Efficient and environment-friendly paint remover and preparation method and paint removing method thereof

Abstract

The invention belongs to the technical field of paint removers, and discloses a high-efficiency and environment-friendly paint remover as well as a preparation method and a paint removal method thereof. The paint remover comprises a main solvent, a cosolvent, a surfactant and a thickening agent, the main solvent comprises diethylene glycol monobutyl ether, the cosolvent comprises glycerol and propylene glycol carbonate, the surfactant comprises an anionic surfactant and a nonionic surfactant, and the thickening agent comprises an anionic surfactant and a nonionic surfactant. The non-ionic surface active agent comprises sorbitan fatty acid ester and an organic silicon surface active agent, and the thickening agent comprises xanthan gum and a nanometer aluminum oxide solution. The paint remover does not contain dichloromethane, is low in toxicity and environment-friendly, can quickly swell and strip high polymer molecules of a paint film, thoroughly destroy the adhesive force of the paint film to a substrate and remove the paint film through selective and matched use of specific components, does not cause any corrosion and adverse effect on an aluminum alloy substrate, and is suitable for industrial production. Residues of the depainted base material can be quickly cleaned away, and the phenomena of blackening or whitening and the like are avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of paint strippers, and particularly relates to a highly efficient and environmentally friendly paint stripper, a preparation method thereof, and a paint stripping method. Background Art

[0002] Aluminum alloy is an alloy based on aluminum with a certain amount of other metal elements added. It has the characteristics of low density, high strength, and convenient processing, and is widely used in industries such as automobile manufacturing, furniture renovation, architectural decoration, and aerospace. In the production and processing of aluminum profiles, a coating treatment is usually carried out on the surface of the aluminum profiles, and a layer of paint is sprayed to form a protective paint film on the surface. This can not only make the metal surface more beautiful but also improve the corrosion resistance of the aluminum profiles and play a role in protecting the substrate. However, when problems such as unqualified production of the paint layer on the surface of the aluminum profiles occur, or the metal ages, peels, or cracks due to long-term use, causing the paint film to lose its protective effect, a paint stripper is needed to remove the paint film on the surface and repaint. Currently, relatively widely used paint strippers such as high-temperature strong alkaline paint strippers containing sodium hydroxide, or organic solvent-based paint strippers containing dichloromethane, etc., have defects such as long paint stripping time, strong odor, poor safety operability, and corrosion to the aluminum alloy substrate; dichloromethane is a volatile toxic organic solvent and causes great harm to the human body.

[0003] Therefore, it is very necessary to develop a paint stripper that is environmentally friendly, has high paint stripping efficiency, and low corrosiveness. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides a highly efficient and environmentally friendly paint stripper, a preparation method thereof, and a paint stripping method. The paint stripper provided by the present invention does not contain dichloromethane, has low toxicity and is friendly to the environment. At the same time, it can quickly strip paint at room temperature and does not corrode the workpiece substrate.

[0005] In the first aspect of the present invention, a paint stripper is provided. The paint stripper includes a main solvent, a co-solvent, a surfactant, and a thickener. The main solvent includes diethylene glycol monobutyl ether, the co-solvent includes glycerol and propylene glycol carbonate, the surfactant includes an anionic surfactant and a non-ionic surfactant, the non-ionic surfactant includes sorbitan fatty acid ester and organosilicon surfactant, and the thickener includes xanthan gum and nano-aluminum oxide solution.

[0006] Specifically, diethylene glycol monobutyl ether is an organic solvent that is soluble in water and alcohol and has a wide range of solubility. Due to the hydroxyl and ether bonds in its molecular structure, diethylene glycol monobutyl ether is both hydrophilic and lipophilic, has good permeability, can penetrate into the paint film, destroy the bonding force between the paint film and the substrate, and thus remove the paint film. At the same time, diethylene glycol monobutyl ether has a high boiling point (about 230°C) and low volatility, which enables it to maintain a stable dissolving effect for a long time without volatilization, which can significantly improve the efficiency and effect of paint stripping. Compared with solvents such as dichloromethane and aromatic hydrocarbons, diethylene glycol monobutyl ether is less toxic and relatively environmentally friendly.

[0007] Specifically, propylene glycol is a colorless, non-toxic, sweet organic solvent that can improve the slight ether taste in the paint stripper. It can also form a binary azeotrope with a lower temperature with the solvent, and cooperate with the solvent molecules to quickly and fully penetrate into the paint film, reduce the bonding force between the paint film and the substrate, thereby enhancing the main solvent's ability to dissolve the paint film and accelerate paint stripping. Propylene glycol carbonate is a highly polar aprotic solvent that can penetrate into macromolecular polymers well, has a strong dissolving ability for polar polymer materials such as epoxy resins, polyurethanes, and acrylic acid, can effectively penetrate and destroy the coating structure, promote the dissolution of the paint film, and help improve the paint stripping performance and paint stripping efficiency. Compared with organic lipids such as dimethyl carbonate and ethyl acetate, propylene glycol carbonate has a stronger dissolving power for the paint film, and its boiling point (about 240°C) is higher, and it is not easy to volatilize, which is conducive to prolonging the contact time between the paint stripper and the paint film, ensuring that the paint film is fully softened or dissolved, and avoiding the decline in the paint stripping effect due to the excessive volatilization of the solvent. Compared with co-solvents such as ethanol, acetone, and dimethyl sulfoxide, the combination of glycerol and propylene glycol carbonate as a co-solvent has a significant promoting effect on the dissolution of the paint film, while the addition of ethylene glycol, isopropanol, etc. will inhibit the dissolution effect of the main solvent.

[0008] Specifically, xanthan gum can increase the viscosity of paint stripper, prolong the time that paint stripper contacts with paint film, help paint stripper to react with the components in paint film more fully, and improve the thoroughness and efficiency of paint stripper. Compared with methylcellulose, hydroxyethyl cellulose, etc., xanthan gum has better thickening effect, and methylcellulose needs higher concentration to achieve similar effect, which increases the amount of raw materials used and affects the dissolution or swelling effect of main solvent. Nano alumina solution has unique dispersibility and thickening property. Compounding with xanthan gum can produce synergistic effect, further improve thickening effect and stability, enable paint stripper to better penetrate into the paint layer, and accelerate the solvent shedding of paint film. At the same time, paint stripper can also be made to maintain a certain thickening effect for a long time, improve the storage stability and use stability of paint stripper.

[0009] In some embodiments of the present invention, the paint stripper further comprises an accelerator, a corrosion inhibitor and a volatility suppressant.

[0010] In some embodiments of the present invention, by mass parts, the paint stripper comprises 45 - 50 parts of a main solvent, 20 - 35 parts of a co-solvent, 1 - 5 parts of a surfactant, 1 - 5 parts of a thickener, 2 - 8 parts of an accelerator, 0.5 - 2 parts of a corrosion inhibitor, and 1 - 5 parts of a volatilization inhibitor.

[0011] In some embodiments of the present invention, by mass parts, the paint stripper comprises 45 - 50 parts of diethylene glycol monobutyl ether, 16 - 18 parts of glycerol, 4 - 10 parts of propylene glycol carbonate, 1 - 1.5 parts of an anionic surfactant, 1 - 2 parts of sorbitan fatty acid ester, 0.2 - 1 part of a silicone surfactant, 1 - 3 parts of xanthan gum, 0.2 - 1 part of a nano-aluminum oxide solution, 2 - 8 parts of an accelerator, 0.5 - 2 parts of a corrosion inhibitor, and 1 - 5 parts of a volatilization inhibitor.

[0012] In some embodiments of the present invention, the anionic surfactant comprises sodium alkyl sulfonate.

[0013] Specifically, sodium alkyl sulfonate has excellent solubility, stability, as well as good wetting and penetration capabilities. It can form a synergistic effect when compounded with the non-ionic surfactant Span-80, assisting the solvents and other components in the paint stripper to quickly penetrate into the gaps between the polymer chain segments of the paint layer, enabling the paint stripper to fully contact the paint film, improving the paint stripping efficiency, and further enhancing the stability of the paint stripper.

[0014] In some embodiments of the present invention, the sorbitan fatty acid ester comprises Span-80.

[0015] Specifically, Span-80 is a lipophilic surfactant that can dissolve in multiple organic solvents simultaneously. It has good emulsifying and dispersing effects, helps to improve the uniform dispersion of the components in the paint stripper, and enhances the overall performance of the paint stripper. At the same time, it can also reduce the surface tension of the solvent, enhance the penetration ability of the solvent into the paint film, and improve the paint stripping efficiency.

[0016] In some embodiments of the present invention, the silicone surfactant comprises TEGOPREN 5840.

[0017] Specifically, TEGOPREN 5840 is a low-foaming modified silicone surfactant with the main component of siloxane polyether. It has better wetting performance, can improve the wettability of the substrate, enhance homogenization, and promote leveling. At the same time, TEGOPREN 5840 is compatible with epoxy resins, polyurethanes, acrylics, etc. When compounded with sodium alkyl sulfonate and Span-80, it produces a synergistic promotion effect, improving emulsifying dispersion, anti-sticking property, and wettability, further promoting the uniform distribution and effective penetration of the paint stripper on the paint film surface, and enhancing the penetration of the paint stripper into the paint film interior. After compounding, it can dissolve and strip the paint film more effectively, reduce the paint stripping time and energy consumption, and improve the stability and paint stripping efficiency of the paint stripper.

[0018] In some embodiments of the present invention, the promoter includes acetic acid.

[0019] Specifically, acetic acid is an organic acid with relatively weak acidity, and its acidity is weaker than that of organic acids such as formic acid and citric acid, which can prevent the corrosion of the metal substrate by the paint stripper. Acetic acid contains functional groups similar to those in the paint film composition and can interact with polar atoms such as oxygen and nitrogen in the cross-linking system, increasing the diffusion rate of the paint stripper in the paint film, thereby promoting the penetration ability of the solvent into the paint layer, enabling the solvent to more effectively soften, swell, or dissolve the paint film, and thus accelerating the paint stripping process.

[0020] In some embodiments of the present invention, the corrosion inhibitor includes DX5810.

[0021] Specifically, the corrosion inhibitor DX5810 can prevent the corrosion effect of the paint stripper on the metal substrate. It can form a protective film on the metal surface, effectively preventing the metal from being corroded during the paint stripping process, having a good corrosion inhibition effect, being able to inhibit the corrosion of the metal substrate by the solvent during the paint stripping process, and effectively preventing the appearance of blackening and discoloration on the surface of the aluminum material after paint stripping. Compared with corrosion inhibitors such as benzotriazole, ethanolamine, and sodium silicate, the corrosion inhibition effect is better and it is relatively more environmentally friendly.

[0022] In some embodiments of the present invention, the volatilization inhibitor includes liquid paraffin.

[0023] Specifically, liquid paraffin can form a thin film in the paint stripper, sealing the paint film surface, effectively slowing down the volatilization of the solvent in the paint stripper, enabling the paint stripper to remain on the paint film surface for a longer time, thereby more fully penetrating and swelling the paint film, accelerating the paint film stripping process, and improving the thoroughness and storage stability of paint stripping.

[0024] In the second aspect of the present invention, a preparation method of the paint stripper described in the first aspect of the present invention is provided, including the following steps:

[0025] Mix and stir the components to obtain the paint stripper.

[0026] In the third aspect of the present invention, a paint stripping method is provided, which includes the following steps: immersing the workpiece to be stripped of paint in the paint stripper described in the first aspect of the present invention.

[0027] In some embodiments of the present invention, the temperature of the immersion ≤ 30°C; and / or, the time of the immersion ≤ 20 min.

[0028] In some embodiments of the present invention, the temperature of the immersion is 20 - 25°C; and / or, the time of the immersion is 10 - 15 min.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) The paint stripper of the present invention is mainly composed of a water-soluble solvent that can be miscible with water, reducing the use of organic solvents, being not easily volatile, having low toxicity and being environmentally friendly.

[0031] (2) Through the selection and combined use of specific components, the paint stripper of the present invention can quickly swell and peel off the polymer molecules of the paint film, completely destroy the adhesion of the paint film to the substrate, remove the paint film, and will not cause any corrosion or adverse effects on the aluminum alloy substrate. The residue on the substrate after paint stripping can be quickly washed off, and there will be no phenomena such as blackening or whitening.

[0032] (3) The paint stripper of the present invention is compounded with several specific surfactants, having excellent emulsifying and dispersing effects and substrate wettability, which can further promote the uniform distribution and effective penetration of the paint stripper on the surface of the paint film, enhance the penetration of the paint stripper into the interior of the paint film, disperse the paint film into smaller particles, prevent the peeled paint film from agglomerating and precipitating in the paint stripper, improve the dispersion state of the paint film in the paint stripper, help the paint particles to form a stable emulsion state in the solvent, enable the solvent in the paint stripper to fully contact the paint film, improve the paint stripping efficiency, and can complete paint stripping at room temperature in 15 minutes.

[0033] (4) The paint stripper of the present invention is simple and convenient to use, highly efficient and environmentally friendly in paint stripping, smokeless and odorless throughout the process, and will not cause any adverse effects such as corrosion or damage to the aluminum alloy substrate during the paint stripping process. Specific Embodiments

[0034] The content of the present invention will be further described in detail through specific examples below. Unless otherwise specified, the raw materials, reagents or devices used in the examples can be obtained from conventional commercial channels or can be obtained by existing technical methods. Unless otherwise specified, the test or measurement methods are all conventional methods in the art.

[0035] Example 1

[0036] A paint stripper, comprising the following components in parts by mass: 45 parts of diethylene glycol monobutyl ether, 18 parts of glycerol, 8 parts of propylene glycol carbonate, 5 parts of acetic acid, 3 parts of liquid paraffin, 1 part of corrosion inhibitor (DX5810), 1 part of alkyl sulfonate, 0.5 part of silicone surfactant (TEGOPREN 5840), 1 part of Span-80, 15 parts of deionized water, 0.5 part of nano-aluminum oxide solution (MAL-1020), and 2 parts of xanthan gum.

[0037] The preparation method of the above paint stripper comprises the following steps: mixing and stirring the above components to obtain the paint stripper.

[0038] Example 2

[0039] A paint stripper, comprising the following components in parts by mass: 47 parts of diethylene glycol monobutyl ether, 16 parts of glycerol, 5 parts of propylene glycol carbonate, 8 parts of acetic acid, 2 parts of liquid paraffin, 2 parts of corrosion inhibitor (DX5810), 1 part of alkyl sulfonate, 0.5 part of silicone surfactant (TEGOPREN 5840), 2 parts of Span-80, 15 parts of deionized water, 0.5 part of nano-aluminum oxide solution (MAL-1020), and 1 part of xanthan gum.

[0040] The preparation method of the above paint stripper comprises the following steps: mixing and stirring the above components to obtain the paint stripper.

[0041] Example 3

[0042] A paint stripper, comprising the following components in parts by mass: 50 parts of diethylene glycol monobutyl ether, 16 parts of glycerol, 5 parts of propylene glycol carbonate, 8 parts of acetic acid, 1 part of liquid paraffin, 1 part of corrosion inhibitor (DX5810), 1 part of alkyl sulfonate, 0.5 part of silicone surfactant (TEGOPREN 5840), 1 part of Span-80, 15 parts of deionized water, 0.5 part of nano-aluminum oxide solution (MAL-1020), and 1 part of xanthan gum.

[0043] The preparation method of the above paint stripper comprises the following steps: mixing and stirring the above components to obtain the paint stripper.

[0044] Comparative Example 1

[0045] A paint stripper, comprising the following components in parts by mass: 45 parts of diethylene glycol monobutyl ether, 18 parts of glycerol, 8 parts of ethylene glycol, 5 parts of acetic acid, 3 parts of liquid paraffin, 1 part of corrosion inhibitor (DX5810), 1 part of alkyl sulfonate, 0.5 part of silicone surfactant (TEGOPREN 5840), 1 part of Span-80, 15 parts of deionized water, 0.5 part of nano-aluminum oxide solution (MAL-1020), and 2 parts of xanthan gum.

[0046] The difference from Example 1 is that propylene glycol carbonate is replaced by ethylene glycol.

[0047] Comparative Example 2

[0048] A paint stripper comprising the following components in parts by mass: 45 parts of diethylene glycol monobutyl ether, 18 parts of glycerol, 8 parts of propylene glycol carbonate, 5 parts of acetic acid, 3 parts of liquid paraffin, 1 part of corrosion inhibitor (DX5810), 1 part of sodium alkyl sulfonate, 0.5 part of silicone surfactant (TEGOPREN 5840), 1 part of Span-80, 15 parts of deionized water, 0.5 part of ethyl cellulose, and 2 parts of xanthan gum.

[0049] The difference from Example 1 is that MAL-1020 is replaced by ethyl cellulose.

[0050] Comparative Example 3

[0051] A paint stripper comprising the following components in parts by mass: 45 parts of diethylene glycol monobutyl ether, 18 parts of glycerol, 8 parts of propylene glycol carbonate, 5 parts of acetic acid, 3 parts of liquid paraffin, 1 part of corrosion inhibitor (DX5810), 1.25 parts of sodium alkyl sulfonate, 1.25 parts of Span-80, 15 parts of deionized water, 0.5 part of nano-aluminum oxide solution (MAL-1020), and 2 parts of xanthan gum.

[0052] The difference from Example 1 is that TEGOPREN 5840 is missing.

[0053] Comparative Example 4

[0054] A paint stripper comprising the following components in parts by mass: 45 parts of diethylene glycol monobutyl ether, 18 parts of glycerol, 8 parts of propylene glycol carbonate, 5 parts of acetic acid, 3 parts of liquid paraffin, 1 part of corrosion inhibitor (DX5810), 1 part of silicone surfactant (TEGOPREN5840), 1.5 parts of Span-80, 15 parts of deionized water, 0.5 part of nano-aluminum oxide solution (MAL-1020), and 2 parts of xanthan gum.

[0055] The difference from Example 1 is that sodium alkyl sulfonate is missing.

[0056] Comparative Example 5

[0057] A paint stripper comprising the following components in parts by mass: 45 parts of diethylene glycol monobutyl ether, 26 parts of dimethyl carbonate, 5 parts of acetic acid, 3 parts of liquid paraffin, 1 part of corrosion inhibitor (DX5810), 2.5 parts of Span-80, 15 parts of deionized water, and 2.5 parts of xanthan gum.

[0058] The difference from Example 1 is that the co-solvent is dimethyl carbonate, and sodium alkyl sulfonate, TEGOPREN 5840, and MAL-1020 are missing.

[0059] Comparative Example 6

[0060] A paint stripper, comprising the following components in parts by mass: 45 parts of diethylene glycol monobutyl ether, 26 parts of propylene glycol carbonate, 5 parts of acetic acid, 3 parts of liquid paraffin, 1 part of corrosion inhibitor (DX5810), 2.5 parts of Span-80, 15 parts of deionized water, and 2.5 parts of xanthan gum.

[0061] It is different from Example 1 in that glycerol, alkyl sulfonate, TEGOPREN 5840, and MAL-1020 are missing.

[0062] Performance Test

[0063] Specimen preparation: Select aluminum alloy material. After conventional degreasing and passivation, spray a layer of polyurethane paint film sample on its surface, and the film thickness is 78 μm.

[0064] Experimental index: The paint stripping efficiency is the main index for measuring the performance of the paint stripper. The test method refers to the industry standard HG / T 2881-1997 "Method for Determining the Paint Stripping Efficiency of Paint Strippers". The paint stripping efficiency (%) = the wrinkled and soft area of the paint film (m 2 ) / the total area of the paint film before paint stripping (m 2 ) × 100%.

[0065] Paint stripping method: At 25°C, soak the above specimens in the paint strippers of Example 1 and Comparative Examples 1-6 respectively, and measure the paint stripping efficiency at regular intervals during this period. The statistical results of the paint stripping efficiency test are shown in Table 1.

[0066] Table 1

[0067]

[0068] As can be seen from Table 1, compared with Example 1, in Comparative Example 5, due to using dimethyl carbonate as the co-solvent and lacking alkyl sulfonate, TEGOPREN 5840, and MAL-1020, the paint stripping efficiency is significantly low, the paint stripping time is long, and a 100% paint stripping effect cannot be achieved.

[0069] After using propylene glycol carbonate as the co-solvent in Comparative Example 6 compared with Comparative Example 5, although the paint stripping effect is improved to some extent, the paint stripping is still not complete enough and the paint stripping time is long.

[0070] In Comparative Examples 1-4, due to the lack or replacement of some specific components in the present invention, although the paint stripping efficiency is improved to a certain extent and the paint stripping effect can reach 100%, the paint stripping time is still longer than that of Example 1.

[0071] In Example 1 of the present invention, through the selection and combined use of specific components, the paint stripping efficiency is significantly improved. After soaking for 10 minutes, it can reach 98%, and all the paint has been stripped after soaking for 15 minutes.

[0072] In addition, the paint strippers of Examples 2-3 of the present invention can also strip all the paint after soaking for 15 minutes according to the above paint stripping method, and there is no obvious difference in the paint stripping efficiency from Example 1.

[0073] The above has specifically described the preferred embodiments of the present invention. However, the present invention is not limited to the described embodiments. Those skilled in the art can also make various equivalent variations or substitutions without departing from the spirit of the present invention, and these equivalent variations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A paint stripper, characterized in that, The paint stripper comprises a main solvent, a co-solvent, a surfactant and a thickener. The main solvent comprises diethylene glycol monobutyl ether. The co-solvent comprises glycerol and propylene glycol carbonate. The surfactant comprises an anionic surfactant and a non-ionic surfactant. The non-ionic surfactant comprises sorbitan fatty acid ester and organosilicon surfactant. The thickener comprises xanthan gum and nano-aluminum oxide solution.

2. The paint stripper according to claim 1, characterized in that, The paint stripper further comprises an accelerator, a corrosion inhibitor and a volatilization inhibitor.

3. The paint stripper according to claim 2, characterized in that, By mass, the paint stripper comprises 45-50 parts of main solvent, 20-35 parts of co-solvent, 1-5 parts of surfactant, 1-5 parts of thickener, 2-8 parts of accelerator, 0.5-2 parts of corrosion inhibitor and 1-5 parts of volatilization inhibitor.

4. The paint stripper according to claim 2, wherein By mass, the paint stripper comprises 45-50 parts of diethylene glycol monobutyl ether, 16-18 parts of glycerol, 4-10 parts of propylene glycol carbonate, 1-1.5 parts of anionic surfactant, 1-2 parts of sorbitan fatty acid ester, 0.2-1 part of organosilicon surfactant, 1-3 parts of xanthan gum, 0.2-1 part of nano-aluminum oxide solution, 2-8 parts of accelerator, 0.5-2 parts of corrosion inhibitor and 1-5 parts of volatilization inhibitor.

5. The paint stripper according to claim 1, wherein The anionic surfactant comprises sodium alkyl sulfonate.

6. The paint stripper according to claim 1, wherein The sorbitan fatty acid ester comprises Span-80.

7. The paint stripper according to claim 1, characterized in that, The organosilicon surfactant comprises TEGOPREN 5840.

8. The preparation method of the paint stripper according to any one of claims 1-7, characterized in that, It includes the following steps: Mix and stir the components to obtain the paint stripper.

9. A paint stripping method, characterized in that, It includes the following steps: Immerse the workpiece to be stripped of paint in the paint stripper according to any one of claims 1-7.

10. The paint stripping method according to claim 9, characterized in that, The temperature of the immersion ≤ 30 °C; and / or, the time of the immersion ≤ 20 min.

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