum production according to claim 4, It is 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.

9. The method for preparing an environmentally friendly paint stripper for aluminum production according to claim 5, It is 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.

10. The method for preparing an environmentally friendly paint stripper for aluminum production according to claim 5, It is characterized in that In step S4.2, the surfactant includes one of AEO-9, cetyltrimethylammonium bromide, and Tween-60.

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