To Al-based plated steel band - precautions due to the surface treatment method and its method of Al-based plated steel band

摘要

PURPOSE: To provide a surface treating method of an Al plated steel band superior in a coating workability. ;CONSTITUTION: This patent is related to a surface treating method successively forming a chromate film of 5-150mg/m² of Cr quantity and an under-mentioned aqueous coating composition film of 0.5-5.0μm thick on a surface of the Al plated steel band and the precoated Al plated steel band produced by this method. The aqueous coating composition is composed of (A): a carboxylated polyethylene type resin dispersion having a carboxyl group quantity of 5-30wt.% in the resin, being 10,000-100,000 of a number average molecular weight and 70-120°C of a minimum film forming temperature, (B): a hydrophilic colloidal silica having ≤100μm of the particle size (C): a thickener, and the composition ratio of (A) to (B) is A/B=90/10 to 60/40 by the solid weight ratio and a solid concentration of the whole composition is 20-35wt.%, the pH value is 8.5-10.5 and the viscosity is 20-400cps.;COPYRIGHT: (C)1993,JPO&Japio