Alkaline paint remover as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of paint removers, and discloses an alkaline paint remover as well as a preparation method and application thereof. The alkaline paint remover comprises alkali, a corrosion inhibitor, a surfactant, a thickening agent, a cosolvent and water. According to the alkaline paint remover disclosed by the invention, specific components are selected and matched for use, so that the alkaline paint remover is not only environment-friendly, but also good in paint removing effect; furthermore, the alkaline paint remover can achieve unexpected technical effects by selecting the types of all the components and the specific dosage.

Description

Technical Field

[0001] The invention belongs to the technical field of paint strippers, and particularly relates to an alkaline paint stripper and a preparation method and application thereof. Background Art

[0002] In industrial production, metal hangers such as iron hangers or aluminum alloy hangers are widely used in various coating production lines, such as automobile manufacturing, home appliance production, metal processing and other industries. As production progresses, the paint layer on the metal hangers will gradually accumulate, age or have quality problems, and regular paint removal is required to ensure the normal use of the hangers and the quality of coating.

[0003] There are different methods for removing old paint films according to different requirements, different substrates, and different coatings. Among them, the use of paint strippers is one of the most commonly used methods. Paint strippers are also known as paint strippers, paint washers, or paint removers. The current paint strippers have different properties according to their components, but their paint stripping mechanism basically relies on a series of physical and chemical comprehensive effects and functions such as dissolution, penetration, swelling, peeling, and reaction. Paint strippers on the market have more or less some shortcomings. Solvent paint strippers are toxic and volatile, and acid paint strippers are more dangerous to use and have higher requirements on equipment. The paint stripping efficiency of existing paint strippers is not good.

[0004] Disadvantages of paint strippers widely used in the market:

[0005] ① Halogenated hydrocarbon paint strippers are generally methylene chloride, but methylene chloride is highly volatile and toxic, causing serious environmental pollution, causing great harm to operators, and destroying the atmospheric ozone layer, so its use is now strictly restricted. ;

[0006] ② Organic paint strippers that do not contain halogenated hydrocarbons, such as phenols, benzene and its homologues, ketones, alcohols, ethers and other organic substances. These organic substances generally have defects such as volatility, flammability, high cost, difficulty in transportation, and toxicity;

[0007] ③ The concentrated sulfuric acid in the acid paint stripper is highly corrosive and requires relatively high safety in operation;

[0008] ④ The use of acidic paint strippers requires very high sealing properties of the equipment, otherwise concentrated sulfuric acid will easily absorb moisture and dilute the concentration, causing it to become ineffective.

[0009] Therefore, it is urgent to provide a paint stripper with good paint stripping effect, which is not easy to volatilize and non-toxic. Summary of the invention

[0010] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides an alkaline paint stripper and a preparation method and application thereof. The alkaline paint stripper of the present invention has good environmental protection, can complete paint stripping within 30 minutes, and has high paint stripping efficiency.

[0011] A first aspect of the present invention provides an alkaline paint stripper.

[0012] Specifically, an alkaline paint stripper includes alkali, corrosion inhibitor, surfactant, thickener, co-solvent and water.

[0013] Preferably, the base comprises at least one of sodium hydroxide or potassium hydroxide.

[0014] Preferably, the corrosion inhibitor includes p-methyltriazole and benzotriazole. P-methyltriazole and benzotriazole are used in combination as novel corrosion inhibitors. On the one hand, they play a corrosion inhibition role, protect the metal hanger substrate, improve the stability of the alkaline paint stripper, and extend the life of the paint stripper; on the other hand, benzotriazole has a strong ultraviolet absorption capacity. When the alkaline paint stripper is used outdoors, benzotriazole can protect the alkaline paint stripper from the ultraviolet rays in the sun and extend the service life of the alkaline paint stripper.

[0015] Preferably, the surfactants are BASF low-foam nonionic surfactant PE6100, Dow PEG-1000 and Clariant Genamin CH 020. The compounding of these three components can reduce the surface tension of the alkaline paint stripper, making it easier to wet the surface of the paint layer. This ensures that the alkaline paint stripper can be spread quickly and evenly on the paint layer, thereby improving the paint stripping efficiency. At the same time, the paint particles generated during the paint stripping process can be emulsified in the paint stripper to form a stable emulsion, thereby preventing the paint particles from being redeposited on the surface of the object being stripped, thereby ensuring the uniformity of the paint stripping effect. In addition, the emulsified paint particles are easier to be cleaned off, reducing the difficulty of subsequent cleaning.

[0016] Preferably, the thickener includes ethyl cellulose. The viscosity of the alkaline paint stripper can be increased to make it have appropriate fluidity, which is convenient for smearing and covering on the surface of the object to be stripped. The thickened alkaline paint stripper can stay on the surface of the object to be stripped for a longer time, so that the active ingredients in the alkaline paint stripper have enough time to react with the paint layer. This helps to improve the paint stripping efficiency, especially for thicker paint layers or paint types that are difficult to remove.

[0017] Preferably, the co-solvent is selected from at least one of trisodium phosphate, sodium metasilicate pentahydrate or sodium metasilicate.

[0018] The cosolvent contains functional groups that can produce hydrogen bonds with polar atoms in the cross-linking system, weaken the interaction between the molecular segments of the thermal adhesive, and release some physical cross-linking points in the system, thereby increasing the diffusion rate of the alkaline paint stripper in the thermal adhesive and improving the swelling and wrinkling ability of the protective film. Trisodium phosphate and sodium metasilicate pentahydrate cosolvents can cooperate with the main solvent to fully penetrate the paint film, enhance the solubility of the main solvent, and accelerate the paint stripping speed. At the same time, the alkaline paint stripper needs to maintain a certain alkalinity stability during use. The above cosolvents have a buffering capacity for pH value and can maintain the alkalinity of the alkaline paint stripper to a certain extent. Even when encountering acidic substances, the pH value of the paint stripper can be kept almost unchanged, ensuring the stability of the performance of the alkaline paint stripper, thereby ensuring the consistency of the paint stripping effect.

[0019] Preferably, the alkaline paint stripper further comprises an auxiliary additive and a volatility suppressant.

[0020] Preferably, the auxiliary additives include glycerol and sorbitol.

[0021] Glycerin and sorbitol are compounded to form auxiliary additives. On the one hand, they can increase the solubility of other solvents in water, promote paint stripping reactions, and thus accelerate the removal of paint films. On the other hand, they can adjust the viscosity of alkaline paint strippers and increase the stability of alkaline paint strippers.

[0022] Preferably, the volatility suppressant includes liquid paraffin. Liquid paraffin, as a volatility suppressant in the formula, can significantly reduce the volatilization rate of various components in the alkaline paint stripper when the paint stripping temperature is too high, in view of the high temperature conditions required for paint stripping in the present invention. It forms a protective film on the surface of the alkaline paint stripper to prevent the escape of solvent molecules, thereby extending the service life of the alkaline paint stripper, so that it can maintain effective paint stripping ability for a long time.

[0023] Preferably, the alkaline paint stripper comprises, by weight, 20-30 parts of alkali, 8-10 parts of corrosion inhibitor, 1-3 parts of surfactant, 3-5 parts of thickener, 10-20 parts of cosolvent and 30-40 parts of water.

[0024] Preferably, the alkaline paint stripper includes auxiliary additives and volatility suppressants, and includes, by weight, 20-30 parts of alkali, 8-10 parts of corrosion inhibitors, 1-3 parts of surfactants, 3-5 parts of thickeners, 10-20 parts of cosolvents, 30-40 parts of water, 2-5 parts of auxiliary additives, and 1-3 parts of volatility suppressants.

[0025] Preferably, the alkaline paint stripper comprises, by weight, 18-20 parts of sodium hydroxide, 9-10 parts of sodium metasilicate pentahydrate, 8-10 parts of trisodium phosphate, 4-5 parts of ethyl cellulose, 4-5 parts of p-methyltriazole, 4-5 parts of benzotriazole, 1-2 parts of glycerol, 1-2 parts of sorbitol, 1-3 parts of liquid paraffin, 1-3 parts of surfactant, and 35-40 parts of water.

[0026] Preferably, the alkaline paint stripper comprises, by weight, 18-20 parts of sodium hydroxide, 9-10 parts of sodium metasilicate pentahydrate, 8-10 parts of trisodium phosphate, 4-5 parts of ethyl cellulose, 4-5 parts of p-methyltriazole, 4-5 parts of benzotriazole, 1-2 parts of glycerol, 1-2 parts of sorbitol, 1-3 parts of liquid paraffin, 0.5-1 parts of BASF low-foaming nonionic surfactant PE6100, 0.5-1 parts of Dow PEG-10000, 0.5-1 parts of ClariantGenamin CH 020, and 35-40 parts of water. The appropriate dosage relationship of each component enables the alkaline paint stripper to have a better paint stripping effect, and this paint stripping effect is an unexpected technical effect.

[0027] A second aspect of the present invention provides a method for preparing an alkaline paint stripper.

[0028] Specifically, a method for preparing an alkaline paint stripper comprises the following steps:

[0029] The components are mixed to obtain the alkaline paint stripper.

[0030] A third aspect of the present invention provides a use of an alkaline paint stripper.

[0031] Application of the alkaline paint stripper in the field of paint stripping.

[0032] Preferably, the paint stripping field includes paint stripping of metal surfaces.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) The present invention selects and uses specific components, so that the alkaline paint stripper is not only environmentally friendly but also has a good paint stripping effect; further, by selecting the type and specific dosage of each component, the alkaline paint stripper can achieve unexpected technical effects.

[0035] (2) The alkaline paint stripper of the present invention is a non-toxic paint stripper with sodium hydroxide as the main solvent, which is less harmful to the human body, is also environmentally friendly, is not easy to volatilize, and has a lower paint stripping cost than organic solvent-based paint strippers; the alkaline paint stripper formula of the present invention also uses co-solvents, activators, surfactants, etc., and has a high paint stripping efficiency. Even for iron hangers that are repeatedly sprayed, paint stripping can be completed within 30 minutes; the alkaline paint stripper of the present invention uses a new type of corrosion inhibitor, which basically does not react with the iron substrate and can effectively protect the surface flatness of the iron hanger; the alkaline paint stripper of the present invention has lower equipment requirements than acidic paint strippers, reducing paint stripping costs. DETAILED DESCRIPTION

[0036] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0037] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0038] Example 1

[0039] An alkaline paint stripper comprises the following components in parts by weight:

[0040]

[0041]

[0042] A method for preparing an alkaline paint stripper comprises the following steps: stirring and mixing the above components to obtain the alkaline paint stripper.

[0043] Example 2

[0044] An alkaline paint stripper comprises the following components in parts by weight:

[0045] A method for preparing an alkaline paint stripper comprises the following steps: stirring and mixing the above components to obtain the alkaline paint stripper.

[0046] Example 3

[0047] An alkaline paint stripper comprises the following components in parts by weight:

[0048]

[0049]

[0050] A method for preparing an alkaline paint stripper comprises the following steps: stirring and mixing the above components to obtain the alkaline paint stripper.

[0051] Example 4

[0052]

[0053] A method for preparing an alkaline paint stripper comprises the following steps:

[0054] The above components are stirred and mixed to obtain an alkaline paint stripper.

[0055] Comparative Example 1

[0056] Compared with Example 1, the difference of Comparative Example 1 is that an equal amount of sodium carbonate is used to replace the sodium metasilicate pentahydrate in Example 1, and other components and processes are the same as those in Example 1.

[0057] Comparative Example 2

[0058] Compared with Example 1, the difference of Comparative Example 2 is that the sodium metasilicate pentahydrate in Example 1 is replaced by an equal amount of calcium hydroxide, and the other components and processes are the same as those in Example 1.

[0059] Comparative Example 3

[0060] Compared with Example 1, the difference of Comparative Example 3 is that the ethyl cellulose in Example 1 is replaced by an equal amount of methyl cellulose, and the other components and processes are the same as those in Example 1.

[0061] Product effect testing

[0062] 1. Paint removal effect on the surface of iron hangers

[0063] The iron hook with a 150 μm thick powder spray coating was immersed in the alkaline paint strippers prepared in the above-mentioned embodiments and comparative examples for a period of time, then the iron hook was taken out and rinsed with tap water, and the time required for the alkaline paint strippers in each embodiment and comparative example to remove the coating on the surface of the iron hook was recorded. The results are shown in Table 1.

[0064] Table 1

[0065]

[0066] As can be seen from Table 1, the time required for Examples 1-2 is significantly lower than that for Example 4, and in particular, Example 1 requires the shortest time, and paint stripping can be completed within 10 minutes. The alkaline paint stripper prepared in Example 1 has the best paint stripping effect on iron hangers.

[0067] In addition, the paint stripping efficiencies of the alkaline paint strippers of different embodiments were compared within a shorter prescribed time (8 min).

[0068] The wrinkle area method of HG / T 2881-1997 "Determination of paint stripper efficiency" is a method for characterizing paint stripping efficiency by observing the wrinkle area of ​​the paint film on the surface of the test piece. This method is simple to operate, suitable for industrial production and laboratories, and is the most commonly used method for testing paint stripping effects. The paint stripping efficiencies corresponding to Examples 1-4 were tested under the same conditions according to this method, and the results are shown in Table 2. The paint stripping efficiency formula is: paint stripping efficiency (%) = paint film wrinkle soft area / total paint film area before paint stripping × 100%.

[0069] Table 2

[0070]

[0071] It can be seen from Table 2 that the alkaline paint stripper of Example 1 of the present invention can have a high paint stripping efficiency of 80% in a relatively short period of time (8 min).

[0072] 2. Effects of paint removal on different metal hangers

[0073] According to the test method corresponding to Table 1 above, the iron hanger is replaced by an aluminum alloy hanger, and the effect of the alkaline paint stripper of Example 1 of the present invention on different metal hangers is observed. The results are shown in Table 3.

[0074] Table 3

[0075]

[0076] As can be seen from Table 3, the alkaline paint stripper of the present invention is more suitable for iron hangers.

[0077] The alkaline paint stripper of the present invention is compounded with alkali, corrosion inhibitor, surfactant, thickener, cosolvent and water. Compared with some solvent-type paint strippers on the market, the alkaline paint stripper has the advantages of being non-volatile, non-toxic and environmentally friendly; compared with acidic paint strippers, the alkaline paint stripper has the advantages of safe operation and low equipment requirements; the alkaline paint stripper of the present invention can quickly decompose the paint film structure, complete paint stripping in a relatively short time, and has basically no corrosion and adverse effects on the metal substrate, and is the most suitable paint stripper for metal hangers.

[0078] The paint stripping mechanism of the alkaline paint stripper of the present invention is different from that of solvent-based and acidic paint strippers. The alkaline paint stripper of the present invention can cause ester bonds, ether bonds, amide bonds and other functional groups of the paint film to undergo alkaline hydrolysis reaction, break the molecular chain of the polymer, and reduce the bonding force between the coating film and the substrate. The strong alkalinity of the paint stripper is utilized to soften and destroy the paint film on the iron hanger.

[0079] The alkaline paint stripper of the invention has the advantages of simple and convenient operation, low cost, low toxicity, fast paint stripping speed, simple sewage discharge treatment after use, and environmental protection.

[0080] The present invention introduces a novel and efficient compound surfactant to improve the wettability and permeability of the alkaline paint stripper to the surface of the metal hanger. For example, the compound surfactant can significantly reduce the surface tension of the alkaline paint stripper at a low concentration, making it easier for the alkaline paint stripper to spread on the metal surface, thereby better contacting the paint layer. In this way, the paint stripping speed can be accelerated and the paint stripping efficiency can be improved.

[0081] The present invention adopts a compound corrosion inhibitor, and uses p-methyltriazole and benzotriazole in a compounded manner. These corrosion inhibitors play a role in different corrosion stages, protecting metal hangers from multiple angles. For example, p-methyltriazole forms a dense protective film at the moment when the alkaline paint stripper contacts the surface of the iron hanger, preventing the corrosion of alkaline substances; benzotriazole continuously repairs possible tiny corrosion points during the paint stripping process, ensuring the integrity of the iron hanger.

Claims

1. An alkaline paint stripper, characterized in that Including alkali, corrosion inhibitor, surfactant, thickener, solvent and water.

2. The alkaline paint stripper according to claim 1, characterized in that The alkali includes at least one of sodium hydroxide and potassium hydroxide; and / or the corrosion inhibitor includes p-methyltriazole and benzotriazole.

3. The alkaline paint stripper according to claim 2, characterized in that The thickener includes ethyl cellulose; and / or the co-solvent is selected from at least one of trisodium phosphate, sodium metasilicate pentahydrate or sodium metasilicate.

4. The alkaline paint stripper according to claim 3, characterized in that The alkaline paint stripper further comprises auxiliary additives and a volatility suppressant.

5. The alkaline paint stripper according to claim 4, characterized in that The auxiliary additives include glycerol and sorbitol; and / or the volatility suppressant includes liquid paraffin.

6. The alkaline paint stripper according to any one of claims 1 to 3, characterized in that: The alkaline paint stripper comprises, by weight, 20-30 parts of alkali, 8-10 parts of corrosion inhibitor, 1-3 parts of surfactant, 3-5 parts of thickener, 10-20 parts of cosolvent and 30-40 parts of water.

7. The alkaline paint stripper according to any one of claims 1 to 3, characterized in that: The alkaline paint stripper comprises auxiliary additives and volatility suppressants, and comprises, by weight, 20-30 parts of alkali, 8-10 parts of corrosion inhibitors, 1-3 parts of surfactants, 3-5 parts of thickeners, 10-20 parts of cosolvents, 30-40 parts of water, 2-5 parts of auxiliary additives, and 1-3 parts of volatility suppressants.

8. The alkaline paint stripper according to any one of claims 1 to 3, characterized in that: The alkaline paint stripper comprises, by weight, 18-20 parts of sodium hydroxide, 9-10 parts of sodium metasilicate pentahydrate, 8-10 parts of trisodium phosphate, 4-5 parts of ethyl cellulose, 4-5 parts of p-methyltriazole, 4-5 parts of benzotriazole, 1-2 parts of glycerol, 1-2 parts of sorbitol, 1-3 parts of liquid paraffin, 1-3 parts of surfactant, and 35-40 parts of water.

9. The method for preparing the alkaline paint stripper according to any one of claims 1 to 8, characterized in that: The following steps are involved: The components are mixed to obtain the alkaline paint stripper.

10. Use of the alkaline paint stripper according to any one of claims 1 to 8 in the field of paint stripping.

Images