Solvent type paint remover without corrosion to metal substrate and preparation method of solvent type paint remover

Abstract

The invention provides a solvent type paint remover without corrosion to a metal substrate and a preparation method of the solvent type paint remover, and solves the problem that the existing mild paint remover does not meet the environmental protection requirement. The paint remover comprises a lower active substance layer and an upper volatilization inhibition layer, the lower active substance layer is prepared from 30-40 wt% of a main solvent, 20-30 wt% of a penetrating agent, 20-30 wt% of an activating agent and 1-10 wt% of a corrosion inhibitor, and the pH value of the lower active substance layer is 8-10; and the upper volatilization inhibition layer is liquid paraffin. The preparation method disclosed by the invention is simple and easy to implement, has no special equipment requirement, is low in environmental requirement and relatively small in environmental pollution, and a matrix subjected to paint stripping by the solvent type paint remover disclosed by the invention can pass a corrosion test specified by HB 5334 and a hydrogen brittleness tensile test specified by ASTM F519.

Description

Technical Field

[0001] This invention belongs to the field of metal surface treatment technology, specifically relating to a solvent-based paint remover that does not corrode metal substrates and its preparation method, especially suitable for chemical paint removal from aluminum and magnesium alloy surfaces. Background Technology

[0002] The low-pressure compressor casing of aero-engines is typically made of aluminum or magnesium alloys. Its surface requires a composite protective system consisting of a chemical oxide film (anodic oxide film), a special thermosetting resin coating, and a topcoat to resist environmental corrosion and oxidation. However, due to the high chemical reactivity of aluminum and magnesium alloys and the tight bond between the resin coating and the oxide film (conversion film), removing the surface coating without damaging the substrate is extremely challenging.

[0003] Currently, methods for removing paint from metal surfaces are mainly divided into physical methods and chemical methods:

[0004] Physical methods refer to paint removal using methods such as sandblasting, laser cleaning, and polishing. Among these, sandblasting and polishing are not cost-effective, and the fine sand and polishing dust can harm the operator's health, and there are also drawbacks such as residue. Laser cleaning, as a new generation of paint removal method, has the advantages of high efficiency and less environmental impact, but its equipment cost is extremely high. Moreover, because laser cleaning involves focal length control issues, it is often only effective for surface cleaning of flat workpieces, and it is difficult to meet the requirements of non-destructive paint removal for complex curved surfaces, irregularly shaped parts, and assemblies.

[0005] Chemical methods refer to the use of traditional chemical paint stripping solutions and other methods to remove paint. Compared to physical methods, chemical methods not only have significant cost-effectiveness but also inherent advantages in removing coatings from blind holes, cavities, deep holes, through holes, and the surfaces of assemblies. However, the current challenge lies in the fact that traditional chemical paint stripping solutions can damage the substrate material to varying degrees. For example, alkaline boiling and concentrated sulfuric acid dehydration and carbonization can cause varying degrees of corrosion to aluminum and magnesium alloys, leading to the scrapping of parts. Therefore, milder paint strippers have become an important choice. Previously, chlorinated hydrocarbon paint strippers used dichloromethane and chlorobenzene as penetrants and benzoic acid or other organic acids as activators. These mixed solutions have proven to have excellent paint stripping efficiency in practice. However, with the increasing awareness of environmental protection and safe production, the "List of Key Controlled New Pollutants" and the EU's "REACH Regulation EC-1907 / 2006" have included dichloromethane and other chlorinated alkanes, strictly restricting their use.

[0006] Therefore, with increasing emphasis on environmental awareness and clean production, there is an urgent need for a solvent-based paint remover that is free of chlorinated alkanes, can protect aluminum and magnesium alloys from corrosion, and can effectively remove paint. Summary of the Invention

[0007] In view of the above-mentioned technical problems, the present invention discloses a solvent-based paint remover that is non-corrosive to metal substrates and its preparation method. The specific solution is as follows:

[0008] The technical solution to achieve the first objective of this invention is: a solvent-based paint remover that does not corrode metal substrates, characterized in that it includes a lower active material layer and an upper volatilization inhibition layer;

[0009] The lower active material layer is composed of 30-40wt% main solvent, 20-30wt% penetrant, 20-30wt% activator and 1-10wt% corrosion inhibitor, with a pH of 8-10, i.e. weakly alkaline.

[0010] The main solvent is an ether with a boiling point higher than 150°C;

[0011] The penetrant is a polar substance containing nitrogen or sulfur atoms;

[0012] The activator is a mixture of organic base and organic acid, wherein the organic base is the main component and the organic acid is the adjusting agent. The two neutralize each other repeatedly to finally achieve the expected acidity or alkalinity, namely the aforementioned pH.

[0013] The corrosion inhibitor is a molecular compound containing nitrogen or sulfur atoms;

[0014] The upper volatile inhibition layer is liquid paraffin. Functionally, the upper volatile inhibition layer should be made of readily available, inexpensive compounds with a boiling point exceeding 200°C and a lower density (allowing it to float) compared to the lower active material layer. After screening hundreds of potential compounds, liquid paraffin is currently the most suitable substance to meet the above requirements.

[0015] Because the solvent-based paint remover needs to be heated to a very high temperature during use, a two-layer design is used in order to prevent the active material from evaporating too quickly and affecting the paint removal effect. That is, a low-density, higher-boiling-point, and inexpensive substance such as liquid paraffin is used as a liquid seal layer on top of the active material to mitigate the evaporation of the expensive active material in the lower layer.

[0016] Furthermore, the main solvent is one or more of ethylene glycol monohexyl ether, diethylene glycol butyl ether, diethylene glycol hexyl ether, ethylene glycol phenyl ether, propylene glycol phenyl ether, diethylene glycol phenyl ether and diphenyl ether, and their derivatives.

[0017] The penetrant is one or more of N,N-dimethylpyrrolidone, dimethyl sulfoxide, dimethylformamide, N-vinylpyrrolidone and N-octyl-2-pyrrolidone, or a mixture or derivative thereof;

[0018] The organic base is one or a mixture of ethylenediamine, monoethanolamine, diethanolamine, triethanolamine and morpholine;

[0019] The organic acid is one or a mixture of benzenesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid and naphthalenesulfonic acid;

[0020] The corrosion inhibitor is one or a mixture of imidazole, thiazole and benzotriazole.

[0021] Furthermore, the volume of the upper volatilization inhibition layer is 1 / 4 to 1 / 5 of the volume of the lower active material layer.

[0022] The technical solution for achieving the second objective of this invention is: the preparation method of the above-mentioned solvent-based paint remover that does not corrode metal substrates is characterized by including the following steps:

[0023] S1. Mix the main solvent and penetrant evenly and heat to 50-60 ℃. Then add the corrosion inhibitor and stir continuously for 1-2 h. Then cool to room temperature and let stand for at least 12 h to ensure that the components are fully diffused and balanced, and improve batch consistency.

[0024] S2. After heating the mixed solution obtained in S1 to 50-60 ℃ again, add the activator and stir continuously for 1-2 h to obtain the lower active material layer.

[0025] S3. After cooling the lower active material layer obtained in S2 to room temperature, add the upper volatilization inhibition layer to finally obtain a solvent-based paint remover that does not corrode the metal substrate.

[0026] The technical solution for achieving the third objective of this invention is: the method of using the above-mentioned solvent-based paint remover that does not corrode metal substrates, characterized by including the following steps:

[0027] 1) Heat the solvent-based paint remover to 80-140℃;

[0028] 2) Immerse the dried paint-removing parts in the solvent-based paint remover heated in step 1) until the paint layer on the surface of the parts swells and is removed; since the difficulty of removing different paint layers varies, it is not a reliable reference. Therefore, during the immersion period, it is necessary to observe the condition of the paint layer in time to avoid over-immersion.

[0029] 3) Use a high-pressure water gun to rinse the parts taken out in step 2) to clean the swollen paint layer on the surface of the parts.

[0030] The principle of this invention:

[0031] This invention, based on a multi-layered structural design and synergistic effects of its components, achieves efficient paint removal while ensuring controllable corrosion of the metal substrate. The lower active material layer of the paint remover, through a weakly alkaline environment (pH approximately 8-10) and a specific component ratio, specifically swells or dissolves the paint polymer, while the upper volatility-inhibiting layer forms a physical barrier, reducing the volatilization of active materials and improving operational safety and efficiency.

[0032] The principles of this invention can be divided into two levels: the chemical reaction level and the engineering practice level. Specifically:

[0033] At the chemical reaction level, the main components of the lower active material in the paint remover—the mixture of the primary solvent and the penetrant—are sufficient to dissolve most resin coatings. Regarding the selection of the primary solvent and penetrant, this invention specifically selects substances with high boiling points to support the removal of stubborn, thick resin coatings by increasing the paint remover temperature. For the dissolution of specific special resin coatings, an appropriate amount of activator is added to the primary solvent and penetrant. The activator typically has a certain degree of acidity or alkalinity, which, through corrosion and acid-base catalysis, can destroy the chemical structure of the resin coating, providing penetration channels for the penetrant and accelerating swelling efficiency. Considering that this invention is used on highly reactive metals, the pH of the paint remover is controlled within a weakly alkaline range through acid-base compounding to minimize corrosion to the metal. As a further supplementary measure to inhibit corrosion, characteristic corrosion inhibitors of aluminum and magnesium alloys are added to the primary solvent and penetrant. This constitutes the basic selection range of the lower active material in this invention, and the optimal ratio of each component is further determined through batch testing.

[0034] In summary, the paint stripping efficiency of this invention stems from the synergistic effect of the components in the lower active material layer. The main solvent is a high-boiling-point ether solvent (boiling point above 150℃), which provides a stable dissolution base, avoids rapid volatilization at high temperatures, and ensures that the paint layer (such as epoxy resin or phenolic resin) can fully swell. The penetrant, with its nitrogen- or sulfur-containing polar structure, enhances its penetration into the micropores of the paint layer and disrupts the bonding forces between polymer chains. The activator is a compound of organic base and organic acid, which accelerates the hydrolysis or swelling of the paint layer through acid-base catalysis. The weakly alkaline pH (8-10) balances the reaction intensity and prevents excessive corrosion of the substrate. The corrosion inhibitor, as a small molecule compound containing nitrogen or sulfur, preferentially adsorbs on the metal surface to form a protective film, blocking contact with the corrosive medium and thus ensuring the integrity of active metals such as aluminum and magnesium alloys. This synergistic design allows the paint stripper to adapt to a variety of resins (from easily handled polyurethane to poorly soluble phenolic resin), with the paint layer swelling and peeling off while the substrate oxide film remains intact, demonstrating a balance between high efficiency and safety.

[0035] In engineering practice, it's crucial to avoid rapid evaporation of the paint remover when users attempt to accelerate paint removal through heating (this increases material consumption and pollutes the environment). To address this, this invention involves covering the lower active material with a layer of a higher-boiling-point, lower-cost, non-flammable material that is incompatible with it. During preparation, the two layers are packaged sequentially according to a prescribed method. In use, the paint remover from the packaging is poured into the paint removal container. Once the two layers have completely separated, the desired state is achieved, and the product can be heated for use.

[0036] The advantages of this invention are:

[0037] 1. The solvent-based paint remover of this invention is not only environmentally friendly and safe, and does not contain chlorinated alkanes, but can also effectively remove most thermosetting and thermoplastic resin paint layers such as epoxy resin, phenolic resin, polyurethane resin and their modified resins. It is also non-corrosive to most metal materials, and is especially suitable for removing organic coatings from aluminum and magnesium alloy surfaces.

[0038] 2. The solvent-based paint remover of the present invention is easy to prepare, requires no special equipment, has low environmental requirements, low labor intensity, and causes little environmental pollution.

[0039] 3. The substrate after paint removal by the solvent-based paint remover of the present invention can pass the corrosion test specified in HB 5334 and the hydrogen embrittlement tensile test specified in ASTM F519, which shows that the solvent-based paint remover of the present invention does not affect the metal substrate. Attached Figure Description

[0040] Figure 1 The solvent-based paint remover of this invention is shown to have a paint removal effect on polyurethane resin (brand name: S04-20);

[0041] Figure 2 The solvent-based paint remover of this invention is shown to have a paint removal effect on phenolic resin (brand name: F-231);

[0042] Figure 3 The images show corrosion test results for 45# steel, LY12, ZM-5 (chemically oxidized), ZM-5 (non-chemically oxidized), and AZ-31B (chemically oxidized) after being stripped with the solvent-based paint remover of this invention.

[0043] Figure 4 The results of the hydrogen embrittlement tensile test on the substrate after paint removal with the solvent-based paint remover of this invention, as specified in ASTM F519. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Steps not specifically described in the embodiments are existing technologies and will not be described in detail here.

[0045] Example 1

[0046] A solvent-based paint remover that does not corrode metal substrates comprises a lower active material layer composed of 20wt% diethylene glycol butyl ether, 15wt% ethylene glycol phenyl ether, 15wt% N,N-dimethylpyrrolidone, 5wt% dimethyl sulfoxide, 10wt% dimethylformamide, 20wt% monoethanolamine, 10wt% ethylenediamine, and 5wt% benzotriazole, and is weakly alkaline; the upper volatility-inhibiting layer is liquid paraffin.

[0047] The preparation method of the above solvent-based paint remover includes the following steps:

[0048] S1. Mix 20wt% diethylene glycol butyl ether, 15wt% ethylene glycol phenyl ether, 15wt% N,N-dimethylpyrrolidone, 5wt% dimethyl sulfoxide, and 10wt% dimethylformamide evenly and heat to 50°C. Then add 5wt% benzotriazole and stir continuously for 1 hour. Then cool to room temperature and let stand for 12 hours.

[0049] S2. After heating the mixed solution obtained in S1 to 55°C again, add 10wt% ethylenediamine and 20wt% monoethanolamine, and stir continuously for 1 hour to obtain the lower active material layer.

[0050] S3. After cooling the lower active material layer obtained in S2 to room temperature, transfer it to a container and add 1 / 4 volume of liquid paraffin to the lower active material layer to finally obtain a solvent-based paint remover.

[0051] The method of using the above solvent-based paint remover includes the following steps:

[0052] 1) Dry the aluminum alloy sample (grade: LY12) with polyurethane resin coating (grade: S04-20);

[0053] 2) Heat the solvent-based paint remover to 100℃;

[0054] 3) Immerse the dried sample in heated solvent-based paint remover. After 10 minutes, the polyurethane coating on the sample surface begins to swell, as shown below. Figure 1 As shown, from Figure 1 As can be seen, the polyurethane coating swelled and peeled off, while the golden oxide film remained undamaged;

[0055] 4) Remove the sample and use a high-pressure water gun to clean the swollen polyurethane coating on the sample surface, thus completing the paint removal process.

[0056] Example 2

[0057] A solvent-based paint remover that does not corrode metal substrates has a lower active material layer composed of 10wt% ethylene glycol monohexyl ether, 30wt% diethylene glycol butyl ether, 30wt% N-vinylpyrrolidone, 15wt% triethanolamine, 5wt% benzenesulfonic acid, 5wt% benzotriazole, and 5wt% imidazole, and is weakly alkaline; the upper volatile inhibition layer is liquid paraffin.

[0058] The preparation method of the above solvent-based paint remover includes the following steps:

[0059] S1. Mix 10wt% ethylene glycol monohexyl ether, 30wt% diethylene glycol butyl ether and 30wt% N-vinylpyrrolidone evenly and heat to 60℃. Then add 5wt% benzotriazole and 5wt% imidazole, stir continuously for 1h, then cool to room temperature and stand for 13h.

[0060] S2. After heating the mixed solution obtained in S1 to 50°C again, add 15wt% triethanolamine and 5wt% benzenesulfonic acid, and stir continuously for 1 hour to obtain the lower active material layer.

[0061] S3. After cooling the lower active material layer obtained in S2 to room temperature, transfer it to a container and add liquid paraffin with 1 / 5 volume of the lower active material layer to finally obtain a solvent-based paint remover.

[0062] The method of using the above solvent-based paint remover includes the following steps:

[0063] 1) Dry the aluminum alloy sample (grade: LY12) with phenolic resin coating (grade: F-231);

[0064] 2) Heat the solvent-based paint remover to 110℃;

[0065] 3) Immerse the dried sample in heated solvent-based paint remover. After 80 minutes, the phenolic resin coating on the sample surface begins to swell, as shown below. Figure 2 As shown, from Figure 2 As can be seen, the phenolic resin coating has swollen, while the underlying golden oxide film remains undamaged;

[0066] 4) Remove the sample and use a high-pressure water gun to clean the swollen phenolic resin coating on the sample surface, thus completing the paint removal process.

[0067] Example 3

[0068] A solvent-based paint remover that does not corrode metal substrates comprises a lower active material layer composed of 10wt% propylene glycol phenyl ether, 10wt% diethylene glycol phenyl ether, 10wt% diphenyl ether ethylene glycol monohexyl ether, 10wt% diethylene glycol butyl ether, 20wt% dimethylformamide, 10wt% N-octyl-2-pyrrolidone, 8wt% diethanolamine, 10wt% morpholine, 2wt% p-toluenesulfonic acid, 5wt% imidazole, and 5wt% thiazole, and is weakly alkaline; the upper volatile inhibition layer is liquid paraffin.

[0069] The preparation method of the above solvent-based paint remover includes the following steps:

[0070] S1. Mix 10wt% propylene glycol phenyl ether, 10wt% diethylene glycol phenyl ether, 10wt% diphenyl ether ethylene glycol monohexyl ether, 10wt% diethylene glycol butyl ether, 20wt% dimethylformamide, and 10wt% N-octyl-2-pyrrolidone evenly and heat to 60℃. Then add 5wt% imidazole and 5wt% thiazole, stir continuously for 1 hour, cool to room temperature and let stand for 13 hours.

[0071] S2. After heating the mixed solution obtained in S1 to 60°C again, add 8wt% diethanolamine, 10wt% morpholine and 2wt% p-toluenesulfonic acid, and stir continuously for 1 hour to obtain the lower active material layer.

[0072] S3. After cooling the lower active material layer obtained in S2 to room temperature, transfer it to a container and add liquid paraffin with 1 / 5 volume of the lower active material layer to finally obtain a solvent-based paint remover.

[0073] The method of using the above solvent-based paint remover includes the following steps:

[0074] 1) Dry the aluminum alloy sample (grade: LY12) with phenolic resin coating (grade: F-231);

[0075] 2) Heat the solvent-based paint remover to 100℃;

[0076] 3) Immerse the dried sample in heated solvent-based paint remover. After 100 minutes, the phenolic resin coating on the sample surface begins to swell and... Figure 2 The states shown are similar;

[0077] 4) Remove the sample and use a high-pressure water gun to clean the swollen phenolic resin coating on the sample surface, thus completing the paint removal process.

[0078] Comparative Example 1

[0079] The metal substrate solvent-based paint remover has a lower active material layer composed of 10 wt% propylene glycol phenyl ether, 30 wt% diethylene glycol phenyl ether, 30 wt% dimethylformamide, and 30 wt% benzenesulfonic acid, and an upper volatile inhibition layer composed of liquid paraffin.

[0080] The preparation method of the above solvent-based paint remover includes the following steps:

[0081] S1. Mix 10wt% propylene glycol phenyl ether, 30wt% diethylene glycol phenyl ether and 30wt% dimethylformamide evenly and heat to 60℃, stirring continuously for 1 hour, then cool to room temperature and let stand for 13 hours.

[0082] S2. After heating the mixed solution obtained in S1 to 60°C again, add 30wt% benzenesulfonic acid and stir continuously for 1 hour to obtain the lower active material layer. At this time, the pH of the lower active material is approximately 1, which is strongly acidic.

[0083] S3. After cooling the lower active material layer obtained in S2 to room temperature, transfer it to a container and add liquid paraffin with 1 / 5 volume of the lower active material layer to finally obtain a solvent-based paint remover.

[0084] The method of using the above solvent-based paint remover includes the following steps:

[0085] 1) Dry the aluminum alloy sample (grade: LY12) with phenolic resin coating (grade: F-231);

[0086] 2) Heat the solvent-based paint remover to 100℃;

[0087] 3) Immerse the dried sample in heated solvent-based paint remover. After 30 minutes, the phenolic resin coating on the sample surface begins to swell and... Figure 2 The conditions shown are similar, but the aluminum alloy sample begins to corrode and evolve hydrogen from about 5 minutes.

[0088] 4) Remove the sample and use a high-pressure water gun to clean the swollen phenolic resin coating on the sample surface to complete the paint removal. At this time, the aluminum alloy is severely corroded.

[0089] Comparative Example 2

[0090] A solvent-based paint remover that does not corrode metal substrates, wherein the lower active material layer is composed of 40wt% diethylene glycol butyl ether, 30wt% N,N-dimethylpyrrolidone, and 30wt% monoethanolamine, and the upper volatile inhibition layer is liquid paraffin.

[0091] The preparation method of the above solvent-based paint remover includes the following steps:

[0092] S1. Mix 40wt% diethylene glycol butyl ether and 30wt% N,N-dimethylpyrrolidone evenly and heat to 60°C, stirring continuously for 1 hour, then cool to room temperature and let stand for 13 hours.

[0093] S2. After heating the mixed solution obtained in S1 to 60°C again, add 30wt% monoethanolamine and stir continuously for 1 hour to obtain the lower active material layer. At this time, the lower active material is alkaline.

[0094] S3. After cooling the lower active material layer obtained in S2 to room temperature, transfer it to a container and add 1 / 5 volume of liquid paraffin to finally obtain a solvent-based paint remover.

[0095] The method of using the above solvent-based paint remover includes the following steps:

[0096] 1) Dry the aluminum alloy sample (grade: LY12) with phenolic resin coating (grade: F-231);

[0097] 2) Heat the solvent-based paint remover to 100℃;

[0098] 3) After the dried sample was immersed in heated solvent-based paint remover, after 500 minutes, only part of the phenolic resin coating on the sample surface swelled, and the aluminum alloy turned black in some areas.

[0099] 4) Remove the sample and use a high-pressure water gun to clean the swollen phenolic resin coating on the sample surface to complete the paint removal. At this time, the aluminum alloy is severely corroded.

[0100] The corrosion test performed on the metal substrate after paint removal with the solvent-based paint remover of Example 1 was conducted according to the method specified in HB / Z 5334, using 45# steel, LY12, ZM-5 (chemically oxidized), ZM-5 (non-chemically oxidized), and AZ-31B (chemically oxidized) for corrosion testing (increasing temperature sequentially). Figure 3 As shown.

[0101] The results of corrosion tests (by gravimetric method) conducted using 45# steel, LY12, ZM-5 (chemically oxidized), ZM-5 (unchemically oxidized), and AZ-31B (chemically oxidized) according to the method specified in GJB 11383 are shown in Table 1.

[0102] Table 1 Weighing results of corrosion detection

[0103]

[0104] As shown in Table 1, at room temperature, after immersion in the paint remover of Example 1 for 48 hours, the mass of all samples did not change significantly, and the mass loss value was less than the criterion given in GJB 11383 (mass change of aluminum alloy less than 0.04 g / cm³). 2 / 24h; the mass change of magnesium alloy is less than 0.2g / cm³. 2 (24h); Compared with the control groups at room temperature and 80℃, the mass loss of all five substrates met the requirements of GJB 11383 after testing at the highest test temperature of 140℃.

[0105] In addition, hydrogen embrittlement tensile tests were performed on parts stripped with the solvent-based paint remover of Example 1 according to ASTM F519. The hydrogen embrittlement test bars (4340 ultra-high strength steel) were continuously immersed in the paint remover of Example 1 at 140°C for 168 hours, followed by air baking at 190°C for 24 hours to expel hydrogen embrittlement. Subsequently, static tensile testing was performed at 75% of the maximum tensile strength for 200 hours. After the tensile test, none of the test bars fractured. Figure 4 As shown, the results indicate that the paint remover of the present invention meets the requirements of ASTM F519 and is suitable for use on ultra-high strength steel.

[0106] Compared to existing environmentally friendly paint removers, this invention employs a chlorinated alkanes-free design, utilizing a volatility-inhibiting layer and a weakly alkaline system to solve the problems of traditional paint removers corroding the substrate or polluting the environment. Experimental data (as shown in Table 1, weighing results) demonstrate that various metals exhibit minimal weight changes at high temperatures, confirming a low corrosion rate. Furthermore, the paint removal efficiency can be adjusted by regulating the temperature (80-140℃) to suit different paint layers. This research approach not only ensures technical feasibility but also complies with environmental regulations (such as REACH), laying the foundation for the invention's innovation and practicality.

[0107] In summary, the paint remover formulated using the method of this invention is not only environmentally friendly and safe with good paint removal effect, but also takes into account the corrosion safety of metal substrates such as aluminum and magnesium alloys, and has a very good application prospect.

[0108] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A solvent-based paint remover that does not corrode metal substrates, characterized in that: It includes a lower active material layer and an upper volatilization inhibition layer; The lower active material layer is formulated with 30-40 wt% main solvent, 20-30 wt% penetrant, 20-30 wt% activator and 1-10 wt% corrosion inhibitor, with a pH of 8-10. The main solvent is an ether with a boiling point higher than 150°C; The penetrant is a polar substance containing nitrogen or sulfur atoms; The activator is a mixture of organic base and organic acid; The corrosion inhibitor is a molecular compound containing nitrogen or sulfur atoms; The upper volatile inhibition layer is liquid paraffin.

2. The solvent-based paint remover according to claim 1, characterized in that: The main solvent is one or more of ethylene glycol monohexyl ether, diethylene glycol butyl ether, diethylene glycol hexyl ether, ethylene glycol phenyl ether, propylene glycol phenyl ether, diethylene glycol phenyl ether and diphenyl ether, and their derivatives. The penetrant is one or more of N,N-dimethylpyrrolidone, dimethyl sulfoxide, dimethylformamide, N-vinylpyrrolidone and N-octyl-2-pyrrolidone, or a mixture and derivative thereof; The organic base is one or a mixture of ethylenediamine, monoethanolamine, diethanolamine, triethanolamine and morpholine; The organic acid is one or a mixture of benzenesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid and naphthalenesulfonic acid; The corrosion inhibitor is one or a mixture of imidazole, thiazole and benzotriazole.

3. The solvent-based paint remover according to claim 1 or 2, characterized in that: The volume of the upper volatilization inhibition layer is 1 / 4 to 1 / 5 of the volume of the lower active material layer.

4. A method for preparing the solvent-based paint remover that does not corrode metal substrates as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Mix the main solvent and penetrant evenly and heat to 50-60 ℃. Then add the corrosion inhibitor and stir continuously for 1-2 hours. Then cool to room temperature and let stand for at least 12 hours. S2. After heating the mixed solution obtained in S1 to 50-60 ℃ again, add the activator and stir continuously for 1-2 h to obtain the lower active material layer. S3. After cooling the lower active material layer obtained in S2 to room temperature, add the upper volatilization inhibition layer to finally obtain a solvent-based paint remover that does not corrode the metal substrate.

5. The method of using the solvent-based paint remover that does not corrode metal substrates as described in any one of claims 1-3, characterized in that, Includes the following steps: 1) Heat the solvent-based paint remover to 80-140℃; 2) Immerse the dried paint-removing parts in the solvent-based paint remover heated in step 1) until the paint layer on the surface of the parts swells and is removed, then take them out. 3) Use a high-pressure water gun to rinse the parts taken out in step 2) to clean the swollen paint layer on the surface of the parts.

Images