German firm kick-starts rainbow revolution for PET

By Ben Bouckley

- Last updated on GMT

German firm kick-starts rainbow revolution for PET

Related tags Bottle Blow molding

Inotech Kunststofftechnik has filed patents concerning technology to blow multi-coloured or multi-component PET bottles using a special ‘two tone’ technique that it claims will allow impressive optical effects and the incorporation of active properties.

The Nabburg firm's patent filings cover both one-step (injection blow-moulding) and two-step (stretch blow moulding) processes, and could revolutionise beverage, food, cosmetics and pharmaceutical packaging, according to a bottle blower that has tested the technology.

German plastic packaging specialist GIZEH revealed to that, through a partnership with Inotech, it was one of three firms to test that company’s innovative multi-component preforms.

Head of GiZEH PET, Daniel Rüth, said that his firm had succeeded in producing multi-coloured polyethylene terephthalate (PET) bottles on conventional stretch blow-moulding machines for the first time, which he said opened-up the “new optical and tactile effects”​ outlined above to a much wider market.

Security pigment potential

Rüth said handling elements – such as soft or anti-slide gripping zones – as well as antibacterial inner wall coatings to increase the shelf life of the finished product, were also being developed.

He said: “It is part of the same technique that our partner Inotech developed. So the idea is, for example, on the inner side of the preform, you bring in a special material in, not the complete preform.

“For example, in a milk bottle, say, you incorporate this antimicrobial material in the preform. After blowing in the bottle, it helps you give the milk a longer shelf life, because this is an active material that works against bacteria,” ​Rüth added.

Security pigments injected in a similar fashion could also ensure brand protection, Rüth said. “If you put in on a scanner you can be sure if there if it is an original body with original content.”

Rüth said Inotech sent the preform to three bottle blowers for testing, of which GIZEH was one, and that one of the other companies had also blown bottles using the same technique; he was not sure about the third.

Before this technique was developed, special preforms could only be processed on stretch blow moulding machines using microwave heating, Rüth explained.

He said: “At the moment, most of the standard machines have infrared heating. Krones have launched a machine [Krones FlexWave] but at the moment it is not really a machine which runs in business, I think, which uses microwave heating.

“The advantage of this heating is that you need less energy, and can have a more constant heating process. So you can, for example, heat up the pre-form with one half with white, the other half black.

“But up until now, you are not able to do this using a standard heating [technique].”

Infrared heating results

Before the Inotech innovation, the precise heating process required for the different colour combinations was only considered feasible using such a system, Rüth said.

He added: “Up to now nobody has really had the idea to make a preform in this kind of way. And maybe until now no-one really thought about bringing different materials together.

Rüth said the novel preforms comprised “PET with two different colours – so maybe transparent with a colour, or two different colours in combination to make it opaque as well as transparent.”

GIZEH said it had succeeded in equipping a conventional two-stage stretch blow moulding plant with infrared heating that obtained “perfect results”​ with the blanks, which the company said allowed it to series manufacture multi-coloured bottles on a conventional system.

For the first time, said GIZEH, bottles could be blown in attractive colour combinations or produced in transparency or colour combinations, including (say) opacity to mask sediment deposits at the bottom of orange juice bottles

According to GIZEH: “The product offers great potential, in particular for customers from the food and beverage industry, as well as for cosmetics, household and technical liquids.”

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