Chromium-free metal surface treatment composition

Abstract

The invention relates to a chromium-free metal surface treatment composition. The composition is characterized by comprising the following components: A) hydroxy-terminated water-soluble polydimethylsiloxane, B) silane coupling agent with alpha-functional group, C) bivalent or high-valent metal ions of Zr<2+>, Ca<2+>, Ce<3+> or Mo<6+> selected from at least one of Zr(CH3COO)2, Ca(CH3COO)2, Ce(NO3)3 and (NH4)6Mo7O24, D) pH regulator selected from at least one of hydroxyethylidene-1,1-diphosphonic acid, 2-phosphonic acid butane-1,2,4-tricarboxylic acid and amino trimethylene phosphonic acid, and E) deionized water, wherein the concentration range of the component A) is 50 to 100 g / L, the concentration range of the component B) is 2 to 10 g / L, the concentration range of the component C) is 0.2 to 5 g / L, and E) the balance of the component shown in the specification.

Description

[0001] technical field [0002] The invention relates to the technical field of metal surface treatment, and relates to a chromium-free metal surface treatment composition, which does not contain chromium and can form a chromium-free conversion film with good corrosion resistance on metal materials. Background technique [0003] Coated metal sheets (such as galvanized sheets, tinned sheets, galvanized sheets, etc.) have good corrosion resistance and are widely used in electronic products, aviation, automobiles, building materials, home appliances, machinery and other fields, but in humid environments , Plated metal is easily corroded, and chromate is widely used as a corrosion inhibitor in the metal surface treatment industry. However, hexavalent chromium is toxic and carcinogenic, so developed countries have issued relevant regulations to restrict the use of hexavalent chromium. Therefore, it is the general trend to research and develop products that can replace chromate ...

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Problems solved by technology

[0004] At present, a variety of chromium-free metal surface treatment composition systems have been proposed at home and abroad. Among them, the organosilane system has the best corrosion resistance, which is equivalent to chromate. However, when the silane coupling agent is used as the main film-forming agent, after hydrolysis in water The content of hydroxyl groups is high, self-condensation is easy to occur, the system stability is poor, and the corrosion resistance is significantly reduced, which limits the popularization and application of silane system chrome-free treatment solution

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