Titanium-free activating agents, process for preparing them and their use in activating a metal surface before zinc phosphating

摘要

The invention relates to titanium-free agents for the activation of metal surfaces of iron or steel, zinc or galvanised steel and also aluminium or aluminised steel before phosphating of the said surfaces with phosphating baths containing zinc ions, in particular before so-called low-zinc phosphating. The invention also relates to a process for preparing the titanium-free activating agents by reacting an alkali metal phosphate with complexing agents, and to the use of the titanium-free activating agents for the activation of metal surfaces before zinc phosphating.