Treating process before spraying aluminum profile

Abstract

The invention discloses a treating process before spraying an aluminum profile. Before spraying, a blank is subjected to treatment of deoiling, alkaline degreasing, neutralizing, oxidizing a positive electrode and sealing half of a hole, so that a semi-closed oxidized film is formed on the surface of the blank; and the oxidization treatment is that: the blank is put into H2SO4 with the concentration of between 160 and 180 g / L, the oxidization temperature is of between 18 and 22 DEG C, and the current density is of between 140 and 160 A / dm<2>. By adoption of the oxidization treatment step, the formed semi-closed oxidized film has a pore structure, so that a good attachment condition is supplied to paints; furthermore, compared with a non-closed oxidized film, the semi-closed oxidized film has the advantages that: impurities, such as dust and the like, cannot be attached to the surface of the profile easily before the profile is sprayed, and a subsequent spraying effect can be guaranteed. Meanwhile, a chromizing treatment step is avoided, and the finally obtained aluminum profile product does not contain chromium; and therefore, the aluminum profile can meet a non-chromizing requirement, and is relatively safe and environment-friendly.

Description

technical field [0001] The invention relates to the technical field of spraying of aluminum profiles, in particular to a treatment process before spraying of aluminum profiles to make the aluminum profiles chrome-free. Background technique [0002] Metal profiles are widely used in various industries such as construction due to their excellent durability, decoration and formability, while aluminum profiles account for more than 80% of metal profiles due to their good processing performance and light weight. The service life of fluorocarbon-coated aluminum profiles can reach 10-15 years, and the colors are rich, which can better meet people's pursuit of diversification and personalization. The surface treatment of aluminum profiles before coating is usually treated by degreasing, chromizing, and drying processes. 6+ A series of complex chemical reactions occur between the ingredients and the aluminum surface of the profile, so that a layer of loose and porous chromate conver...

AI Technical Summary

Problems solved by technology

The surface treatment of aluminum profiles before coating is usually treated by degreasing, chromizing, and drying processes. 6+ A series of complex chemical reactions occur between the ingredients and the aluminum surface of the profile, so that a layer of loose and porous chromate conversion film is formed on the surface of the profile, so that the aluminum profile substrate can have good adhesion with the coating, but the resulting conversion Film contains Cr 6+ and Cr 3+ , has strong toxicity, especially Cr 6+ Belonging to carcinogens, a series of policies formulated by governments of various countries restrict the adoption of this process in certain fields, and chromate has been listed as extremely poisonous by environmental protection associations such as the United States; on February 13, 2003, the European Union passed "The Restriction of the use of certain Hazardous substances in Electrical and Electronic", that is, "instructions to restrict the use of certain hazardous substances in electrical and electronic equipment", Cr 6+ Classified as hazardous substances; and the existing technology, its production waste liquid contains a large amount of Cr 6+ and Cr 3+ , the treatment of waste liquid is more complicated