PRETREATMENT OF TINPLATE PRIOR TO THE COATING THEREOF WITH LACQUER

摘要

22The invention relates to a method for the anti corrosive pretreatment of tinplate in which an anti corrosive primer coating is applied in a single step said primer coating effectively preventing the shiny metal surface of the pretreated tinplate from turning black when the pretreated tinplate of the invention that is provided with a coating lacquer is in contact with liquids releasing or containing sulfur compounds and with food containing protein. In the disclosed method the tinplate is anodically polarized in an electrolyte containing silicates of formula MO�nSiO where M is an alkali metal ion or quaternary ammonium ion and n is a natural number between 0.8 and 7. Tinplate pretreated according to the invention can be used in particular for the production of food safe packaging such as beverage cans or tin cans.