Short-duration hot seal process for anodised metal surfaces

摘要

A process for sealing anodised metal surfaces, in which the anodised metal is placed in contact, for 0.5-2 mins. per micron of anodised layer thickness, with an aqueous solution at a temp. between 75 deg C and the b.pt., and a pH of 5.5-8.5. This solution contains: (a) 0.0001-5 g/l alkali and/or alkaline earth metal ions; and (b) 0.0005-0.5 g/l organic acid(s), comprising cyclic polycarboxylic acids with 3-6 COOH groups and/or phosphonic acids and/or polyphosphino-carboxylic acids. The content of metal ions (a) being greater than that required for the complete neutralisation of (b). Also claimed is an aqueous concentrate for making the above solution by diluting with water by a factor of 10-1000.