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To begin with, they are at least 40%
lighter than conventional PVC or
rubber boots. PU’s excellent thermal
properties also enable them to be worn
in a much wider range of
environments. Due to further
developments in PU systems, they can
also have excellent resistance to all the
normal chemicals, oils or acids found
in industry. As regards safety, the key
factor is slip resistance in wet
conditions. Combining a correctly
formulated PU and a good tread
pattern on the outsole gives excellent
results, particularly if the latter is
designed such that any dirt comes
away quickly and easily. There is also
the possibility to produce them in
limitless colour combinations so that
they can be matched to company
overalls.
Wellingtons can now be produced
entirely from PU in a one step process
which uses one density for the main
body of the boot and another for the
sole. Alternative outsole materials,
such as pre-moulded rubber inserts for
very wet conditions or TPU where a
higher abrasion resistance to that of
standard PU is required, can also be
incorporated. This multifunctional
ability has opened new possibilities for
boot producers to widen their ranges
and at the same time lower
manufacturing costs. The extra -
ordinary versatility of polyurethane
appears to have no limits and the
material will doubtless find further
applications in footwear manufacture
in the future.
29
VERSATILE PU
SEPTEMBER/OCTOBER 2012 | www.footwearbiz.com
Fig 4 – Four-part mould mounted horizontally are used to produce PU boots.
CREDIT: KLÖCKNER DESMA