In recent decades, foamed products have been experiencing rapid growth, e.g. in packaging, insulation, acoustic insulation and as upholstery material. Their benefits are indisputable (depending on the requirements): alongside the low consumption of raw materials, they are the low densities, outstanding thermal and acoustic insulation, mechanical cushioning, low/high water vapor permeability and reduced/high moisture absorption.
The physical propellant is first injected into the polymer melt using a metering device and then dissolves in the polymer. The pressure is maintained throughout the extruder. A quick drop in pressure creates a homogeneous cell structure throughout the polymer.
Leistritz offers many years of know-how in this area. Thus, for example, the majority of extruded plastic corks produced around the world are manufactured on Leistritz systems. For this, pentane is integrated into the basic polymer PE in a continuous extrusion process. The PE coating is applied subsequently by a co-extruder.
Leistritz is also leading in the production of flame retardant EPS micro-pellets (expanded polystyrene). In contrast to directly extruded foams, the gas is incorporated into these micro-pellets. The pellets are foamed and shaped at a later point in time with the help of 100 to 120 °C steam.