Flexible insulating sheet

Abstract

The present invention is a twin-wall rigid plastic sheet intended to provide protection and insulation in applications where a small bending radius for the twin-wall plastic sheet is desired. The twin-wall configuration includes a smooth or flat outer single sheet and a contoured inner single sheet separated by a series of similar plastic ribs to form a connected row of longitudinal cavities or “channels”. The inner wall is contoured in a concave manner to form a relief between each rib. When the twin-wall sheet is flexed, each relief distorts to minimize stress in the transverse direction while maintaining high rigidity in the longitudinal direction. In another embodiment of the present invention, multiple single sheets separated by ribs and contoured similarly to that of the inner wall are added between the contoured inner wall and smooth outer wall.

I claim: 
     
         1 . An extruded thermoplastic twin-wall sheet with a Modulus of Elasticity greater than 2 GPa, having a structure comprising: a first wall comprising a single generally flat sheet; a second wall comprising a single sheet generally parallel to, extending the length of, and separated from the first wall, having a transverse contour of a form incorporating a series of alternating flat and arced sections each with an apex toward the first wall and extending the length of the second wall in the direction of extrusion; and a plurality of ribs located between, perpendicular to, and connected to the first wall and second wall and each rib equidistant between two adjacent arcs in the contour of the second wall and extending the length of the first and second walls in the direction of extrusion. 
     
     
         2 . An extruded thermoplastic twin-wall sheet with a Modulus of Elasticity greater than 2 GPa, having a structure comprising: a first wall comprising a single generally flat sheet; a second wall comprising a single sheet generally parallel to, extending the length of, and separated from the first wall, having a transverse contour of a form incorporating a series of alternating flat and arced sections each with an apex toward the first wall and extending the length of the second wall in the direction of extrusion; an intermediate single sheet between, generally parallel to, extending the length of, and separated from the first wall and second wall, having a contour of a form similar to the second wall and having an apex of each arc generally aligned to the apex of each corresponding arc of the second wall and extending the length of the intermediate sheet; a plurality of ribs located between, perpendicular to, and connected to the first wall and the intermediate sheet and each rib equidistant between two adjacent arcs in the contour of the intermediate sheet and extending the length of the first and second walls in the direction of extrusion; and a plurality of ribs located between, perpendicular to, and connected to the second wall and the intermediate sheet and each rib equidistant between two adjacent arcs in the contour of the second wall and extending the length of the first and second walls in the direction of extrusion. 
     
     
         3 . An extruded thermoplastic twin-wall sheet with a Modulus of Elasticity greater than 2 GPa, having a structure comprising: a first wall comprising a single generally flat sheet; a second wall comprising a single sheet generally parallel to, extending the length of, and separated from the first wall, having a transverse contour of a form incorporating a series of alternating flat and arced sections each with an apex toward the first wall and extending the length of the second wall in the direction of extrusion; a plurality of intermediate single sheets between, generally parallel to, extending the length of, and separated from the first wall and second wall, each having a contour of a form similar to the second wall and having an apex of each arc of each intermediate sheet generally aligned to the apex of each corresponding arc of the second wall and extending the length of an intermediate sheet; a plurality of ribs located between, perpendicular to, and connected to the first wall and an intermediate sheet adjacent the first wall and each rib equidistant between two adjacent arcs in the contour of the intermediate sheet adjacent the first wall and extending the length of the first wall and intermediate sheets in the direction of extrusion; a plurality of ribs located between, perpendicular to, and connected to adjacent intermediate sheets and each rib equidistant between two adjacent arcs in the contour of each intermediate sheet and extending the length of the intermediate sheets in the direction of extrusion; a plurality of ribs located between, perpendicular to, and connected to the second wall and an intermediate sheet adjacent the second wall and each rib equidistant between two adjacent arcs of the contour of the second wall and extending the length of the second wall and intermediate sheets in the direction of extrusion.