Foamed plastic sheet

Abstract

An unmixed plastic sheet, which is made of a thermoplastic material and which is composed of a number of body segments that are adjacent to one another in a plane, interconnected and made of a closed-cell foam material. The body segments are thermoplastically welded to one another at their abutting lateral faces while forming flat weld seams. The flat weld seams form a plastic intermediate layer, which has few pores, and which is provided in the form of a web structure that, when viewed from above, is reticular and reinforces the plastic sheet. The inventive plastic sheet is preferably used as a core layer in sandwich composites.

1 - 20 . (canceled) 
     
     
         21 . A structural element, comprising: a block which comprises a plurality of body segments of a foamed, thermoplastic material having a stretched polymer structure in one direction, the body segments being arranged next to each other and joined together on a plane defining foam sheets running transverse or perpendicular to the one direction of the stretched polymer structure, wherein the structural element is a plastic sheet having opposed relatively large area sides, and relatively small area edges, and where the stretched polymer structure is in a direction perpendicular to the relatively large area sides, wherein the structural element is made wholly of plastic and the body segments are welded together at abutting side faces forming weld seams, whereby the weld seams form a substantially pore-free intermediate plastic layer in the form of a network of stiffening struts defined by intersecting weld seams, wherein each of the weld seams have a thickness such that a network strut structure is formed by the weld seams which increases the compressive strength of the structural element with respect to surface pressure wherein the structural element has a specific weight less than 130 kg/m 3 . 
     
     
         22 . The structural element of  claim 21 , wherein the specific weight is between 20 kg/m 3  and 130 kg/m 3 . 
     
     
         23 . The structural element of  claim 21 , wherein the body segments are made of a closed-cell foam material. 
     
     
         24 . The structural element of  claim 21 , wherein the thermoplastic material is polyethylene-terephthalate (PET) or styrene/acrylnitrile-copolymer (SAN). 
     
     
         25 . The structural element of  claim 21 , wherein the weld seams comprises melted plastic of the body segments. 
     
     
         26 . The structural element of  claim 21 , wherein the body segments are formed from lengths cut from rod-shaped or column-shaped foam bodies. 
     
     
         27 . The structural element of  claim 26 , wherein the rod-shaped or column-shaped foam bodies are formed by means of extrusion, and the direction of extrusion in the body segments manufactured from the foam bodies lies substantially parallel to a line of intersection of two intersecting weld seams. 
     
     
         28 . The structural element of  claim 21 , wherein the body segments have a polygonal shape. 
     
     
         29 . The structural element of  claim 21 , wherein the structural element ( 10 ) is a plastic sheet. 
     
     
         30 . The structural element of  claim 21 , wherein the weld seams form a structure with uninterrupted transverse weld seams and longitudinal weld seams that are offset with respect to each other. 
     
     
         31 . The structural element of  claim 21 , wherein the body segments are arranged on a plane next to each other and are welded together forming the weld seams.