Cellular polycarbodiimide article prodn. - by heating cellular polycarbodiimide plate in mould-punch assembly, compressing softened plate, cooling before demoulding

摘要

The articles, e.g. wall and ceiling panels, pipe insulating jackets, and similar articles, are moulded by heating a foamed polycarbodiimide plate, by radiation and direct contact, in a mould/punch assembly, and compressing the plate when the foam reaches its softening point. Compression is effected so that the plate is deformed and densified, and its material becomes less brittle, stronger, and more elastic and smooth, while its innate non-flammability is preserved. After moulding, the mould is cooled slightly, e.g. by means of an air jet, so that the moulded prod. is slightly hardened before the punch is withdrawn, and the prod. is demoulded. The process gives non-flammable articles having a smooth solid surface, and goof mechanical strength. The relief of the mould surface is accurately reproduced. The cellular structure of the foam can be controlled, and open-celled foams can be converted into closed-celled foams. A surfactant is pref. added to the base compsn. for the cellular polycarbodiimide, this surfactant pref. consisting of 0.05-0.15 pt. wt. silicone oil per 100 pts. wt. base compsn. The softening point of the foam is pref. Ca. 130 degrees C for a foam density of 16 kg/m3. Simultaneously with compression, the heat is supplied over the surface of the piece to be moulded. The operating temp. of the mould/punch assembly is pref. 175-190 degrees C.