In the surface treatment process of aluminum profile or […]
In the surface treatment process of aluminum profile organic coating, it is inevitable that the product with unqualified coating quality will appear. For example, the defects often appear in electrophoretic coating are defects such as low film, yellowing, particles, bubbles, etc. Pinholes and bubbles often appear in powder electrostatic spraying. Defects such as granules and cross-colors, if they are scrapped, will inevitably affect the yield and timeliness of delivery, resulting in unnecessary losses. Therefore, more and more aluminum profile companies are concerned about how to remove the unqualified coating on the aluminum profile and recycle the substrate for rework. In addition, in order to ensure the electrical conductivity of the workpiece during the electrostatic spraying process, the spray coating is also subjected to the peeling treatment of the organic coating.
The methods for stripping aluminum coatings can be roughly divided into three categories: chemical methods, pyrolysis methods, and mechanical methods. The chemical stripping method uses a corrosive agent, a solvent or a combination of the two; the pyrolysis method uses a high temperature furnace, an open flame, a hot fluidized bed, a molten salt bath and a laser to perform a stripping treatment; the mechanical stripping method uses a high pressure water and an abrasive medium. , brushes, mills, scrapers, cutting machines, low temperature treatment, etc.
The chemical stripper works by softening or dissolving the coating film, splitting the coating film with the substrate, and then releasing the coating film mechanically. Chemical release agents can be classified according to operating temperature (hot or cold) and can be classified according to their composition, such as corrosives (acidic or basic), solvents or etchants/solvents. The corrosive type release agent generally adopts a heating process, and the release temperature reaches 80 to 100 °C.
Solvent-based chemical release agents are available in a cold process with an operating temperature of room temperature or near room temperature. The solvent-based chemical release agent is usually a liquid obtained by mixing a solvent such as a chlorinated hydrocarbon, a ketone, an ester, an alcohol or a benzene compound. The solvent is applied to the coating layer to have an osmotic swelling effect, and the various aluminum surface-treated coatings can be effectively removed, and the coating film can be directly peeled off or the coating film can be easily peeled off. The release of the release agent is achieved by a series of physical and chemical processes such as dissolution, infiltration, swelling, stripping and reaction.