| 摘要 |
A process for producing a foamed polymer comprises the steps of: mixing, in a dissolver, a mixture constituted by at least one isocyanate and a first unsaturated anhydride, which is charged to the dissolver in the liquid state and at a relatively high temperature; progressively cooling said mixture, with continued stirring, until a temperature not higher than 22.degree.C is reached; adding to the mixture, with the latter being stilt kept with continuous stirring, a second aromatic anhydride, at least one foaming agent, a vinylidene compound, polyvinyl chloride) and a heat stabilizer; maintaining the mixture with continuous stirring, at said temperature, until a paste is obtained which is poured, after being preliminarily filtered, into a mould or container; curing said paste by charging the container to an oven at atmospheric pressure, and at a temperature not higher than 80.degree.C; completing the curing of the paste-like mixture under pressure, by increasing temperature up to 180.degree.C and subsequent cooling, until partially foamed germs are obtained; and completing the germ foaming process, by heating.
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