Louis Esposito
Business Development Manager
Merquinsa North America
Seabrook, N.H.
It’s almost a given that as products become more complex, they demand better performing
materials. This pressures designers to find materials able to meet tougher specs at a
competitive cost. In this regard, PVCs (polyvinyl chlorides) are often out of the picture
because of consumer complaints and some thermoplastic
elastomers (TPEs) have limited
performance. This has opened the door for a range of aliphatic and aromatic thermoplastic
urethanes (TPUs) made from polyester or polyether formulations.
The advanced TPUs let designers spec alternatives to PVCs and TPEs that are plasticizer
and halogen-free, resist yellowing, and are softer, tougher, and more transparent. Additionally,
this new class of TPUs sport excellent hydrolysis and microbial resistance, remain
flexible at temperatures as low as 70°C (94°F),
and depending on grade, can be injection and blow
molded, overmolded, or extruded.
TPUs consist of linear-segmented
block copolymers composed
of hard and soft segments.
They are formed by the reaction
of diisocyanates with short-chain
diols (so-called chain extenders)
and diisocyanates with long-chain
difunctional diols (known as polyols).
The possible combinations
of the three reaction compounds
give practically unlimited variation
in structure and molecular
weight. This lets urethane chemists
fine-tune polymer structure
to the desired final properties.
Military and automotive
TPUs serve in the most rigorous
applications thanks to their
ability to work at low temperatures
combined with good flexibility,
abrasion resistance, and
general overall durability. Good
compression set makes them
candidates for seals and gaskets
in offshore-oil applications from
the North Sea to the North Slope.
And the improved properties that TPUs bring to the table also benefit
fuel tanks, fuel lines, hoses and
cables, and high-wear parts needing
a high degree of puncture and
chemical resistance.
Automotive designers are also
speccing TPUs in place of PVCs.
Newer TPUs with a hardness range
of 58 Shore A to 75 Shore D are increasingly
widely used in luxury cars for gear knobs thanks
to their excellent scratch
and abrasion resistance,
mold-texture reproducibility,
adhesion to acetals and
nylons, and exceptional
colorability. Gear knobs,
door panels, and grips in
high-end automobiles were
once limited to darker colors
or grey. But new TPU
grades offer a more lightstable
(UV resistant) color
palette, strong abrasion,
and better scratch resistance,
along with the desired
feel or haptics.
New applications such
as dashboard vents and
central console parts use
TPU skins overmolded
onto ABS. The combination
gives a quality finish
with better economics.
TPU films also protect vehicle
lower bodies, front
and mirror components,
and paint layers from
sand, stones, and salt.
Sports and Leisure
TPUs have made major
inroads into sports
and leisure applications
as breathable fabrics,
goggles, grips, bumper
pieces (snowmobiles), ski
boots, footwear and decorative
parts for sports apparel,
to name a few. Here
abrasion resistance, durability,
low temperature
flexibility, sealing (as in
seam tapes and adhesive films)
along with puncture resistance
and breathability are all key differentiators
for the new ester and
ether-based TPUs.
Make contact:
Merquinsa North America Inc., (603) 474-0971, www.merquinsa.com