Two-step surface conditioning agent used before aluminum anodic oxidation dyeing and preparation and application thereof

Abstract

The invention discloses a two-step surface conditioning agent used before aluminum anodic oxidation dyeing. The two-step surface conditioning agent comprises an alkaline surface conditioning agent andan acidic surface conditioning agent. The alkaline surface conditioning agent is one of a sodium bicarbonate solution, a potassium bicarbonate solution and an ammonia water solution, and the concentrations of the sodium bicarbonate solution, the potassium bicarbonate solution and the ammonia water solution are 5-50g / l; the acidic surface conditioning agent is prepared from, by mass parts, 20-70 parts of organic acid, 1-10 parts of corrosion inhibitor, 5-20 parts of inorganic salt and the balance deionized water. The acidic surface conditioning agent is diluted into 40-200 ml / l of working solution in use and the pH is adjusted to 1.2-2.5. Two-step surface conditioning can effectively prevent the undesirable phenomena of uneven dyeing, floating, corrosion spots and the like caused by residual acid introduced in the pretreatment and anodic oxidation processes of aluminum and aluminum alloy materials and aluminum-plastic composite materials and die-casting aluminum extruded aluminum composite material; meanwhile, the coloring speed can be increased by cleaning and arranging the oxide film holes so that the use of dyes is reduced or the dyeing time is shortened and the same dyeing effect is achieved.

Description

Technical field [0001] The invention relates to the technical field of aluminum surface treatment, in particular to a two-step table conditioning agent before aluminum anodizing and dyeing, and its preparation and application. Background technique [0002] With the upgrading of the electronic product industry and the in-depth development and application of aluminum and aluminum alloy materials, pure aluminum, aluminum magnesium, aluminum magnesium silicon, aluminum magnesium zinc and other aluminum and aluminum alloy materials, aluminum-plastic composite materials, and die-cast aluminum extrusion aluminum composite materials have become The new trend of electronic product housing. The electronic product housings of these aluminum and aluminum alloy materials, aluminum-plastic composite materials, and die-cast aluminum extrusion aluminum composite products are usually treated with anodizing and dyeing processes to improve the decoration and durability of electronic products. [000...

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Problems solved by technology

[0004] 1. Aluminum and aluminum alloy materials, especially aluminum-plastic composite materials and die-cast aluminum extruded aluminum composite materials, have tiny pores and defects at the joints, which are likely to cause acid residues and incomplete cleaning during the anodic oxidation process, resulting in Bad defects such as uneven dyeing, blooming, corrosion spots, etc., resulting in extremely low output yield

[0005] 2. In the process of sandblasting aluminum and aluminum alloy materials, aluminum-plastic composite materials, die-cast aluminum extruded aluminum composite materials, and the anodizing process and dyeing process of cast aluminum, due to the inhomogeneity and Due to the pollution of the casting mold and the inhomogeneity of the aluminum melt in the casting process, the surface of sandblasted aluminum and cast aluminum is more prone to shrinkage caused by thermal expansion and contraction, holes formed by embedding of release oil, The holes formed by defects such as sand holes in the die-casting process and the holes designed by the mold itself will retain residual acid during the anodizing process, which will directly lead to undesirable defects such as uneven dyeing, blooming, and pitting corrosion, resulting in extremely high output yields. Low

[0006] 3. For aluminum and aluminum alloy materials, aluminum-plastic composite materials and die-cast aluminum extruded aluminum composite materials that have dyeing requirements in the hard anodizing process, due to the small film pores formed under the hard anodizing conditions, the dyeing process is colored Difficulty and uneven dyeing, usually it is impossible to carry out the dyeing process normally

Since the surface adjustment solution on the market usually uses a mixture of some organic acids, these mixtures replace and clean the sulfuric acid remaining in the pores on the surface of the anodized film of aluminum and aluminum alloys, dilute the concentration of residual acid, and reduce the anodic oxidation process to a certain extent. And the phenomenon of uneven dyeing, blooming, and pitting corrosion during the dyeing process, but the replaced and diluted acid will still corrode the surface of the anodized film to a certain extent, and the adverse effects of residual acid on the surface of the anodized film cannot be completely removed

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