Extruded thermoplastic profiles - comprising thin, hard PVC sheath simultaneously extruded with a foamed PVC core

摘要

Extruded profile comprises a foamed thermoplastic core surrounded by a thermoplastic coating or sheath with a prescribed cross-section. During simultaneous extrusion, the core expands outwards and presses against the sheath, which resists the pressure. The sheath is pref. thin, and consists of hard PVC, whereas the core pref. consists of foamed PVC. Pref. the fluid sheath material is fed through the axial channel of an extruded head and then via a ring channel or a gap with the desired shape of the profile. The ring channel or gap is formed by an insert in a multipart die. The die has a side inlet channel for fluid, foamed core material, which flows via a channel shaped like an inverted "U" to an axial hole in the die; and the two materials are extruded from the die orifice. Used for the mfr. of inexpensive extrudates, for doors, window frames, panels, pillars, decoration, accessories etc.