Importance

Loading Importance Indicators...

Abstract

A foamed polyester extrusion process and equipment can be used in plants for producing sheets, boards or tubes of foamed polyester, preferably of the type operating continuously which has a thermoregulated frame provided with a feeding inlet of pure and/or recycled polyester material inside the frame. Two co-rotating screws are arranged inside the frame, the co-rotating screws defining, with the internal walls of the frame, a first degassing zone interposed between a feeding zone placed at the feeding inlet and a first tight zone. A second degassing zone is placed downstream from the first degassing zone and is separated from the latter through the first tight zone. A foaming agent inlet zone is placed downstream from the second degassing zone and is separated from the latter through a second tight zone and a pumping end zone of the melted material is placed downstream from the foaming agent inlet zone. The first degassing zone has a first vent placed at a first segment of the first degassing zone adjacent to the first tight zone, wherein the first degassing zone is adapted to carry out a forced atmospheric degassing at a temperature lower than the melting point of a treated polyester material, and the second degassing zone is adapted to carry out a vacuum degassing at a temperature equal to or greater than the melting point of the treated polyester material.

Loading the Abstract Image...

First Claim