Simplified process for the pretreatment of metallic substrates for cold forming and a reactive lubricant for this purpose

Abstract

The present invention relates to a simplified process for the pretreatment of metallic substrates for cold forming, wherein a metallic substrate is successively 1) preferably cleaned and subsequently rinsed, 2) preferably pickled and subsequently rinsed, 3) brought into contact with a water-based, acidic, reactive lubricant comprising a) oxalic acid, b) at least one accelerator which comprises nitroguanidine and/or at least one iron(III) source and c) at least one film former, at least one wax and/or at least one emulsified lubricating oil and 4) is optionally dried, where the at least one film former is selected from the group consisting of homopolymers and copolymers of ethylene, propylene, styrene, (meth)acrylic acid, (meth)acrylate, vinylamine, vinylformamide, vinylpyrrolidone, vinylcaprolactam, vinyl acetate, vinylimidazole and/or epoxide and salts thereof and polyurethanes, polyamides, polyethylenimines, polyamines and salts thereof, where the at least one wax is selected from the group consisting of nonionic waxes and cationically stabilized waxes, and where the at least one emulsified lubricating oil is selected from the group consisting of synthetic oils, mineral oils, vegetable oils and animal oils, to a corresponding reactive lubricant and to a metallic substrate which has been pretreated by the process and the use thereof.

1 . A process for a pretreatment of a metallic substrate for cold forming, wherein the metallic substrate is successively
 1) optionally mechanically or chemically cleaned and subsequently rinsed,   2) optionally pickled and subsequently rinsed,   3) brought into contact with a water-based, acidic, reactive lubricant comprising   a) oxalic acid,   b) at least one accelerator which comprises nitroguanidine and/or at least one iron(III) source, and   c) at least one wax and optionally at least one film former and/or at least one emulsified lubricating oil,    and   4) optionally dried,   wherein the at least one film former is selected from the group consisting of homopolymers and copolymers of ethylene, propylene, styrene, (meth)acrylic acid, (meth)acrylate, vinylamine, vinylformamide, vinylpyrrolidone, vinylcaprolactam, vinyl acetate, vinylimidazole and/or epoxide and salts thereof, and polyurethanes, polyamides, polyethyleneimines, polyamines and salts thereof,   wherein the at least one wax is selected from the group consisting of nonionic waxes and cationically stabilized waxes, and   wherein the at least one emulsified lubricating oil is selected from the group consisting of synthetic oils, mineral oils, vegetable oils and animal oils.   
     
     
         2 . The process according to  claim 1 , wherein the component c) of the reactive lubricant comprises at least one film former, selected from the group consisting of homopolymers and copolymers of ethylene, propylene, (meth)acrylic acid, (meth)acrylate, vinylamine, vinylformamide, vinylpyrrolidone, vinylcaprolactam, vinyl acetate, vinylimidazole and/or epoxide and salts thereof, and polyethylenimines, polyamines and salts thereof. 
     
     
         3 . The process according to  claim 1 , wherein the component c) of the reactive lubricant comprises at least one wax selected from the group consisting of nonionic waxes and cationically stabilized waxes. 
     
     
         4 . The process according to  claim 3 , wherein the at least one wax comprises at least three, waxes having different melting points. 
     
     
         5 . The process according to  claim 1 , wherein the component c) of the reactive lubricant comprises at least one emulsified lubricating oil. 
     
     
         6 . The process according to  claim 1 , wherein the reactive lubricant comprises at least one antifoam e). 
     
     
         7 . The process according to  claim 1 , wherein the reactive lubricant comprises at least one acid-stable surfactant g). 
     
     
         8 . The process according to  claim 1 , wherein the reactive lubricant comprises at least one corrosion inhibitor h). 
     
     
         9 . The process according to  claim 1 , wherein a pH of the reactive lubricant is less than 2.0 
     
     
         10 . The process according to  claim 1 , wherein a temperature of the reactive lubricant is in a range from 60 to 90° C. 
     
     
         11 . A water-based, acidic, reactive lubricant for cold forming of metallic substrates, wherein the reactive lubricant comprises
 a) oxalic acid,   b) at least one accelerator which comprises nitroguanidine and/or at least one iron (III) source, and   c) at least one wax and optionally at least one film former and/or at least one emulsified lubricating oil,   
       wherein the at least one film former is selected from the group consisting of homopolymers and copolymers of ethylene, propylene, styrene, (meth)acrylic acid, (meth)acrylate, vinylamine, vinylformamide, vinylpyrrolidone, vinylcaprolactam, vinyl acetate, vinylimidazole and/or epoxide and salts thereof, and polyurethanes, polyamides, polyethyleneimines, polyamines and salts thereof, 
       wherein the at least one wax is selected from the group consisting of nonionic waxes and cationically stabilized waxes, and 
       wherein the at least one emulsified lubricating oil is selected from the group consisting of synthetic oils, mineral oils, vegetable oils and animal oils. 
     
     
         12 . A concentrate from which the reactive lubricant according to  claim 11  can be obtained by dilution, and optionally setting of a pH by means of a pH-modifying substance. 
     
     
         13 . A pretreated metallic substrate comprising a combined conversion and lubricant layer and obtained by a process according to  claim 1 . 
     
     
         14 . The metallic substrate according to  claim 13 , wherein the layer weight of the combined conversion and lubricant layer determined by a method of gravimetric detachment is in a range from 0.3 to 15 g/m2, calculated as lubricant layer, and in a range from 0.3 to 30 g/m2, calculated as separation/conversion layer. 
     
     
         15 . A method of using the metallic substrate according to  claim 13 , the method comprising using the metallic substrate in a cold forming process. 
     
     
         16 . The process according to  claim 1 , wherein the component c) of the reactive lubricant comprises only one film former selected from the group consisting of homopolymers and copolymers of ethylene, propylene, (meth)acrylic acid, (meth)acrylate, vinylamine, vinylformamide, vinylpyrrolidone, vinylcaprolactam, vinyl acetate, vinylimidazole and/or epoxide and salts thereof, and polyethylenimines, polyamines and salts thereof. 
     
     
         17 . The process according to  claim 1 , wherein the component c) of the reactive lubricant comprises only one film former selected from the group consisting of homopolymers and copolymers of vinylpyrrolidone, but no other film former. 
     
     
         18 . The process according to  claim 1 , wherein the component c) of the reactive lubricant comprises only one wax selected from the group consisting of nonionic waxes and cationically stabilized waxes. 
     
     
         19 . The process according to  claim 1 , wherein the component c) of the reactive lubricant comprises only one wax selected from the group consisting of cationically stabilized waxes, but no other wax. 
     
     
         20 . The process according to  claim 3 , wherein the at least one wax comprises at least five waxes having different melting points.