Page 38 - Plastics Nuews October 2017

to bounce back and forth between the layers of the film in Wrapping up safe shipping
a manner that made it a stronger IR emitter. Yin wondered Windmoeller & Hoelscher KG is adding
whether there was a simpler way to do this. From previous focus to stretch film equipment
work, Yin knew that spherical objects can act like tiny
hen it comes to securing loads on goods for
resonance chambers—much as the sound box of a guitar
Wtransport, stretch wrap plays a key role in keeping
encourages sound waves of a particular frequency to the loads from shifting around in an economical and
bounce back and forth inside. He and his colleagues effective fashion.
calculated that glass beads about 8 micrometers in Load stability is a matter of safety, since shifting
diameter—little bigger than a red blood cell—would make loads can cause serious highway accidents and cause
powerful IR resonators and thus strong IR emitters. damage to products. And the process of stretch-
wrapping pallets, which happens in factories and
So they bought a batch of glass powder from a commercial shipping centers everywhere, is a critical function, as
supplier and mixed it with the starting material for a is the consistent quality of the film, according to David
Finnemore, senior technical consultant at Windmöller
transparent plastic called polymethylpentene. They then & Hölscher KG.
formed their material into 300-millimeter-wide sheets and
backed them with a thin mirrorlike coating of silver. When
laid across objects in the midday sun, the bottom layer of
silver reflected almost all the visible light that hit it: The
film absorbed only about 4% of incoming photons. At the
same time, the film sucked heat out of whatever surface
it was sitting on and radiated that energy at a mid-IR
frequency of 10 micrometers. Because few air molecules
absorb IR at that frequency, the radiation drifts into
empty space without warming the air or the surrounding
materials, causing the objects below to cool by as much Europe is taking a leading role in regulating load
stability on highways. A European standard says that,
as 10°C. Just as important, Yin notes that the new film as of 2018, trucks will be subject to inspection and
can be made in a roll-to-roll setup for a cost of only $0.25 must show proof of load stability. The rules follow the
to $0.50 per square meter. European Union's Directive of Road Worthiness and
the EUMOS 40509 regulation. EUMOS stands for the
“This is very nice work demonstrating a pathway toward European Safe Logistics Association, based in Brussels.
large-scale applications of the concept of radiative W&H, based in Lengerich, Germany, makes the
cooling,” says Fan, who did not work on the current equipment that produces the stretch film. Finnemore
said good pallet wrapping is important for all shipped
project. Yin says that he and his colleagues are already
solid goods. "Load stability is a global issue, no
working on one such application, chilling water that could matter what form of transportation is used, whether
then be used to cool buildings and other large structures. it be road, rail, sea or air," he said. "Each method of
That could be particularly useful in electricity-generating transportation places different stresses on the loads."
power plants, where cooling water even a few degrees W&H is active in the load-stability movement.
Finnemore, who came to W&H in 2010 after 13 years
can increase energy production efficiency by a percentage
at Gloucester Engineering, said the issue was brought
point or two, a “big gain,” Yin says. And without the silver to W&H's attention in 2011 during a meeting with
backing, he adds, the plastic film could also increase the David Angel Hernandez of Grupo Valueing, the Spanish
power generation from solar cells, which operate more packaging consultancy, professor Marc Juwet from
the KaHO Institute at Catholic University of Lueven,
efficiently at lower temperatures. Belgium, and Jelle Dendauw, managing director of
ESTL NV, the Belgian load stability engineering firm.

Plastics News | Octob er 2017 38