Zotefoams three stage process 2020

The Zotefoams difference: Zotefoams manufactures a wide range of crosslinked, lightweight block foams using variations of our unique nitrogen-expansion manufacturing process. This affords an exclusive combination of beneficial characteristics – uniformity, purity, low toxicity and durability – that differentiates Zotefoams’ materials from all other foams. Our core autoclave process is capital-intensive, with a long investment cycle, and represents a considerable barrier to entry for potential competitors.
Operating at temperatures up to 250ºC, this environmentally friendly technology is extremely flexible, allowing us to foam a wide range of polymers. The combination of foaming process and polymer performance delivers properties such as excellent fire resistance, high-temperature stability, toughness and insulation, which are prized in a wide range of demanding applications.
Stage 1: Extrusion and crosslinking
Polymer and any additives (colours, fire retardants, conductive agents) are extruded into a continuous solid plate. The plate passes through an oven which activates the crosslinking process. It then cools and is cut into slabs.

Stage 2: Nitrogen saturation
Slabs are loaded into a high-pressure autoclave. The material is heated above its melting point and pressurised with pure nitrogen gas. Over a long period of time the nitrogen gas diffuses into the slabs. A rapid depressurisation destabilises the absorbed nitrogen nucleating cells in the slab. The slabs are then cooled under pressure in the autoclave, locking the nitrogen in the unexpanded slabs, prior to them being unloaded.

Stage 3: Expansion
The nitrogen-charged slabs are loaded into a large lower-pressure autoclave and, under moderate pressure, are heated to above their melting point. When the pressure is reduced the nitrogen expands turning the slab into a larger foam sheet. This expansion process is unconstrained, so uniform in each dimension.