Patent ID: 7955550

Claim:
A method of preparing a molded article comprising: (a) providing a mold apparatus comprising, (i) a first mold portion having an interior mold surface, and a perimeter edge, said interior mold surface having a contour and a plurality of perforations, and (ii) at least one tubular sheet retainer having an exterior surface, at least a portion of the exterior surface of said tubular sheet retainer having a plurality of perforations, said tubular sheet retainer having a longitudinal axis that is oriented along at least a portion of said perimeter edge, said tubular sheet retainer being reversibly and controllably positionable along at least one of an x-axis, a y-axis and a z-axis relative to said perimeter edge, and said tubular sheet retainer being rotatable around said longitudinal axis of said tubular sheet retainer; (b) positioning said tubular sheet retainer such that at least a portion the exterior surface of said tubular sheet retainer is located above said perimeter edge; (c) forming, from at least one thermoplastic composition, a heated thermoplastic sheet having a temperature that allows said heated thermoplastic sheet to be thermoformable, said heated thermoplastic sheet having a first surface and a second surface; (d) contacting a first portion of said second surface of said heated thermoplastic sheet with a portion of the exterior surface of said sheet retainer; (e) drawing reduced pressure through said plurality of perforations of said exterior surface of said tubular sheet retainer, thereby retaining said first portion of said second surface of said heated thermoplastic sheet on the exterior surface of said tubular sheet retainer; (f) contacting a second portion of the second surface of said heated thermoplastic sheet with at least a portion of the interior mold surface of said first mold portion; (g) (i) rotating each tubular sheet retainer, around said longitudinal axis of said tubular sheet retainer, independently at least one of towards said perimeter edge and away from said perimeter edge, and (ii) moving each tubular sheet retainer independently at least one of towards said perimeter edge and away from said perimeter edge, in each case independently along at least one of said x-axis, said y-axis and said z-axis; (h) drawing reduced pressure through said plurality of perforations of said interior mold surface of said first mold portion, such that said second portion of said second surface of said heated thermoplastic sheet substantially matches said contour of said interior mold surface of said first mold portion; (i) cooling said heated thermoplastic sheet thereby forming a shaped thermoplastic sheet that retains said contour of said interior mold surface of said first mold portion; and (j) removing said shaped thermoplastic sheet from said first mold portion, wherein said shaped thermoplastic sheet is said molded article.