Extrusion International 2-2016

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Extrusion International 2/2016 30
“DoubleCoat” combines extrusion coating with hot melt lami-
nation and thus facilitates coating thickness minimisation.
For example, a minimum coating layer thickness of 7 m can be
achieved using TPE on a PP nonwoven. This corresponds with
roughly a mere quarter of the current average for such coatings
and results in enormous material savings.
Excellent product quality is guaranteed and even with thin coat-
ing layers adhesion to the substrate is perfect and no pinholes
occur.
Another exciting feature of the process is enhanced product
breathability. The coating thickness has a significant effect on
the water vapour transmission rate (WVTR), as a thinner layer
results in a reduction in water vapour flow resistance.
Consequently, standard product breathability can be increased
several times over.
A further advantage offered by the new process is a reduction
in the melt temperature to a minimum. This has a very positive
effect on the mechanical characteristics of the coating because
the material is subject to less stress during extrusion.
The advantages of the “DoubleCoat” process at a glance:
• Reduced coating layer thickness
• Material savings and hence lower costs
New Technology
for Breathable Products
SML has developed and installed a new
laminating line that is capable of
downgauging the coating layer to a pre-
viously unobtainable extent using the
so-called “DoubleCoat” process.
“DoubleCoat”, for which a patent is
pending, has been integrated into the
proven FlexPack extrusion coating line
thereby enlarging considerably the
attainable range of breathable products.
• Strong adhesion
• Improved breathability
• High water column
• Enhanced mechanical properties
The “DoubleCoat” process provides fresh possibilities for en-
hanced product properties and lower production costs with re-
gard to a variety of applications.
These include medical products such as surgical drapes, which
are highly breathable, flexible and serve as an effective barrier
against viruses and bacteria. Theprocess could also be used for
protective clothing such as disposal overalls, or in view of its soft
touch, stretchability and high breathability, for hygiene products.
Moreover traditional construction industry products such as
roofing underlay can benefit to an equal extent from this new
method.
Interested customers will soon be able to see the outstanding
performance of SML’s FlexPack extrusion coating line with the
“DoubleCoat” process for themselves, as a production scale
pilot plant will be available for trials from April 2016.