One-step pretreatment method of metallic substrates at non-neutral ph values for metal cold forming

Abstract

Disclosed herein is a method of pretreatment of a metallic substrate for a subsequent metal cold forming process. The method includes at least steps (1) and (2), namely providing at least one substrate having at least one surface at least partially made of at least one metal (step (1)), contacting the at least one surface of the substrate provided in step (1) with an aqueous lubricant composition (B) (step (2)), where the aqueous lubricant composition (B) includes besides water at least constituents (b1) to (b4) and optionally (b5).Further disclosed herein are a pretreated metallic substrate obtained by the method, a method of cold forming of a metallic substrate, and an aqueous lubricant composition (B).

1 . A method of pretreatment of a metallic substrate for a subsequent metal cold forming process, said method comprising at least steps (1) and (2) and optionally step (3), namely
 (1) providing at least one substrate having at least one surface at least partially made of at least one metal and/or alloy thereof, wherein said metal and/or alloy thereof is at least one of steel, aluminum and alloys of aluminum and/or steel,   (2) contacting the at least one surface of the substrate provided in step (1) with an aqueous lubricant composition (B) having a pH value, which is in the non-neutral pH range, wherein the neutral pH range is a pH range of from >6.0 to <8.0,
 wherein the aqueous lubricant composition (B) comprises besides water at least constituents (b1) to (b4) and optionally (b5), which are different from one another, namely
 (b1) at least one film-forming polymer, which is a homopolymer and/or copolymer prepared by polymerization of at least vinyl pyrrolidone as at least one monomer, wherein said homopolymer and/or copolymer has a polydispersity index (PDI) in a range of from 1.5 to 8.0, 
 (b2) at least one wax, 
 (b3) at least one defoamer, 
 (b4) (i) oxalate anions and/or phosphate anions or (ii) calcium cations, chloride anions and hydroxide anions, and 
 (b5) optionally Fe(III) ions, wherein constituent (b5) is present in case at least oxalate anions are present as constituent (b4), 
 
 and 
   (3) optionally drying the coating film obtained after having performed step (2).   
     
     
         2 . The method according to  claim 1 , wherein the film-forming polymer (b1) has a polydispersity index (PDI) in a range of from 1.8 to 7.5. 
     
     
         3 . The method according to  claim 1 , wherein the film-forming polymer (b1) has at least one glass transition temperature (T g ) in a range of from 40 to 200° C. 
     
     
         4 . The method according to  claim 1 , wherein the film-forming polymer (b1) is a homopolymer being prepared from vinyl pyrrolidone or a copolymer prepared from vinyl pyrrolidone and at least one monomer selected from the group consisting of (meth)acrylate monomers, vinyl amine, vinyl alcohol, vinyl formamide, vinyl caprolactam, vinyl acetate and vinyl imidazole. 
     
     
         5 . The method according to  claim 1 , wherein the film-forming polymer (b1) is present in the composition (B) in an amount in a range of from 0.05 to 20 wt.-%, based on the total weight of the composition (B). 
     
     
         6 . The method according to  claim 1 , wherein the aqueous lubricant composition (B) has a
 pH value in a range of from 0.1 to 6.0, or has a   pH value in a range of from 8.0 to 14.0.   
     
     
         7 . The method according to  claim 1 , wherein the aqueous lubricant composition (B) has a
 pH value in a range of from 0.1 to <2.0, or has a   pH value in a range of from ≥2.0 to 6.0, or has a   pH value in a range of from 8.0 to 14.0,   
     
     
         8 . The method according to  claim 1 , wherein the at least one wax (b2) is selected from the group consisting of polyolefin waxes. 
     
     
         9 . The method according to  claim 1 , wherein the composition (B) further comprises at least one corrosion inhibitor as constituent (b6), which is different from each of constituents (b1) to (b4) and optional constituent (b5). 
     
     
         10 . The method according to  claim 1 , wherein the defoamer constituent (b3) is a defoamer, which is free of silicone. 
     
     
         11 . The method according to  claim 1 , wherein the contacting step (2) is performed by at least partially dipping the substrate into a bath containing the aqueous lubricant composition (B) having a bath temperature in a range of from 20 to 95° C. 
     
     
         12 . A pretreated metallic substrate obtained by the method according to  claim 1 . 
     
     
         13 . The pretreated metallic substrate according to  claim 12 , wherein the coating film present on the surface of the substrate after having performed step (3) has a coating weight in a range of from 1.0 to 40.0 g/m 2 . 
     
     
         14 . A method of cold forming a metallic substrate, comprising a step of subjecting the pretreated metallic substrate according to  claim 12  to a cold forming process. 
     
     
         15 . An aqueous lubricant composition (B), comprising:
 water; and   at least constituents (b1) to (b4) and optionally (b5), which are different from one another, namely
 (b1) at least one film-forming polymer, which is a homopolymer and/or copolymer prepared by polymerization of at least vinyl pyrrolidone as at least one monomer, wherein said homopolymer and/or copolymer has a polydispersity index (PDI) in a range of from 1.5 to 8.0, 
 (b2) at least one wax, 
 (b3) at least one defoamer, 
 (b4) (i) oxalate anions and/or phosphate anions or (ii) calcium cations, chloride anions and hydroxide anions, and 
 (b5) optionally Fe(III) ions, wherein constituent (b5) is present in case at least oxalate anions are present as constituent (b4). 
   
     
     
         16 . The method according to  claim 1 , wherein the film-forming polymer (b1) has a polydispersity index (PDI) in a range of from 2.0 to 7.0. 
     
     
         17 . The method according to  claim 1 , wherein the film-forming polymer (b1) has at least one glass transition temperature (T g ) in a range of from 50 to 190° C. 
     
     
         18 . The method according to  claim 1 , wherein the film-forming polymer (b1) is present in the composition (B) in an amount in a range of from 0.10 to 15 wt.-% based on the total weight of the composition (B). 
     
     
         19 . The method according to  claim 1 , wherein the at least one wax (b2) is selected from the group consisting of polyethylene waxes and polypropylene waxes, montan waxes, bees waxes and carnauba waxes, and mixtures thereof. 
     
     
         20 . The method according to  claim 1 , wherein the at least one wax (b2) is present in the composition (B) in an amount in the range of from 0.1 to 20 wt.-% based on the total weight of the composition (B).