Polypropylene film: BOPP and CPP in plain words
Polypropylene (PP) is one of the two main plastics in packaging, alongside polyethylene. It is valued for stiffness, clarity and heat resistance. But under the name PP there are two different materials with different jobs: BOPP and CPP. Let us look at how they differ and when to choose polypropylene.
BOPP is an oriented, stiff and clear film with good gloss and barrier, used for the outer layer and print, including flow wrap for snacks and confectionery. CPP is a softer cast film that seals well and takes impact, so it works as the inner sealant layer and in retort pouches. Polypropylene overall is growing faster than other plastics, and we work with a strong PP supplier, so we can build a solution around it.
Polypropylene versus polyethylene
First, the difference between the two main materials. Polyethylene (PE) is softer, stretches well and seals excellently even at a low temperature, which is why it makes many basic bags and freezer films. Polypropylene (PP) is stiffer, clearer, gives more gloss and handles heat better, including the microwave and sterilization.
In plain words: PE is about softness, sealing and freezing, while PP is about clarity, stiffness and heat. That is exactly why crunchy snacks, confectionery and ready meals in retort often use polypropylene.
BOPP: the stiff clear film for print
BOPP is biaxially oriented polypropylene. During production the film is stretched in two directions, which makes it strong, dimensionally stable, very clear and glossy. About 70 percent of all BOPP goes into packaging.
What this gives in practice:
- Bright print and gloss, so the product looks good on the shelf.
- A good barrier against moisture and gases, meaning kept freshness.
- Stiffness that lets the film run well on fast packaging lines.
That is why BOPP is the workhorse of flow wrap: biscuits, wafers, bars, snacks. One nuance to remember: because of the orientation, the film resists tear propagation less well, so once a tear starts it can run along a line. This is allowed for in the pack design.
CPP: the soft film for sealing
CPP is a cast polypropylene film. It is not oriented, so it is softer and more flexible than BOPP. Its main advantage is sealing: CPP fuses well at a relatively low temperature, takes impact and works in the cold.
Because of this CPP is rarely used on its own, more often as the inner sealing layer (the sealant) in a multilayer laminate. Some grades of CPP withstand sterilization, so they are used for retort pouches. On barrier BOPP beats CPP, but CPP itself holds moisture better than most ordinary polyethylene films.
When to choose PP and when PE
A rough but working rule of thumb:
| Choose polypropylene (PP) | Snacks, confectionery, bakery, flow wrap, clear display packaging, ready meals for retort and the microwave |
| Choose polyethylene (PE) | Freezing, products that need softness and a reliable seal, and mono-material solutions aimed at recycling |
In practice the choice is often a combination: for example an outer BOPP for print and stiffness plus an inner sealant for sealing. The main thing is to match the structure to the specific product, not the other way round.
We work with polypropylene
We have a strong supplier who works with PP, so we can offer solutions built on polypropylene: film, print and pouches. If you pack snacks, confectionery or ready meals and are torn between PP and PE, tell us about the product, the shelf life and the equipment. We will select the material and structure and tell you honestly where polypropylene gives an advantage and where it is wiser to keep polyethylene.
Need polypropylene packaging?
We will select BOPP or CPP and the structure for your product. Artwork design is free.