Better barrier properties for biodegradable films

Materials World magazine
1 Nov 2008
Schematic of ultrasonic atomisation spraying system

Ultrasonic application of clay nanoparticles to biodegradable films
could enhance their barrier properties, according to spray technology
company Sono-Tek, based in New York, USA.

The company says that the technique prolongs the shelf-life of food and
pharmaceuticals and offers the packaging industry more accurate and
economical treatment.

‘The capability of nanoclay particles to create efficient barrier
protection against water and oxygen molecules is well known, but
commercialising this phenomenon using conventional coating techniques
such as air pressure spraying, or printing press technologies, lacks
sufficient uniformity, as well as being costly,’ explains Joseph
Reimer, President of Sono-Tek.

'Nanoparticles have a tendency to agglomerate while being dispensed,
resulting in an uneven layer thickness of the final coating. Our
technique imparts vibrations into the liquid suspension and provides an
agglomerate-free, uniform coating.’

The system features an ultrasonic atomising nozzle, which uses high
frequency sound waves to produce a soft, low velocity spray, typically
three to five inches per second.

'The unpressurised spray reduces the amount of overspray since the
drops settle on the substrate rather than bouncing off, reducing
waste,’ says Reimer.

A pilot scale production line is being built to test the feasibility of the continuous process for industrial applications.

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