Method for coating a metal strip

A process for coating both faces of an aluminum alloy strip material with polymer comprising:

• heating a strip of aluminum alloy approximately 0.004 to 0.030 inch thick to a temperature in a range of about 250-550.degree. F.;
• moving said heated strip downwardly through the nip between a first pair of rolls;
• extruding and applying to said heated strip a first thin molten polymer web comprising high melt viscosity resin simultaneously with said moving of said strip through the nip between a first pair of rolls and drawing said web downwardly through the nip in said first pair of rolls to reduce the thickness of said web in a range of about 10:1 to 40:1 and press the web against one face of said strip to adhere it to such face;
• moving said strip from said first pair of rolls downwardly through the nip between a second pair of rolls;
• extruding and applying to said strip a second molten polymer web comprising high melt viscosity resin simultaneously with moving said strip through the nip between said second pair of rolls and drawing said web downwardly through the nip between said second pair of rolls to reduce the thickness of said web in a range of about 10:1 to 40:1 and press the web against the second face of said strip to adhere it to said face;
• postheating said strip to approximately 256-600.degree. F.;
• and
• quickly cooling said strip promptly after it has been postheated to solidify said polymer on the strip.

A continuous process for coating both faces of an aluminum alloy strip material with polymer in an uninterrupted sequence comprising:

• heating a strip of aluminum alloy approximately 0.007 to 0.014 inch thick to a temperature in a range of about 250-550.degree. F.;
• moving said heated strip downwardly through the nip between a first pair of rolls which comprise a casting roll and a backup roll while at the same time extruding and applying to said metal strip a first continuous thin molten polymer web containing high melt viscosity resin, drawing said first molten web to reduce its thickness in a range of about 10:1 to 40:1 and feeding said first web between said strip and said casting roll at approximately the nip in said first pair of rolls to press the web against one face of said strip and adhere it to such face;
• reheating the strip, which has a first coated face with said web thereon and a second uncoated face, to approximately 250-550.degree. F.;
• moving said strip from said first pair of rolls downwardly at an angle of about 20-70.degree. to vertical through the nip between a second pair of rolls which comprise a casting roll and a backup roll, with the strip entering and exiting said nip at approximately 90.degree. to a plane through the axes of the rolls in said second pair of rolls while at the same time extruding and applying to said strip a second continuous thin molten polymer web containing high melt viscosity resin, drawing said second molten web to reduce its thickness in a range of about 10:1 to 40:1 and feeding said second web between said uncoated face and the casting roll at approximately the nip in said second pair of rolls to press the web against the second face of said strip and adhere it to said second face;
• postheating said strip to at least the melting point of the polymer in said webs;
• air cooling said postheated strip to below the melting point of the polymer in said webs;
• and
• quenching said air cooled strip with a liquid.