New dairy application for PET container blow moulding process

By Mike Stones

- Last updated on GMT

Related tags Bottle

Longer shelf life and more attractive packaging are the benefits claimed for a lightweight foamed polyethylene terephthalate (PET) container blow moulding process applied for the first time to dairy products.

The oPTI process is particularly suitable for milk, drinkable yogurts and other specialty dairy products, claims plastic packaging specialist Plastic Technologies.

The containers, it adds, are ideally-suited for companies with organic positioning who want package performance attributes without additives.

Negative effects

Frank Semersky, vice president chief innovation officer, told “The oPTI technology provides a bottle that is 100 per cent PET that, because of the introduction of foam, provides up to 50 per cent opacity - thus protecting the product from the negative effects of light.

If more light protection is desired then conventional additives can be utilized at much lower levels​.”

The technology is said to provide opacity without the use of additives that compromise the recyclability. In providing the opacity, the bottle is also light weighted by up to 6 per cent.

To protect milk and specialty drinks against the UV rays which decrease shelf life, additives such as titanium dioxide [TiO2] are often added to high-density polyethylene or traditional PET containers.

In addition to impacting the recycling stream, these additives are expensive, significantly increasing packaging costs​,” said Semersky.

Available in monolayer and over-moulded variations, oxygen and CO2 barriers can be incorporated into the foam layer.

The introduction of foaming occurs in the preform so preforms can be centrally manufactured and distributed to blow moulding locations​,” said Semersky. “The preforms are foamed in the injection process where a supercritical gas is blended into the polymer melt​.”

In addition to longer shelf life, the process is said to offer improved container aesthetics and performance capabilities. For example, the process enables white or silvery foamed bottles to be made without additives which can limit package recycling.

The company said that white or silvery foamed bottles can be moulded into a transparent bottle after remelting and processing, while blue and green colours can be used because they exist already in traditional PET recycling streams.

Pastel colours, including chocolate and strawberry are also available but they cannot be recycled as part of the clear PET stream.

Containers can be made from translucent to opaque depending on the desired aesthetics and performance characteristics.

Embossed logos

Details can be blow moulded more prominently onto containers which allows decorations, such as embossed logos and art work, to stand out more effectively, claims the company.

Also, containers are said to have a unique surface feel and provide tactile traction which minimizes slipping.

The first stock container is 300 ml (10-ounces) and features a tall, square profile, with a 38 mm finish.

Launched last year, Plastic Technologies’ oPTI process is based on MuCell technology licensed from Trexel. This microcellular foam injection technology moulds preforms which then can be blow-moulded on conventional equipment.

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