Polyamide-imide coated substrate

Abstract

Steel substrate suitable for forming operations which includes a coating thereon wherein the coating includes a corrosion resistant layer of polyamide-imide having a dry film thickness between 1 and 10 μm.

1 . A steel substrate suitable for forming operations comprising a corrosion protective coating wherein the corrosion protective coating comprises a layer of polyamide-imide having a dry film thickness between 1 and 10 μm, and wherein the layer of polyamide-imide further comprises a hydroxyl amine. 
     
     
         2 . The steel substrate according to  claim 1 , wherein the hydroxyl amine comprises diethylaminoethanol, diisopropanolamine or aminoethylpropanediol. 
     
     
         3 . The steel substrate according to  claim 1 , wherein the hydroxyl amine has a boiling point of at least 160° C. 
     
     
         4 . The steel substrate according to  claim 1 , wherein the layer of polyamide-imide has a dry film thickness between 2 and 5 μm. 
     
     
         5 . The steel substrate according to  claim 1 , wherein the layer of polyamide-imide has a coefficient of friction between 0.13 and 0.25, at a temperature between −10 and 120° C. 
     
     
         6 . The steel substrate according to  claim 1 , wherein the thermal degradation temperature of the layer of polyamide-imide is at least 250° C. 
     
     
         7 . The steel substrate according to  claim 1 , wherein the steel substrate comprises a strip, sheet or blank. 
     
     
         8 . The steel substrate according to  claim 1 , wherein the steel comprises a cold-rolled steel. 
     
     
         9 . The steel substrate according to  claim 1 , wherein a zinc or a zinc alloy corrosion protective coating is present on the steel substrate. 
     
     
         10 . The steel substrate according to  claim 1 , wherein the steel is selected from the group consisting of carbon steel, low carbon steel, high strength steel, advanced high strength steel, boron steel, nickel chromium steel, electrical steel, tin-plated steel, nickel-plated steel and electro-coated chromium steel. 
     
     
         11 . A method of manufacturing a steel substrate according to  claim 1 , which comprises the steps of:
 a. providing a steel substrate;   b. providing a curable coating on the steel substrate, which curable coating comprises water, polyamide-amic acid and a hydroxyl amine;   c. curing the curable coating to form the corrosion protective coating comprising a layer of polyamide-imide having a dry film thickness between 1 and 10 μm.   
     
     
         12 . The method of manufacturing a steel substrate according to  claim 11 , wherein the curable coating comprises up to 20% polyamide-amic acid, up to 7% hydroxyl amine, and water. 
     
     
         13 . The method of manufacturing a steel substrate according to  claim 11 , wherein the curable coating comprises 5 to 20% polyamide-amic acid, 1 to 7% hydroxyl amine, and water. 
     
     
         14 . The method of manufacturing a steel substrate according to  claim 11 , wherein the curable coating is cured using near infrared radiation which causes the steel substrate to heat up and transfer heat to the curable coating. 
     
     
         15 . The method of manufacturing a steel substrate according to  claim 11 , wherein the curable coating is cured between 160 and 300° C. 
     
     
         16 . A method of use comprising forming a part from the steel substrate according to  claim 1 . 
     
     
         17 . The method of use of the steel substrate according  claim 16 , in forming operations to form the part wherein the forming is carried out without lubricant. 
     
     
         18 . The steel substrate according to  claim 1 , wherein the hydroxyl amine has a boiling point above 240° C. 
     
     
         19 . The steel substrate according to  claim 1 , wherein the layer of polyamide-imide has a coefficient of friction between 0.13 and 0.2 at a temperature between −10 and 120° C. 
     
     
         20 . The steel substrate according to  claim 1 , wherein the thermal degradation temperature of the layer of polyamide-imide is at least 400° C. 
     
     
         21 . The steel substrate according to  claim 1 , wherein a zinc or a zinc alloy corrosion protective coating is present on the steel substrate, wherein the zinc alloy comprises more than 50% zinc and one or more of Mg, Al, Si, Mn, Cu, Fe and Cr. 
     
     
         22 . The method of manufacturing a steel substrate according to  claim 11 , wherein the curable coating is cured between 180 and 265° C.