The results showed that there was no linear relationship between solvent concentration and paint removal rate, and there was no paint removal effect when the solution did not contain the main solvent. Environmentally friendly paint remover is made by uniformly mixing a certain amount of each component (alcohol, phenol, surfactant, thickener, paraffin, and penetrant). The paint remover is a liquid composed of aromatic compounds and highly solvent-soluble agents, possessing an extremely strong ability to dissolve paint films. It is fast-acting, highly efficient, and can remove a wide range of coatings, including alkyd, nitrocellulose, polyurea-formaldehyde rubber, ethylene, epoxy, polyester, polyurethane, and other paints, exterior wall coatings, and powder coatings. It has extremely strong paint removal capabilities. Compared with similar foreign products, this product achieves the same paint removal effect but saves approximately 20% of the paint removal time. Application method: For large workpieces, use a brush or cotton yarn to apply the paint remover to the painted areas. For thick paint films, apply repeatedly 2-3 times until the paint film is removed. The subsequent cleaning process is the same as the immersion method. As the solvent concentration increases, the film begins to wrinkle and soften before being removed. When the solvent concentration reaches a certain value, the paint removal effect weakens. The effectiveness of the paint remover varies depending on the solvent. The solvent concentrations are different. Strictly speaking, the main solvent should match the chemical composition of the paint to be removed.
The effects of acids and alkalis.
The stripping process is a complex physical and chemical process. Adding acid or alkali activators to the stripping process will disrupt the chemical cross-linking, significantly reducing the stripping time. Due to the high degree of film cross-linking, although the swelling degree of the solid segment is greatly reduced under the penetrating force of the solvent molecules, it may still be impossible to break the adhesion between the substrate and the film, and the stripping process will still be slow. If an acid or alkali is added, the pH value will change, and a certain degree of acidolysis, aminolysis, or alcoholysis may occur between the swelling segments, which plays an activating and promoting role. However, the addition of acids and alkalis may have a corrosive effect on certain substrates. Therefore, the addition of acid or alkali should be determined based on the different substrates. In formulations using acids or alkalis as activators, the addition of corrosion inhibitors should be fully considered.
The Influence of Temperature.
The removal of this membrane is primarily achieved through the permeation and erosion of the main solvent molecules. Because the NPC (Polymer Injection Process) possesses a certain affinity between polymer and solvent molecules, it can retain the main solvent molecules. This affinity is a key factor in the removal of the membrane. The affinity (Gr, represented by the change in free energy ΔS), the permeation and diffusion between different molecules, is determined by the interaction between solvent molecules (represented by the product of entropy and temperature difference ΔS) (represented by enthalpy difference ΔH). The mathematical equation is:
ΔG = ΔH - TΔS
Where ΔG is the affinity between the solvent and polymer, and between them. The greater the decrease in this value, i.e., the larger the entropy difference ΔS, the greater the diffusion and permeation force, and the greater the affinity. When the affinity energy between the main solvent molecules and the macromolecular structure of the coating film exceeds the energy of the mutual promotion between other polymer molecules, the coating film will cause significant swelling, making removal possible. Analysis of the formula shows that as T increases (i.e., the degree of deterioration increases), the penetration force during diffusion continuously strengthens. Therefore, the larger the negative value of ΔG, the greater the affinity, and the faster the paint removal speed should be. However, as the paint film thickens, the resistance of the main solvent system to penetrating to the bottom of the substrate through technical diffusion increases, thus the paint removal speed will also increase accordingly.
Increasing temperature does indeed greatly accelerate the paint removal rate, but with increasing temperature, solution evaporation and a shortened service life lead to increased costs. Therefore, the development of paint removers generally only meets the paint removal requirements.
The Influence of Stirring Speed
Studies have found that stirring speed has no effect on the paint removal speed, possibly for the following reasons:
Better dispersion, even without stirring, allows for uniformity of components.
The rate at which the main solvent penetrates the paint film is the controlling factor in the paint removal speed, and it does not increase with increasing stirring reaction rate.