METHOD OF PRODUCTION OF FOAMED POLYESTER, POLYETHYLENE TEREPHTHALATE IN PARTICULAR Russian patent published in 2003 - IPC

FIELD: manufacture of panels, sheets and pipes for construction and packaging. SUBSTANCE: proposed method includes extrusion of polyester starting material at density of 0.8 dl/g with foaming agent introduced in it from two-screw extruder. Two-screw extruder has two engageable screws at ratio of axial distance to diameter ranging from 0.6 to 0.8. Screw rotate simultaneously at speed between 14 and 40 r/min. Proposed method makes it possible to produce foamed polyester at density of at least 40 kg/cu m, homogeneous structure consisting of small cells without destruction confirmed by reduction of molecular mass and viscosity relative to starting product. EFFECT: enhanced efficiency. 15 cl, 3 dwg _