Zinc-aluminum-magnesium plating layer surface treating agent as well as preparation method and use method thereof

Abstract

The invention discloses a zinc-aluminum-magnesium plating layer surface treating agent as well as a preparation method and a use method thereof, and belongs to the technical field of zinc-aluminum-magnesium alloy plating layer steel plate surface treatment. In order to meet the requirements of household appliances and automobile users on blackening resistance and environmental friendliness of hot-dip galvanized aluminum-magnesium alloy coated steel plates, the invention provides a zinc-aluminum-magnesium plating layer surface treating agent which comprises 1-5 parts of fluoride, 3-10 parts ofperiodate, 0.5-5 parts of weakly alkaline medium, 20-50 parts of water-based organic resin, 5-15 parts of colloidal silicon dioxide and 100 parts of water. Fluoride and periodate react with Mg on thesurface of a plating layer under the weak alkaline condition to generate a compact film layer, water-based organic resin adheres to the surface of the plating layer, gaps are filled with colloidal silicon dioxide, contact between the plating layer and water vapor and oxygen in the environment is effectively hindered, and the corrosion resistance, blackening resistance, water resistance and fingerprint resistance of the surface coating are remarkably improved.

Description

technical field [0001] The invention belongs to the technical field of surface treatment of zinc-aluminum-magnesium alloy coated steel sheets, and in particular relates to a surface treatment agent for zinc-aluminum-magnesium coatings and a preparation method and application method thereof. Background technique [0002] Zn-Al-Mg alloy coated steel sheet has better corrosion resistance, excellent processing and application performance (formability, weldability and coating property), and the trend of replacing the current corresponding hot-dip galvanized or zinc alloy coated steel sheet is becoming increasingly obvious. [0003] Existing hot-dip Zn-Al-Mg alloy coated steel sheet can be divided into "low aluminum" (WAl<5%), "medium aluminum" (5%≤WAl<13%) and "high aluminum" (47%≤WAl ≤57%) three types. With the increase of Al and Mg content, the corrosion resistance of the coating increases, but the formability and weldability decrease. In the fields of home appliances a...

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Problems solved by technology

[0006] Although the above three coatings disclose that the environmental passivation coating has good corrosion resistance and blackening resistance, there is no clear or standard test method to characterize it, and it is impossible to determine the pros and cons of its performance; and by production practice According to the results obtained by users, blackening is a chronic disease of zinc, aluminum and magnesium products. At present, there is no environmentally friendly surface coating with excellent blackening resistance in China.

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