cast film extrusion

Cast film extrusion technology is on the rise, offering several major advantages, including elevated processing speeds and a large number of applications for a wide variety of market segments, including high-volume medicine, food and textiles packaging.

Producing a multilayer film gives additional flexibility in the design of the film and its product properties. For example, specific layers can be incorporated for improved barrier properties, among other things, or layers from recycled materials can be added.

The multilayer film can also be applied directly to textiles as an extrusion coating. Thus, in a 1-step process, a multilayer coating can be applied to functionalize textiles.

Custom-designed cast film extrusion line

Compostion

extruder section
feedblock and die section
rolling stack section
winding and trimming section
processing control unit

Principle

Cast Film (CF) extrusion is a processing technique for the mass production of flexible packaging. The film thickness can range from less than 10 microns to 200 microns (above 200 microns it is called sheet).

The cast film can be either monolayer or multilayer.

The molten polymer is placed on a chill roll and stretched in the machine direction to the desired film thickness and, depending on the application, the final film is slit to the desired film width. Cast film extrusion is typically used for LLDPE stretch film and PP packaging film.

Polyethylene (PE) and polypropylene (PP) are the most commonly used resins for cast film extrusion.

Extruder section

The three extruders of the line are used to heat, melt and homogeneously mix the polymer pellets by conveying the material along a heated barrel with a rotating screw.
One extruder is equipped with a bi-metallic barrel to allow PVC processing.

1 x LE25-30 extruder - Layer B

Technical characteristics:

Diameter: 25
L/D 30
5 Temperature zone (4 barrel + 1 Die)
Max. temp: 400°C
200 rpm – high torque extruders
Max. throughput 15kg/h
Manual screen changer with melt temperature and pressure sensor
Height adjustable (between 600 – 1100 mm)
1 standard mixing screw and 1 EVOH screw

2 x LE30-30 extruder - Layers A & C

Technical characteristics:

Diameter: 30
L/D 30
5 Temperature zone (4 barrel + 1 Die)
Max. temp: 400°C
200 rpm – high torque extruders
Max. throughput 20kg/h
Manual screen changer with melt temperature and pressure sensor
Height adjustable between 600 and 1100 mm
2 standard mixing screws, 1 PVC screw, 1 PET screw

Feedblock and Die section

The feedblock shapes and combines the multiple polymer flows into a well-defined stack of polymers that will be fed to the flat die.

The polymer melt is pushed through a flat die, which has been designed to impart the desired shape to the stream of melted plastic.

Feedblock

Technical characteristics:

3 polymer melt streams are guided to a single multilayered polymer flow
A/B/C configuration
450°C

The polymer melt is pushed through a flat die, which has been designed to impart the desired shape to the stream of melted plastic.

Flat die

Technical characteristics:

Flat coat hanger-type die
Width die exit: 600mm (final width 450 – 500 mm)
- adjustable lips between 0,3 – 2mm
- minimal film thickness: 20-30 µm
450°C
Design based on PET/EVOH/PET (40/20/40)