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Aluminum coating organic coating surface coating process will inevitably appear unqualified products, such as electrophoretic coating defects often appear low, yellow, particles, bubbles and other defects, powder electrostatic spraying often appear pinholes, bubbles , Particles, color and other defects, if this scrapped, will inevitably affect the yield and timeliness of delivery, resulting in unnecessary losses. So more and more aluminum companies are concerned about how to remove the aluminum coating on the failure to recover the substrate for rework treatment. In addition, in order to ensure the electrostatic spraying process of the workpiece conductivity, spray rack also organic coating stripping treatment.

Aluminum stripping method of organic coating can be divided into three categories: chemical methods, high-temperature decomposition methods and mechanical methods. High temperature decomposition method using high-temperature furnace, open flame, hot fluidized bed, molten salt bath and laser stripping treatment; mechanical stripping method using high-pressure water, abrasive media (abrasive media), the use of high- , Brush, mill, scraper, cutting machine, low temperature processing.

Chemical stripping

The chemical release agent works by softening or dissolving the coating film, splitting the coating film from the substrate, and then releasing the coated film to be mechanically removed. Chemical release agents can be classified according to operating temperature (hot or cold) and can be classified according to their composition such as etchant (acidic or basic), solvent or etchant / solvent combination. Corrosion agent release agent generally used heating process, stripping temperature of 80 ~ 100 ℃.

Solvent-based chemical release agent using cold process, the working temperature is at or near room temperature. Solvent-based chemical release agent is usually composed of chlorinated hydrocarbons, ketones, esters, alcohols, benzene and other solvents mixed solvent. By using the solvent to cover the coating with osmotic swelling effect, which can effectively remove all kinds of aluminum surface treatment of the coating, directly stripping the coating or peeled off easily. The stripping action of the release agent is achieved by a series of physical and chemical processes such as dissolution, infiltration, swelling, peeling and reaction.

There are many chemical release agents that have been commercialized. Chemical release agent has the advantage of diverse formulations, can get rid of acrylic, epoxy, polyester, polyurethane and other high durability coating, and the impact of the aluminum substrate is very small. Disadvantages are the potential health and environmental hazards associated with the use of corrosive materials, chlorinated solvents and flammable solvents.

Corrosive release agent is usually acidic, is a strong acid such as concentrated sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid composition of the release agent. Concentrated hydrochloric acid, nitric acid volatile acid mist, while corrosion of aluminum substrate; concentrated phosphoric acid stripping time is longer, there are corrosive effect on the substrate, so the use of less than three kinds of acid. Concentrated sulfuric acid and aluminum, iron and other metal passivation reaction, the corrosion of aluminum is very small, while the organic matter has a strong dehydration, carbonation and sulfonation and make it soluble in water, so concentrated sulfuric acid is often used as acid release agent . & Lt; / RTI & gt;

Since the solvent-based release agents are cold, that is, at or near room temperature, they operate at a slower rate than hot corrosive release agents and have a longer coating time. Therefore, the combination of mold release agent came into being. Combination of mold release agent using a corrosive materials and solvents, both the advantages. They can remove the most durable and chemical resistance of the coating. They can work at room temperature or near room temperature, operating temperature is lower than the boiling point of solvent, the role of speed between the corrosive release agent and solvent-based release agent between. Domestic products have been listed, the use of good results.