PROCESS FOR TREATING METAL SURFACES, ESPECIALLY STEEL SHEETS, IN PARTICULAR FOR IMPROVING THEIR TRIBOLOGICAL PERFORMANCE

摘要

Metal surface treatment by applying an aqueous pretreatment solution of a polyalkoxylate of a fatty acid ester, drying and oiling, is new. A metal surface treatment process involves applying an aqueous pretreatment solution of a polyalkoxylate of an optionally saturated 15-26C fatty acid ester, drying and oiling. An Independent claim is also included for a metal part obtained by the above process, the metal surface being coated with two distinct layers comprising the treatment product layer and a superficial oil layer. Preferred Features: The fatty acid is selected from monoethylenically or polyethylenically unsaturated aliphatic acids, hydroxylated and ketonic acids and saturated aliphatic acids, e.g. palimitoleic, oleic, gadoleic, erucic, hiragonic, linoleic, arachidonic, clupanodonic, phellonic, ricinoleic, ricinelaidic, licanic, palmitic, stearic, arachidic, behenic, lignoceric and cerotic acids. The fatty acid is especially a 18-24C hydroxyacid, particularly ricinoleic acid used in the form of hydrogenated ricin oil. The polyalkoxylate is a polyethoxylate with alkylene oxide groups adjusted to an HLB (hydrophilic lipophilic balance) index of greater than 10, especially -18. The fatty acid polyethoxylate is present in the form of a ricin oil polyethoxylate containing 200 ethylene oxide groups. The aqueous solution also contains 0.3-3% corrosion inhibitor selected from amine products, morpholine benzoate, tertiary amine salts of benzothiazolyl thiosuccinic acid, phosphated amines and zinc salts of branched 6-19C fatty acids and/or naphthenic acid. The solution is applied to provide a dried film of greater than 200 mg/m2 weight, especially 200-1000 mg/m2 when applied to bare steel.