Method of producing self-extinguishing foamable polystyrene by brominating foamable polystyrene in aqueous suspension

Claim 1

METHOD OF MAKING SELF-EXTINGUISHING EXPANDABLE STYRENE POLYMERS COMPRISING SUSPENDING PARTICLES OF STYRENE POLYMERS IN AN AQUEOUS MEDIUM CONTAINING AT LEAST 1.5% BY WEIGHT BROMINE BASED UPON THE QUALITY OF SAID PARTICLES AND 5-40 PARTS PER 100 PARTS POLYMER OF A WATER SOLUBLE METAL SALT OF AN ACID AT LEAST AS STRONG AS CARBONIC ACID, PROVIDING SAID MEDIUM WITH AN ACTIVATING AGENT FOR THE BROMINATION TO THE EXTENT OF AT LEAST 0.5 MOLE PER MOLE OF BROMINATION, MAINTAINING SAID MEDIUM AT A TEMPERATURE OF 60-120* C. AT LEAST UNTIL THE COLOR THEREOF CHANGES FROM ORANGE TO A PALE YELLOW, AND INCLUDING THE STEP OF RENDERING SAID PARTICLES CAPABLE OF EXPANSION BY THE INTEGRATION THEREWITH OF A VOLATILE ALIPHATIC HYDROCARBON BOILING IN THE RANGE OF -10 TO 81* C.