Plastic foam pipes and profiles mfr. - by foam moulding in multi-zone, differentially temp. controlled tool; and removing under foaming pressure

摘要

Mfr. of pipes and profiles from liq., foam-forming, reactive compsns., e.g. polyurethane-forming compsns., comprises continuously charging the reaction mixt. to a tool that is divided into at least 3 zones which are differentially temp. -controlled to correspond with the course of the reaction and the reate at which the intended profile is formed. The prod. having been shaped in the last zone is removed whilst maintaining the required foaming pressure. Used for mfr. of divers foamed profiles, especially pipes for drinking water supply and effluent and drainage pipes. Good resistance to external pressure and buckling under continuous load e.g. when laid underground.