bioplasticsMAGAZINE_0703

Special
There are different technologies available in order to
complete the packaging unit with a film. Most common
technologies are based on flow pack top seal films.
Additionally, specifically for the packaging of food, one
of the most common technologies is the one based on
cling films. Today, especially based on biopolymers,
there are different technologies available, depending
on the needs of the product to be packed and/or the
packaging technology.
Most commonly used on transparent punnets are
transparent top seal films. Different combinations in
terms of transparency may be used, meaning a transparent
film on an opaque punnet or vice versa, or both
the same. The first products are meant for food that
does not need special MAP treatment. New developments
are proving that amongst biopolymers there are
some, which do offer differential barrier properties
(WVTR, N 2
TR, O 2
TR, CO 2
TR) and that will open new applications
for MAP packaging.
Importantly, in order to obtain adequate sealing
properties, the Tm of the sealing layer of the film does
need to fit with the tray on which the film is sealed.
New biopolymers which offer differential sealing properties
seem to perfectly match such needs.
Similar properties are given for flow pack films, in
order to achieve both good sealing results and high
speed processing. It is evident that for most of the applications
good printing, COF, hot tack etc. are needed,
whether they be top seal films or flow pack.
For some years different development activities have
been carried out in order to develop cling films based
on compostable polymers. Some positive results have
been claimed by the market, and it is expected that
by next year some first producers will present their
products. In this specific case the opportunity to use
biopolymers will just enlarge the application range of
PVC cling films, as there is already a certain trend (in
some European countries) to replace it with PE or alternative
polymers.
But much of the success, on which the use of compostable
packaging is based, is the need to find new solutions
in terms of waste treatment, as food packaging
means:
• Highly food-contaminated plastic.
• Difficult to recycle.
• Low potential energy recovery content (due to the
high contamination) in case of thermal recycling.
The new opportunity given by compostable bioplastics
has an added value for both retailers and consumers,
as:
• Retailers do not need any longer to separate the content
from the packaging (when the product expires).
• This means a space reduction in terms of waste collection
(packaging and food may be collected and
treated together).
• Waste management and treatment of such products
would save energy.
• The consumer gets packaging, especially when he
purchases organic produce, which is more coherent
with the nature of the produce.
Some European retailers are starting to adopt more
and more such materials, as on the one hand consumers
are starting to ask for them, on the other hand it is
proven that recycling, meaning composting of packaging,
when contaminated with food, offers a valuable way
of recycling.
It is not only the source of the biopolymers which defines
their environmental contribution or impact, it is
very often more the recycling system that stands behind
them, which defines their impact.
Conventional polymers, when clean and not contaminated
(as in the case of industrial waste), do offer their
highest potential (environmentally) if recycled. Biopolymers,
when used as packaging, do offer their best profile
when composted.
20 bioplastics MAGAZINE [03/07] Vol. 2