PLASTIC SHEET HAVING A LARGE NUMBER OF RECESSED AND PROTRUDED PARTS AND DOUBLE WALL SHEET HAVING THE PLASTIC SHEET

摘要

A plastic sheet having a large number of recessed and protruded parts useful as a protective sheet in moving and construction and as a cushioning package and an insulating material and a double wall sheet formed in two or three layers by sticking one or two sheets of flat plastic sheets on the plastic sheet, having a high rigidity against bending, improved in warpage more than a conventional plastic foam board, and useful as various types of panel materials and packaging container materials, the double wall sheet comprising the plastic sheet having the large number of recessed and protruded parts distributed on the flat surface portion thereof comprising a large number of trapezoidal projected portions formed on a flat sheet by the vacuum-formation of the plastic sheet and annular recesses continuously surrounding the projected portions and portions. The double wall sheet comprising a back sheet and/or a liner sheet stuck on the plastic sheet.