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Chemical Technology • May 2016
WACKER expands Engineering Silicones
laboratory in Dubai
The Dubai Technical Centre is a highly spe-
cialised, applications-focused lab, supporting
customers from the Middle East and Africa.
The Engineering Silicones Lab is equipped to
carry out necessary developments for Silicone
Elastomers. The main applications are insula-
tor coatings, mould-making, and baking trays.
The lab has ‘state-of-the-art’ mixing equipment for developing low viscosity
Silicone Elastomers formulations. It also houses a Spray Chamber (see
photo) which is a unique facility to support local customers in the electri-
cal industry within the Middle East and Africa region.
liners. The properties of silicone release coatings include
the following:
• Good coverage of the substrate’s surface
• Minimal silicone consumption
• No matrix breaks at high die-cutting speeds
• Smooth, pin-hole free surfaces
• Custom controlled-release
• Reproducible release force
• Release values that do not change during storage
• Ease of processing under widely various production
temperatures and speeds
• Application and adhesion to different kinds of substrates.
At the pilot coater, a 1 to 1,3 µm layer is applied to the
backing material and then dried in an airflotation dryer at
100 - 180 °C – depending on the material properties – for
1,2 to 18 seconds. Here, the WACKER experts simulate the
customer’s industrial processing conditions exactly.
The subsequent use of the release liner is also of great
importance. In industrial labelling, a machine applies up to
five labels per second to packaging – such as a shampoo
bottle. The skill of the laminate manufacturer now lies in
finding a compromise in the release force between the
label and the release liner so that both matrix peeling and
labelling run smoothly.
Doublesided adhesive tape poses another challenge
for laminate manufacturers. The release liner must feature
two different release forces for the two sides, so that the
adhesive tape peels off of the underside of the release liner
first. This allows the doublesided adhesive tape to cleanly
peel off for further processing.
Testing with Xrays
On a lab bench at the coating centre, a colour test provides
information on the level of cover of a coating immediately
after it has been applied. Xrays measure the thickness of
the applied silicone release layer. After it has cured, the
release coating still contains reactive groups that can
interact with the adhesive during storage. Long-term tests
are also undertaken to ensure that the release coating still
meets quality requirements after prolonged storage.
To determine whether the curing reaction is complete,
the coated substrate is placed in solvent, which dissolves
out any uncured silicone. The amount of such uncured
silicone is then measured analytically. As a result, the
amount of platinum required can be determined precisely.
Optimising the formulation can therefore reduce platinum
consumption by as much as one third.
New challenges
Technical service engineers measure the coating’s release
force electronically with the aid of a peelforce measuring
device. Different tests show how the coating behaves at a
peel angle of 90 º or 180 º, for example. The test results are
illustrated graphically. Lautenschlager believes that, while
the test results to date point the way ahead, they are by
no means definitive. Release coatings thus require further
research, so that shampoo, melons, and other products,
will be optimally labelled in the future, too.
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CORROSION & COATINGS
WACKER’s Burghausen site, with its nearly 10 000 employees, is the largest chemical plant in Bavaria, Germany.