Process for expanding polystyrene

Abstract

Abstract PROCESS AND APPARATUS FOR THE EXPANSION OF GRANULES OF POLYSTYRENE CONTAINING A BLOWING AGENT. THE GRANULES ARE FIRST SUBJECTED FOR A FEW MINUTES, TO STEAM AT LOW PRESSURE, FOLLOWING BY CONDITIONING FOR A FEW HOURS AT ABOUT 20* TO 40*C. AFTER THIS THE EXPANDED GRANULES ARE REHEATED WITH HOT AIR TO ABOUT 100*C., THEN AGAIN TREATED WITH STEAM FOR 30 TO 40 SECONDS. THIS IS FOLLOWED BY CONDITIONING FOR 1 TO 24 HOURS. IN EACH INSTANCE, CONDITIONING IS EFFECTED BY INSUFFLATING THE GRANULES WITH WARM AIR AT THE DESIRED TEMPERATURE. THE CYCLE JUST DESCRIBED MAY BE REPEATED ONE OR MORE TIMES TO RESULT IN A FURTHER REDUCTION IN SPECIFIC MASS. THE INVENTION PROVIDES A MEANS AND PROCEDURE BY WHICH POLYSTYRENE OF AN INITIAL SPECIFIC MASS OF ABOUT 650 KG./M.3 MAY BE EXPANDED TO AN APPARENT SPECIFIC MASS OF FROM 3.5 TO 5 KG./M3. THE CYCLE MAY ALSO BE CARRIED OUT BY FIRST TREATING THE MASS WITH HOT AIR AND THEN, FOLLOWING THE REST OR CONDITIONING PERIOD, WITH STEAM. THE APPARATUS AFFORDS MEANS BY WHICH THE PROCESS CAN BE CARRIED OUT IN A CONTINUOUS MANNER.

Inventors

• 👤 Daniel Hanton

Bibliographic Details