Latent foaming compositions of vinyl aromatic resins and method of making

Claim 1

A PROCESS FOR MAKING A RESINOUS POLYMERIC COMPOSITION SUITABLE FOR FORMING A CELLULAR ARTICLE POSSESSING GOOD DIMENSIONAL STABILITY AT TEMPERATURES ABOVE THE HEAT-PLASTIFYING TEMPERATURE OF THE POLYMER INGREDIENT OF THE COMPOSITION, WHICH PROCESS COMPRISES POLYMERIZING A LIQUID MIXTURE CONTAINING AS THE ESSENTIAL INGREDIENTS FROM 99.5 TO 99.99 PARTS BY WEIGHT OF AT LEAST ONE MONOVINYL AROMATIC COMPOUND OF THE BENZENE SERIES HAVING THE VINYL RADICAL DIRECTLY ATTACHED TO A CARBON ATOM OF THE AROMATIC NUCLEUS AND FROM 0.5 TO 0.1 PART OF A POLYVINYL AROMATIC HYDROCARBON, TOGETHER WITH FROM 0.05 TO 0.3 GRAM MOLE PER 100 GRAMS OF THE POLYMERIZABLE VINYL AROMATIC COMPOUNDS OF A FLUID FOAMING AGENT SELECTED FROM THE GROUP CONSISTING OF SATURATED ALIPHATIC HYDROCARBONS AND PERCHLOROFLUOROCARBONS HAVING A MOLECULAR WEIGHT OF AT LEAST 58 AND BOILING AT A TEMPERATURE BELOW 95*C., BY SUBJECTING SAID LIQUID MIXTURE UNDER AT LEAST AUTOGENOUS PRESSURE TO A POLYMERIZATION TEMPERATURE OF FROM 40* TO 150*C. UNTIL A SOLID POLYMERIC PRODUCT IS BELOW THE HEAT DISTORTION TEMPERATURE OF SAID PRODUCT.