Production Process of Expandable Polystyrene Foam
The expandable polystyrene is a translucent bead composed of polystyrene and a
foaming agent. The blowing agent is n-butane, pentane, heptane, petroleum ether or
dichlorodifluoromethane. The most common ones are pentane and petroleum ether.
Commercially available expandable polystyrene having a blowing agent content of ab-
out 6%, an apparent density of 680 g/l, and a bead diameter of 0.25-2 mm.
The process of producing foamed plastic parts using expandable polystyrene pellets
is as follows:
The expandable polystyrene beads are heated to heat-vaporize the blowing agent,
thereby expanding the volume of the beads to ensure that the molded product reaches
a prescribed density and uniformity.
The pre-expanded beads need to be stored for a period of time, and the air is absorbed
for aging to prevent shrinkage after molding. Usually done in large silos or open contain-
Commonly used molding methods are steam heating molding and extrusion.
(1) Steam heating molding method is divided into steaming cylinder foaming and hydraulic
machine direct steaming foaming according to the heating method.
①Steam foaming method is suitable for producing small, thin-walled and complex shaped
② The hydraulic press directly through the steam foaming method is suitable for producing
foam sheets with a large thickness.
(2) Extrusion foam molding
Extrusion foam molding is suitable for the production of sheets and films.