Accordion folded laminate of fiber sheet reinforced with thermoplastic film

Claim 1

In a window shade assembly including a shade support for mounting at a portion of a window, an accordion folded shade having a series of panels formed by alternately directed folds, said shade being oriented with the folds extending horizontally and supported at its upper end to the shade support for hanging downwardly at the window opening, draw string openings formed in said panels, a draw string assembly connected in supporting relationship to the lower portion of said shade and extending upwardly through the openings of the panels of said shade and through said shade support for raising and lowering the shade, the improvement therein of said shade comprising a laminate formed of a fiber sheet and a thermoplastic sheet with an intermediate layer of adhesive bonding said sheets together uniformly over their facing surfaces, said adhesive having a temperature of liquification lower than the temperature of liquification of said thermoplastic sheet, said laminate characterized by having been folded into an accordion folded configuration and the panels of the accordion folded laminate compressed to substantially flat overlying stacked relationship with respect to each other and while the panels are compressed heat having been applied to the folds of the compressed stack of panels to raise the temperature of the adhesive in the folds of the panels above the temperature of liquification of the adhesive and sufficiently high to allow for significant molecular rearrangement of the thermoplastic sheet to relieve stresses in the thermoplastic sheet in the vicinity of the folds, and then cooled to a temperature lower than the temperature of liquification of the adhesive so that the adhesive was first liquefied and later solidified to create a memory in each fold, with the fold memory of each fold being sufficient to require the panels to assume an S-shape when the panels are stretched away from one another.