Extrusion is the first stage of the transformation process. Polypropylene granules, together with the
additives, are appropriately measured, sent to a pre-mixer and supplied to the extruders. Here they are
melted and therefore extruded forming a flat sheet that is stabilized thanks
to an immediate cooling by contact with a chill-roll and immersion in a water
bath and then dried of the remaining surface water. During the Machine
Direction Orientation (MDO) the sheet is warmed up again and stretched
longitudinally using rolls that rotate at different speeds. Afterwards, the
film is locked on the edges by clips and stretched transversely during the
Transversal Direction Orientation process (TDO). The output film is now
subject to an appropriate surface treatment (flame or corona treatment) to
make the product printable and then winded into jumbo rolls, measuring 4
or 8 meters wide.
It is an additional process that may be required by the customer. It takes
place on a high-vacuum system that deposits a thin layer of aluminium
on one of the two surfaces of the film, improving its barrier effect. A
slitter provides one or more by-product rolls that are then stored in
the finished products warehouse, awaiting shipping. The lateral scraps
produced by the slitters during the metallised roll slitting are stored in
specific containers and destined to external sale.
Regranulation is a scraps reprocessing procedure from which it is possible to obtain the granule,
which is then stocked in special silos and will be reused during the extrusion process in variable
percentages, depending on the type of product. The scraps deriving from film break-offs (during the
stretching process or during the start up of the extrusion lines), slitter scraps, grinding of jumbo rolls
or by-product rolls that do not match the standards are all appropriately grinded through grinding
machines. The material derived from this process is then sent to an extrusion system through which,
by material melting, it is possible to obtain the granule thanks to a specific regranulation machine.
The granule is then cooled in a water tank, dried, weighed and sent for stocking to the extrusion
MainSlitting, Secondary SlittingandPackaging
After an adequate seasoning period spent in a heated
warehouse, the jumbo rolls are sent to the slitting area
where they are cut into multiple by-product rolls that
comply with the specifications of the client’s order.
When in need of additional processing, these rolls are
sent to the secondary slitting, before being moved to
the packaging area.