New Particle Foams
New particle foams, new possibilities!
For a long time, the number of particle foams available was manageable. It all began with EPS (expanded polystyrene), registered for patent in 1950 and also known in Germany under the brand name “Styropor”. EPP (expanded polypropylene) and EPE (expanded polyethylene) followed at the end of the 1980s and were mainly used as packaging material. Since 2010, the development of new materials has literally exploded – think of ETPU, for example, which causes a sensation in running thanks to its properties in terms of elasticity and suspension.
Recently, two other particle foams with interesting properties were launched on the market. Both have the makings to revolutionise the branch – we are talking about ecovio® (BASF) and ArmaShape® (Armacell). ecovio® is biologically degradable and made of bioplastics and poly lactic acid (PLA) gained from corn. Thanks to its special chemical structure, the bio-based compound can be degraded in just a few weeks by micro-organisms and their enzymes. As a polymer compound, ecovio® can be processed on standard machines to make particle foam shaped parts (EPS and EPP); it is particularly interesting as packaging material and thanks to its variable share of renewable raw materials.
ArmaShape® was presented at the beginning of 2018 and is a particle foam made of 100% recycled PET bottles (PET = polyethylene terephthalate). The expanded PET is produced by Armacell Benelux S.A. from Thimister-Clermont, Belgium: with 3,000 employees and 603 million Euros turnover in 2017 the competence centre for PET foam technology. The latest creation, ArmaShape®, opens up new possibilities for many branches that are relying more and more on light yet sturdy plastic parts. The automotive branch in particular will benefit from large-scale applications for body shells or chassis suspensions. As loose pearls on a PET basis for producing ready-to-use 3D foam cores for sandwich compound structures, ArmaShape® offers better mechanical and thermal properties than EPP or EPS, is heat-resistant up to 200 °C, non-combustible thanks to flame protection additives and can be made in almost any shape. “New materials such as ecovio® and ArmaShape® often need new processing methods – expandable PET requires a bonding temperature of 250 °C. For the standard steam process this means pressures of 25 to 30 bar. This is difficult to achieve in terms of both machines and tools. The Kurtz team has managed to develop a bonding technology on the basis of electromagnetic waves. The particle foam is heated through excitation with high frequency (27.12 MHz) and high voltage up to 10,000 V,” says Victor Romanov, Head of Technology Department at Kurtz GmbH, who has already presented the innovative bonding method in Bayreuth and Würzburg (see report opposite). There was a huge amount of interest which led to specific project inquiries – a clear sign that the branch has recognised the potential connected with the new particle foams.
Great future for particle foam materials
New developments for materials and machining processes open up new application options for lightweight engineering in the particle foam branch. Just how great the interest is was demonstrated by the popularity of two events in spring 2018: the NMB TechDays in Bayreuth and the SKZ conference “Polymer foam” in Würzburg. More than 100 experts came along to Bayreuth and Würzburg to find out about current trends and developments in particle foam technology. New developments in the fields of tooling technology, pre-foaming and shape-foaming were presented, all of which significantly extend the application possibilities for different particle foams. The challenge is that new particle foams made of technical plastics such as PBT (short for polybutlyene terephthalate) must be processed at temperatures up to 220 °C (EPET even requires 250 °C), whereas normal particle foams only require 150 °C. In addition, an innovative high-pressure tool was presented that achieves a steam pressure of up to 25 bar – which corresponds to around 220 °C.
Another focus was on the processing of humidity-sensitive materials which have been very difficult to process using conventional steam-based methods up to now. As renewable materials, bio-based particle foams in particular open up completely new areas of application. The solutions possible for shape-foaming using steamless processing technology were presented by Kurtz Head of Technology Department, Victor Romanov, in his lecture “Alternative bonding methods with electromagnetic waves”. Without any doubt, these are key technologies with enormous potential for new foam applications!
