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Chemical Technology • May 2016
Numerous properties of precision silicone films make them
particularly interesting for the industry. Not only are they ex-
tremely elastic, they also do not wear out. Tests have shown
that Elastosil
®
Film can survive over 10 million load cycles
without the slightest fatigue. Silicone films hold back water
but grant free passage to water vapour and certain gases.
This gas permeability is highly selective: carbon dioxide,
oxygen and water vapour pass through the silicone layer
much faster than nitrogen. Elastosil
®
Film could therefore
serve as a membrane for removing a specific gas, such as
carbon dioxide.
Experts expect that, over the coming years, relays,
switches and valves based on dielectric electroactive
elastomers will come onto the market. Such components
could, in the future, also give rise to new technologies,
such as shape-changing touchscreens that the visually
impaired could read with their hands. In the healthcare
industry, for example, WACKER’s Silpuran
®
Film is breath-
able, biocompatible and easy to sterilise. These silicone
films are therefore ideal for the manufacture of soft and
flexible wound dressings.
Simulation with silicone
For pressure-sensitive adhesive (PSA) labels to function
properly, the release coatings, adhesives and backing
materials must be optimally matched and must suit the
industrial processing conditions. WACKER tests this out in
its new Dehesive
®
Coating Centre.
Not all labels are the same. While product information
should permanently adhere to a shampoo bottle, the price
label on a water melon must peel off easily. Different ad-
hesive mixtures make specific applications of self-adhesive
materials possible, but also present the coatings industry
with the challenge of providing a constant stream of new,
modified silicone formulations for release liners.
In addition, the substrate itself and subsequent process-
ing play a role in deciding the composition of the release
coating. For automated dispensing of labels, for example,
it is important that the paper lattice between the individual
labels – the matrix – can be pulled off easily without tearing
or removing the labels from the backing material as well.
Testing and optimising
At the new coating centre in Burghausen, engineers work
on a 380 m
²
area to simulate industrial processing condi-
tions for silicone release coating and to devise coating
solutions to meet various requirements. The new centre
combines a pilot coater, a test lab and a large selection
of base papers and films used in the industry. This makes
it possible to simulate and evaluate industrial processing
conditions for silicone release coatings as realistically as
possible, allowing the company to prepare new products
for the market more quickly.
Dr Hans Lautenschlager, who is in charge of technical
support for silicone release coatings at WACKER, and his
team are currently testing formulations for seven different
substrates supplied by a US partner. There is a choice of 30
silicone polymers and five crosslinking agents available for
the coating. Depending on their composition, the individual
formulations vary with regard to flow properties, release
force and curing rate.
Dehesive
®
silicone release coatings have been used in
the paper coatings industry for many years to make self-
adhesive materials that separate perfectly from release
Dr Robert Gnann took over as president of WACKER
SILICONES, effective April 1, 2016. He succeeded
Dr Christian Hartel, who was appointed to the
WACKER Group’s Executive Board in early November
2015. Gnann comes to WACKER from Momentive
Performance Materials, where, from 2008, he was
responsible for the elastomers business unit and,
in 2010, additionally took charge of the company’s
European activities.
The requirements imposed on PSA labels vary considerably
depending on the intended application and production method.
Consequently, demands on the silicone release coating are high.
The mechanism for removing the adhesive
from the silicone release coating forms the
basis of tailor-made solutions.