PROCESS FOR PRODUCING A FOAMED POLYMER ENDOWED WITH HIGH RESISTANCE TO SOLVENTS AND HIGH TEMPERATURE RESISTANCE, AND PRODUCT OBTAINED BY MEANS OF SAID PROCESS

摘要

A process for producing a foamed polymer comprisesthe steps of: mixing, in a dissolver, a mixtureconstituted by at least one isocyanate and a firstunsaturated anhydride, which is charged to thedissolver in the liquid state and at a relatively hightemperature; progressively cooling said mixture, withcontinued stirring, until a temperature not higher than22°C is reached; adding to the mixture, with the latterbeing stilt kept with continuous stirring, a secondaromatic anhydride, at least one foaming agent, avinylidene compound, polyvinyl chloride) and a heatstabilizer; maintaining the mixture with continuousstirring, at said temperature, until a paste isobtained which is poured, after being preliminarilyfiltered, into a mould or container; curing said pasteby charging the container to an oven at atmospheric pressure,and at a temperature not higher than 80°C; completingthe curing of the paste-like mixture under pressure, byincreasing temperature up to 180°C and subsequentcooling, until partially foamed germs are obtained; andcompleting the germ foaming process, by heating.