METHOD OF CONTINUOUS OR SEMICONTINUOUS PRODUCTION OF RIGID FOAMED PLASTIC Russian patent published in 1995 - IPC

FIELD: plastics production. SUBSTANCE: when initial material has been stirred in plastic processing machine under temperature and pressure conditions, enabling foaming of plastic after drop of pressure, plastic coming out of machine is transferred directly into cooling zone. Plastic is cooled with formation of continuous mixture featuring heavy viscosity and rigidity and possessing approximately "flat" profile of flow speed under pressure created by upstream-directed pressure element. After cooling zone, plastic is transferred as mildly as possible into retarding and delaying zone. Upstream-directed pressure element, which appears in this case, will increase pressure in plastic material, which is in the previous zones, to the level which prevents foaming of plastic. After plastic is transferred into warming up, foaming and moulding zones, controlled foaming is performed until plastic acquires required densitу. EFFECT: improved efficiency. 2 dwg