Acidic aqueous phosphating solution for treating steel surfaces contains zinc ions, phosphate ions, and organic nitro-compound(s) as accelerator selected from nitroarginine (derivatives) and 5-nitro-2-furfurylidenedicarboxylates

摘要

Acidic aqueous phosphating solution contains zinc ions, phosphate ions, and at least one organic nitro-compound as accelerator selected from nitroarginine, its esters with 1-4 C alcohols, and 5-nitro-2-furfurylidenedicarboxylates of specified formula. Acidic aqueous phosphating solution contains 0.2-3 g/l zinc ions, 3-50 g/l phosphate ions calculated as PO4<3->, and 0.5-5 g/l of at least one organic nitro-compound as accelerator selected from nitroarginine, its esters with 1-4 C alcohols, and 5-nitro-2-furfurylidenedicarboxylates of formula (I): R = 1-3 C alkyl. Independent claims are also included for the following: (A) an aqueous concentrate produced from the phosphating solution; and (B) a process for phosphating metal surfaces made of steel, galvanized or alloy-galvanized steel or aluminum comprising contacting the metal surfaces with the phosphating solution by spraying with and/or immersing in the phosphating solution for 3 seconds to 8 minutes.