Patent ID: 9114562
Filing Date: 2015-08-25
Classification: B29B,B29C,B29K

Abstract:
1. A foamed polyester extrusion process, comprising the steps of: a) feeding a mixture of non pre-dried polyester material into a foamed polyester extrusion equipment; b) heating said polyester material by bringing it to a temperature lower than its melting point; c) performing a forced atmospheric degassing of said heated polyester material in an atmospheric degassing zone by employing an extractor hood to activate the draught of a vent stack placed at a segment of said atmospheric degassing zone adjacent to a tight zone, said extractor hood being arranged on top of said vent stack for the discharge of gas from said atmospheric degassing zone, the forced atmospheric degassing being performed by introducing a preheated nitrogen gas flow for the entrainment of vapors towards the atmosphere; d) bringing said polyester material to a temperature greater than or equal to its melting point; e) performing a vacuum degassing of said melted material in a vacuum degassing zone arranged downstream from said atmospheric degassing zone and sealingly separated from the latter; f) lowering the temperature of said polyester material and introducing, in contact with it, at least one foaming agent at a foaming agent inlet zone placed downstream from said vacuum degassing zone and sealingly separated from the latter; and g) increasing the pressure of said material in order to be able to expel it at a pumping end zone placed downstream from said foaming agent inlet zone.