Patents Examined by Paul Thiobodeau
  • Patent number: 6482526
    Abstract: The present invention relates to a polyester resin-covered metal sheet exhibiting superior formability and particularly suitable to withstand the stresses of drawing, drawing and ironing, drawing and stretch forming, or drawing and stretch forming followed by ironing. The resin-covered metal sheet is produced by contacting a biaxially oriented polyester resin film to a metal sheet heated above the melting temperature of the resin, covering the metal sheet with the polyester resin, pinching and press laminating the film-metal sheet composite, and cooling the laminate at a rate of 600° C./second immediately thereafter. It is essential that the resulting resin-covered metal sheets exhibit a true stress of 3.0 to 15.0 kg/mm2, corresponding to a true strain of 1.0 at 75° C. These laminates also exhibits a gradation of retention of the polyester resin's original biaxial orientation.
    Type: Grant
    Filed: June 15, 1999
    Date of Patent: November 19, 2002
    Assignee: Toyo Kohan Co., LTD
    Inventors: Hiroyuki Iwashita, Fumiko Gotoh, Atsuo Tanaka