| abstract |
The invention relates to sheet-like plastic packaging particles formed with a normally curved configuration having two spaced apart, curved coextensive surfaces, one of said surfaces being a substantially unfoamed skin and the remainder of said particle including the other surface being foamed, and to methods for producing packaging particles which comprise warped or distorted, foamed sheet particles suitable for use as packaging particles from an extrudable, expandable synthetic plastic material, such as, a polymerized vinyl aromatic monomer, e.g., styrene, comprising the steps of extruding a foamed sheet of the material while chilling one surface thereof more rapidly than the other surface thereof as it is extruded to form on said one surface a skin of substantially unfoamed material or of higher density material than said other surface and the remaining portions of the sheet, thereafter, cutting said sheet to form sheet like pieces of the desired configuration and subjecting said pieces to heat at a foaming temperature to cause further foaming and distortion of said pieces to form a curved configuration. |