Method for coating a metal strip
AssigneeAluminum Company of America
InventorsDavid A. Smith, Susan A. Stanton, Gary J. DiFranco, Roy B. Steidley, John M. Stinson, Thomas L. Levendusky, Vincent J. Downard, William F. Forster, John R. McAllister
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Abstract
A method for extrusion coating both sides of a metal strip. A metal strip, such as aluminum alloy strip, is moved through a pre-conditioner, two extrusion dies, a post heater and a cooling system. Both sides of the strip are coated with thin coatings of polyester material. The coated metal strip is useful for containers, such as cans and can ends, as well as for automobiles, appliances, aerospace, construction and electrical devices.
Claims38
A process for extrusion coating a metal strip to produce a coated metal strip comprising:
- providing a strip of metal about 0.007 to 0.014 inches (0.1778-0.356 mm) thick;
- heating said metal strip to at least about 400.degree. F. (204.degree. C.) but not so high as to deleteriously affect the desired properties of the metal strip;
- extruding high melt viscosity polyester resin substantially simultaneously onto both sides of said heated metal strip to form coatings which are at least partially bonded to said metal strip, said coatings each having a thickness in a range of about 0.0003 inches to 0.0015 inches (0.0076-0.038 mm);
- heating said coated metal strip to at least the glass transition point of said resin but not so high as to deleteriously affect the desired properties of the metal strip such that said resin bonds to said metal strip;
- and
- cooling said coated metal strip to less than about 104.degree. F. (40.degree. C.) to solidify said resin in a substantially non-crystalline form.
A method of coating both sides of a strip of aluminum alloy sheet with polyester comprising:
- moving an elongated aluminum alloy strip substantially vertically;
- heating the strip;
- extruding molten polyester webs on opposite sides thereof as it moves substantially vertically;
- drawing said webs while substantially maintaining their width to thereby reduce their thickness by at least approximately 80%;
- pressing said webs against opposite sides of said strip to produce a coated strip;
- heating said coated strip;
- and
- cooling said heated coated strip.
A process for extrusion coating an aluminum alloy metal strip to produce a coated aluminum alloy metal strip suitable for use in making containers, the process comprising:
- providing an elongate strip of aluminum alloy metal having a thickness in the range of about 0.1778 to 0.356 mm;
- heating said strip to a temperature in the range of about 121.degree. to 260.degree. C.;
- extruding a high melt viscosity polyester resin onto both sides of said heated strip to form a coating on said strip, said coating having a thickness in the range of about 0.0076 to 0.038 mm;
- heating said coated strip to a temperature in the range of about 200.degree. F. to 260.degree. C.;
- and
- cooling said coated strip quickly to a temperature of less than about 40.degree. C. to solidify said resin thereon in a substantially non-crystalline form.
A method of coating both sides of a strip of aluminum alloy sheet with polyester comprising:
- providing a strip of metal having a first surface and a second surface;
- heating said strip:
- moving said strip generally vertically downward at an angle of about 30.degree. from vertical;
- extruding a first molten polyester web on said first surface of said strip as said strip moves generally vertically downward;
- extruding a second molten polyester web on said second surface of said strip as said strip moves generally vertically downward to produce a coated strip;
- heating said coated strip;
- and
- cooling said heated coated strip.
A process for coating a metal strip comprising:
- uncoiling a metal strip from a coil and causing the strip to move longitudinally;
- heating the moving strip to at least about 250.degree. F. (121.degree. C.) but not so high as to substantially deleteriously affect the desired metal properties in the strip;
- extruding heated polymer resin substantially directly onto each side of the heated strip at substantially directly opposed surfaces of the strip so that the pressure of the extrudate substantially centers the strip and forms a coated strip;
- heating said coated strip to at least about 425.degree. F. (215.degree. C.) but not so high as to substantially deleteriously affect the desired metal properties;
- and
- promptly cooling the heated, coated strip to solidify said resin in a substantially non-crystalline form.
Dependencies are inferred from the claim text.