What are polypropylene films?
Polypropylene films, PP films for short, are among the most versatile plastic films used in industry today. They are made from the thermoplastic polypropylene (PP), a semi-crystalline polymer characterised by high strength, chemical resistance and temperature tolerance.
PP film is a true all-rounder, whether in food packaging, label printing or as a composite film in technical applications. It is easy to process, economical to produce and visually attractive thanks to its transparency.
GOBA processes polypropylene films as part of its range of insulation materials for technical applications in the electrical industry.
Definition and fundamentals of polypropylene
Polypropylene is a linear hydrocarbon polymer produced by polymerisation of the monomer unit propene. It is one of the standard plastics, produced in enormous quantities worldwide for films, packaging, textiles, plastic parts and much more.
In short, it is known as PP. The material stands out for:
- high stiffness
- good heat deflection resistance
- good chemical resistance
- excellent mechanical properties.
Properties of polypropylene films
PP films offer a range of technical advantages:
- Low density (~0.91 g/cm³): light and efficient
- High transparency (depending on type)
- Resistance to many chemicals
- Odour and taste neutrality (ideal for food)
- High stiffness and abrasion resistance
- Thermally loadable up to around 100 °C (briefly higher)
- Very good printability (after surface treatment)
This combination makes PP films particularly popular as packaging material for food, hygiene products and technical goods.
How are polypropylene films manufactured?
The manufacturing process is carried out by extrusion. PP granulate is melted and formed into a film through a slit or ring die. There are two main processes:
Cast polypropylene (CPP)
- Flat films
- High clarity
- Soft, easily sealable
- Ideal for fresh food packaging
Biaxially oriented polypropylene (BOPP)
- Stretched in longitudinal and transverse directions
- Very high strength
- Higher stiffness and transparency
- Frequently used for label printing or snack packaging
Both variants have different mechanical properties and are suited to different application areas.
Processing and machining of polypropylene
PP films can be easily:
- Cut
- Laminated
- Printed
- Sealed
- Thermoformed
Prerequisite: processing temperatures must be precisely tuned. PP has a relatively narrow processing window. In addition, corona or plasma pretreatment is often required to increase surface energy for printing.
What advantages do polypropylene films offer?
PP films excel in many disciplines:
- Light yet stable
- Good welding and sealing properties
- Food-safe and taste neutral
- Recyclable (monomaterial solutions possible)
- Outstanding printability
- Moisture resistant
- Grease-proof
And all this at an attractive price-performance ratio. In times of rising raw material costs this is a strong argument.
In which areas are polypropylene films used?
The application areas are broad:
- Food packaging: snacks, confectionery, cheese, cold cuts
- Labels and banderoles: BOPP films for roll labels
- Medical packaging: blisters, protective films
- Consumer goods packaging: cosmetics, hygiene articles
- Technical applications: insulating films, separator layers
- Composite films: for sustainable packaging
Depending on the structure (single-layer, multi-layer, coated), the function of the PP film can be tailored ideally to the application.
Differences from other plastics
Compared with polyethylene (PE):
- Higher stiffness
- Better temperature resistance
- Lower density
- Better transparency with BOPP
Compared with PET films:
- Less thermally loadable
- But more economical and more flexibly usable
Crystallinity also plays a role: depending on the manufacturing process, PP films can exhibit high or moderate crystallinity, which in turn influences transparency, heat deflection resistance and sealing behaviour.
Processing challenges
Not everything is perfect. PP films also have their pitfalls:
- Lamination with other plastics (for example PET or aluminium) requires good process control
- Tendency to shrink at incorrect temperature control
- Printability only with pretreatment
- Difficult processing at low temperatures (brittleness)
Therefore careful material selection and process parameters are decisive.
Sustainability and recycling
PP is one of the most recyclable plastics, especially in monomaterial composites. Trends are moving towards:
- PP-only packaging solutions
- Substitution of PET with BOPP
- Elimination of aluminium barrier layers
- Reuse of production waste
All this makes polypropylene future-ready in the context of the circular economy, provided it is properly collected and sorted.
GOBA Takeaway
Polypropylene films are an indispensable part of modern packaging technology. Their combination of strength, flexibility, food safety and cost-efficiency makes them the ideal solution across many industries.
Whether as a BOPP label, CPP packaging, technical film or laminate layer, PP films are lightweight, strong and economical. And in times of growing sustainability requirements, a real ace in the sleeve of plastic processing.