Manufacture of high-density foamed polymer

Abstract From the Canadian patent

A method and apparatus are disclosed for the manufacture of foamed polystyrene particles of moderately great density, such as 3 to 25 lbs. per cubic foot (50 to 400 milligrams per cubic centimeter). Beads are fed by a constantdisplacement auger to an expander vessel having the form of in its lowest part, a cylinder with a vertical axis and, thereabove, of a frustrum of an inverted cone having a base angle of about 83 to 70°. Steam is supplied to the vessel in an appropriate, controlled manner. The vessel also contains stator bars, to break lumps and retard the rotation of the material in the vessel, and rotating bars to provide the, necessary agitation. Desirably the equipment includes a, …