Nanoparticles boost barrier properties of plastic film
The film, which uses nanoparticles to plug defects in the barrier oxide layer, is said to be as effective as aluminium in prolonging shelf life while being stretchable, transparent and less expensive.
The 700nm encapsulated nanoparticle barrier films are able to be made thinner than current offerings and can be recycled.
It was initially targeted at focus, display and solar cell manufacturers but a recent breakthrough offered new packaging structures for niche applications in areas such as food.
The films will allow see-through packing, a longer shelf life and stretchability, Senthil Ramadas, director and chief technology officer of TBF told FoodProductionDaily.com.
“The film can replace aluminium packaging due to the barrier properties and it being transparent and stretchable.
“We are in the initial development stage with the nanoparticle layer as the breakthrough encapsulate nanoparticle was put into each polymer only recently.”
Barrier benefits
The plastic has an air and moisture barrier about 10 times better than transparent oxide barriers used to package food, according to the spin-off company from A*STAR’s Institute of Materials Research and Engineering’s (IMRE).
Aluminium-based packaging has high oxygen and moisture barrier properties, but comes at a higher processing cost, is opaque, non-stretchable, and interferes with electronics, making the integration of RFID devices difficult, said the firm.
TBF’s film uses minimal layers as its encapsulated nanoparticles increase the packing density, which makes it difficult for water and oxygen molecules to pass through.
Conventional multilayer barrier plastics have successive layers of barrier plastic films to enhance the impermeability to air and moisture.
The secret behind the film lies in the patented encapsulated layer made up of nanoparticles in polymer shells, said Ramadas.
“In September 2014 we will complete the trials and we will have a mass production line of 60m2 per annum by early 2015, probably in Singapore."
“We may establish others with companies in the food and medical packaging sectors but the one production line in Singapore is with a high end market focus.”
He added that the next steps include finding partners in food and medical packaging and continuing to work closely with existing companies.
Technical tests
The patented encapsulated nanoparticle layer has been coated onto polyethylene terephthalate (PET) and achieved the moisture vapour transmission rate (MVTR) of 5 x 10-2g/m2.day at 40°C and 100% relative humidity.
Ramadas said they had experimented with other plastic, such as bioxially orientated polypropylene (BOPP), with similar results.
The encapsulated nanoparticle layer can be coated onto the polymer substrate at a speed of 50 metres per minute.
It consists of nanoparticles encapsulated by an organic species via a self-assembly method in which the nanoparticle concentration is up to 70% to 80% by weight.
The ratio of nanoparticles to the organic species is critical for the desired transmittance properties, said TBF.
It works by the high packing density of nanoparticles which creates a non-linear path for moisture and oxygen diffusion and then the nanoparticles adsorb and react with the moisture and oxygen.
