3. Material feed

Today, all sheet or plate lines are coextrusion lines, because the sheets or plates are structured in 3 layers of type A-B-A or A-B-C: three extruders are needed in case A-B-C, two may suffice in case A-B-A.

The central layer B is generally made up of a mixture of virgin material and crushed material consisting of the edges crushed in line and the scraps from a previous production run.

In the case of in-line thermoforming, layer B can even be made exclusively of ground material, from the thermoforming "skeletons" that are recycled in-line.

It's rare for outer layers A and C to be made of just one material: applications generally call for blends of 3 materials, two polymers of different grades and a masterbatch for coloring.

All these materials are usually granules, rarely powders or beads....